JP3931691B2 - Image generating apparatus and program - Google Patents

Description

次に図２のブロック図を用いて画像生成装置２２の構成を説明する。画像生成装置２２は主に、ＣＰＵ２４と、ＲＯＭ２６と、ＲＡＭ２８と、ＶＲＡＭ（ビデオＲＡＭ）３０と、ＩＦ（インタフェース）３２とを備え、これらはバス３４で相互に接続されている。
【００３５】
ＣＰＵ２４（制御手段、内包判定手段、不交差判定手段として機能する）は各種演算や制御を司り、ＲＯＭ２６には光線追跡法によって２次元画像を生成するためのプログラムが格納され、ＲＡＭ２８はプログラムを実行するための一時領域として利用され、ＶＲＡＭ３０には生成結果の２次元画像が格納される。また、ＶＲＡＭ３０に格納された２次元画像は、ＩＦ３２より接続ケーブル３８を介して表示装置３６に伝達され、表示装置３６で画像として表示される。
【００３６】
そして、図示しない操作部を利用者が操作すると、ＣＰＵ２４はＲＯＭ２６からプログラムを読み込み、画像生成処理を開始する。
図３は画像生成処理を表すフローチャートである。本処理が開始されると、まずＳ１００で光線１２を設定する。これは、視点１０を起点とし、２次元画像が投影されると仮定するスクリーン上の一点（ピクセル）を通って更に延びる半直線を設定することである。尚、本ステップでは毎回異なるスクリーン上のピクセルを選択し、全てのピクセルを選択し終えた場合は、光線の設定は行わない。
【００３７】
続いてＳ１１０では、Ｓ１００において光線１２の設定が行われたか否かによって分岐する。光線１２の設定が行われた場合はＳ１２０に進み、光線１２の設定が行われなかった場合は画像生成処理を終了する。
Ｓ１２０では、交差判定対象の設定及び選択を行う。これは、バウンディングボックス４を設定したり、その設定したバウンディングボックス４もしくは直接物体要素を選択することである。尚、バウンディングボックス４は各辺がｘｙｚ直行座標系における各座標軸に対して平行になるように設定する。
【００３８】
続いてＳ１３０で交差判定対象が存在するか否かを判定する。交差判定対象が存在する場合はＳ１４０に進み、交差判定対象が存在しない場合（例えばこの時点で全てのバウンディングボックス４との交差判定を終了してしまった場合等）は、Ｓ１００に戻って光線１２の設定を行う。
【００３９】
Ｓ１４０では、交差判定の対象がバウンディングボックス４か否かを判定する。交差判定の対象がバウンディングボックス４である場合はＳ１５０に進み、交差判定の対象がバウンディングボックス４でない場合、すなわち物体要素である場合はＳ１８０に進む。
【００４０】
Ｓ１５０では、後述するバウンディングボックス交差判定処理を実行する。続くＳ１６０では、Ｓ１５０の結果に基づいて光線１２とバウンディングボックス４とが交差するか否かによって分岐する。光線１２とバウンディングボックス４とが交差しない場合はＳ１７０に進み、光線１２とバウンディングボックス４とが交差する場合はＳ１２０に戻る。
【００４１】
Ｓ１７０では、当該バウンディングボックス４を交差判定対象から除外する。そしてＳ１２０に戻る。
一方、Ｓ１８０では、光線１２と物体要素とが交差するか否かの判定を行う。その結果に応じてＳ１９０で分岐し、交差する場合はＳ２００に進み、交差しない場合はＳ１００に戻る。
【００４２】
Ｓ２００では、光線１２と物体要素との交点を求め、その交点における光の状態を算出する。そして、射影されるスクリーン上のピクセルを設定しＶＲＡＭ３０に画像データを書き込む。書き込が終了するとＳ１００に戻る。尚、ＶＲＡＭ３０に書き込まれた画像データは、ＩＦ３２及び接続ケーブル３８を介して逐一表示装置３６に送られる。
【００４３】
ここで、Ｓ１５０のバウンディングボックス交差判定処理について詳しく説明する。図４はバウンディングボックス交差判定処理を表すフローチャートである。本処理もＣＰＵ２４で起動され実行される。
まず、Ｓ３００で不交差判定を行う。これは、図５（１）、（２）、（３）に各々示すＡｘ領域、Ａｙ領域、Ａｚ領域の和集合である不交差領域Ａ（図５（４））に視点１０が含まれるか否かを判定する。尚、Ａｘ領域は、ｘ＝Ｘｍａｘ平面によって分けられる領域のうち、バウンディングボックス４側ではない領域（ｘ＝Ｘｍａｘ平面を含まず）である。また、Ａｙ領域は、ｙ＝Ｙｍａｘ平面によって分けられる領域のうち、バウンディングボックス４側ではない領域（ｙ＝Ｙｍａｘ平面を含まず）である。また、Ａｚ領域は、ｚ＝Ｚｍｉｎ平面によって分けられる領域のうち、バウンディングボックス４側の領域（ｚ＝Ｚｍｉｎ平面を含まず）である。
【００４４】
続いて、図２のＳ３１０ではＳ３００の結果に応じて分岐する。不交差領域Ａに視点１０が存在する場合は、バウンディングボックス４と光線１２とは交差しないと判定して本処理を終了し、図３のＳ１６０へ移行する。一方、不交差領域Ａに視点１０が存在しない場合は、Ｓ３２０に進む。
【００４５】
Ｓ３２０では内包判定を行う。これは、図６（１）、（２）、（３）に示すＢｘ領域、Ｂｙ領域、Ｂｚ領域の積集合である領域Ｂ（図６（４））に視点１０が含まれるか否かを判定する。尚、Ｂｘ領域は、ｘ＝Ｘｍｉｎ平面によって分けられる領域のうち、バウンディングボックス４側の領域（ｘ＝Ｘｍｉｎ平面を含む）である。また、Ｂｙ領域は、ｙ＝Ｙｍｉｎ平面によって分けられる領域のうち、バウンディングボックス４側の領域（ｙ＝Ｙｍｉｎ平面を含む）である。また、Ｂｚ領域は、ｚ＝Ｚｍａｘ平面によって分けられる領域のうち、バウンディングボックス４側の領域（ｚ＝Ｚｍａｘ平面を含む）である。
【００４６】
前述の不交差判定によって、視点１０は不交差領域Ａに存在しない（すなわち視点は図６（５）の領域に存在する）ことがわかっているため、図６（４）に示す領域Ｂに視点１０が含まれるか否かを判定することによって、視点１０がバウンディングボックス４に内包されるか否かが判定できる（図６（６）参照）。
