JP2004295661A

JP2004295661A - Generation program, generation method and generation device of building model with three-dimensional roof

Info

Publication number: JP2004295661A
Application number: JP2003089051A
Authority: JP
Inventors: Kenichi Sugihara; 健一杉原
Original assignee: Individual
Current assignee: Individual
Priority date: 2003-03-27
Filing date: 2003-03-27
Publication date: 2004-10-21

Abstract

<P>PROBLEM TO BE SOLVED: To automatically generate a building model with a roof of an actual form with further high precision. <P>SOLUTION: This program makes a computer execute the following processing to generate a building model with a three-dimensional roof. When the second edge K2 of a 6-point polygon is shorter than the fourth edge K4, a main roof R5 is generated on a building model B2 on a "second 4-point polygon" P2. The main roof R5 has a roof length L5 longer than the third edge K3 of the 6-point polygon by an eaves portion and a roof width W5 longer than the fourth edge K4 by the edge portion. A sub-roof R6 is generated on a building model B1 on a "first 4-point polygon" P1. The sub-roof R6 has a roof length L6 shorter than the longest edge K1 of the 6-point polygon. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】本発明は、３次元屋根付き建物モデルを、コンピュータなどを利用して自動的に生成する技術に関する。
【０００２】
【従来の技術】（第１従来技術）３次元ＣＧソフトを用いて制作する「３次元都市モデル」は、典型的には、ディスプレイなどに表示させて利用する。「３次元都市モデル」は、３次元建物モデルを主な構成要素とする。「３次元都市モデル」は、現実世界の都市を、コンピュータの世界に写像するものであり、都市計画や景観設計、土木、建築、防災、環境といったアカデミックな分野の活用から公共事業の情報公開、まちづくりへの市民参加の場として、あるいは、ゲームやアミューズメントの分野での活用など広範囲の分野で利活用が期待される重要な「情報基盤」である。
【０００３】
第１の従来の技術では、ＧＩＳの３次元表示機能を用いて、３次元都市モデルを生成する。図１と図２は、従来の３次元都市モデルの例を示す。図１と図２には、３次元都市モデルとして、柱状体の建物モデルの集合が表示されている。これら従来の３次元都市モデルは、２次元デジタル地図上の建物ポリゴンを、ポリゴンに「属性情報」として関連付けられている階数データに応じて、押し出し（ｅｘｔｒｕｄｅ）処理を行い生成する。この様な３次元表示機能を有するＧＩＳソフトをコンピュータで実行することによって、屋根無しの３次元都市モデルを自動的に生成できる。
【０００４】
（第２従来技術）これに対し、３次元屋根付き建物モデルを自動生成する方法が提案されている（関連する技術として、特許文献１参照）。図３はこの方法で生成した屋根付き建物モデルの一例の平面図を示し、図４はその斜視図を示す。
この方法では、全ての頂角がほぼ直角の６点ポリゴン上に、以下に説明する方法で屋根付き建物モデルを生成する。図３の点線で示す部分がこの６点ポリゴンである。この６点ポリゴンは、最長辺Ｋ１と、第２辺Ｋ２と、第３辺Ｋ３と、第４辺Ｋ４を有する。第２辺Ｋ２は、６点ポリゴンの最長辺Ｋ１に隣接する２つの辺のうち短い方の辺である。第３辺Ｋ３は、６点ポリゴンの最長辺Ｋ１に隣接する２つの辺のうち長い方の辺である。第４辺Ｋ４は、第３辺Ｋ３に隣接するとともに最長辺Ｋ１に対向する辺である。また、６点ポリゴンのうち最長辺Ｋ１と第２辺Ｋ２を境界辺とする４個の頂点を持つポリゴンを「第１の４点ポリゴン」Ｐ１とする。６点ポリゴンのうち第３辺Ｋ３と第４辺Ｋ４を境界辺とする４個の頂点を持つポリゴンを「第２の４点ポリゴン」Ｐ２とする。「第１の４点ポリゴン」Ｐ１と「第２の４点ポリゴン」Ｐ２は、重複する領域が存在する。
【０００５】
【特許文献１】
特開２００２−０５６４１２号公報（その公報の図１３参照）
【０００６】
図３と図４に示すように、「第１の４点ポリゴン」Ｐ１上に、直方体である第１建物モデルＢ１を生成する。「第２の４点ポリゴン」Ｐ２上に、直方体である第２建物モデルＢ２を生成する。「第１の４点ポリゴン」Ｐ１と「第２の４点ポリゴン」Ｐ２は重複する領域が存在するため、第１建物モデルＢ１と第２建物モデルＢ２も重複する領域が存在する。
「第１の４点ポリゴン」Ｐ１上の第１建物モデルＢ１に、常に、最長辺Ｋ１に平行な頂線Ｔ７、最長辺Ｋ１より軒部だけ長い屋根長（頂線Ｔ７方向の屋根の長さ）Ｌ７、第２辺Ｋ２より軒部だけ長い屋根幅（頂線Ｔ７に垂直な方向の屋根の長さ）Ｗ７を持つ「主屋根」Ｒ７を生成する。「第２の４点ポリゴン」Ｐ２上の第２建物モデルＢ２に、常に、第３辺Ｋ３に平行な頂線Ｔ８、第３辺Ｋ３より短い屋根長Ｌ８、第４辺Ｋ４より軒部だけ長い屋根幅Ｗ８を持つ「従屋根」Ｒ８を生成する。
【０００７】
【発明が解決しようとする課題】第１の従来の技術で解決しようとする課題は、図１と図２に示す従来のモデルでは、屋根が存在しない建物モデルのみで構成されており、現実の屋根付き建物を表現していないことである。全ての建物を単に柱状体で生成したのでは、現実からはほど遠い３次元都市モデルとなってしまう。図１と図２に示す従来のモデルは、屋根が存在しない建物モデルのみで構成されており、景観設計やまちづくりにおいて街並みの「３次元のたたき台」や「景観評価ツール」として、活用することが困難である。そこで、傾斜した複数の屋根を備えた建物モデルを生成し、現実世界の建物をよりよく表現する３次元都市モデルを生成することが必要である。
【０００８】
３次元屋根付き建物モデルの制作において、通常、３次元ＣＧソフトを使って、手作業で屋根付き建物の形状モデルを作成する。しかし、手作業として、屋根となる基本立体（プリズムや直方体等）のサイズ（長さ、高さ、第１側面幅、第２側面幅等）を決め、それらをコピー・移動し、それらのブール演算を施し、屋根形状を作成し、作成した建物モデルを適切な場所に配置するために、建物モデルを回転し、水平方向と垂直方向の平行移動を行うこと等、時間のかかる作業が必要である。例えば、手作業で１軒の屋根付き建物モデルの作成・配置に３０分程度かかるとすると、この屋根付き建物が５０００軒程度集合した街のモデルを、手作業で作成する場合、約２５００時間もの人手による時間を要することになる。
【０００９】
第２従来技術では、「第１の４点ポリゴン」Ｐ１上の第１建物モデルＢ１に、常に、６点ポリゴンの最長辺Ｋ１（即ち、「第１の４点ポリゴン」Ｐ１の長辺）に平行な頂線Ｔ７を持つ主屋根Ｒ７を生成する。しかし、現実には、４点ポリゴンの長辺に垂直な頂線を持つ屋根を有する建物が多く存在する。例えば、図５と図６に示すような旧街道沿いに連なる町屋には、４点ポリゴンの長辺に垂直な頂線を持つ屋根（横長の切妻屋根）を有する建物が多くみられる。このような屋根付き建物のモデルは、第２従来技術の方法では生成することが困難である。
【００１０】
第２従来技術では、６点ポリゴンの「第１の４点ポリゴン」Ｐ１に対して、常に、「主屋根」Ｒ７を生成し、「第２の４点ポリゴン」Ｐ２に対して、常に、「従屋根」Ｒ８を生成する。一方、電子地図上にある６点ポリゴンは、その各辺の長さが様々な値をとりうるので、第４辺Ｋ４が第２辺Ｋ２より長い６点ポリゴンが存在する。
【００１１】
第２従来技術では、第４辺が第２辺より長い６点ポリゴンの、幅の狭い「第１の４点ポリゴン」に対して、「主屋根」を生成し、幅の広い「第２の４点ポリゴン」に対して、「従屋根」を生成し、図５、図６に示すような不自然な形態の屋根となってしまう。即ち、幅の広い「第２の４点ポリゴン」の上部の全ての領域をおおうことなく、常に屋根長が短くなる「従屋根」を生成するので、屋根が途中で切れてしまうような形態となる。また、両屋根が同じ勾配であるとき、幅の広い「従屋根」の頂線が幅の狭い「主屋根」の頂線より高くなるので、本来なら高くなるべき「主屋根」が「従屋根」より低くなるという不自然な形態となる。ポリゴンの各辺は様々な長さをとり、色々な形態をとりうるのに、第２従来技術では、辺の長さを考慮せず「主屋根」と「従屋根」を固定して生成し、一般的な屋根付き建物にはみられない形態の屋根を自動生成することになった。
【００１２】
本発明は、現実に存在する形態の屋根を持つ建物モデルをより高い精度で自動生成できる技術を実現することを目的とする。
【００１３】
【課題を解決するための手段および作用と効果】本発明の１つの態様の３次元屋根付き建物モデルの生成プログラムは、以下の処理をコンピュータに実行させるためのものである。
（１）全ての頂角がほぼ直角の６個の頂点を持つ建物境界線としての６点ポリゴン上に建物モデルを生成する。
（２）（ａ）６点ポリゴンの最長辺に隣接する２つの辺のうち短い方の第２辺が、最長辺に隣接する２つの辺のうち長い方の第３辺に隣接するとともに最長辺に対向する第４辺よりも長い場合は、前記最長辺と前記第２辺を境界辺とする４個の頂点を持つ「第１の４点ポリゴン」上の建物モデルに、前記最長辺より軒部だけ長い屋根長、前記第２辺より軒部だけ長い屋根幅を持つ第１の「主屋根」か、又は前記第２辺より軒部だけ長い屋根長、前記最長辺より軒部だけ長い屋根幅を持つ第２の「主屋根」を生成するとともに、前記第３辺と前記第４辺を境界辺とする４個の頂点を持つ「第２の４点ポリゴン」上の建物モデルに、前記第３辺より短い屋根長を持つ「従屋根」を生成する。
（ｂ）前記第２辺が前記第４辺よりも短い場合は、前記「第２の４点ポリゴン」上の建物モデルに、前記第３辺より軒部だけ長い屋根長、前記第４辺より軒部だけ長い屋根幅を持つ第１の「主屋根」か、又は前記第４辺より軒部だけ長い屋根長、前記第３辺より軒部だけ長い屋根幅を持つ第２の「主屋根」を生成するとともに、前記「第１の４点ポリゴン」上の建物モデルに、前記最長辺より短い屋根長を持つ「従屋根」を生成する。
【００１４】
本態様では、６点ポリゴンの第２辺が第４辺よりも長い場合と短い場合で、上記したように建物モデルに生成する屋根の形態を異なるものとしている。よって、従来技術の問題である、第２辺が第４辺よりも短い場合、幅の広い「第２の４点ポリゴン」に対して、その上に生成される屋根が途中で切れてしまうような形態となることや、「主屋根」が「従屋根」より低くなることを回避できる。従って、本態様によると、現実に存在する形態の屋根を持つ建物モデルを、従来よりも高い精度で自動生成できる。
【００１５】
前記第１の「主屋根」を生成するか、又は前記第２の「主屋根」を生成するかは、前記６点ポリゴンに関連付けられた「属性情報」に基づいて定められることが望ましい。
この態様によると、設計者は、６点ポリゴンに関連付けられた「属性情報」として、建物形態を指定する情報である「建物種類」、「屋根種類」や「建物階数」という項目（フィールド）を設定し、それらに適切なデータを入力するだけで、これら「属性情報」と６点ポリゴンの持つ頂点座標などの「図形情報」に基づいて、設計者が意図する形態となる建物モデルを自動的に生成することができる。通常、建物モデルは、３次元ＣＡＤソフト等を使って、平面図、正面図、側面図を描き、それに基づいて、モデルを制作するという労力のかかる作業が必要である。このように、設計者が意図する形態を持つ建物モデルを、「屋根形態を指定する属性情報が関連付けられていない場合」と比べて、より高い精度で、労力をかけずに生成することができる。
【００１６】
８個以上の頂点を持つ建物ポリゴンを前記６点ポリゴンに分割する処理は、８個以上の頂点を持つ建物ポリゴンを「辺の曲がる向きの情報」で記述する処理と、その８個以上の頂点を持つ建物ポリゴンを「辺の曲がる向きの情報」に基づいて６点ポリゴンに分割する処理を有することが望ましい。
この態様によると、８個以上の頂点を持つ前記建物ポリゴンを「辺の曲がる向きの情報」に基づいて６点ポリゴンに分割できるため、頂点数が８個以上の多様な形態をもつ建物ポリゴンから多様な形態となる３次元屋根付き建物モデルを自動生成することができる。
【００１７】
本発明の他の態様の３次元屋根付き建物モデルの生成プログラムは、以下の処理をコンピュータに実行させるためのものである。
（１）全ての頂角がほぼ直角で４個の頂点を持つ建物境界線としての４点ポリゴン上に建物モデルを生成する。
（２）（ａ）第１の場合は、４点ポリゴン上の建物モデルに、４点ポリゴンの長辺より軒部だけ長い屋根長、４点ポリゴンの短辺より軒部だけ長い屋根幅を持つ屋根を生成する。
（ｂ）第２の場合は、４点ポリゴン上の建物モデルに、４点ポリゴンの短辺より軒部だけ長い屋根長、４点ポリゴンの長辺より軒部だけ長い屋根幅を持つ屋根を生成する処理をコンピュータに実行させるための３次元屋根付き建物モデルの生成する。
【００１８】
本態様では、場合によっては４点ポリゴンの長辺に平行な頂線を持つ屋根を生成し、場合によっては４点ポリゴンの長辺に垂直な頂線を持つ屋根を生成する。従って、本態様によると、従来のように、常に４点ポリゴンの長辺に平行な頂線を持つ屋根を生成する場合に比べて、現実に存在する形態の屋根を持つ建物モデルを高い精度で自動生成できる。
【００１９】
前記第１の場合及び／又は第２の場合は、４点ポリゴンに関連付けられた「属性情報」に基づいて定められることが望ましい。
この態様によると、設計者は、４点ポリゴンに関連付けられた「属性情報」として、建物形態を指定する情報である「建物種類」、「屋根種類」や「建物階数」という項目（フィールド）を設定し、それらに適切なデータを入力するだけで、これら「属性情報」と４点ポリゴンの持つ頂点座標などの「図形情報」に基づいて、設計者が意図する形態となる建物モデルを自動的に生成することができる。通常、建物モデルは、３次元ＣＡＤソフト等を使って、平面図、正面図、側面図を描き、それに基づいて、モデルを制作するという労力のかかる作業が必要である。このように、設計者が意図する形態を持つ建物モデルを、「屋根形態を指定する属性情報が関連付けられていない場合」と比べて、より高い精度で、労力をかけずに生成することができる。
【００２０】
本発明は、３次元屋根付き建物モデルの生成方法や、３次元屋根付き建物モデルの生成装置にも具現化できる。これらの方法や装置も、上記した態様と同様の作用効果を得ることができる。
【００２１】
【発明の実施の形態】本発明の実施例の３次元屋根付き建物モデルの生成技術を説明する。図７は、本発明の実施例の３次元屋根付き建物モデルの生成装置（以下では「モデル生成装置」という）２０のブロック図を示す。モデル生成装置２０は、コンピュータを有する。モデル生成装置２０は、入力装置（キーボード等）５２と、制御装置（中央演算処理装置（ＣＰＵ）等）５６と、主記憶装置５４と、補助記憶装置（ハードディスク等）２４と、表示装置（ディスプレイ等）５８を有する。
【００２２】
補助記憶装置２４には、モデル生成用情報２６と、ＧＩＳ（地理情報システム）ソフト４４と、ＧＩＳモジュール（プログラム）４６と、３次元ＣＧ（コンピュータグラフィック）ソフト４８と、３次元ＣＧモジュール（プログラム）５０が格納されている。
モデル生成用情報２６とは、３次元屋根付き建物モデルを生成するための情報である。モデル生成用情報２６は、図形情報２８と、属性情報３６を有する。
【００２３】
図形情報２８は、電子地図上の建物ポリゴンの形状や位置に関する情報である。建物ポリゴンとは、建物を平面視したときの多角形となる建物境界線である。ＧＩＳソフト４４は、建物ポリゴンの各頂点の座標を蓄積及び管理する。
【００２４】
属性情報３６は、電子地図上の建物ポリゴンに関連付けられた建物階数、建物種類などの情報である。通常、電子地図上の建物ポリゴンは、ＧＩＳによって、蓄積及び管理される。ＧＩＳは、関係型データベースの一種で、電子地図上の建物ポリゴンをキーとして、電子地図とテーブル形式の「属性情報」を関連付けている。例えば、属性情報３６のテーブルの項目（フィールド）としては、建物階数、建物種類、屋根種類、屋根勾配、階高、窓の数、窓の大きさなどが挙げられる。
建物種類とは、例えば、屋根付き建物、屋根無し建物（ビルディング）などである。屋根種類とは、例えば、切妻屋根、横長の切妻屋根、寄せ棟屋根、入母屋屋根などである。
【００２５】
「属性情報」は、建物ポリゴンの「図形情報」から得られない建物概形の、主に、垂直方向の寸法を決めるために設定される。建物を平面視した建物ポリゴンの各辺の長さなどから、屋根の概形の平面図は推定できるが、屋根の勾配は推定できない。そこで、屋根勾配を決めるために、屋根勾配を項目として設定し、そこに勾配データを入力して、屋根の概形モデルの形状を決定する。通常、屋根付き建物は階数が少なく、垂直方向の建物の形状の変化が少ない。この様な建物は、建物境界線である建物ポリゴンから３次元形状を推定しても、現実の建物の形状によくあったモデルを生成できる。
【００２６】
図形情報２８は、地図図形情報３２と、２次図形情報３４を有する。属性情報３６は、地図属性情報３８と、入力属性情報４２を有する。地図図形情報３２と、地図属性情報３８は、電子地図３０に含まれているものである。電子地図３０は、住宅地図会社が販売する電子住宅地図や、国土地理院が販売する空間データ基盤である数値地図などである。電子地図３０は、典型的には記録媒体（ＣＤ−ＲＯＭ、ＤＶＤ−ＲＯＭなど）に格納されているものを、補助記憶装置２４に格納したものである。
【００２７】
２次図形情報３４は、電子地図３０に含まれる地図図形情報３２を利用して２次的に求めたものである。２次図形情報３４は、電子地図３０上の地図図形情報３２である建物ポリゴンの各頂点の座標から算出又は測定したポリゴンの頂点数、頂角、辺の長さ、辺の傾きなどである。入力属性情報４２は、モデル生成装置２０の使用者が、入力装置５２によって入力するものである。
【００２８】
ＧＩＳモジュール４６は、地図図形情報３２を元に、２次図形情報３４を作成する。２次図形情報３４は属性情報３６とともにＣＧモジュール５０への入力データであるモデル生成用情報２６となる。ＧＩＳソフト４４を用いると、それが蓄積及び管理する建物ポリゴンに対して、３次元モデル生成のための「属性情報」を関連付けたデータベースを作成できる。ＧＩＳソフト４４を用いて、建物ポリゴンの属性情報３６として、任意に項目（フィールド）を設け、データを入力することで、建物ポリゴン毎に「属性情報」を蓄積及び管理できる。ＣＧモジュール５０は、ＧＩＳモジュール４６によって作成されたモデル生成用情報２６を元に、ＣＧソフト４８の動作を制御して、３次元屋根付き建物モデルを生成する。
【００２９】
主記憶装置５４には、後述する処理の内容に応じて、補助記憶装置２４に記憶されたデータ（ソフト及びモジュールを含む）２６、４４、４６、４８、５０が適宜ロードされる。制御装置５６は、主記憶装置５４にロードされた上記データを読み取る。制御装置５６は、ＧＩＳソフト４４、ＧＩＳモジュール４６、ＣＧソフト４８、ＣＧモジュール５０の各機能を実行する。表示装置５８は、３次元屋根付きモデルを表示する。
【００３０】
図８は、本発明の実施例の３次元屋根付き建物モデルの生成処理の手順を示すフローチャートである。図８のＳ１０の処理は、モデル生成装置２０の使用者が行う。Ｓ２０〜Ｓ６０の処理は、ＧＩＳモジュール４６をモデル生成装置２０（制御装置５６）で実行させることで行う。Ｓ７０とＳ８０の処理は、ＣＧモジュール５０をモデル生成装置２０で実行させることで行う。
【００３１】
必要に応じて、３次元化のための「属性情報」に入力装置を介して、データ入力する（Ｓ１０）。既製の電子地図３０が有する地図属性情報３８のみでは、３次元屋根付き建物モデルを生成するために必要な情報が不足する場合には、このように属性情報４２を入力する。
図９は、ＧＩＳソフト４４を用いて表示装置５８に表示した電子住宅地図（大垣市内）の一例を示す。図９には、電子地図３０の地図図形情報３２と、入力属性情報４２が示されている。このような地図図形情報３２や入力属性情報４２を含むモデル生成用情報２６は、ＧＩＳソフト４４を用いて管理・表示する。
【００３２】
図９の画面には、地図図形情報３２として、建物境界線となる建物ポリゴン群が表示されている。また、各建物ポリゴンに対応付けられた入力属性情報４２がテーブル形式で表示されている。入力属性情報４２として、建物階数の項目４２ａ、建物種類の項目４２ｂ、屋根種類の項目４２ｃが表示されている。建物階数の項目４２ａには階数データ、建物種類の項目４２ｂには建物種類に対応するコード番号、屋根種類の項目４２ｃには屋根種類に対応するコード番号が表示されている。
【００３３】
電子地図上の建物ポリゴンの「図形情報」を取得し、頂点数や頂角、辺の長さ、辺の傾きを求める。（Ｓ２０）。ＧＩＳモジュール４６は、ＧＩＳソフト４４が蓄積及び管理する電子地図３０上の建物ポリゴンの図形情報を取得する。次に、電子地図３０の図形情報３２である建物ポリゴンの各頂点の座標から、建物ポリゴンの頂点数を求め、全ての頂角、辺の長さ、辺の傾きを算出する。算出したこれら情報を、２次図形情報３４として、補助記憶装置２４に格納する。
【００３４】
頂点数と頂角を調べて、以降の処理（３次元屋根付き建物モデルの生成）を行うか否かを判定する（Ｓ３０）。ＧＩＳモジュール４６は、各建物ポリゴンに対して、求めた頂点数と頂角を調べて、以降の処理である３次元屋根付き建物モデルの生成処理を行うか否かを判定する。具体的には、頂点数が４以上の偶数で、１０以下の数であり、建物ポリゴンの全ての頂角がほぼ直角（約８５〜９５度）の場合は、その建物ポリゴンについては、以降の処理を行う。一方、建物ポリゴンの頂角の少なくとも１つがほぼ直角でない場合は、その建物ポリゴンについては、以降の処理を行わない。
【００３５】
本発明者は、岐阜県大垣市の電子住宅地図上の１５００の建物ポリゴンについて全ての頂角と頂点数を調べた。図１０は、その電子住宅地図上の建物ポリゴンの各頂点の角度分布を示す。この調査により、図１０に示すように、建物ポリゴンの頂角は、大部分がほぼ直角であることが判明した。このことは、自動生成のプロセスにおいて、大部分の建物ポリゴン上に、建物モデルとして直方体やプリズムなどの基本立体や、それらのブール演算を行った立体、あるいは、それらを組み合わせた立体を配置できることを意味する。
【００３６】
また、ポリゴンの頂点数は、建物形状がとり得るパターンの種類の数を決めるので、その頂点数を調べた。図１１は、上記した電子住宅地図上の建物ポリゴンの頂点数の分布を示す。この調査により、図１１に示すように、１０点以下の頂点を持つポリゴンが大部分（９４．９％）を占めることが判明した。この結果より、頂角がほぼ直角で、頂点数が１０点以下の建物ポリゴンに対して建物モデルを生成すれば、現実の建物の大部分をモデル化できることになる。
【００３７】
頂点数に応じて、辺の長さ（最長辺、第２辺、第３辺など）、建物中心、屋根中心、建物の傾きなどを求める（Ｓ４０）。ＧＩＳモジュール４６は、全ての頂角がほぼ直角の建物ポリゴンに対して、各頂点の座標から、辺の長さ（最長辺、第２辺、第３辺など）、建物中心、屋根中心、建物の傾きなどを算出し、建物モデルや屋根モデルとなる基本立体のサイズ、位置、傾きを求める。算出したこれら情報を、２次図形情報３４として、補助記憶装置２４に格納する。
【００３８】
建物ポリゴンを辺の曲がる向きの情報で表現する（Ｓ５０）。ＧＩＳモジュール４６は、建物ポリゴンを、辺の曲がる向きの情報（ＲＬ情報）で表現する。図１２は、全ての頂角が直角の建物ポリゴンを辺の曲がる向きの情報で表現した例を示す。図１２では、頂角が直角である建物ポリゴンの所定の頂点を基準にして、その頂点から時計回りに番号を付している。時計回りに順番に頂点を調べると、頂角は直角なので、ある辺は、前の辺に対して右に直角に曲がるか、左に直角に曲がるかの２通りしかない。各頂点で、進行してきた元の辺に対し右向きに曲がる場合を「Ｒ」とし、左向きに曲がる場合を「Ｌ」とする。すると、図１２に示す建物ポリゴンの辺の曲がる向きは、番号１から順に、「ＲＬＲＲＬＲＲＲＬＲ」となる。ここで、ポリゴンの頂点数と右曲がりの頂点の数と左曲がりの頂点の数の間には、以下の関係が成り立つ。
（１）頂点数＝右曲がりの辺の数＋左曲がりの辺の数
（２）右曲がりの頂点の数−左曲がりの頂点の数＝４
【００３９】
近似的に、建物ポリゴンの全ての頂角が直角であるとした場合、建物ポリゴンの頂点数によって建物ポリゴンがとり得る形状パターンを決めることができる。例えば、図１３（ａ）（ｂ）に示すような６点ポリゴンの場合、辺の長さは様々な値をとりうるが、左曲がりの頂点は１つしかない。よって、辺の長さや相対的な辺の比を無視すると、形状パターンは「ＬＲＲＲＲＲ」の１種類である。また、８点ポリゴンの形状パターンは、図１４（ａ）に示す「ＬＬＲＲＲＲＲＲ」、図１４（ｂ）示す「ＬＲＬＲＲＲＲＲ」、図１４（ｃ）に示す「ＬＲＲＬＲＲＲＲ」、図１４（ｄ）に示す「ＬＲＲＲＬＲＲＲ」の４種類である。形状パターンの数は、同じものを含む円順列の式によって計算することができる。
【００４０】
頂点数が増えた場合、１０点ポリゴンでは、形状パターンは１２種類となる。１２点ポリゴンでは、形状パターンは４３種類となる。このように、全ての頂角がほぼ直角である建物ポリゴンの形状パターンを、２通りの辺の曲がる向きの情報で表現すると、データ量を低減しながらも、形状パターンの種類を特定することができる。また、辺の曲がる向きの情報によって建物ポリゴンを表現すると、８個以上の頂点を持つ建物ポリゴンを６点ポリゴンに分割する分割線を引く頂点を決めることができる。
【００４１】
頂角がほぼ直角の８頂点以上の建物ポリゴンを、辺の曲がる向き情報に基づいて６点ポリゴンに分割する（Ｓ６０）。ＧＩＳモジュール４６は、全ての頂角がほぼ直角で８個以上の頂点を持つ建物ポリゴンを、中心となる「幹部」と、これに付随した「枝部」と見なし、「枝部」を切り取り、６点ポリゴンに分割する。ここで、「幹部」とは、建物ポリゴンが複数の６点ポリゴンに分けられた場合に、２つ以上の６点ポリゴンに共通の構成要素となるものである。「枝部」とは、１つの６点ポリゴンのみの構成要素となるものである。
【００４２】
ここでは、図１５（ａ）に示す「ＬＲＲＬＲＲＲＲ」型の８点ポリゴンを、６点ポリゴンに分割する手順について説明する。この８点ポリゴンは、幹部Ａ１と、２つの枝部Ａ２、Ａ３を有する。
この８点ポリゴンでは、辺が左に曲がる頂点「Ｌ」に注目し、その頂点から、時計回りの方向か反時計回りの方向に分割線を伸ばして、連続する「Ｒ」で構成される「枝部」を分割する。例えば、図１５（ａ）では、頂点１で左曲がり「Ｌ」であり、この頂点１から反時計回りの方向に分割線ａを伸ばす。この分割線ａによって８点ポリゴンから枝部Ａ２を切り取ると、この８点ポリゴンは、図１５（ｂ）に示す第１の６点ポリゴンに分割される。次に、図１５（ａ）において、２つ目の左曲がり「Ｌ」である頂点４から時計回りの方向に分割線ｂを伸ばす。この分割線ｂによって８点ポリゴンから枝部Ａ３を切り取ると、この８点ポリゴンは、図１５（ｃ）に示す第２の６点ポリゴンに分割される。
【００４３】
辺の長さ（最長辺、第２辺など）、建物中心、建物の傾きなどから３次元建物モデルのサイズ、傾き、位置を決めて、建物モデルを生成・配置する（Ｓ７０）。
ＣＧモジュール５０は、モデル生成用情報２６を利用して、建物ポリゴン上に生成する基本立体のサイズ、傾き、位置などを決めて、建物ポリゴン上に３次元建物モデルを生成・配置する。
【００４４】
頂角の全てが直角の建物ポリゴンは、４点ポリゴンと、６点ポリゴンと、８点以上の頂点を持つポリゴンに限定される。このうち、８点以上の頂点を持つポリゴンは、上記したように６点ポリゴンに分割される。よって、建物モデルを生成する基本のポリゴンは、４点ポリゴンと６点ポリゴンに限定される。従って、以下では、４点ポリゴンと６点ポリゴン上に建物モデルを生成する処理の手順を説明する。後述する屋根モデルについても同様である。
