JPH0567219A - Three-dimensional graphic hidden-surface elimination processing system - Google Patents
Three-dimensional graphic hidden-surface elimination processing systemInfo
- Publication number
- JPH0567219A JPH0567219A JP3227904A JP22790491A JPH0567219A JP H0567219 A JPH0567219 A JP H0567219A JP 3227904 A JP3227904 A JP 3227904A JP 22790491 A JP22790491 A JP 22790491A JP H0567219 A JPH0567219 A JP H0567219A
- Authority
- JP
- Japan
- Prior art keywords
- processing
- hidden
- dimensional graphic
- dimensional
- viewpoint
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
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- Digital Computer Display Output (AREA)
- Image Generation (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は，３次元ソリッドモデル
等を扱うデータ処理装置において，隠面消去処理を高速
化した３次元図形隠面消去処理方式に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a three-dimensional figure hidden surface erasing processing system for accelerating hidden surface erasing processing in a data processing device which handles a three-dimensional solid model or the like.
【０００２】コンピュータの利用が多方面に広がるにつ
れ，従来のテキスト主体の情報表示方法から，グラフィ
ックを多用した，より視覚的な表示方法の利用が増えて
きている。特に，３次元の図形を表示する用途がＣＡ
Ｄ，ＣＧ分野で増加してきており，多くの３次元図形の
表示方法が考案されているが，一般に３次元図形の表示
処理は時間がかかるため，その表示処理の高速化が必要
とされている。[0002] As the use of computers has expanded in various fields, the use of more visual display methods using a lot of graphics has been increasing from the conventional text-based information display method. In particular, CA is used for displaying three-dimensional figures.
Although the number of D and CG fields has been increasing and many methods for displaying three-dimensional figures have been devised, since the display processing of three-dimensional figures generally takes time, it is necessary to speed up the display processing. ..
【０００３】[0003]
【従来の技術】３次元ソリッドモデル等の３次元図形を
表示する際には，通常，物体の表面を近似して多数のポ
リゴンに分割するが，視点から見て奥にあるポリゴンが
手前のポリゴンに隠されている場合に，奥のポリゴンを
見えないようにする隠面消去処理が必要となる。これら
の処理アルゴリズムとして，従来，例えばＺバッファ
法，スキャンライン法などが考案されている。2. Description of the Related Art When a three-dimensional figure such as a three-dimensional solid model is displayed, the surface of an object is usually approximated and divided into a large number of polygons. When hidden in the background, hidden surface removal processing is required to make the inner polygons invisible. Conventionally, for example, a Z buffer method, a scan line method, etc. have been devised as these processing algorithms.
【０００４】Ｚバッファ法は，３次元空間に対応するよ
うなメモリ・バッファを持ち，そのバッファに物体が存
在する位置を示す情報を設定しておいて，視点側から視
線方向にたどった場合に，その視線が最初に物体と交差
する面を見える面と判断する方法である。スキャンライ
ン法では，高さ方向でスライスした物体の断面につい
て，視線による走査を行うことにより，隠面消去処理を
行う。The Z-buffer method has a memory buffer corresponding to a three-dimensional space, sets information indicating a position where an object exists in the buffer, and sets the information in the direction of the line of sight from the viewpoint side. ， It is a method to judge the surface where the line of sight first intersects with the object as the visible surface. In the scan line method, the hidden surface removal process is performed by scanning the cross section of the object sliced in the height direction by the line of sight.
【０００５】[0005]
【発明が解決しようとする課題】以上のような従来の手
法により隠面処理を行った場合，多量の３次元ポリゴン
について隠面処理を行う必要があるため，多くの計算時
間が必要となり，図形表示などの処理が遅くなるという
問題があった。When the hidden surface processing is performed by the conventional method as described above, it is necessary to perform the hidden surface processing for a large amount of three-dimensional polygons, which requires a lot of calculation time, and There is a problem that processing such as display becomes slow.
【０００６】本発明は上記問題点の解決を図り，隠面処
理の対象となるポリゴンの数を事前に減らすことによ
り，処理の高速化を可能とすることを目的としている。An object of the present invention is to solve the above problems and to speed up the processing by reducing the number of polygons to be hidden surface processing in advance.