【００４７】
図４に戻り、Ｓ３３０ではＳ３２０の内包判定の結果によって分岐する。バウンディングボックス４に視点１０が内包されると判定された場合は、バウンディングボックス４と視点１０とは交差すると判定し、画像生成処理に戻る。一方、バウンディングボックス４に視点が内包されないと判定された場合は、Ｓ３４０に進む。
【００４８】
Ｓ３４０では面と光線１２とが交差するか否かを判定する面交差判定を行う。今までの経過から、視点１０の存在領域は不交差領域Ａでない領域からバウンディングボックス４を除いた領域（図７（１）参照）であることがわかる。更にその領域は、光線１２が、バウンディングボックス４の負頂点８を共有する３面のうちいくつの面と交差する可能性があるかによって、３つのグループに分けることができる。すなわち、光線１２が１つの面とのみ交差する可能性があるグループ（図７（２）参照）、光線１２が２つの面と交差する可能性があるグループ（図７（３）参照）、光線１２が３つの面と交差する可能性があるグループ（図７（４）参照）の３つのグループに分けられる。また、この３つのグループのうち何れに視点１０が存在するかは、Ｓ３２０の内包判定を実施した時点で判明している。このため、視点１０がどのグループに属するかに応じて、必要最低限の面とのみ面交差判定を実施する。
【００４９】
続いて、Ｓ３５０ではＳ３４０の結果に応じて分岐する。面と光線１２とが交差する場合はバウンディングボックス４と光線１２とは交差することになり、面と光線１２とが交差しない場合はバウンディングボックス４と光線１２とは交差しないことになる。そして、共にそれぞれの判定結果を保持しつつ画像生成処理に戻る。
【００５０】
尚、Ｓ３４０における面交差判定は以下に示す方法で行う。
例えば対象面がｙｚ平面に平行な面のうちＸ成分が大きい面（図８において符号４０で示す面）であった場合、交点は下記の式１で表される。
【００５１】
【数２】

対象面に存在するか否かを判定する判定式は下記の式２で表される。
【００５２】
【数３】

ここで、対象面の各要素及び交点座標に、光線を表すベクトルのＸ成分を乗じると下記の式３又は式４になる。
【００５３】
【数４】

光線１２を表すベクトルのＸ成分が正の場合は式３のようになり、負の場合は式４のようになる。式３又は式４を用いて面交差判定を行うことにより、式２を用いた場合に比べ乗算回数は増加するが除算はなくなる。尚、図９に乗算及び除算の実行時間を比較した実験結果を示す。実験の概要は、コンピューター上で乱数を発生させてその中から任意の２つの数字を選択し、乗算（０回〜３２回）を行う処理を１０００万回実行。この処理のうち、乗算にかかった時間を測定した。また、同様の処理を乗算の替わりに除算についても行った。
【００５４】
この実験によると、除算の実行時間は乗算の実行時間のおよそ１８倍かかる。したがって、式３を用いて面交差判定を行えば、面交差判定の実行時間は減少すると言える。
このように、バウンディングボックス交差判定処理において、面交差判定に比べ少ない計算量である不交差判定及び内包判定を行うことによってバウンディングボックス４と光線１２とが交差するか否かが判別できる場合ができる。また、これら不交差判定及び内包判定によってバウンディングボックス４と光線１２とが交差するか否かが判別できない場合でも、最小限の面に対してのみ交差判定をおこなうことによって、バウンディングボックス４と光線１２とが交差するか否かが確定できる。
【００５５】
したがって、本画像生成装置２によればバウンディングボックス４と光線１２とが交差するか否かが少ない計算量で判別でき、画像生成処理にかかる時間を短縮できる。
［第２実施形態］
第２実施形態の画像生成装置は、第１実施形態のバウンディングボックス交差判定処理とは別の方法のバウンディングボックス交差判定処理を行う。尚、装置の構成及びその他の処理は第１実施形態と同様であるため説明を省略する。
【００５６】
図１０は、第２実施形態のバウンディングボックス交差判定処理である。まずＳ４００で不交差判定を行う。この不交差判定は、第１実施形態における不交差判定（図４のＳ３００）と同様である。続いて、Ｓ４１０においてＳ４００の結果に応じて分岐する。不交差領域に視点１０が存在する場合は、バウンディングボックス４と視点１０とは交差しないと判定し、画像生成処理に戻る。一方、不交差領域に視点１０が存在しない場合は、Ｓ４２０に進む。
【００５７】
Ｓ４２０では、バウンディングボックス４の面と光線１２とが交差するか否かを判定する面交差判定を行う。この面交差判定は正頂点６を共有する３面に対して行う。その際、対象面において正頂点６と対角に位置する頂点を含む２辺についてその頂点と反対側一端を延長し、対象面を含む平面を２つの部分平面に分ける。そして、２つの部分平面のうち対象面を含まない方の部分平面を非交差部分平面４２（図１１参照）とする。光線１２と対象面を含む平面との交点が、非交差部分平面４２に存在する場合は、以降の面交差判定を実行せずにバウンディングボックス４と光線１２とは交差しないと判定する。
【００５８】
続いて、Ｓ４３０ではＳ４２０の結果に応じて分岐する。面と光線１２とが交差する場合はバウンディングボックス４と光線１２とは交差することになり、面と光線１２とが交差しない場合はバウンディングボックス４と光線１２とは交差しないことになる。そして、共にそれぞれの判定結果を保持しつつ画像生成処理に戻る。
【００５９】
このように、バウンディングボックス交差判定処理において、面交差判定に比べ少ない計算量である不交差判定によってバウンディングボックス４と光線１２とが交差するか否かが判別できる場合ができる。また、これら不交差判定によってバウンディングボックス４と光線１２とが交差するか否かが判別できない場合でも、６面全ての面について面交差判定を行わずに３面について行うだけでよい。そして更に、その３面との面交差判定を実行する途中においても、光線１２と該当面を含む平面との交点を求め、その交点の存在場所によって後の面交差判定を省略できる場合がある。