【００４５】
（４点ポリゴン上への建物モデルの生成）全ての頂角が直角の４点ポリゴン上に３次元建物モデルを生成する処理を、図１６を参照して、説明する。図１６は、４点ポリゴン上に生成した３次元建物モデルＢの一例を示す。
この４点ポリゴンは、長辺Ｊ１と短辺Ｊ２を有する。この４点ポリゴン上に、直方体である建物モデルＢを生成する。建物モデルＢの長さと幅はそれぞれ、４点ポリゴンの長辺Ｊ１の長さと短辺Ｊ２の長さと等しい値に設定する。建物モデルＢの高さは、属性情報３６の建物階数、階高のデータを利用して決める。
【００４６】
このように建物モデルＢのサイズを設定した後、建物モデルＢの長さ方向と４点ポリゴンの長辺Ｊ１が平行になるように建物モデルＢを回転させる。また、平面視したときに、建物モデルＢの中心と４点ポリゴンの中心が一致するように建物モデルＢを移動させる。これにより、４点ポリゴン上に建物モデルＢを配置する。
【００４７】
（６点ポリゴン上への建物モデルの生成）全ての頂角がほぼ直角の６点ポリゴン上に３次元建物モデルを生成する処理を図１７と図１８を参照して説明する。図１７は、６点ポリゴンの一例を「第１の４点ポリゴン」Ｐ１と「第２の４点ポリゴン」Ｐ２に区画した図を示す。図１８は、６点ポリゴン上に生成した３次元建物モデルＢ１、Ｂ２の一例の斜視図を示す。
【００４８】
図１７に示す６点ポリゴンは、最長辺Ｋ１と、第２辺Ｋ２と、第３辺Ｋ３と、第４辺Ｋ４を有する。第２辺Ｋ２は、６点ポリゴンの最長辺Ｋ１に隣接する２つの辺のうち短い方の辺である。第３辺Ｋ３は、６点ポリゴンの最長辺Ｋ１に隣接する２つの辺のうち長い方の辺である。第４辺Ｋ４は、第３辺Ｋ３に隣接するとともに最長辺Ｋ１に対向する辺である。また、６点ポリゴンのうち最長辺Ｋ１と第２辺Ｋ２を境界辺とする４個の頂点を持つものを「第１の４点ポリゴン」Ｐ１とする。６点ポリゴンのうち第３辺Ｋ３と第４辺Ｋ４を境界辺とする４個の頂点を持つものを「第２の４点ポリゴン」Ｐ２とする。「第１の４点ポリゴン」Ｐ１と、「第２の４点ポリゴン」Ｐ２は、重複する領域が存在する。
【００４９】
図１８に示すように、「第１の４点ポリゴン」Ｐ１上に、直方体である第１建物モデルＢ１を生成する。「第２の４点ポリゴン」Ｐ２上に、直方体である第２建物モデルＢ２を生成する。第１建物モデルＢ１の長さと幅はそれぞれ、最長辺Ｋ１と第２辺Ｋ２の長さに等しい値に設定する。第２建物モデルＢ２の長さと幅はそれぞれ、第３辺Ｋ３と第４辺Ｋ４の長さに等しい値に設定する。「第１の４点ポリゴン」Ｐ１と「第２の４点ポリゴン」Ｐ２は重複する領域が存在するため、第１建物モデルＢ１と第２建物モデルＢ２も重複する領域が存在する。建物モデルＢ１、Ｂ２の高さは、属性情報３６の建物階数、階高のデータを利用して設定する。
【００５０】
このように建物モデルＢ１、Ｂ２のサイズを設定した後、第１建物モデルＢ１の長さ方向と「第１の４点ポリゴン」Ｐ１の最長辺Ｋ１が平行になるように第１建物モデルＢ１を回転させる。また、平面視したときに、第１建物モデルＢ１の中心と「第１の４点ポリゴン」Ｐ１の中心が一致するように第１建物モデルＢ１を移動させる。これにより、「第１の４点ポリゴン」Ｐ１上に第１建物モデルＢ１を配置する。同様にして、第２建物モデルＢ２の長さ方向と第３辺Ｋ３が平行になるように第２建物モデルＢ２を回転させる。平面視したときに、第２建物モデルＢ２の中心と「第２の４点ポリゴン」Ｐ２の中心が一致するように、第２建物モデルＢ２を「第２の４点ポリゴン」Ｐ２の上に配置する。
【００５１】
辺の長さ（最長辺、第２辺など）、屋根中心、屋根の傾きなどから３次元屋根モデルのサイズ、傾き、位置を決めて、屋根モデルを生成・配置する（Ｓ８０）。ＣＧモジュール５０は、モデル生成用情報２６を利用して、屋根モデルとなる基本立体のサイズ、傾き、位置などを決めて、建物モデル上に屋根モデルを生成・配置する。
【００５２】
（４点ポリゴン上への屋根の生成）４点ポリゴン上の建物モデルに屋根を生成する処理を、図１９〜図２２を参照して、説明する。図１９は４点ポリゴン上に生成した第１の態様の屋根付き建物モデルの平面図を示し、図２０はその斜視図を示す。図２１は４点ポリゴン上に生成した第２の態様の屋根付き建物モデルの平面図を示し、図２２はその斜視図を示す。
【００５３】
第１の場合は、図１６に示す４点ポリゴン上の建物モデルＢに、図１９と図２０に示すように、屋根Ｒ１を生成する。屋根Ｒ１は、頂線Ｔ１を境とする２つの傾斜屋根部Ｆ１１、Ｆ１２によって構成される。屋根Ｒ１の頂線Ｔ１は、４点ポリゴンの長辺Ｊ１に平行で、その長辺Ｊ１の長さ以上に設定する。本実施例では、屋根Ｒ１の頂線Ｔ１は、４点ポリゴンの長辺Ｊ１よりも軒（のき）部だけ長い値に設定する。屋根Ｒ１の長さＬ１は、頂線Ｔ１の長さと等しい値に設定する。屋根Ｒ１の幅Ｗ１は、４点ポリゴンの短辺Ｊ２より軒部だけ長い値に設定する。なお、屋根部Ｆ１１、Ｆ１２は傾斜しているので、屋根Ｒ１の幅Ｗ１は、屋根部Ｆ１１の幅と屋根部Ｆ１２の幅の合計値よりも短い。屋根Ｒ１の厚さはｔに設定する（図２０参照）。
【００５４】
このように屋根Ｒ１のサイズを設定した後、屋根Ｒ１の頂線Ｔ１と４点ポリゴンの長辺Ｊ１が平行になるように屋根Ｒ１を回転させる。また、平面視したときに、屋根Ｒ１の中心と建物モデルＢの中心が一致するように屋根Ｒ１を移動させる。これにより、建物モデルＢ上に屋根Ｒ１を配置する。
【００５５】
第２の場合は、図１６に示す４点ポリゴン上の建物モデルＢに、図２１と図２２に示すように、屋根Ｒ２を生成する。屋根Ｒ２は、頂線Ｔ２を境とする２つの傾斜屋根部Ｆ２１、Ｆ２２によって構成する。屋根Ｒ２の頂線Ｔ２は、４点ポリゴンの長辺Ｊ１に垂直で（短辺Ｊ２に平行）、短辺Ｊ２の長さ以上に設定する。本実施例では、屋根Ｒ２の頂線Ｔ２は、４点ポリゴンの短辺Ｊ２より軒部だけ長い値に設定する。屋根Ｒ２の長さＬ２は、頂線Ｔ２の長さと等しい値に設定する。屋根Ｒ２の幅Ｗ２は、４点ポリゴンの長辺Ｊ１より軒部だけ長い値に設定する。屋根Ｒ２の厚さはｔに設定する（図２２参照）。
【００５６】
このように屋根Ｒ２のサイズを設定した後は、平面視したときに、屋根Ｒ２の頂線Ｔ２と４点ポリゴンの長辺Ｊ１が垂直になるように屋根Ｒ２を回転させる。また、平面視したときに、屋根Ｒ２の中心と建物モデルＢの中心が一致するように屋根Ｒ２を移動させる。これにより、建物モデルＢ上に屋根Ｒ２を配置する。
【００５７】
屋根の頂線を４点ポリゴンの長辺Ｊ１に平行にするか、又は垂直にするかは、属性情報３６の屋根種類のデータに基づいて定めている。例えば、ある４点ポリゴンに関連付けられた属性情報の屋根種類が、「切妻屋根」、「寄せ棟屋根」、「入母屋屋根」などである場合は、４点ポリゴンの長辺Ｊ１に平行な頂線を持つ屋根を生成する。これに対し、屋根種類が「横長の切妻屋根」などである場合は、４点ポリゴンの長辺Ｊ１に垂直な頂線を持つ屋根を生成する。ここで、「長辺Ｊ１に平行な頂線を持つ屋根」は、第１の「主屋根」に相当し、また、「長辺Ｊ１に垂直な頂線を持つ屋根」は、第２の「主屋根」に相当する。実際には、４点ポリゴンの長辺に垂直な頂線を持つ屋根は、先に図５と図６を参照して説明したように、旧街道沿いに連なる町屋などの建物の屋根の形態として、多く見られる。
【００５８】
（６点ポリゴン上への屋根の生成）６点ポリゴン上の建物モデルに屋根を生成する処理を、図２３〜図２６を参照して、説明する。図２３は６点ポリゴン上に生成した第１の態様の屋根付き建物モデルの平面図を示し、図２４はその斜視図を示す。図２５は６点ポリゴン上に生成した第２の態様の屋根付き建物モデルの平面図を示し、図２６はその斜視図を示す。
【００５９】
第１の場合として、図２３と図２４に示すように、６点ポリゴンの第２辺Ｋ２が第４辺Ｋ４よりも長い場合は、第１建物モデルＢ１に主屋根Ｒ３を生成し、第２建物モデルＢ２に従屋根Ｒ４を生成する。
主屋根Ｒ３は頂線Ｔ３を境とする２つの傾斜屋根部Ｆ３１、Ｆ３２によって構成される。主屋根Ｒ３の頂線Ｔ３の伸びる方向は、６点ポリゴンの最長辺Ｋ１に平行に設定する。主屋根Ｒ３の長さ（頂線Ｔ３の伸びる方向の長さ）Ｌ３は、６点ポリゴンの最長辺Ｋ１の長さ以上に設定する。本実施例では、主屋根Ｒ３の長さＬ３は、６点ポリゴンの最長辺Ｋ１より軒部だけ長い値に設定する。本実施例では、属性情報３６の屋根種類のデータに基づいて、切妻屋根を生成するので、主屋根Ｒ３の長さＬ３と、頂線Ｔ３の長さは、等しい値に設定する。主屋根Ｒ３の幅Ｗ３は、６点ポリゴンの第２辺Ｋ２より軒部だけ長い値に設定する。なお、屋根部Ｆ３１、Ｆ３２は傾斜しているので、主屋根Ｒ３の幅Ｗ３は、屋根部Ｆ３１の幅と屋根部Ｆ３２の幅の合計値よりも短い。主屋根Ｒ３の厚さはｔに設定する（図２４参照）。
【００６０】
このように主屋根Ｒ３のサイズを設定した後、主屋根Ｒ３の頂線Ｔ３と６点ポリゴンの最長辺Ｋ１が平行になるように主屋根Ｒ３を回転させる。また、平面視したときに、主屋根Ｒ３の中心と第１建物モデルＢ１の中心が一致するように主屋根Ｒ３を移動させる。これにより、第１建物モデルＢ１上に主屋根Ｒ３を配置する。
【００６１】
従屋根Ｒ４は頂線Ｔ４を境とする２つの傾斜屋根部Ｆ４１、Ｆ４２によって構成する。従屋根Ｒ４の頂線Ｔ４は、６点ポリゴンの第３辺Ｋ３に平行で、主屋根Ｒ３の頂線Ｔ３と交差しない長さに設定する。よって、頂線Ｔ４の長さは、第３辺Ｋ３の長さ未満に設定される。本実施例では、従屋根Ｒ４の頂線Ｔ４は、主屋根Ｒ３の頂線Ｔ３と、６点ポリゴンの第４辺Ｋ４の間の最短距離に概ね等しい値に設定する。言い換えると、頂線Ｔ４の長さは、（第３辺Ｋ３−０．５×第２辺Ｋ２）に概ね等しい値に設定する。このように、従屋根Ｒ４が主屋根Ｒ３の頂線を越えて、主屋根Ｒ３の傾斜屋根部Ｆ３１の表面から突き出さないように、従屋根Ｒ４の頂線Ｔ４の長さと位置を設定する。従屋根Ｒ４の最大の長さＬ４は、頂線Ｔ４の長さと等しい値に設定する。従屋根Ｒ４の幅Ｗ４は、６点ポリゴンの第４辺Ｋ４より軒部だけ長い値に設定する。従屋根Ｒ４の厚さはｔに設定する（図２４参照）。
【００６２】
このように従屋根Ｒ４のサイズを設定した後、従屋根Ｒ４の頂線Ｔ４と６点ポリゴンの第３辺Ｋ３が平行になるように従屋根Ｒ４を回転させる。また、平面視したときに、従屋根Ｒ４の中心と、第２建物モデルＢ２の所定領域の中心がほぼ一致するように従屋根Ｒ４を移動させる。これにより、第２建物モデルＢ２上に従屋根Ｒ４を配置する。第２建物モデルＢ２の所定領域とは、第２建物モデルＢ２のうち主屋根Ｒ３で覆われた領域を除いた領域である。
【００６３】
これに対し、第２の場合として、図２５と図２６に示すように、６点ポリゴンの第２辺Ｋ２が第４辺Ｋ４よりも短い場合は、第２建物モデルＢ２に主屋根Ｒ５を生成し、第１建物モデルＢ１に従屋根Ｒ６を生成する。
主屋根Ｒ５は頂線Ｔ５を境とする２つの傾斜屋根部Ｆ５１、Ｆ５２によって構成される。主屋根Ｒ５の頂線Ｔ５の伸びる方向は、６点ポリゴンの第３辺Ｋ３に平行に設定する。主屋根Ｒ５の長さ（頂線Ｔ５の伸びる方向の長さ）Ｌ５は、６点ポリゴンの第３辺Ｋ３の長さ以上に設定する。本実施例では、主屋根Ｒ５の長さＬ５は、６点ポリゴンの第３辺Ｋ３より軒部だけ長い値に設定する。本実施例では、主屋根Ｒ５の長さＬ５と、頂線Ｔ５の長さは、等しい値に設定する。主屋根Ｒ５の幅Ｗ５は、６点ポリゴンの第４辺Ｋ４より軒部だけ長い値に設定する。主屋根Ｒ５の厚さはｔに設定する（図２６）。
【００６４】
このように主屋根Ｒ５のサイズを設定した後は、主屋根Ｒ５の頂線Ｔ５と６点ポリゴンの第３辺Ｋ３が平行になるように主屋根Ｒ５を回転させる。また、平面視したときに、主屋根Ｒ５の中心と第２建物モデルＢ２の中心が一致するように主屋根Ｒ５を移動させる。これにより、第２建物モデルＢ２上に主屋根Ｒ５を配置する。
【００６５】
従屋根Ｒ６は頂線Ｔ６を境とする２つの傾斜屋根部Ｆ６１、Ｆ６２によって構成される。従屋根Ｒ６の頂線Ｔ６は、６点ポリゴンの最長辺Ｋ１に平行で、主屋根Ｒ５の頂線Ｔ５と交差しない長さに設定する。よって、頂線Ｔ６の長さは、最長辺Ｋ１の長さ未満に設定される。本実施例では、従屋根Ｒ６の頂線Ｔ６は、主屋根Ｒ５の頂線Ｔ５と、６点ポリゴンの第２辺Ｋ２の間の最短距離に概ね等しい値に設定する。言い換えると、頂線Ｔ６の長さは、（最長辺Ｋ１−０．５×第４辺Ｋ４）に概ね等しい値に設定する。従屋根Ｒ６の最大の長さＬ６は、頂線Ｔ６の長さと等しい値に設定する。従屋根Ｒ６の幅Ｗ６は、６点ポリゴンの第２辺Ｋ２より軒部だけ長い値に設定する。従屋根Ｒ６の厚さはｔに設定する（図２６）。
【００６６】
このように従屋根Ｒ６のサイズを設定した後、従屋根Ｒ６の頂線Ｔ６と６点ポリゴンの最長辺Ｋ１が平行になるように従屋根Ｒ６を回転させる。また、平面視したときに、従屋根Ｒ６の中心と、第１建物モデルＢ１の所定領域の中心が一致するように従屋根Ｒ６を移動させる。これにより、第１建物モデルＢ１上に従屋根Ｒ６を配置する。第１建物モデルＢ１の所定領域とは、第１建物モデルＢ１のうち主屋根Ｒ５で覆われた領域を除いた領域である。
【００６７】
図２３〜図２６に示す屋根Ｒ３〜Ｒ６の頂線の伸びる方向は、属性情報３６の屋根種類のデータに基づいて定めている。具体的な内容は、先に説明した場合（屋根の頂線を４点ポリゴンの長辺Ｊ１に平行にするか、又は垂直にするかを属性情報３６の屋根種類のデータに基づいて定める場合（図１９〜図２２参照））と同様である。
例えば、図２３と図２４に示す屋根付き建物モデルは、主屋根Ｒ３の頂線Ｔ３の伸びる方向が、６点ポリゴンの最長辺Ｋ１に平行となっているが、最長辺Ｋ１に垂直に設定する場合もある。ここで、「最長辺Ｋ１に平行な頂線を持つ屋根」である図２３と図２４に示す屋根モデルは、第１の「主屋根」に相当する。また、「最長辺Ｋ１に垂直な頂線を持つ屋根」は、第２の「主屋根」に相当する。主屋根Ｒ３の頂線Ｔ３を６点ポリゴンの最長辺Ｋ１に平行（第１の「主屋根」）にするか、最長辺Ｋ１に垂直（第２の「主屋根」）にするかは、属性情報３６の屋根種類のデータに基づいて定める。具体的には、切妻屋根、寄せ棟屋根、入母屋屋根は、第１の「主屋根」に相当し、横長の切妻屋根は、第２の「主屋根」に相当する。
【００６８】
全ての頂角が直角で、８個以上の頂点を持つ建物ポリゴンに対しては、図８に示したＳ６０の処理により複数の６点ポリゴンに分割し、Ｓ７０の処理により各６点ポリゴン上に建物モデルを生成し、Ｓ８０の処理により屋根を生成することで３次元屋根付き建物モデルを自動生成できる。図２７は、８点ポリゴン上に生成した屋根付き建物モデル群の斜視図を示す。
【００６９】
辺の曲がる向きの情報（ＲＬ情報）による分類によると、図１４に示すように、８点ポリゴンは４種類の形状パターンに分けられる。図２７の各列には、この４種類の同じ形をした建物ポリゴンを並べている。手前から１行目のポリゴンには「切妻屋根」、２行目には「寄せ棟屋根」、３行目には「横長の切妻屋根」となるデータを属性情報である屋根種類に与えて、自動生成を行っている。
【００７０】
８点ポリゴンの場合、図１５（ｂ）に例示する第１の６点ポリゴンと、図１５（ｃ）に例示する第２の６点ポリゴンに分割できる。第１の６点ポリゴン上に屋根付き建物モデルを先に生成した場合、第２の６点ポリゴン上への屋根付き建物モデルの生成処理では、枝部Ａ２のみに屋根付き建物モデルを生成すればよい。
幹部Ａ１は第１の６点ポリゴンの構成要素にもなっているため、幹部Ａ１には屋根付き建物モデルが既に生成されているからである。
【００７１】
図２８は、同一形状の６点ポリゴン上に属性情報を異ならせて生成した屋根付き建物モデル群の斜視図を示す。これらのモデル群は、属性情報として、具体的には、屋根種類、屋根の勾配、２階部の位置、２階部と１階部の大きさの比率、寄せ棟屋根の頂線と屋根長の比率、窓の間隔、窓の大きさなどを様々に異ならせて生成したものである。図２８に示すように、同一形状の６点ポリゴンに対しても、属性情報を異ならせることで、種々の形状の３次元屋根付き建物モデルを生成できる。図２８において、左から１列目の４つの建物モデルの屋根は「切妻屋根」、左から２列目の４つの建物モデルの屋根は「寄せ棟屋根」、左から３列目の４つの建物モデルの屋根は「横長の切妻屋根」、右端の列の４つの建物モデルの屋根は「入母屋屋根」である。ここで、左から３列目の建物モデルの屋根は第２の「主屋根」、それ以外の屋根は第１の「主屋根」となる。
【００７２】
次に、以上のような処理により生成した３次元屋根付き建物モデルの活用事例を説明する。３次元屋根付き建物モデルを含む「３次元都市モデル」は、建物や道路、川といった現実世界のハードウェアを仮想空間に写像し、ＧＩＳ等の情報システムでデータを蓄積・管理し、広範囲の分野で様々な利用や活用が期待される重要な「情報基盤」である。高層化や地下化が進み、３次元的な広がりを見せる都市を、「３次元都市モデル」はコンピュータの中に再構築し、都市計画や景観設計、土木、建築、交通工学、教育、防災といったアカデミックな分野の活用から公共事業の情報公開、まちづくりへの市民参加の場として、あるいは、ゲームやアミューズメントの分野で活用することが数多く試みられている。例えば、米国では、その主要な都市の３次元モデルを構築し、不動産情報などを中心に有料で配信している企業（ＵｒｂａｎＤａｔａＳｏｌｕｔｉｏｎｓ）も存在する。また、住民参加型まちづくりでは、住民・地権者と行政、専門家が目標とするまちの３次元イメージを共有し、改善案や代替案を検討していくことがよりよいまちづくりにつながる。関係者間で、まちの３次元イメージを生成する道具として、ＣＧによる３次元モデルを作成することが有効である。
【００７３】
本実施例では、３次元建物モデルの情報源としているものは、建物境界線である２次元の「図形情報」と、建物階数や建物種類などの「属性情報」である。そのため、２次元形状から３次元の建物形状を推定して、モデルを生成する。本実施例のプロセスでは、建物を色々な角度から写真撮影し、得られるステレオ画像を使って、３次元形状を推定することをしない。建物を１軒１軒、色々な角度で写真撮影し、３次元形状を推定するという手作業をせずに、２次元の建物境界線から最もｐｒｏｂａｂｌｅな３次元建物形状を推定して、生成する。特に、一般的な屋根付き建物は、階数が少なく、建物境界線から３次元形状を推定・生成する手法によって、現実に近い建物モデルを効率よく生成することができる。
【００７４】
３次元ＣＧソフトを使って、時間をかけて「３次元都市モデル」の制作を行い、精緻なモデルを作ることは可能である。労力とモデルの精緻さはトレードオフの関係にあるが、都市計画や街の将来のイメージや代替案のイメージが必要な「まちづくり」において利用される「３次元都市モデル」では、看板や窓の形や色、壁の模様や染みといったディテールを必要とせず、容積率や建蔽率、斜線制限、屋根種類などで形状が決まる建物概形モデルで十分である。また、本実施例の手法を使えば、「３次元都市モデル」を、まちづくりなどの代替案に対する変更や要望に対応して、時間をかけずに制作することができる。こうした概形モデルを、要求に応じて迅速に制作する際に、本実施例の手法は有効である。
【００７５】
活用事例として、中心市街地が衰退するという問題をかかえる地方都市の中心市街地活性化の案となるモデルを生成した。活性化案として、歴史的建造物、例えば、「城」を中心に商店街を再構築する「３次元都市モデル」を自動生成した。図２９は現況を再現する大垣城一帯の３次元イメージで、大垣城へ至る道路は狭く、周辺のビルディングに囲まれて目立たない。そこで、大垣城が周辺から見えるように、周囲に低層の町屋型の店舗を配置し、城に至る道路も太くした場合のモデルを図３０に示す。このモデルでは、歴史的な遺産である城がどこからでも見えるように、周辺には低い店舗が軒を並べるように建設されている。
【００７６】
２つ目の活用事例として、総合設計制度を利用して、高層ビルディングが建てられる前後の「３次元都市モデル」を生成した。総合設計制度とは、容積率及ぴ高さの制限について、統一的な緩和規定を設けることによって、建築敷地の共同化、大規模化による土地の有効かつ合理的な利用の促進と、公共的なオープンスペース（公開空地）を確保することなどにより、市街地環境の整備を図ることを目的として設けられたものである。但し、超高層ビルディングの出現により、生活環境が著しく阻害され、まち全体が大きく変わってしまうのではないかという危惧が住民の間に生じる可能性がある。そのため、総合設計制度が利用された時にまちがどのように変わるのか、あるいは変わる可能性があるのか、総合設計制度を認めてもいいのか、よくないのかを関係者で検討する必要がある。即ち、まちの３次元イメージを「３次元のたたき台」として、地域の住民で共有して、地域の将来像を検討し、住民の目指す将来像を描いていくことが大事だとされる。
【００７７】
その３次元イメージとして、本システムが生成した「３次元都市モデル」を活用することができる。本実施例の手法によって生成された３次元屋根付き建物モデルを含む「３次元都市モデル」の活用例を図３１〜図３４に示す。図３１は、岐阜市問屋町西部地区の現況を再現する３次元都市モデルを示す。図３２は、上記地区に対して総合設計制度を適用した場合の３次元都市モデルを示す。図３３は、大垣市高屋町地域の現況を再現する３次元都市モデルを示す。図３４は、上記地域に対して総合設計制度を適用した場合の３次元都市モデルを示す。
【００７８】
以上、本発明の具体例を詳細に説明したが、これらは例示に過ぎず、特許請求の範囲を限定するものではない。特許請求の範囲に記載の技術には、以上に例示した具体例を様々に変形、変更したものが含まれる。
また、本明細書または図面に説明した技術要素は、単独であるいは各種の組合せによって技術的有用性を発揮するものであり、出願時請求項記載の組合せに限定されるものではない。また、本明細書または図面に例示した技術は複数目的を同時に達成し得るものであり、そのうちの一つの目的を達成すること自体で技術的有用性を持つものである。
【図面の簡単な説明】
【図１】従来の３次元都市モデルの一例を示す。
【図２】従来の３次元都市モデルの他の一例を示す。
【図３】従来の屋根付き建物モデルの一例の平面図を示す。
【図４】従来の屋根付き建物モデルの一例の斜視図を示す。
【図５】旧街道沿いに連なる幅広の切り妻屋根の建物の写真の一例を示す。
【図６】旧街道沿いに連なる幅広の切り妻屋根の建物の写真の他の一例を示す。
【図７】本発明の実施例の３次元の屋根付き建物モデルの生成装置のブロック図を示す。
【図８】本発明の実施例の３次元の屋根付き建物モデルの生成処理の手順を示すフローチャートである。
【図９】ＧＩＳソフトを用いて表示装置に表示した電子住宅地図（大垣市内）の一例を示す。
【図１０】電子住宅地図上の建物ポリゴンの各頂点の角度分布を示す。
【図１１】電子住宅地図上の建物ポリゴンの頂点数の分布を示す。
【図１２】全ての頂角が直角の建物ポリゴンを辺の曲がる向きの情報で表現した例を示す。
【図１３】６点ポリゴンの形状パターンを示し、（ａ）と（ｂ）は共に「ＬＲＲＲＲＲ」型を示す。
【図１４】８点ポリゴンの形状パターンを示し、（ａ）は「ＬＬＲＲＲＲＲＲ」型、（ｂ）は「ＬＲＬＲＲＲＲＲ」型、（ｃ）は「ＬＲＲＬＲＲＲＲ」型、（ｄ）は「ＬＲＲＲＬＲＲＲ」型を示す。
【図１５】（ａ）「ＬＲＲＬＲＲＲＲ」型の８点ポリゴンの一例を示し、（ｂ）は（ａ）の８点ポリゴンを第１の６点ポリゴンに分割した図を示し、（ｃ）は（ａ）の８点ポリゴンを第２の６点ポリゴンに分割した図を示す。
【図１６】４点ポリゴン上に生成した３次元建物モデルの一例を示す。
【図１７】６点ポリゴンの一例を第１の４点ポリゴンと第２の４点ポリゴンに区画した図を示す。
【図１８】６点ポリゴン上に生成した３次元建物モデルの一例の斜視図を示す。
【図１９】４点ポリゴン上に生成した第１の態様の屋根付き建物モデルの平面図を示す。
【図２０】４点ポリゴン上に生成した第１の態様の屋根付き建物モデルの斜視図を示す。
【図２１】４点ポリゴン上に生成した第２の態様の屋根付き建物モデルの平面図を示す。
【図２２】４点ポリゴン上に生成した第２の態様の屋根付き建物モデルの斜視図を示す。
【図２３】６点ポリゴン上に生成した第１の態様の屋根付き建物モデルの平面図を示す。
【図２４】６点ポリゴン上に生成した第１の態様の屋根付き建物モデルの斜視図を示す。
【図２５】６点ポリゴン上に生成した第２の態様の屋根付き建物モデルの平面図を示す。
【図２６】６点ポリゴン上に生成した第２の態様の屋根付き建物モデルの斜視図を示す。
【図２７】８点ポリゴン上に生成した屋根付き建物モデル群の斜視図を示す。
【図２８】同一形状の６点ポリゴン上に属性情報を異ならせて生成した屋根付き建物モデル群の斜視図を示す。
【図２９】大垣城一帯の現況を再現する３次元都市モデルを示す。
【図３０】大垣城周辺に低層の店舗を配置した活性化案の３次元都市モデルを示す。
【図３１】岐阜市問屋町西部地区の現況を再現する３次元都市モデルを示す。
【図３２】岐阜市問屋町西部地区に対して総合設計制度を適用した場合の３次元都市モデルを示す。
【図３３】大垣市高屋町地域の現況を再現する３次元都市モデルを示す。
【図３４】大垣市高屋町地域に対して総合設計制度を適用した場合の３次元都市モデルを示す。
【符号の説明】
Ｊ１：４点ポリゴンの長辺
Ｊ２：４点ポリゴンの短辺
Ｋ１：６点ポリゴンの最長辺
Ｋ２：６点ポリゴンの第２辺
Ｋ３：６点ポリゴンの第３辺
Ｋ４：６点ポリゴンの第４辺
Ｐ１：第１の４点ポリゴン
Ｐ２：第２の４点ポリゴン
Ｂ、Ｂ１、Ｂ２：建物モデル
Ｒ１〜Ｒ８：屋根
Ｆ１１〜Ｆ６２：傾斜屋根部
Ｔ１〜Ｔ８：屋根の頂線
Ｌ１〜Ｌ８：屋根の長さ
Ｗ１〜Ｗ８：屋根の幅[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for automatically generating a three-dimensional building model with a roof using a computer or the like.
[0002]
2. Description of the Related Art (First Prior Art) A "three-dimensional city model" produced using three-dimensional CG software is typically used by displaying it on a display or the like. The “three-dimensional city model” has a three-dimensional building model as a main component. The "3D city model" maps real-world cities to the world of computers. From the use of academic fields such as urban planning and landscape design, civil engineering, architecture, disaster prevention, and the environment, information disclosure of public works, It is an important "information infrastructure" that is expected to be used in a wide range of fields, such as a place for citizen participation in community development or in the field of games and amusement.
[0003]
In the first conventional technique, a three-dimensional city model is generated using a three-dimensional display function of GIS. 1 and 2 show examples of a conventional three-dimensional city model. FIGS. 1 and 2 show a set of pillar-shaped building models as a three-dimensional city model. These conventional three-dimensional city models generate building polygons on a two-dimensional digital map by performing extrusion processing according to floor data associated with the polygons as “attribute information”. By executing GIS software having such a three-dimensional display function on a computer, a three-dimensional city model without a roof can be automatically generated.