【０００７】[0007]
【課題を解決するための手段】図１は本発明の原理説明
図である。特に，図１の（イ）は本発明に係る処理構成
図，（ロ）は本発明の説明のための隠面消去処理対象の
物体を上から見た図である。FIG. 1 illustrates the principle of the present invention. In particular, FIG. 1A is a processing configuration diagram according to the present invention, and FIG. 1B is a diagram of an object as a hidden surface removal processing object as viewed from above for explaining the present invention.
【０００８】図１において，１０はＣＰＵおよびメモリ
等からなるデータ処理装置，１１は法線チェックによる
表示要素選択処理手段，１２は隠面消去処理手段，１３
はグラフィックディスプレイ等の表示装置，Ｖは視方向
ベクトル，Ｓ１〜Ｓ４は表示対象となっている物体の
面，Ｎ１〜Ｎ４は法線ベクトルを表す。In FIG. 1, reference numeral 10 is a data processing device including a CPU and memory, 11 is a display element selection processing means by normal line check, 12 is a hidden surface removal processing means, 13
Is a display device such as a graphic display, V is a viewing direction vector, S1 to S4 are surfaces of an object to be displayed, and N1 to N4 are normal vectors.
【０００９】データ処理装置１０は，物体等の３次元幾
何データをもとに，３次元図形を表示装置１３に表示す
る装置である。本発明では，３次元図形を表示するにあ
たって，まず法線チェックによる表示要素選択処理手段
１１により，表示する３次元図形に対する視方向ベクト
ルＶと３次元図形を構成する面の法線ベクトルＮ１，Ｎ
２，…のなす角度から，その面が視点に対して表側を向
いているか裏側を向いているかを判定し，視点に対して
表側を向いている面だけを隠面処理対象として選択す
る。The data processing device 10 is a device for displaying a three-dimensional figure on the display device 13 based on three-dimensional geometric data of an object or the like. In the present invention, in displaying a three-dimensional figure, first, the display element selection processing means 11 by checking the normal line, the viewing direction vector V for the three-dimensional figure to be displayed and the normal vectors N1 and N of the surfaces forming the three-dimensional figure.
From the angle formed by 2, ..., it is determined whether the surface faces the front side or the back side with respect to the viewpoint, and only the surface facing the front side with respect to the viewpoint is selected as the hidden surface processing target.
【００１０】そして，隠面消去処理手段１２により，法
線チェックによる表示要素選択処理手段１１によって選
択された処理対象の面について，従来技術によるＺバッ
ファ法やスキャンライン法などを用いた隠面消去処理を
行う。Then, the hidden surface erasing processing means 12 performs hidden surface erasing on the surface to be processed selected by the display element selection processing means 11 by the normal line check by using the Z buffer method or the scan line method according to the prior art. Perform processing.
【００１１】[0011]
【作用】図１の（ロ）に示すように，視点からの視方向
ベクトルＶと物体の各面Ｓ１〜Ｓ４の法線ベクトルＮ１
〜Ｎ４との角度を調べれば，視点からみて裏側を向いて
いるポリゴンを検出することができる。裏側を向いてい
る面は表示の必要がない面であるので，これを隠面消去
処理の前段階で隠面処理対象から外す。これにより，隠
面処理対象となるポリゴン数を減らして処理を高速化す
ることが可能になる。As shown in FIG. 1B, the view direction vector V from the viewpoint and the normal vector N1 of each surface S1 to S4 of the object.
By examining the angle with respect to N4, it is possible to detect the polygon facing the back side from the viewpoint. Since the surface facing the back side is the surface that does not need to be displayed, it is removed from the hidden surface processing target before the hidden surface removal processing. This makes it possible to reduce the number of polygons to be hidden and to speed up the processing.
【００１２】[0012]
【実施例】図２は本発明の実施例説明図であって，表示
対象を上から見た図を示している。以下の本実施例の説
明では，面の法線ベクトルは物体の外側へ向かい，視方
向ベクトルは視点から物体側へ向かうものとする。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 2 is an explanatory view of an embodiment of the present invention, showing a view of a display object from above. In the following description of the present embodiment, it is assumed that the normal vector of the surface goes to the outside of the object and the view direction vector goes from the viewpoint to the object side.