【００６０】
したがって、本画像生成装置２によればバウンディングボックス４と光線１２とが交差するか否かが少ない計算量で判別でき、画像生成処理にかかる時間を短縮できる。
［第３実施形態］
第３実施形態の画像生成装置は、第１実施形態及び第２実施形態のバウンディングボックス交差判定処理とは別の方法のバウンディングボックス交差判定処理を実行する。尚、装置の構成及びその他の処理は第１実施形態及び第２実施形態と同様であるため説明を省略する。
【００６１】
図１２は、第３実施形態のバウンディングボックス交差判定処理である。まずＳ５００で方向ベクトル１４の成分のうちの何れか２成分がゼロであるか否かを判定する。何れか２成分が０であった場合はＳ５１０に進み、そうでなかった場合はＳ５３０に進む。
【００６２】
Ｓ５１０では不交差判定を実行する。バウンディングボックス４を構成する面のうち負無限方向に最も位置する１面を選択する。そして、選択した１面を除く５面をそれぞれ含む５つの平面について、各平面によって２つに分けられる領域のうちその平面自体を含まず且つバウンディングボックス４側でない領域の和集合を不交差領域Ｃ（図１３参照）とし、視点１０がその不交差領域Ｃに含まれるか否かを判定する。
【００６３】
続いて、Ｓ５２０ではＳ５１０の結果に応じて分岐する。視点１０が不交差領域Ｃに存在する場合はバウンディングボックス４と光線１２とは交差しないと判定し、視点１０が不交差領域Ｃに存在しない場合はバウンディングボックス４と光線１２とは交差すると判定する。そして、共にそれぞれの判定結果を保持しつつ画像生成処理に戻る。
【００６４】
一方Ｓ５３０では面交差判定を実行する。これは、バウンディングボックス４の各面と光線１２とが交差するか否かを判定する。そして、Ｓ５４０でＳ５３０の結果に応じて分岐する。光線１２がバウンディングボックス４の何れかの面と交点を持つ場合はバウンディングボックス４と光線１２とは交差するという判定結果を保持して画像生成処理に戻る。一方、光線１２がバウンディングボックス４の何れの面とも交点を持たない場合はバウンディングボックス４と光線１２とは交差しないという判定結果を保持して画像生成処理に戻る。
【００６５】
このように、方向ベクトル１４の成分のうちの何れか２成分がゼロである場合、バウンディングボックス４と光線１２とが交差するか否かの判定が不交差判定を実行するだけで判定できる。したがって、本画像生成装置２によれば、画像生成処理にかかる時間を短縮できる。
【００６６】
以上、本実施形態を説明したが、本発明は上記の実施形態に限定されるものではなく種々の態様を取ることができる。例えば第３実施形態において、座標軸の何れか１軸が方向ベクトル１４と平行になるように座標系を設定してもよい。このようにすれば、常に方向ベクトル１４の成分のうちの何れか２成分がゼロになり、常に不交差判定が実行できる。
【００６７】
また、第１実施形態においてバウンディングボックス交差判定処理は、不交差判定・内包判定・面交差判定の順に行ったが、内包判定・不交差判定・面交差判定の順に行うことも可能である。更に、内包判定と面交差判定のみを行うようにすることも可能である。このようにしても、従来の画像生成装置より画像生成処理にかかる時間を短縮できる。
【００６８】
また、バウンディングボックス４が所定の大きさより大きい場合だけ内包判定を実行するようにしてもよい。この所定の大きさについては、視点１０がバウンディングボックス４に内包される確率（バウンディングボックス４が占める領域の体積を視点１０が存在する可能性のある領域の体積で割ったもの）と、面交差判定及び内包判定の計算量とを算出し、最も効率的な内包判定の実行可否が判断できるように画像生成処理中に定める方法が考えられる。
【図面の簡単な説明】
【図１】 バウンディングボックスを用いた光線追跡法の３次元モデルの説明図である。
【図２】 画像生成装置のブロック図である。
【図３】 第１実施形態の画像生成処理を表すフローチャートである。
【図４】 第１実施形態のバウンディングボックス交差判定処理を表すフローチャートである。
【図５】 第１実施形態の不交差判定を説明するための３次元モデルである。
【図６】 第１実施形態の内包判定を説明するための３次元モデルである。
【図７】 第１実施形態の面交差判定を説明するための３次元モデルである。
【図８】 第１実施形態の面交差判定一例を説明するための３次元モデルである。
【図９】 乗算と除算の実行時間を比較した実験の概要及び結果である。
【図１０】 第２実施形態のバウンディングボックス交差判定処理を表すフローチャートである。
【図１１】 第２実施形態の面交差判定を説明するための３次元モデルである。
【図１２】 第３実施形態のバウンディングボックス交差判定処理を表すフローチャートである。
【図１３】 第３実施形態の不交差判定を説明するための３次元モデルである。
【符号の説明】
２…３次元空間、４…バウンディングボックス、６…正頂点、８…負頂点、１０…視点、１２…光線、１４…方向ベクトル、２２…画像生成装置、２４…ＣＰＵ、２６…ＲＯＭ、２８…ＲＡＭ、３０…ＶＲＡＭ、３２…ＩＦ、３４…バス、３６…表示装置、３８…接続ケーブル。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image generation apparatus using a ray tracing method.
[0002]
[Prior art]