[0004]
(Second Prior Art) On the other hand, a method of automatically generating a three-dimensional roofed building model has been proposed (refer to Patent Document 1 as a related technique). FIG. 3 shows a plan view of an example of a covered building model generated by this method, and FIG. 4 shows a perspective view thereof.
In this method, a covered building model is generated on a six-point polygon having all the apex angles at substantially right angles by a method described below. The portion indicated by the dotted line in FIG. 3 is the six-point polygon. The six-point polygon has a longest side K1, a second side K2, a third side K3, and a fourth side K4. The second side K2 is the shorter side of the two sides adjacent to the longest side K1 of the six-point polygon. The third side K3 is the longer side of the two sides adjacent to the longest side K1 of the six-point polygon. The fourth side K4 is a side adjacent to the third side K3 and facing the longest side K1. Further, a polygon having four vertices having the longest side K1 and the second side K2 as boundary sides among the six-point polygons is referred to as a "first four-point polygon" P1. Among the six-point polygons, a polygon having four vertices with the third side K3 and the fourth side K4 as boundary sides is referred to as a "second four-point polygon" P2. The “first four-point polygon” P1 and the “second four-point polygon” P2 have overlapping areas.
[0005]
[Patent Document 1]
JP-A-2002-056412 (see FIG. 13 of the publication)
[0006]
As shown in FIGS. 3 and 4, a first cuboid building model B1 is generated on the "first four-point polygon" P1. A second building model B2, which is a rectangular parallelepiped, is generated on the "second four-point polygon" P2. Since the "first four-point polygon" P1 and the "second four-point polygon" P2 have an overlapping area, the first building model B1 and the second building model B2 also have an overlapping area.
The first building model B1 on the “first four-point polygon” P1 always has a top line T7 parallel to the longest side K1 and a roof length longer than the longest side K1 by the eaves (the roof length in the direction of the top line T7). ) L7, a "main roof" R7 having a roof width (length of roof in a direction perpendicular to the top line T7) W7 longer than the second side K2 by the eaves is generated. The second building model B2 on the "second four-point polygon" P2 always has a top line T8 parallel to the third side K3, a roof length L8 shorter than the third side K3, and a longer eaves section than the fourth side K4. A “sub-roof” R8 having a roof width W8 is generated.
[0007]
The problem to be solved by the first prior art is that the conventional model shown in FIGS. 1 and 2 is constituted only by a building model having no roof, and is not a real model. It does not represent a covered building. If all buildings are simply made of pillars, it will be a three-dimensional city model far from reality. The conventional model shown in FIGS. 1 and 2 is composed of only a building model having no roof, and can be used as a “3D springboard” or a “scenery evaluation tool” of a cityscape in landscape design and town development. Have difficulty. Therefore, it is necessary to generate a building model having a plurality of inclined roofs, and to generate a three-dimensional city model that better represents a building in the real world.
[0008]
In the production of a three-dimensional covered building model, a three-dimensional CG software is usually used to manually create a shape model of the covered building. However, as a manual operation, the size (length, height, first side width, second side width, etc.) of the basic solid (prism, rectangular parallelepiped, etc.) to be the roof is determined, and they are copied and moved, and the Performing calculations, creating a roof shape, and arranging the created building model at an appropriate location require time-consuming operations such as rotating the building model and performing horizontal and vertical translations. is there. For example, if it takes about 30 minutes to manually create and arrange a model of a covered building by hand, a model of a town in which about 5,000 such covered buildings are gathered requires approximately 2500 hours to be manually created. This would require manual time.
[0009]
In the second related art, the first building model B1 on the “first four-point polygon” P1 always has the longest side K1 of the six-point polygon (that is, the long side of the “first four-point polygon” P1). Generate a main roof R7 with a parallel top line T7. However, in reality, many buildings have a roof having a top line perpendicular to the long side of the four-point polygon. For example, many townhouses along the old highway as shown in FIGS. 5 and 6 have a roof having a top line perpendicular to the long side of the four-point polygon (horizontal gable roof). It is difficult to generate such a model of a covered building by the method of the second related art.
[0010]
In the second related art, a “main roof” R7 is always generated for a “first four-point polygon” P1 of a six-point polygon, and a “main roof” R7 is always generated for a “second four-point polygon” P2. The secondary roof "R8" is generated. On the other hand, since the length of each side of the six-point polygon on the electronic map can take various values, there is a six-point polygon in which the fourth side K4 is longer than the second side K2.
[0011]
In the second conventional technique, a “main roof” is generated for a narrow “first four-point polygon” of a six-point polygon whose fourth side is longer than the second side, and a “second roof” having a wide width is formed. A “following roof” is generated for the “four-point polygon”, resulting in an unnatural roof as shown in FIGS. 5 and 6. In other words, a "slaved roof" in which the roof length is always shortened without covering the entire area above the wide "second four-point polygon" is generated. Become. Also, when both roofs have the same slope, the top line of the wide “slave roof” is higher than the top line of the narrow “main roof”. ”Is unnatural. Although each side of the polygon has various lengths and can take various forms, in the second prior art, the "main roof" and the "slave roof" are fixed and generated without considering the side length. The company has decided to automatically generate roofs that are not found in typical covered buildings.
[0012]
An object of the present invention is to realize a technology capable of automatically generating a building model having a roof having a form that actually exists with higher accuracy.
[0013]
A program for generating a three-dimensional covered building model according to one embodiment of the present invention is for causing a computer to execute the following processing.
(1) A building model is generated on a six-point polygon as a building boundary line having six vertices whose all apex angles are substantially right angles.
(2) (a) The shorter second side of the two sides adjacent to the longest side of the six-point polygon is adjacent to the longer third side of the two sides adjacent to the longest side and the longest side If the longest side is longer than the fourth side, the building model on the “first four-point polygon” having four vertices with the longest side and the second side as boundaries is added to the building model from the longest side. A first main roof having a roof length that is longer than the second side, a roof width that is longer than the second side, or a roof length that is longer than the second side and a roof that is longer than the longest side A second “main roof” having a width is generated, and a building model on a “second four-point polygon” having four vertices having the third side and the fourth side as boundaries is added to the building model. Generate a “slave roof” with a roof length shorter than the third side.
(B) When the second side is shorter than the fourth side, the building model on the “second four-point polygon” has a roof length longer by the eaves than the third side and a roof length longer than the fourth side. A first "main roof" having a roof width longer only by the eaves, or a second "main roof" having a roof length longer by the eaves than the fourth side and a roof width longer by the eaves than the third side And a “sub-roof” having a roof length shorter than the longest side is generated in the building model on the “first four-point polygon”.
[0014]
In this embodiment, the form of the roof generated in the building model is different depending on whether the second side of the six-point polygon is longer than the fourth side or shorter. Therefore, if the second side is shorter than the fourth side, which is a problem of the related art, the roof generated on the wide “second four-point polygon” may be cut off halfway. And that the “main roof” becomes lower than the “slave roof”. Therefore, according to this aspect, a building model having a roof in a form that actually exists can be automatically generated with higher accuracy than before.
[0015]
It is desirable that whether to generate the first “main roof” or the second “main roof” is determined based on “attribute information” associated with the six-point polygon.
According to this aspect, the designer sets items (fields) such as "building type", "roof type", and "floor number of floors", which are information for specifying a building form, as "attribute information" associated with the six-point polygon. By simply setting and inputting appropriate data, a building model in the form intended by the designer is automatically created based on the "attribute information" and "graphic information" such as the vertex coordinates of the six-point polygon. Can be generated. In general, a building model requires a laborious work of drawing a plan view, a front view, and a side view using three-dimensional CAD software or the like, and creating a model based on the plan view, the front view, and the side view. As described above, a building model having a form intended by the designer can be generated with higher accuracy and less effort than in the case where "attribute information specifying the roof form is not associated". .
[0016]
The process of dividing a building polygon having eight or more vertices into the six-point polygon includes a process of describing a building polygon having eight or more vertices by “information of a direction in which a side turns” and a process of dividing the building polygon having eight or more vertices. It is desirable to have a process of dividing the building polygon having the shape into six-point polygons based on “information of the direction in which the side turns”.
According to this aspect, since the building polygon having eight or more vertices can be divided into six-point polygons based on “information of the direction in which the side turns”, building polygons having various shapes having eight or more vertices can be used. It is possible to automatically generate three-dimensional roofed building models in various forms.
[0017]
A program for generating a three-dimensional roofed building model according to another embodiment of the present invention causes a computer to execute the following processing.
(1) A building model is generated on a four-point polygon as a building boundary line having all the apex angles being substantially right angles and four vertices.
(2) (a) In the first case, the building model on the four-point polygon has a roof length longer than the long side of the four-point polygon by the eaves, and a roof width longer than the short side of the four-point polygon by the eaves. Generate a roof.
(B) In the second case, a roof having a roof length longer than the shorter side of the four-point polygon by the eaves and a roof width longer than the long side of the four-point polygon by the eaves is generated in the building model on the four-point polygon. Of a three-dimensional building model with a roof for causing a computer to execute the processing to be performed.
[0018]
In this embodiment, a roof having a top line parallel to the long side of the four-point polygon is generated in some cases, and a roof having a top line perpendicular to the long side of the four-point polygon is generated in some cases. Therefore, according to this aspect, a building model having a roof in a form that actually exists can be obtained with higher accuracy than a conventional case in which a roof having a top line that is always parallel to the long side of a four-point polygon is generated. Can be automatically generated.