【００１３】図２の（イ）に示すように，視方向ベクト
ルＶと面Ｓ１の法線ベクトルＮ１との角度の絶対値が９
０°より大きい場合，その面Ｓ１は視線に対して表側を
向いており，見える可能性がある。一方，図２の（ロ）
に示すように，視方向ベクトルＶと面Ｓ２の法線ベクト
ルＮ２との角度の絶対値が９０°より小さい場合，その
面Ｓ２は視線に対して裏側を向いているので不可視であ
る。As shown in FIG. 2A, the absolute value of the angle between the view direction vector V and the normal vector N1 of the surface S1 is 9
When it is larger than 0 °, the surface S1 faces the front side with respect to the line of sight and may be visible. On the other hand, (b) in Figure 2
As shown in, when the absolute value of the angle between the view direction vector V and the normal vector N2 of the surface S2 is smaller than 90 °, the surface S2 faces the back side with respect to the line of sight and is invisible.
【００１４】すなわち，図２の（ハ）に示す法線ベクト
ルＮc ，Ｎd のように，視方向ベクトルＶに対して，斜
線を施した不可視領域に法線ベクトルがあるとき，その
法線ベクトルＮc ，Ｎd の面は不可視である。それ以外
の可視領域にある法線ベクトルＮa ，Ｎb は表側を向い
ているので可視である。そこで，その表側を向いている
面だけを選択して隠面処理の対象とすることにより，処
理対象のポリゴン数を減らす。That is, when the normal vector is in the invisible region shaded with respect to the view direction vector V, as in the normal vectors Nc and Nd shown in FIG. 2C, the normal vector Nc , Nd are invisible. The normal vectors Na and Nb in the other visible regions are visible because they face the front side. Therefore, the number of polygons to be processed is reduced by selecting only the surface facing the front side and subjecting it to the hidden surface processing.
【００１５】図３は本発明の一実施例処理フローを示す
図であって，特に図１の（イ）に示す法線チェックによ
る表示要素選択処理手段１１による処理の流れを示して
いる。FIG. 3 is a diagram showing a processing flow of an embodiment of the present invention, and particularly shows a processing flow by the display element selection processing means 11 by the normal line check shown in FIG.
【００１６】(a) まず，物体の面αを構成する３次元幾
何データをもとに，面αの法線ベクトルを計算する。も
ちろん，この計算は３次元幾何データ中に法線ベクトル
のデータが含まれている場合には不要である。(A) First, the normal vector of the surface α is calculated based on the three-dimensional geometric data that constitutes the surface α of the object. Of course, this calculation is not necessary when the normal vector data is included in the three-dimensional geometric data.
【００１７】(b) 次に，面αの法線ベクトルと視線の方
向ベクトル（視方向ベクトル）との角度θを計算する。 (c) 角度θの絶対値がπ／２以下であるかどうかを判定
する。π／２以下の場合，その面は裏側を向いているの
で，表示処理は不要とする。(B) Next, the angle θ between the normal vector of the plane α and the direction vector of the line of sight (viewing direction vector) is calculated. (c) Determine whether the absolute value of the angle θ is π / 2 or less. In the case of π / 2 or less, the display surface is not necessary because the surface faces the back side.
【００１８】(d) 角度θの絶対値がπ／２より大きい場
合，隠面消去処理へ進む。この隠面消去処理は，従来技
術と同様でよいので，ここでの詳しい説明は省略する。 例えば面αの法線ベクトルをａ＝（ａx ，ａy ，ａz）
とし，視方向ベクトルをｄ＝（ｄx ，ｄy ，ｄz ）とす
ると，上記処理(b) ，(c) は，両ベクトルａ，ｄの内積
の計算と判定により処理可能であり， ａ・ｄ ≦ ０ の真偽によって，処理することができる。なお，視方向
ベクトルを視点側からではなく，物体側から逆にとる
と，上記内積の正負の判定も逆になる。(D) When the absolute value of the angle θ is larger than π / 2, the hidden surface erasing process is performed. This hidden surface removal processing may be the same as that of the conventional technique, and a detailed description thereof will be omitted here. For example the normal vector of the plane α a = (a x, a y, a z)
And the viewing direction vector is d = (d x , d y , d z ), the above processes (b) and (c) can be processed by calculating and determining the inner product of both vectors a and d. It can be processed according to the truth of d ≤ 0. It should be noted that if the viewing direction vector is reversed from the object side rather than from the viewpoint side, the positive / negative determination of the inner product is also reversed.