In the ray tracing method, an image is traced from the viewpoint in the direction of an object, and if the ray intersects with the object, the light state of the object at the intersection is obtained and projected onto an image plane (screen) to obtain a two-dimensional image. Is a method for generating Although it is necessary to obtain the intersection between the ray and the object, it takes a very long time to calculate the intersection. Therefore, various speed-up methods have been devised, and one of them is a method using a bounding volume.
[0003]
The bounding volume includes one or more objects, and has a shape of a sphere or a rectangular parallelepiped (this case is particularly referred to as a “bounding box”). Before determining the intersection of a ray and an object, determine whether the bounding volume containing the object and the ray intersect, and obtain the intersection of the ray and the object only when the bounding volume and the ray intersect , Reducing unnecessary intersection calculation.
[0004]
[Problems to be solved by the invention]
However, even if such a method is used, the calculation amount is still very large, and it takes a long time to obtain an image. Therefore, an object of the present invention is to provide an image generation apparatus and program capable of reducing the amount of calculation and shortening the time to obtain a two-dimensional image, particularly when a bounding box which is one of the bounding volumes is used.
[0005]
[Means for Solving the Problems and Effects of the Invention]
The image generation apparatus according to claim 1, wherein the control unit is configured to perform a plane intersection determination (any one of six surfaces constituting a bounding box made of a rectangular parallelepiped including a three-dimensional object). The bounding box having a surface determined to intersect with the ray is selected, and the intersection with the ray is obtained only for the three-dimensional object included in the bounding box. Perform intersection calculation. Further, the inclusion determination unit executes the inclusion determination (determination as to whether or not the viewpoint is included in the bounding box) according to a command from the control unit. Then, the control means first causes the inclusion determination means to execute the inclusion determination, and if it is determined by the inclusion determination that the viewpoint is included in the bounding box, the bounding box and the ray intersect without performing the plane intersection determination. Then, when it is determined that the viewpoint is not included by the inclusion determination, the plane intersection determination is executed to determine whether the bounding box and the viewpoint intersect.