[0019]
It is desirable that the first case and / or the second case be determined based on “attribute information” associated with the four-point polygon.
According to this aspect, the designer sets items (fields) such as “building type”, “roof type”, and “floor number of floors”, which are information specifying a building type, as “attribute information” associated with the four-point polygon. By simply setting and inputting appropriate data, a building model in the form intended by the designer is automatically created based on these "attribute information" and "graphic information" such as the vertex coordinates of the four-point polygon. Can be generated. In general, a building model requires a laborious work of drawing a plan view, a front view, and a side view using three-dimensional CAD software or the like, and creating a model based on the plan view, the front view, and the side view. As described above, a building model having a form intended by the designer can be generated with higher accuracy and less effort than in the case where "attribute information specifying the roof form is not associated". .
[0020]
The present invention can also be embodied in a method for generating a three-dimensional roofed building model and a three-dimensional roofed building model generation device. These methods and apparatuses can also obtain the same operation and effects as those of the above embodiment.
[0021]
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A description will be given of a technique for generating a three-dimensional covered building model according to an embodiment of the present invention. FIG. 7 is a block diagram of a device for generating a three-dimensional building model with a roof (hereinafter, referred to as a “model generating device”) 20 according to an embodiment of the present invention. The model generation device 20 has a computer. The model generation device 20 includes an input device (such as a keyboard) 52, a control device (such as a central processing unit (CPU)) 56, a main storage device 54, an auxiliary storage device (such as a hard disk) 24, and a display device (display). Etc.) 58.
[0022]
In the auxiliary storage device 24, model generation information 26, GIS (Geographic Information System) software 44, GIS module (program) 46, three-dimensional CG (computer graphic) software 48, and three-dimensional CG module (program) 50 are stored.
The model generation information 26 is information for generating a three-dimensional building model with a roof. The model generation information 26 has graphic information 28 and attribute information 36.
[0023]
The graphic information 28 is information on the shape and position of the building polygon on the electronic map. The building polygon is a building boundary that becomes a polygon when the building is viewed in plan. The GIS software 44 stores and manages the coordinates of each vertex of the building polygon.
[0024]
The attribute information 36 is information such as the number of floors and the type of building associated with the building polygon on the electronic map. Usually, building polygons on an electronic map are stored and managed by GIS. The GIS is a type of relational database, and associates an electronic map with "attribute information" in a table format using building polygons on the electronic map as keys. For example, the items (fields) of the table of the attribute information 36 include the number of floors, the building type, the roof type, the roof slope, the floor height, the number of windows, the size of windows, and the like.
The building type is, for example, a building with a roof or a building without a roof (building). The roof type is, for example, a gable roof, a horizontally long gable roof, a ridge roof, an lintel roof, or the like.
[0025]
The “attribute information” is set to determine mainly the vertical dimension of the building outline that cannot be obtained from the “figure information” of the building polygon. From the length of each side of the building polygon in a plan view of the building, a schematic plan view of the roof can be estimated, but the slope of the roof cannot be estimated. Therefore, in order to determine the roof slope, the roof slope is set as an item, and the slope data is input thereto to determine the shape of the roof outline model. In general, a covered building has a small number of floors and a change in the shape of the building in the vertical direction is small. For such a building, even if the three-dimensional shape is estimated from the building polygon which is the building boundary line, a model suitable for the actual building shape can be generated.
[0026]
The graphic information 28 has map graphic information 32 and secondary graphic information 34. The attribute information 36 includes map attribute information 38 and input attribute information 42. The map graphic information 32 and the map attribute information 38 are included in the electronic map 30. The electronic map 30 is an electronic house map sold by a house map company, a numerical map which is a spatial data base sold by the Geographical Survey Institute, and the like. The electronic map 30 is typically stored in a storage medium (CD-ROM, DVD-ROM, or the like) and stored in the auxiliary storage device 24.
[0027]
The secondary graphic information 34 is obtained secondarily using the map graphic information 32 included in the electronic map 30. The secondary graphic information 34 is the number of vertices of the polygon calculated or measured from the coordinates of each vertex of the building polygon, which is the map graphic information 32 on the electronic map 30, the vertex angle, the length of the side, the inclination of the side, and the like. The input attribute information 42 is input by the user of the model generation device 20 through the input device 52.
[0028]
The GIS module 46 creates the secondary graphic information 34 based on the map graphic information 32. The secondary graphic information 34, together with the attribute information 36, becomes the model generation information 26 which is input data to the CG module 50. When the GIS software 44 is used, a database in which "attribute information" for generating a three-dimensional model is associated with a building polygon stored and managed by the GIS software 44 can be created. By using the GIS software 44 and arbitrarily setting items (fields) as the attribute information 36 of the building polygon and inputting data, “attribute information” can be accumulated and managed for each building polygon. The CG module 50 controls the operation of the CG software 48 based on the model generation information 26 created by the GIS module 46 to generate a three-dimensional building model with a roof.
[0029]
Data (including software and modules) 26, 44, 46, 48, and 50 stored in the auxiliary storage device 24 are appropriately loaded into the main storage device 54 in accordance with the contents of processing to be described later. The control device 56 reads the data loaded in the main storage device 54. The control device 56 executes the functions of the GIS software 44, the GIS module 46, the CG software 48, and the CG module 50. The display device 58 displays the three-dimensional covered model.
[0030]
FIG. 8 is a flowchart illustrating a procedure of a process of generating a three-dimensional building model with a roof according to the embodiment of this invention. The process of S10 in FIG. 8 is performed by the user of the model generation device 20. The processes in S20 to S60 are performed by causing the GIS module 46 to be executed by the model generation device 20 (control device 56). The processes in S70 and S80 are performed by causing the model generation device 20 to execute the CG module 50.
[0031]
If necessary, data is input to "attribute information" for three-dimensionalization via an input device (S10). When only the map attribute information 38 of the ready-made electronic map 30 does not provide enough information for generating a three-dimensional roofed building model, the attribute information 42 is input as described above.
FIG. 9 shows an example of an electronic house map (Ogaki city) displayed on the display device 58 using the GIS software 44. FIG. 9 shows map figure information 32 of the electronic map 30 and input attribute information 42. The model generation information 26 including the map graphic information 32 and the input attribute information 42 is managed and displayed using the GIS software 44.
[0032]
On the screen in FIG. 9, a group of building polygons serving as building boundary lines is displayed as map graphic information 32. The input attribute information 42 associated with each building polygon is displayed in a table format. As the input attribute information 42, an item 42a of building floor number, an item 42b of building type, and an item 42c of roof type are displayed. The floor number item 42a displays floor number data, the building type item 42b displays a code number corresponding to the building type, and the roof type item 42c displays a code number corresponding to the roof type.
[0033]
The “figure information” of the building polygon on the electronic map is acquired, and the number of vertices, the vertex angle, the length of the side, and the inclination of the side are obtained. (S20). The GIS module 46 acquires graphic information of building polygons on the electronic map 30 stored and managed by the GIS software 44. Next, the number of vertices of the building polygon is obtained from the coordinates of each vertex of the building polygon, which is the graphic information 32 of the electronic map 30, and all the apex angles, the lengths of the sides, and the inclinations of the sides are calculated. The calculated information is stored in the auxiliary storage device 24 as the secondary graphic information 34.
[0034]
The number of vertices and the apex angle are checked, and it is determined whether or not to perform the subsequent processing (generation of a three-dimensional building model with a roof) (S30). The GIS module 46 checks the obtained number of vertices and the apex angle for each building polygon, and determines whether or not to perform a subsequent process of generating a three-dimensional roofed building model. Specifically, when the number of vertices is an even number of 4 or more and a number of 10 or less, and all the apex angles of the building polygon are almost right angles (about 85 to 95 degrees), the building polygon is Perform processing. On the other hand, when at least one of the vertex angles of the building polygon is not substantially a right angle, the subsequent processing is not performed on the building polygon.
[0035]
The present inventor examined all the apex angles and the number of vertices for 1500 building polygons on an electronic house map in Ogaki City, Gifu Prefecture. FIG. 10 shows the angular distribution of each vertex of the building polygon on the electronic house map. As a result of this investigation, it was found that the apex angles of the building polygons were almost right angles, as shown in FIG. This means that in the process of automatic generation, basic solids such as cuboids and prisms, solids obtained by performing a Boolean operation on them, or solids combining them can be placed on most building polygons as building models. means.
[0036]
Also, the number of vertices of the polygon determines the number of types of patterns that the building shape can take, so the number of vertices was examined. FIG. 11 shows the distribution of the number of vertices of the building polygon on the electronic house map described above. As a result of this investigation, as shown in FIG. 11, it was found that polygons having vertices of 10 or less occupy most (94.9%). From this result, if a building model is generated for a building polygon having an apex angle of substantially a right angle and a vertex number of 10 or less, most of a real building can be modeled.
[0037]
According to the number of vertices, the length of the side (the longest side, the second side, the third side, etc.), the center of the building, the center of the roof, the inclination of the building, and the like are obtained (S40). The GIS module 46 calculates the side length (longest side, second side, third side, etc.), building center, roof center, building Calculate the size, position, and inclination of the basic solid that will be the building model and the roof model. The calculated information is stored in the auxiliary storage device 24 as the secondary graphic information 34.