【００１９】図４は本発明の実施例に係る表示要素が曲
面の場合の例を示している。表示対象となっている物体
の面等の表示要素が平面の場合には，既に説明した基本
的処理だけで本発明を実施することができる。しかし，
表示要素が曲面の場合には，面の法線を一意に決定でき
ないので，前述したような処理をそのまま適用すること
はできない。FIG. 4 shows an example in which the display element according to the embodiment of the present invention is a curved surface. When the display element such as the surface of the object to be displayed is a plane, the present invention can be implemented only by the basic processing described above. However,
When the display element is a curved surface, the normal of the surface cannot be uniquely determined, and therefore the above-described processing cannot be applied as it is.
【００２０】そこで，図４の（イ）に示す方式では，面
の法線を求める代わりに，面の各頂点の法線ベクトルＮ
１，Ｎ２，Ｎ３，Ｎ４を求め，各頂点ごとに可視／不可
視の判定を実施する。すべての頂点が不可視であった場
合には，表示処理を行わず，１つでも可視と判定される
頂点があった場合には，面が見える可能性があるため，
隠面消去処理へと進める。Therefore, in the method shown in FIG. 4A, instead of obtaining the normal line of the surface, the normal vector N of each vertex of the surface is obtained.
1, N2, N3, N4 are obtained, and visible / invisible determination is performed for each vertex. If all vertices are invisible, display processing is not performed, and if even one vertex is determined to be visible, the face may be visible, so
Proceed to the hidden surface removal process.
【００２１】図４の（ロ）に示すように，球面や円筒面
のような面上の法線が大きく変化する曲面の場合には，
前述の図４の（イ）で説明した処理だけでは，正しく処
理できないことがある。面の各頂点の法線ベクトルをＮ
１，Ｎ２とすると，図４の（ロ）に示す円筒面は「不可
視」であると判定されるからである。しかし，実際に
は，この面の法線ベクトルは様々な方向を向いており，
「可視」と判定されなければならない。As shown in FIG. 4B, in the case of a curved surface such as a spherical surface or a cylindrical surface whose normal line changes greatly,
In some cases, the processing described above with reference to FIG. 4A may not be performed correctly. Set the normal vector of each vertex of the surface to N
This is because the cylindrical surface shown in (b) of FIG. 4 is determined to be “invisible” when set to 1, N2. However, in reality, the normal vector of this surface points in various directions,
It must be judged as "visible".
【００２２】このような面の場合には，全体の面をそれ
ぞれ平面に近似した適当なポリゴンに分割し，分割した
各ポリゴンごとにその法線ベクトルを計算して，可視／
不可視の判定を行い，その結果により隠面処理対象の面
を選択する。In the case of such a surface, the entire surface is divided into appropriate polygons each approximated to a plane, the normal vector of each divided polygon is calculated, and the visible / visible
Invisible is determined, and the surface to be hidden is selected based on the result.
【００２３】以上，隠面消去処理について説明したが，
３次元線画図形の場合の隠線処理も同様であり，本発明
にいう隠面には，その面を構成する辺の隠線も含まれ
る。The hidden surface removal processing has been described above.
The same applies to the hidden line processing in the case of a three-dimensional line drawing figure, and the hidden surface referred to in the present invention includes the hidden lines of the sides forming the surface.
【００２４】[0024]
【発明の効果】以上説明したように，本発明によれば，
３次元図形の隠面消去処理の前段階において，不要な表
示要素を消去することにより，隠面消去処理を高速化す
ることができるようになる。As described above, according to the present invention,
By deleting unnecessary display elements before the hidden surface erasing process of the three-dimensional figure, the hidden surface erasing process can be speeded up.
【図１】本発明の原理説明図である。FIG. 1 is a diagram illustrating the principle of the present invention.
【図２】本発明の実施例説明図である。FIG. 2 is an explanatory diagram of an embodiment of the present invention.
【図３】本発明の一実施例処理フローを示す図である。FIG. 3 is a diagram showing a processing flow of an embodiment of the present invention.