[0006]
As described above, by including the inclusion determination unit, the control unit can determine that the bounding box and the ray intersect without performing the plane intersection determination. Therefore, it is possible to reduce the number of times the control means executes the surface intersection determination, which has a higher calculation cost than the inclusion determination, and the time until the image is generated by the image generation apparatus is shortened.
[0007]
The control means may always cause the inclusion determination means to execute the inclusion determination, but generally, the smaller the bounding box, the lower the probability that the viewpoint is included in the bounding box. For this reason, an effect commensurate with the calculation amount for performing the inclusion determination cannot be obtained unless the bounding box has a certain size. Therefore, as described in claim 2, the control means determines whether or not the target bounding box is larger than a predetermined size prior to causing the inclusion determination means to execute the inclusion determination. The inclusion determination unit may execute the inclusion determination, and if it is determined that the value is small, the surface intersection determination may be performed without causing the inclusion determination unit to execute the inclusion determination.
[0008]
In this case, the inclusion determination is performed only when the calculation amount is likely to be reduced by the inclusion determination, and the inclusion determination is not performed when the possibility of the calculation amount being reduced by the inclusion determination is low. . Therefore, the calculation amount is further reduced.
The predetermined size mentioned here can be determined, for example, by experiment in consideration of the probability that the viewpoint is included in the bounding box and the amount of calculation of the plane intersection determination and the inclusion determination.
[0009]
On the other hand, the image generating apparatus according to claim 3 is the same as in claim 1 and claim 2, wherein the control means performs a surface intersection determination to select a bounding box having a surface determined to intersect with a light beam, The intersection calculation for obtaining the intersection with the light ray is executed only for the three-dimensional object included in the bounding box. Further, the non-crossing determination means performs the following non-crossing determination according to a command from the control means. That is, for three infinite planes each including three faces sharing the positive vertex among the vertices of the target bounding box, the infinite plane itself is not included in the area divided into two by each infinite plane and the bounding An area represented by a union of areas that are not on the box side is defined as a non-crossing area (see FIG. 5 (4)), and it is determined whether the viewpoint is included in the non-crossing area. In addition, regarding the straight line including the ray, when the infinity in the vector direction of the ray is set to positive infinity and the infinity in the opposite direction is set to negative infinity when viewed from the viewpoint, the vertical line is dropped from each vertex of the bounding box. The vertex whose intersection point is located in the most positive infinity direction is defined as the positive vertex, and the vertex located in the most negative infinity direction is defined as the negative vertex.
[0010]
Then, the control unit first causes the non-crossing determination unit to execute the non-crossing determination, and performs the surface crossing determination only when it is determined that the viewpoint is not included in the non-crossing region. It is determined whether or not to intersect, and if it is determined by the non-intersection determination that the viewpoint is included in the non-intersection area, it is determined that the bounding box and the ray do not intersect without executing the surface intersection determination.
[0011]
As described above, by providing the non-intersection determining unit, the control unit can determine that the bounding box and the ray do not intersect without executing the plane crossing determination. Therefore, it is possible to reduce the number of times the control means executes the plane intersection determination, which has a higher calculation cost than the non-intersection determination, and the time until the image is generated by the image generation apparatus is shortened.
[0012]
The procedure for setting the positive vertex and the negative vertex is not limited to the above-described procedure, and any procedure may be used as long as it points to substantially the same vertex as the vertex set by the above-described procedure. Also good.
In addition to the non-crossing determination unit, an inclusion determination unit may be provided as in the image generation apparatus according to the fourth aspect. In that case, the control means first causes the inclusion determination means to execute the inclusion determination, and if the determination determines that the viewpoint is included in the bounding box, the bounding box and the ray intersect without performing another determination. Judge that. On the other hand, if it is determined by the inclusion determination that the viewpoint is not included in the bounding box, the non-crossing determination means is made to execute the non-crossing determination. If it is determined by the non-crossing determination that the viewpoint is included in the non-crossing determination area, it is determined that the ray and the bounding box do not cross each other, and the non-crossing determination determines that the viewpoint is not included in the non-crossing area. If it does, the intersection determination is executed to determine whether or not the bounding box and the viewpoint intersect.
[0013]
In this way, it is possible to further reduce the number of times the control means executes the surface intersection determination, which has a higher calculation cost than the inclusion determination and the non-intersection determination, and shorten the time until the image is generated by the image generation device. Is done.