[0038]
The building polygon is represented by the information of the direction in which the side turns (S50). The GIS module 46 expresses the building polygon by information (RL information) of the direction in which the side turns. FIG. 12 shows an example in which all building polygons whose vertical angles are right angles are represented by information on the direction in which the side turns. In FIG. 12, a predetermined vertex of a building polygon whose apex angle is a right angle is used as a reference, and a number is given clockwise from the vertex. When examining the vertices in a clockwise order, the vertex angle is a right angle, so there are only two ways to turn a right side or right side to the previous side. At each vertex, “R” indicates that the vehicle turns right with respect to the original side that has advanced, and “L” indicates that the vehicle turns left with respect to the original side. Then, the directions in which the sides of the building polygon shown in FIG. 12 bend are “RLRRRLRRRRR” in order from number 1. Here, the following relationship is established between the number of vertices of the polygon, the number of right-turning vertices, and the number of left-turning vertices.
(1) The number of vertices = the number of sides that turn right + the number of sides that turn left
(2) Number of vertices of right turn−number of vertices of left turn = 4
[0039]
Approximately, if all the apex angles of the building polygon are right angles, the shape pattern that the building polygon can take can be determined by the number of vertices of the building polygon. For example, in the case of a six-point polygon as shown in FIGS. 13A and 13B, the length of the side can take various values, but there is only one vertex of the left turn. Therefore, if the length of the side and the relative side ratio are ignored, the shape pattern is one type of “LRRRRR”. The shape pattern of the eight-point polygon is “LLRRRRRR” shown in FIG. 14A, “LRLRRRRR” shown in FIG. 14B, “LRRRRRRR” shown in FIG. 14C, and “LLRRRRRR” shown in FIG. LRRRLRRR ". The number of shape patterns can be calculated by a circular permutation formula including the same.
[0040]
When the number of vertices increases, there are 12 types of shape patterns for a 10-point polygon. In the case of a 12-point polygon, there are 43 types of shape patterns. As described above, when the shape pattern of a building polygon in which all the apex angles are substantially right angles is represented by the information on the directions in which the two sides bend, it is possible to identify the type of the shape pattern while reducing the data amount. it can. Also, when a building polygon is represented by information on the direction in which a side is bent, it is possible to determine a vertex at which a dividing line for dividing a building polygon having eight or more vertices into six-point polygons is drawn.
[0041]
The building polygon having eight or more vertices whose apex angle is almost a right angle is divided into six-point polygons based on the bending direction information of the side (S60). The GIS module 46 regards the building polygon having all the apex angles being substantially right angles and having eight or more vertices as the central "trunk" and the accompanying "branch", and cuts the "branch". Divide into 6-point polygons. Here, the “trunk” is a component common to two or more six-point polygons when the building polygon is divided into a plurality of six-point polygons. The “branch” is a component of only one six-point polygon.
[0042]
Here, a procedure for dividing the “LRRLRRRR” type eight-point polygon shown in FIG. 15A into six-point polygons will be described. This 8-point polygon has a trunk portion A1 and two branch portions A2 and A3.
In this 8-point polygon, a vertex “L” whose side turns to the left is noticed, and a dividing line is extended from the vertex in a clockwise direction or a counterclockwise direction to form a continuous “R”. Branch ". For example, in FIG. 15A, a left turn “L” is formed at the vertex 1, and the dividing line a extends in a counterclockwise direction from the vertex 1. When the branch A2 is cut from the eight-point polygon by the dividing line a, the eight-point polygon is divided into a first six-point polygon shown in FIG. Next, in FIG. 15A, the dividing line b is extended in the clockwise direction from the vertex 4 that is the second left turn “L”. When the branch A3 is cut from the eight-point polygon by the dividing line b, the eight-point polygon is divided into the second six-point polygon shown in FIG.
[0043]
The size, inclination, and position of the three-dimensional building model are determined based on the length of the side (the longest side, the second side, and the like), the center of the building, the inclination of the building, and the like, and the building model is generated and arranged (S70).
The CG module 50 uses the model generation information 26 to determine the size, inclination, position, and the like of the basic solid to be generated on the building polygon, and generates and arranges a three-dimensional building model on the building polygon.
[0044]
The building polygons whose vertical angles are all right angles are limited to four-point polygons, six-point polygons, and polygons having eight or more vertices. Among them, polygons having eight or more vertices are divided into six-point polygons as described above. Therefore, basic polygons for generating a building model are limited to four-point polygons and six-point polygons. Therefore, the procedure of processing for generating a building model on a 4-point polygon and a 6-point polygon will be described below. The same applies to a roof model described later.
[0045]
(Generation of Building Model on Four-Point Polygon) A process of generating a three-dimensional building model on a four-point polygon having all the vertical angles at right angles will be described with reference to FIG. FIG. 16 shows an example of a three-dimensional building model B generated on a four-point polygon.
This four-point polygon has a long side J1 and a short side J2. A building model B, which is a rectangular parallelepiped, is generated on the four-point polygon. The length and width of the building model B are set to values equal to the length of the long side J1 and the length of the short side J2 of the four-point polygon, respectively. The height of the building model B is determined using the data on the number of floors and the floor height of the attribute information 36.
[0046]
After setting the size of the building model B in this way, the building model B is rotated so that the length direction of the building model B and the long side J1 of the four-point polygon are parallel. Further, the building model B is moved so that the center of the building model B coincides with the center of the four-point polygon when viewed in a plan view. Thereby, the building model B is arranged on the four-point polygon.
[0047]
(Generation of Building Model on Six-Point Polygon) A process of generating a three-dimensional building model on a six-point polygon having all the apex angles approximately right will be described with reference to FIGS. 17 and 18. FIG. 17 shows a diagram in which an example of a six-point polygon is divided into a “first four-point polygon” P1 and a “second four-point polygon” P2. FIG. 18 shows a perspective view of an example of the three-dimensional building models B1 and B2 generated on the six-point polygon.
[0048]
The six-point polygon illustrated in FIG. 17 has a longest side K1, a second side K2, a third side K3, and a fourth side K4. The second side K2 is the shorter side of the two sides adjacent to the longest side K1 of the six-point polygon. The third side K3 is the longer side of the two sides adjacent to the longest side K1 of the six-point polygon. The fourth side K4 is a side adjacent to the third side K3 and facing the longest side K1. A polygon having four vertices with the longest side K1 and the second side K2 as boundary sides among the six-point polygons is referred to as a "first four-point polygon" P1. A polygon having four vertices having the third side K3 and the fourth side K4 as boundary sides among the six-point polygons is referred to as a "second four-point polygon" P2. The “first four-point polygon” P1 and the “second four-point polygon” P2 have overlapping areas.
[0049]
As shown in FIG. 18, a first building model B1 that is a rectangular parallelepiped is generated on a “first four-point polygon” P1. A second building model B2, which is a rectangular parallelepiped, is generated on the "second four-point polygon" P2. The length and width of the first building model B1 are set to values equal to the lengths of the longest side K1 and the second side K2, respectively. The length and width of the second building model B2 are set to values equal to the lengths of the third side K3 and the fourth side K4, respectively. Since the "first four-point polygon" P1 and the "second four-point polygon" P2 have an overlapping area, the first building model B1 and the second building model B2 also have an overlapping area. The heights of the building models B1 and B2 are set using the data of the number of floors and the height of the building in the attribute information 36.
[0050]
After setting the sizes of the building models B1 and B2 in this way, the first building model B1 is set such that the length direction of the first building model B1 is parallel to the longest side K1 of the “first four-point polygon” P1. Rotate. Further, the first building model B1 is moved so that the center of the first building model B1 and the center of the "first four-point polygon" P1 coincide when viewed in a plan view. Thereby, the first building model B1 is arranged on the “first four-point polygon” P1. Similarly, the second building model B2 is rotated such that the length direction of the second building model B2 is parallel to the third side K3. The second building model B2 is arranged on the "second four-point polygon" P2 so that the center of the second building model B2 and the center of the "second four-point polygon" P2 match when viewed in a plan view. I do.
[0051]
The size, inclination, and position of the three-dimensional roof model are determined from the length of the side (the longest side, the second side, and the like), the center of the roof, the inclination of the roof, and the like, and the roof model is generated and arranged (S80). The CG module 50 generates and arranges a roof model on a building model by determining the size, inclination, position, and the like of a basic solid serving as a roof model using the model generation information 26.
[0052]
(Generation of Roof on Four-Point Polygon) Processing for generating a roof on a building model on a four-point polygon will be described with reference to FIGS. FIG. 19 shows a plan view of the covered building model of the first embodiment generated on a four-point polygon, and FIG. 20 shows a perspective view thereof. FIG. 21 shows a plan view of a second embodiment of a covered building model generated on a four-point polygon, and FIG. 22 shows a perspective view thereof.
[0053]
In the first case, a roof R1 is generated in the building model B on the four-point polygon shown in FIG. 16 as shown in FIGS. The roof R1 is constituted by two inclined roof portions F11 and F12 bordering on the top line T1. The top line T1 of the roof R1 is parallel to the long side J1 of the four-point polygon and is set to be longer than the length of the long side J1. In the present embodiment, the top line T1 of the roof R1 is set to a value that is longer than the long side J1 of the four-point polygon by only the eaves. The length L1 of the roof R1 is set to a value equal to the length of the top line T1. The width W1 of the roof R1 is set to a value that is longer than the short side J2 of the four-point polygon by the eaves. Since the roofs F11 and F12 are inclined, the width W1 of the roof R1 is shorter than the sum of the width of the roof F11 and the width of the roof F12. The thickness of the roof R1 is set to t (see FIG. 20).
[0054]
After setting the size of the roof R1, the roof R1 is rotated such that the top line T1 of the roof R1 and the long side J1 of the four-point polygon are parallel. In addition, the roof R1 is moved so that the center of the roof R1 and the center of the building model B coincide when viewed in a plan view. Thereby, the roof R1 is arranged on the building model B.
[0055]