【図４】本発明の実施例に係る表示要素が曲面の場合の
例を示す図である。FIG. 4 is a diagram showing an example in which the display element according to the embodiment of the present invention is a curved surface.
１０ データ処理装置 １１ 法線チェックによる表示要素選択処理手段 １２ 隠面消去処理手段 １３ 表示装置 Ｖ 視方向ベクトル Ｓ１〜Ｓ４ 面 Ｎ１〜Ｎ４ 法線ベクトル 10 data processing device 11 display element selection processing means by normal line check 12 hidden surface removal processing means 13 display device V view direction vector S1 to S4 surface N1 to N4 normal vector
Claims (1)
0)における３次元図形隠面消去処理方式において，表示
する３次元図形に対する視方向ベクトル(V) と３次元図
形を構成する面の法線ベクトル(N1,N2, …) のなす角度
から，その面が視点に対して表側を向いているか裏側を
向いているかを判定し，視点に対して表側を向いている
面だけを隠面処理対象として選択する処理手段(11)と，
選択された隠面処理対象の面について隠面消去処理を行
う処理手段(12)とを備えたことを特徴とする３次元図形
隠面消去処理方式。1. A data processing device (1) for displaying a three-dimensional figure.
In the 3D figure hidden surface removal processing method in (0), from the angle formed by the view direction vector (V) for the 3D figure to be displayed and the normal vector (N1, N2, ...) of the surface forming the 3D figure, A processing means (11) for determining whether the surface faces the front side or the back side with respect to the viewpoint, and selecting only the surface facing the front side with respect to the viewpoint as a hidden surface processing target,
A three-dimensional figure hidden surface erasing method, comprising: a processing means (12) for performing a hidden surface erasing process on a selected surface to be hidden surface processing target.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3227904A JPH0567219A (en) | 1991-09-09 | 1991-09-09 | Three-dimensional graphic hidden-surface elimination processing system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3227904A JPH0567219A (en) | 1991-09-09 | 1991-09-09 | Three-dimensional graphic hidden-surface elimination processing system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH0567219A true JPH0567219A (en) | 1993-03-19 |
Family
ID=16868128
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP3227904A Withdrawn JPH0567219A (en) | 1991-09-09 | 1991-09-09 | Three-dimensional graphic hidden-surface elimination processing system |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0567219A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2000002165A1 (en) * | 1998-07-03 | 2000-01-13 | Sega Enterprises, Ltd. | Method for generating polygon data and image display using the same |
| JP2007076037A (en) * | 2005-09-12 | 2007-03-29 | Roland Dg Corp | Dividing position calculating method of three-dimensional model data and three-dimensional shaping apparatus |
| US7218321B2 (en) | 2003-03-31 | 2007-05-15 | Fujitsu Limited | Hidden line processing method for erasing hidden lines in projecting a three-dimensional model consisting of a plurality of polygons onto a two-dimensional plane |
| JP2007255989A (en) * | 2006-03-22 | 2007-10-04 | Navitime Japan Co Ltd | Navigation system, route retrieving server, terminal device, and map display method |
-
1991
- 1991-09-09 JP JP3227904A patent/JPH0567219A/en not_active Withdrawn
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2000002165A1 (en) * | 1998-07-03 | 2000-01-13 | Sega Enterprises, Ltd. | Method for generating polygon data and image display using the same |
| US6600485B1 (en) | 1998-07-03 | 2003-07-29 | Sega Enterprises, Ltd. | Polygon data generation method and image display apparatus using same |
| US7218321B2 (en) | 2003-03-31 | 2007-05-15 | Fujitsu Limited | Hidden line processing method for erasing hidden lines in projecting a three-dimensional model consisting of a plurality of polygons onto a two-dimensional plane |
| JP2007076037A (en) * | 2005-09-12 | 2007-03-29 | Roland Dg Corp | Dividing position calculating method of three-dimensional model data and three-dimensional shaping apparatus |
| JP2007255989A (en) * | 2006-03-22 | 2007-10-04 | Navitime Japan Co Ltd | Navigation system, route retrieving server, terminal device, and map display method |
| JP4550756B2 (en) * | 2006-03-22 | 2010-09-22 | 株式会社ナビタイムジャパン | Navigation system, route search server, terminal device, and map display method |
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