Note that the order in which the non-intersection determination and the inclusion determination are executed may be reversed. That is, as in the image generating apparatus according to claim 5, the control unit first causes the non-crossing determination unit to execute the non-crossing determination, and if the determination determines that the viewpoint is included in the non-crossing region, the control unit And the bounding box are determined not to intersect. On the other hand, when it is determined by the non-crossing determination that the viewpoint is not included in the non-crossing region, the internal determination is performed by the internal determination unit. If it is determined by the inclusion determination that the viewpoint is included in the bounding box, it is determined that the bounding box and the ray intersect without performing the plane intersection determination, and the viewpoint is not included in the bounding box by the inclusion determination. If it is determined, it may be determined whether or not the bounding box and the viewpoint intersect by executing a plane intersection determination.
[0014]
Even if it does in this way, the effect | action and effect similar to the image generation apparatus of Claim 4 are acquired.
The inclusion determination performed by the inclusion determination unit in the image generation apparatus according to the fifth aspect may be as described in the sixth aspect. That is, for three infinite planes each including three surfaces sharing a negative vertex, the region on the bounding box side among the two regions divided by each infinite plane is set as the target region, and the product set of the three target regions is If the viewpoint is included in the represented area (see FIG. 6 (4)), it is determined that the viewpoint is included in the bounding box, and the viewpoint is included in the area represented by the product set of the three target areas. If not, it is determined that the viewpoint is not included in the bounding box.
[0015]
The reason why such a determination may be made is that it is ensured that there is no viewpoint in the non-intersection area when the inclusion determination unit executes the inclusion determination. Therefore, in the above-described inclusion determination, the determination is made on the assumption that no viewpoint exists in the non-intersection area. As a result, the time until an image is generated by the image generation apparatus is shortened.
[0016]
Furthermore, as described in claim 7, in the image generating apparatus according to claim 6, the control unit selects a target region that does not include a viewpoint from the three target regions used by the inclusion determination unit in the inclusion determination. Then, the plane crossing determination may be executed only for the bounding box planes included in the infinite plane dividing the target area (see FIGS. 6A to 6 and FIG. 7).
[0017]
This is because the region where the viewpoint can exist is estimated by the non-intersection determination and the inclusion determination already performed at the stage where the control means performs the surface intersection determination. Therefore, it is only necessary to perform the plane crossing determination for the bounding box plane that may cross the light ray in the region.
[0018]
For this reason, the number of faces on which the plane intersection determination is performed can be reduced, the amount of calculation is reduced, and the time until the image is generated by the image generation apparatus is shortened.
In addition, in the image generating apparatus according to any one of claims 1 and 4 to 6, the surface on which the control unit determines whether or not to intersect with the light beam in the surface crossing determination is defined in claim 8. As described, three faces sharing a negative vertex may be selected.
[0019]
This is because when a light ray intersects with the bounding box, the light ray always passes through two surfaces, and therefore it can be said that the light ray and the bounding box intersect if one of the two passing surfaces can be confirmed. Therefore, by doing as described above, the number of planes for determining whether or not to intersect with light rays in the plane intersection determination is reduced, and the amount of calculation executed by the control means is reduced. As a result, the time until an image is generated by the image generation apparatus is shortened. Note that if you do not select three surfaces as described above, you may not be able to determine that the ray does not intersect the bounding box unless you do at least five surface intersection determinations. Thus, the time for generating an image can be greatly shortened.
[0020]
On the other hand, as in the image generating apparatus according to claim 9, the control means determines whether the light ray intersects with any of the six surfaces constituting the bounding box composed of a rectangular parallelepiped including a three-dimensional object. A bounding box having a surface determined to intersect with the ray is selected by executing (determination of whether or not), and intersection calculation for obtaining an intersection with the ray only for the three-dimensional object included in the bounding box is executed. And
The control means selects and determines three surfaces that share the positive vertex in the surface intersection determination. The positive vertex here refers to the intersection of a straight line including a ray when the infinity in the vector direction of the ray is set to positive infinity when viewed from the viewpoint, and a perpendicular line is dropped from each vertex of the bounding box on the straight line. The vertex is located in the most positive or infinite direction.
[0021]
For the reasons described above, the number of planes for determining whether or not to intersect with a ray can be reduced in the plane crossing determination, so that the amount of calculation executed by the control means is reduced and the time until an image is generated by the image generation apparatus Is shortened.
Further, as described in claim 10, the image generation apparatus according to claim 9 further includes a non-crossing determination unit, and the control unit first causes the non-crossing determination unit to execute a non-crossing determination, and by the determination Only when it is determined that the viewpoint is not included in the non-crossing area, the plane crossing determination is performed to determine whether the bounding box and the viewpoint intersect, and if the viewpoint is included in the non-crossing area by the non-crossing determination When it is determined, it may be determined that the bounding box and the light beam do not intersect without executing the plane intersection determination.