In the second case, a roof R2 is generated in the building model B on the four-point polygon shown in FIG. 16 as shown in FIGS. 21 and 22. The roof R2 is constituted by two inclined roof portions F21 and F22 bordering the top line T2. The top line T2 of the roof R2 is set perpendicular to the long side J1 of the four-point polygon (parallel to the short side J2) and equal to or longer than the length of the short side J2. In this embodiment, the top line T2 of the roof R2 is set to a value longer by the eaves than the short side J2 of the four-point polygon. The length L2 of the roof R2 is set to a value equal to the length of the top line T2. The width W2 of the roof R2 is set to a value longer by the eaves than the long side J1 of the four-point polygon. The thickness of the roof R2 is set to t (see FIG. 22).
[0056]
After setting the size of the roof R2, the roof R2 is rotated so that the top line T2 of the roof R2 and the long side J1 of the four-point polygon are perpendicular to each other when viewed in a plan view. In addition, the roof R2 is moved so that the center of the roof R2 and the center of the building model B coincide when viewed in a plan view. Thereby, the roof R2 is arranged on the building model B.
[0057]
Whether the top line of the roof is parallel to the long side J1 of the four-point polygon or vertical is determined based on the roof type data of the attribute information 36. For example, if the roof type of the attribute information associated with a certain four-point polygon is “gable roof”, “gully roof”, “Imperial roof”, etc., the top line parallel to the long side J1 of the four-point polygon Produces a roof with On the other hand, when the roof type is “horizontal gable roof” or the like, a roof having a top line perpendicular to the long side J1 of the four-point polygon is generated. Here, the “roof having a top line parallel to the long side J1” corresponds to the first “main roof”, and the “roof having a top line perpendicular to the long side J1” corresponds to the second “main roof”. Main roof ". Actually, the roof having a top line perpendicular to the long side of the four-point polygon is, as described above with reference to FIGS. 5 and 6, a form of a roof of a building such as a machiya along the old highway. , Are often seen.
[0058]
(Generation of Roof on Six-Point Polygon) A process of generating a roof on a building model on a six-point polygon will be described with reference to FIGS. FIG. 23 shows a plan view of the covered building model of the first embodiment generated on a six-point polygon, and FIG. 24 shows a perspective view thereof. FIG. 25 shows a plan view of the covered building model of the second embodiment generated on a six-point polygon, and FIG. 26 shows a perspective view thereof.
[0059]
As a first case, as shown in FIGS. 23 and 24, when the second side K2 of the six-point polygon is longer than the fourth side K4, the main roof R3 is generated in the first building model B1, and the second roof is generated. A roof R4 is generated according to the building model B2.
The main roof R3 is constituted by two inclined roof portions F31 and F32 bordering the top line T3. The direction in which the top line T3 of the main roof R3 extends is set parallel to the longest side K1 of the six-point polygon. The length L3 of the main roof R3 (the length in the direction in which the top line T3 extends) is set to be equal to or longer than the length of the longest side K1 of the six-point polygon. In the present embodiment, the length L3 of the main roof R3 is set to a value longer than the longest side K1 of the six-point polygon by the eaves. In the present embodiment, the gable roof is generated based on the roof type data of the attribute information 36, so that the length L3 of the main roof R3 and the length of the top line T3 are set to the same value. The width W3 of the main roof R3 is set to a value longer by the eaves than the second side K2 of the six-point polygon. Since the roofs F31 and F32 are inclined, the width W3 of the main roof R3 is shorter than the sum of the width of the roof F31 and the width of the roof F32. The thickness of the main roof R3 is set to t (see FIG. 24).
[0060]
After setting the size of the main roof R3 in this way, the main roof R3 is rotated such that the top line T3 of the main roof R3 and the longest side K1 of the six-point polygon are parallel. Further, the main roof R3 is moved so that the center of the main roof R3 and the center of the first building model B1 coincide when viewed in a plan view. Thereby, the main roof R3 is arranged on the first building model B1.
[0061]
The secondary roof R4 is constituted by two inclined roof portions F41 and F42 bordering the top line T4. The top line T4 of the sub-roof R4 is set to a length that is parallel to the third side K3 of the six-point polygon and does not intersect with the top line T3 of the main roof R3. Therefore, the length of the top line T4 is set to be less than the length of the third side K3. In this embodiment, the top line T4 of the sub-roof R4 is set to a value substantially equal to the shortest distance between the top line T3 of the main roof R3 and the fourth side K4 of the six-point polygon. In other words, the length of the top line T4 is set to a value substantially equal to (the third side K3-0.5 × the second side K2). Thus, the length and position of the top line T4 of the sub-roof R4 are set so that the sub-roof R4 does not protrude from the surface of the inclined roof portion F31 of the main roof R3 beyond the top line of the main roof R3. The maximum length L4 of the sub-roof R4 is set to a value equal to the length of the top line T4. The width W4 of the sub-roof R4 is set to a value longer than the fourth side K4 of the six-point polygon by the eaves. The thickness of the sub-roof R4 is set to t (see FIG. 24).
[0062]
After setting the size of the sub-roof R4 in this way, the sub-roof R4 is rotated so that the top line T4 of the sub-roof R4 and the third side K3 of the six-point polygon are parallel. Further, when viewed in a plan view, the sub-roof R4 is moved such that the center of the sub-roof R4 and the center of the predetermined area of the second building model B2 substantially coincide with each other. Thus, the roof R4 is arranged on the second building model B2. The predetermined area of the second building model B2 is an area excluding the area covered by the main roof R3 in the second building model B2.
[0063]
On the other hand, as a second case, as shown in FIGS. 25 and 26, when the second side K2 of the six-point polygon is shorter than the fourth side K4, the main roof R5 is generated in the second building model B2. Then, a roof R6 is generated according to the first building model B1.
The main roof R5 is constituted by two inclined roof portions F51 and F52 bordering the top line T5. The direction in which the top line T5 of the main roof R5 extends is set parallel to the third side K3 of the six-point polygon. The length of the main roof R5 (the length in the direction in which the top line T5 extends) L5 is set to be equal to or longer than the length of the third side K3 of the six-point polygon. In the present embodiment, the length L5 of the main roof R5 is set to a value longer than the third side K3 of the six-point polygon by the eaves. In this embodiment, the length L5 of the main roof R5 and the length of the top line T5 are set to the same value. The width W5 of the main roof R5 is set to a value that is longer than the fourth side K4 of the six-point polygon by the eaves. The thickness of the main roof R5 is set to t (FIG. 26).
[0064]
After setting the size of the main roof R5 in this way, the main roof R5 is rotated such that the top line T5 of the main roof R5 and the third side K3 of the six-point polygon are parallel. Further, the main roof R5 is moved so that the center of the main roof R5 and the center of the second building model B2 coincide when viewed in a plan view. Thereby, the main roof R5 is arranged on the second building model B2.
[0065]
The secondary roof R6 is constituted by two inclined roof portions F61 and F62 bordering the top line T6. The top line T6 of the sub-roof R6 is set to a length that is parallel to the longest side K1 of the six-point polygon and does not intersect with the top line T5 of the main roof R5. Therefore, the length of the top line T6 is set to be less than the length of the longest side K1. In this embodiment, the top line T6 of the sub-roof R6 is set to a value substantially equal to the shortest distance between the top line T5 of the main roof R5 and the second side K2 of the six-point polygon. In other words, the length of the top line T6 is set to a value substantially equal to (the longest side K1−0.5 × the fourth side K4). The maximum length L6 of the sub-roof R6 is set to a value equal to the length of the top line T6. The width W6 of the sub-roof R6 is set to a value longer by the eaves than the second side K2 of the six-point polygon. The thickness of the secondary roof R6 is set to t (FIG. 26).
[0066]
After setting the size of the sub-roof R6 in this way, the sub-roof R6 is rotated so that the top line T6 of the sub-roof R6 and the longest side K1 of the six-point polygon are parallel. Further, when viewed in a plan view, the sub-roof R6 is moved so that the center of the sub-roof R6 and the center of the predetermined area of the first building model B1 coincide. Thus, the roof R6 is arranged on the first building model B1. The predetermined area of the first building model B1 is an area excluding the area covered by the main roof R5 in the first building model B1.
[0067]
The direction in which the top lines of the roofs R3 to R6 shown in FIGS. 23 to 26 extend is determined based on the roof type data in the attribute information 36. The specific contents are described above (in the case where it is determined based on the roof type data of the attribute information 36 whether the top line of the roof is parallel to the long side J1 of the four-point polygon or vertical) ( 19 to 22)).
For example, in the covered building model shown in FIGS. 23 and 24, the direction in which the top line T3 of the main roof R3 extends is parallel to the longest side K1 of the six-point polygon, but is set perpendicular to the longest side K1. In some cases. Here, the roof model shown in FIGS. 23 and 24, which is the “roof having a top line parallel to the longest side K1”, corresponds to the first “main roof”. The “roof having a top line perpendicular to the longest side K1” corresponds to the second “main roof”. Whether the top line T3 of the main roof R3 is parallel to the longest side K1 of the six-point polygon (first "main roof") or perpendicular to the longest side K1 (second "main roof") is an attribute. Determined based on the roof type data in the information 36. Specifically, the gable roof, the ridge roof, and the gable roof are equivalent to the first “main roof”, and the horizontally long gable roof is equivalent to the second “main roof”.
[0068]
A building polygon having all vertical angles at right angles and having eight or more vertices is divided into a plurality of six-point polygons by the processing of S60 shown in FIG. A three-dimensional building model with a roof can be automatically generated by generating a building model and generating a roof by the processing of S80. FIG. 27 shows a perspective view of a group of building models with a roof generated on an 8-point polygon.
[0069]
According to the classification based on the information of the direction in which the side is bent (RL information), as shown in FIG. 14, the eight-point polygon is divided into four types of shape patterns. In each column of FIG. 27, these four types of building polygons having the same shape are arranged. The first row of polygons from the front side is given "gable roof", the second row is "ridge roof", and the third row is "horizontal gable roof". Automatic generation is being performed.
[0070]
In the case of an 8-point polygon, it can be divided into a first 6-point polygon illustrated in FIG. 15B and a second 6-point polygon illustrated in FIG. 15C. When a covered building model is first generated on the first six-point polygon, in the process of generating a covered building model on the second six-point polygon, a covered building model is generated only for the branch A2. Good.
This is because the trunk A1 is also a constituent element of the first six-point polygon, so that a building model with a roof is already generated for the trunk A1.
[0071]
FIG. 28 is a perspective view of a roofed building model group generated by changing attribute information on six-point polygons having the same shape. These model groups are, as attribute information, specifically, roof type, roof gradient, position of the second floor, ratio of the size of the second floor to the first floor, the top line of the ridge roof and the roof length. , The interval between windows, the size of windows, etc., are made to vary in various ways. As shown in FIG. 28, even for a six-point polygon having the same shape, a three-dimensional roofed building model of various shapes can be generated by making the attribute information different. In FIG. 28, the roofs of the four building models in the first column from the left are “gable roofs”, the roofs of the four building models in the second column from the left are “ridge roofs”, and four buildings in the third column from the left. The roof of the model is the "horizontal gable roof", and the roof of the four building models in the rightmost row is the "plinth roof". Here, the roof of the building model in the third row from the left is the second “main roof”, and the other roofs are the first “main roof”.
[0072]
Next, an example of using the three-dimensional building model with a roof generated by the above processing will be described. The “3D city model” including the 3D roofed building model maps real-world hardware such as buildings, roads, and rivers into a virtual space, stores and manages data using an information system such as GIS, and covers a wide range of fields. It is an important "information infrastructure" that is expected to be used and utilized in various ways. A city that shows a three-dimensional expanse with an increase in height and underground is rebuilt in a computer using a “three-dimensional city model”, and is used for urban planning, landscape design, civil engineering, architecture, traffic engineering, education, disaster prevention, etc. Many attempts have been made to use it in the academic field, public information disclosure, citizen participation in community development, or in the field of games and amusement. For example, in the United States, there is also a company (Urban Data Solutions) that builds a three-dimensional model of the major city and distributes it mainly for real estate information and the like for a fee. In addition, in community-based community development, it is better for residents and landowners, governments and experts to share a three-dimensional image of the targeted town and to consider improvement plans and alternatives, leading to better town development. It is effective to create a three-dimensional model by CG as a tool for generating a three-dimensional image of a town between concerned parties.
[0073]
In the present embodiment, the information sources of the three-dimensional building model are two-dimensional “graphic information” that is a building boundary line and “attribute information” such as the number of floors and the type of building. Therefore, a model is generated by estimating a three-dimensional building shape from a two-dimensional shape. In the process of this embodiment, photographs of the building are taken from various angles, and the obtained stereo images are not used to estimate the three-dimensional shape. Estimate and generate the most probable three-dimensional building shape from the two-dimensional building boundary line without taking the manual work of estimating the three-dimensional shape by photographing each building at various angles. . In particular, a general covered building has a small number of floors, and a method of estimating and generating a three-dimensional shape from a building boundary line can efficiently generate a building model close to reality.
[0074]
Using 3D CG software, it is possible to spend a lot of time creating a “3D city model” and creating an elaborate model. Efficiency and model elaboration are in a trade-off relationship. However, in “three-dimensional city models” used in city planning, “town planning” that requires an image of the future of the city and images of alternatives, signs and windows It does not require details such as shape, color, wall pattern or stain, and a building outline model whose shape is determined by the floor area ratio, building coverage ratio, diagonal limit, roof type, etc. is sufficient. Also, if the method of the present embodiment is used, a “three-dimensional city model” can be produced in a short time in response to a change or a request for an alternative such as town development. The method of the present embodiment is effective in quickly producing such a schematic model according to a request.
[0075]
As an application example, a model was proposed to revitalize the central city area of a local city, which has the problem of the central city area declining. As an activation plan, a "three-dimensional city model" for rebuilding a shopping center around a historic building, for example, a "castle" was automatically generated. FIG. 29 is a three-dimensional image of the entire Ogaki Castle that reproduces the present situation. The road leading to the Ogaki Castle is narrow and is not noticeable surrounded by surrounding buildings. Accordingly, FIG. 30 shows a model in which low-rise townhouse-type stores are arranged around the Ogaki Castle so that the road leading to the castle is thickened so that the Ogaki Castle can be seen from the surroundings. In this model, low-rise shops are built around the eaves so that the historic heritage castle can be seen from anywhere.
[0076]
As a second use case, a “three-dimensional city model” before and after a high-rise building was built using the comprehensive design system. The Comprehensive Design System is a system that promotes effective and rational use of land through the communalization of building sites and the enlargement of scale by establishing unified mitigation rules for floor area ratio and height restrictions. It has been established with the aim of improving the urban environment by securing an open space (open space). However, with the emergence of the skyscrapers, residents may be worried that the living environment will be significantly impaired and that the whole town will change significantly. For this reason, it is necessary for stakeholders to consider how the town will change when the comprehensive design system is used, whether it will change, whether the comprehensive design system is acceptable, or not. In other words, it is important to share the three-dimensional image of the town with the local residents as a “three-dimensional platform”, examine the future image of the region, and draw the future image that the residents aim for.
[0077]
As the three-dimensional image, the “three-dimensional city model” generated by the present system can be used. FIGS. 31 to 34 show utilization examples of the “three-dimensional city model” including the three-dimensional roofed building model generated by the method of the present embodiment. FIG. 31 shows a three-dimensional city model that reproduces the present situation of the western part of Toya-cho, Gifu City. FIG. 32 shows a three-dimensional city model when the comprehensive design system is applied to the above district. FIG. 33 shows a three-dimensional city model that reproduces the current situation of the Takayacho area in Ogaki city. FIG. 34 shows a three-dimensional city model when the comprehensive design system is applied to the above-mentioned area.
[0078]
As mentioned above, although the specific example of this invention was demonstrated in detail, these are only illustrations and do not limit a claim. The technology described in the claims includes various modifications and alterations of the specific examples illustrated above.
Further, the technical elements described in the present specification or the drawings exert technical utility singly or in various combinations, and are not limited to the combinations described in the claims at the time of filing. The technology illustrated in the present specification or the drawings can simultaneously achieve a plurality of objects, and has technical utility by achieving one of the objects.
[Brief description of the drawings]
FIG. 1 shows an example of a conventional three-dimensional city model.
FIG. 2 shows another example of a conventional three-dimensional city model.
FIG. 3 shows a plan view of an example of a conventional covered building model.
FIG. 4 shows a perspective view of an example of a conventional covered building model.
FIG. 5 shows an example of a photograph of a wide gable-roof building connected along the old highway.
FIG. 6 shows another example of a photograph of a building with a wide gabled roof extending along the old highway.
FIG. 7 is a block diagram showing a three-dimensional covered building model generating apparatus according to an embodiment of the present invention.
FIG. 8 is a flowchart illustrating a procedure of a process of generating a three-dimensional covered building model according to the embodiment of the present invention.
FIG. 9 shows an example of an electronic house map (in Ogaki city) displayed on a display device using GIS software.
FIG. 10 shows the angular distribution of each vertex of a building polygon on the electronic house map.
FIG. 11 shows the distribution of the number of vertices of building polygons on an electronic house map.
FIG. 12 shows an example in which all building polygons whose apex angle is a right angle are represented by information of a direction in which a side turns.
FIG. 13 shows a shape pattern of a six-point polygon, and (a) and (b) both show the “LRRRRR” type.
14A and 14B show an 8-point polygon shape pattern, wherein FIG. 14A shows an “LLRRRRRR” type, FIG. 14B shows an “LRRRRRRR” type, FIG. 14C shows an “LRRRRRRR” type, and FIG. 14D shows a “LRRRRRRR” type. .
15A shows an example of an “LRRLRRRR” type eight-point polygon, FIG. 15B shows a diagram in which the eight-point polygon shown in FIG. 15A is divided into first six-point polygons, and FIG. FIG. 5A is a diagram in which the 8-point polygon is divided into second 6-point polygons.
FIG. 16 shows an example of a three-dimensional building model generated on a four-point polygon.
FIG. 17 shows a diagram in which an example of a six-point polygon is divided into a first four-point polygon and a second four-point polygon.
FIG. 18 shows a perspective view of an example of a three-dimensional building model generated on a six-point polygon.
FIG. 19 shows a plan view of the covered building model of the first embodiment generated on a four-point polygon.
FIG. 20 is a perspective view of a covered building model of the first embodiment generated on a four-point polygon.
FIG. 21 shows a plan view of a covered building model according to a second embodiment generated on a four-point polygon.
FIG. 22 is a perspective view of a covered building model of a second embodiment generated on a four-point polygon.
FIG. 23 shows a plan view of the covered building model of the first embodiment generated on a six-point polygon.
FIG. 24 shows a perspective view of the covered building model of the first embodiment generated on a six-point polygon.
FIG. 25 shows a plan view of a covered building model of a second embodiment generated on a six-point polygon.
FIG. 26 is a perspective view of a covered building model of a second embodiment generated on a six-point polygon.
FIG. 27 shows a perspective view of a group of building models with a roof generated on an 8-point polygon.
FIG. 28 is a perspective view of a roofed building model group generated by changing attribute information on six-point polygons having the same shape.
FIG. 29 shows a three-dimensional city model that reproduces the current state of Ogaki Castle area.
FIG. 30 shows a three-dimensional city model of an activation plan in which low-rise stores are arranged around Ogaki Castle.
FIG. 31 shows a three-dimensional city model reproducing the present situation of the western part of Toya-cho, Gifu city.
FIG. 32 shows a three-dimensional city model when the comprehensive design system is applied to the western part of Toya-machi, Gifu city.
FIG. 33 shows a three-dimensional city model that reproduces the current state of the Takayacho area in Ogaki city.
FIG. 34 shows a three-dimensional city model when the comprehensive design system is applied to the Takayacho area in Ogaki city.
[Explanation of symbols]
J1: Long side of 4-point polygon
J2: Short side of 4-point polygon
K1: Longest side of 6-point polygon
K2: the second side of the 6-point polygon
K3: Third side of 6-point polygon
K4: 4th side of 6-point polygon
P1: First 4-point polygon
P2: second 4-point polygon
B, B1, B2: Building model
R1 to R8: Roof
F11 to F62: Inclined roof
T1 to T8: Top line of the roof
L1 to L8: roof length
W1 to W8: width of roof