[0022]
By doing so, there arises a case where the control means can determine that the bounding box and the light beam do not intersect without executing the surface intersection determination. Therefore, it is possible to reduce the number of times the control means executes the plane intersection determination, which has a higher calculation cost than the non-intersection determination, and the time until the image is generated by the image generation apparatus is shortened.
[0023]
In addition, as described in claim 11, in the image generating apparatus according to any one of claims 1 to 10, the control unit intersects with an infinite plane including a target surface when executing the surface intersection determination. And whether or not the intersection exists in the following non-intersecting partial plane is determined. Non-intersecting partial planes are two sides including vertices that are diagonally opposite to the positive or negative vertices on the target plane of the bounding box. It is a partial plane that is divided into partial planes and that does not include the target surface of the two partial planes (see FIG. 11).
[0024]
When the control means determines that there is an intersection on the non-intersecting partial plane, the control means determines that the bounding box and the ray do not intersect without performing subsequent surface intersection determination on the bounding box.
This is because when the intersection exists in the non-intersecting partial plane, the ray does not intersect with the bounding box. Therefore, if it carries out as mentioned above, the surface which performs a surface intersection determination can be reduced and the amount of calculations can be reduced. Therefore, the time until the image is generated by the image generation device is shortened.
[0025]
In the plane intersection determination performed by the control means, the intersection coordinates between the plane including the target surface and the light beam may be obtained, and it may be determined whether or not the intersection coordinates exist on the target surface. In the plane intersection determination, it is only necessary to know whether or not the ray intersects the target plane, and it is not necessary to accurately determine the intersection coordinates.
For this reason, as described in claim 12, in the image generating apparatus according to any one of claims 1 to 10, the control means sets the bounding box so that each side of the bounding box is parallel to the coordinate axis. It is better to set and determine the intersection determination as shown below.
[0026]
(1) When the plane including the target surface is parallel to the yz plane
Judgment is made by multiplying each element and intersection coordinates of the target surface by the x component of the direction vector of the light ray.
(2) When the plane including the target surface is parallel to the xz plane
Judgment is made by multiplying each element and intersection coordinates of the target surface by the y component of the direction vector of the light ray.
[0027]
(3) When the plane including the target surface is parallel to the xy plane
Judgment is made by multiplying each element and intersection coordinates of the target surface by the z component of the direction vector of the light ray.
By doing in this way, plane crossing determination can be performed without performing division. In general, when calculation is performed using a computer, division takes time compared to other four arithmetic operations. Therefore, it is possible to avoid performing the division by doing as described above, and it is possible to provide an image generation apparatus that shortens the time until an image is generated. In addition, when each component is multiplied, even if it is a constant multiple of that component, the same operation and effect can be obtained.
[0028]
Further, the calculation method may be applied to a conventional image generation apparatus as in the image generation apparatus according to claim 13.
In that case, the same operation and effect can be obtained.
Further, in the image generation apparatus according to claim 14, as in the past, the control unit executes a surface intersection determination to select a bounding box having a surface determined to intersect with the light ray, and is included in the bounding box. The intersection calculation for obtaining the intersection with the light ray is executed only for the three-dimensional object. Moreover, the non-crossing determination means which performs the following non-crossing determination by the instruction | indication of a control means is provided. It is the sum of the regions that do not include the infinite plane itself and that are not on the bounding box side among the five infinite planes including each of the five surfaces except for one specified by the control means. This is a determination for determining whether or not a set includes a non-crossing area and a viewpoint is included in the non-crossing area.
[0029]
Then, the control means sets the bounding box so that each side of the bounding box is parallel to the coordinate axis, and in the negative infinite direction only when any two of the components of the light direction vector are zero. Designate the non-crossing determination means by designating the most positioned surface and the non-crossing determination means. As a result, when it is determined that the viewpoint is included in the non-intersection area, it is determined that the bounding box and the ray do not intersect, and when it is determined that the viewpoint is not included in the non-intersection area, the bounding box and the ray are determined. It is determined that they intersect (see FIG. 13). In addition, regarding a straight line including a light ray, infinity in the direction opposite to the vector direction of the light ray as viewed from the viewpoint is defined as negative infinity.
[0030]
In this way, if any two of the ray direction vector components are zero, whether the ray intersects the bounding box in a simple manner without the control means performing the plane crossing determination. It can be determined whether or not. Therefore, the amount of calculation can be reduced, and the time until an image is generated by the image generation apparatus is shortened.
[0031]
In addition, each unit constituting the image generation device according to any one of claims 1 to 14 may be realized on hardware, but as shown in claim 15, for causing a computer to function. It may be realized as a program.
When realized by such a program, it can be used by recording on a computer-readable recording medium such as a magnetic disk, a magneto-optical disk, a memory card, etc., and loading and starting the computer as necessary. It can also be used by loading and starting up via a network.