Claims

(1) a process of generating a building model on a six-point polygon serving as a building boundary line having six vertices each having a vertex at a substantially right angle;
(2) (a) The shorter second side of the two sides adjacent to the longest side of the six-point polygon is adjacent to the longer third side of the two sides adjacent to the longest side and the longest side If the longest side is longer than the fourth side, the building model on the “first four-point polygon” having four vertices with the longest side and the second side as boundaries is added to the building model from the longest side. A first main roof having a roof length that is longer than the second side, a roof width that is longer than the second side, or a roof length that is longer than the second side and a roof that is longer than the longest side A second “main roof” having a width is generated, and a building model on a “second four-point polygon” having four vertices having the third side and the fourth side as boundaries is added to the building model. Generate a “slave roof” with a roof length shorter than the third side,
(B) When the second side is shorter than the fourth side, the building model on the “second four-point polygon” has a roof length longer by the eaves than the third side and a roof length longer than the fourth side. A first "main roof" having a roof width longer only by the eaves, or a second "main roof" having a roof length longer by the eaves than the fourth side and a roof width longer by the eaves than the third side And a computer-executable process for generating a “sub-roof” having a roof length shorter than the longest side in the building model on the “first four-point polygon”. Generation program.

Whether to generate the first “main roof” or the second “main roof” is determined based on “attribute information” associated with the six-point polygon. The program according to claim 1.

A process of describing a building polygon having eight or more vertices with information on the direction in which a side turns, and a process of dividing the building polygon having eight or more vertices into six-point polygons based on the information on the direction in which the side turns. 3. The program according to claim 1, further causing a computer to execute the program.

(1) a process of generating a building model on a four-point polygon as a building boundary line having all the apex angles being substantially right angles and having four vertices;
(2) (a) In the first case, the building model on the four-point polygon has a roof length longer than the long side of the four-point polygon by the eaves, and a roof width longer than the short side of the four-point polygon by the eaves. Generate a roof,
(B) In the second case, a roof having a roof length longer than the shorter side of the four-point polygon by the eaves and a roof width longer than the long side of the four-point polygon by the eaves is generated in the building model on the four-point polygon. A program for generating a three-dimensional roofed building model for causing a computer to execute processing to be performed.

The program according to claim 4, wherein the first case and / or the second case are determined based on "attribute information" associated with a four-point polygon.

(1) a step of generating a building model on a six-point polygon as a building boundary line having six vertices whose all apex angles are substantially right angles;
(2) (a) The shorter second side of the two sides adjacent to the longest side of the six-point polygon is adjacent to the longer third side of the two sides adjacent to the longest side and the longest side If the longest side is longer than the fourth side, the building model on the “first four-point polygon” having four vertices with the longest side and the second side as boundaries is added to the building model from the longest side. A first main roof having a roof length that is longer than the second side, a roof width that is longer than the second side, or a roof length that is longer than the second side and a roof that is longer than the longest side A second “main roof” having a width is generated, and a building model on a “second four-point polygon” having four vertices having the third side and the fourth side as boundaries is added to the building model. Generate a “slave roof” with a roof length shorter than the third side,
(B) If the second side is shorter than the fourth side, the roof model is longer than the third side in the building model on the “second four-point polygon”; A first "main roof" having a roof width that is longer than the third side, or a second "main roof" having a roof length longer than the fourth side by the eaves and a roof width longer than the third side by the eaves. A method for generating a three-dimensional roofed building model, comprising: generating a “slave roof” having a roof length shorter than the longest side in the building model on the “first four-point polygon”.

(1) a step of generating a building model on a four-point polygon as a building boundary line in which all the apex angles are almost right angles and have four vertices;
(2) (a) In the first case, the building model on the four-point polygon has a roof length longer than the long side of the four-point polygon by the eaves, and a roof width longer than the short side of the four-point polygon by the eaves. Generate a roof,
(B) In the second case, a roof having a roof length longer than the shorter side of the four-point polygon by the eaves and a roof width longer than the long side of the four-point polygon by the eaves is generated in the building model on the four-point polygon. A method for generating a three-dimensional building model with a roof, comprising the steps of:

Having a control device and a display device,
The control device (1) causes a display device to display a building model generated on a six-point polygon serving as a building boundary line having six vertices whose all apex angles are substantially right angles;
(2) (a) The shorter second side of the two sides adjacent to the longest side of the six-point polygon is adjacent to the longer third side of the two sides adjacent to the longest side and the longest side If the longest side is longer than the fourth side, the building model on the “first four-point polygon” having four vertices with the longest side and the second side as boundaries is added to the building model from the longest side. A first main roof having a roof length that is longer than the second side, a roof width that is longer than the second side, or a roof length that is longer than the second side and a roof that is longer than the longest side A building model on a "second four-point polygon" having four vertices having the third side and the fourth side as boundaries, along with a second "main roof" having a width, Display a “slave roof” with a shorter roof length on the display device,
(B) When the second side is shorter than the fourth side, the building model on the “second four-point polygon” has a roof length longer by the eaves than the third side and a roof length longer than the fourth side. A first "main roof" having a roof width longer only by the eaves, or a second "main roof" having a roof length longer by the eaves than the fourth side and a roof width longer by the eaves than the third side A three-dimensional building model with a roof that executes a process of causing a display device to display a “slaved roof” having a roof length shorter than the longest side on a building model on the “first four-point polygon”.

Having a control device and a display device,
The control device includes: (1) a process of displaying a building model on a display device on a four-point polygon serving as a building boundary line having four vertices, all of the apex angles being substantially right angles;
(2) (a) In the first case, the building model on the four-point polygon has a roof length longer than the long side of the four-point polygon by the eaves, and a roof width longer than the short side of the four-point polygon by the eaves. Display the roof on the display device,
(B) In the second case, a roof model having a roof length longer than the shorter side of the four-point polygon by the eaves is displayed on the building model on the four-point polygon having a roof width longer by the eaves than the longer side of the four-point polygon. An apparatus for generating a three-dimensional roofed building model that executes processing to be displayed on the apparatus.