[0032]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[First Embodiment]
First, a three-dimensional model to be used will be described with reference to FIG. An outer cube indicated by reference numeral 2 represents a three-dimensional space, and a rectangular parallelepiped indicated by reference numeral 4 placed therein represents a bounding box. A vertex represented by reference numeral 6 represents a positive vertex, and a vertex represented by reference numeral 8 represents a negative vertex. Note that an object element (not shown) is included in the bounding box indicated by reference numeral 4.
[0033]
A point represented by reference numeral 10 represents a viewpoint, and an arrow represented by reference numeral 12 represents a light ray. And the arrow represented by the code | symbol 14 represents the direction vector of a light ray.
The bounding box 4, the viewpoint 10, and the direction vector 14 are set as follows.
[0034]
[Expression 1]

Next, the configuration of the image generation device 22 will be described with reference to the block diagram of FIG. The image generation apparatus 22 mainly includes a CPU 24, a ROM 26, a RAM 28, a VRAM (video RAM) 30, and an IF (interface) 32, which are connected to each other via a bus 34.
[0035]
The CPU 24 (functioning as a control means, an inclusion determination means, and a non-intersection determination means) manages various calculations and controls. The ROM 26 stores a program for generating a two-dimensional image by the ray tracing method, and the RAM 28 executes the program. The VRAM 30 stores a two-dimensional image as a generation result. The two-dimensional image stored in the VRAM 30 is transmitted from the IF 32 to the display device 36 via the connection cable 38 and displayed as an image on the display device 36.
[0036]
When the user operates an operation unit (not shown), the CPU 24 reads a program from the ROM 26 and starts image generation processing.
FIG. 3 is a flowchart showing image generation processing. When this process is started, the light beam 12 is first set in S100. This is to set a half line that starts from the viewpoint 10 and extends further through a point (pixel) on the screen assuming that a two-dimensional image is projected. In this step, a different pixel on the screen is selected each time, and when all the pixels have been selected, no light beam is set.
[0037]
In S110, the process branches depending on whether or not the setting of the light beam 12 is performed in S100. When the setting of the light beam 12 is performed, the process proceeds to S120, and when the setting of the light beam 12 is not performed, the image generation process is ended.
In S120, the intersection determination target is set and selected. This is to set the bounding box 4 or to select the set bounding box 4 or directly the object element. The bounding box 4 is set so that each side is parallel to each coordinate axis in the xyz orthogonal coordinate system.
[0038]
Subsequently, in S130, it is determined whether or not an intersection determination target exists. If there is an intersection determination target, the process proceeds to S140, and if there is no intersection determination target (for example, if the intersection determination with all the bounding boxes 4 has been completed at this time), the process returns to S100 to return to the ray 12 Set up.
[0039]
In S140, it is determined whether or not the intersection determination target is the bounding box 4. If the intersection determination target is the bounding box 4, the process proceeds to S150, and if the intersection determination target is not the bounding box 4, that is, an object element, the process proceeds to S180.
[0040]
In S150, a bounding box intersection determination process described later is executed. In the subsequent S160, the process branches depending on whether the ray 12 and the bounding box 4 intersect based on the result of S150. If the ray 12 and the bounding box 4 do not intersect, the process proceeds to S170, and if the ray 12 and the bounding box 4 intersect, the process returns to S120.
[0041]
In S170, the bounding box 4 is excluded from the intersection determination target. Then, the process returns to S120.
On the other hand, in S180, it is determined whether or not the light beam 12 and the object element intersect. Depending on the result, the process branches at S190, and if it intersects, it proceeds to S200, and if it does not intersect, it returns to S100.
[0042]
In S200, the intersection of the light beam 12 and the object element is obtained, and the light state at the intersection is calculated. Then, the pixels on the screen to be projected are set and the image data is written into the VRAM 30. When the writing is completed, the process returns to S100. The image data written in the VRAM 30 is sent to the display device 36 one by one via the IF 32 and the connection cable 38.
[0043]
Here, the bounding box intersection determination process in S150 will be described in detail. FIG. 4 is a flowchart showing the bounding box intersection determination process. This process is also started and executed by the CPU 24.
First, non-crossing determination is performed in S300. This is because the viewpoint 10 is included in the non-intersecting region A (FIG. 5 (4)), which is the union of the Ax region, Ay region, and Az region shown in FIGS. 5 (1), (2), and (3), respectively. Determine whether or not. The Ax area is an area (not including the x = Xmax plane) that is not on the bounding box 4 side among the areas divided by the x = Xmax plane. The Ay region is a region (not including the y = Ymax plane) that is not on the bounding box 4 side among the regions divided by the y = Ymax plane. The Az region is a region on the bounding box 4 side (not including the z = Zmin plane) among the regions divided by the z = Zmin plane.
[0044]
Subsequently, in S310 of FIG. 2, the process branches according to the result of S300. If the viewpoint 10 is present in the non-intersecting area A, it is determined that the bounding box 4 and the light ray 12 do not intersect with each other, the present process is terminated, and the process proceeds to S160 in FIG. On the other hand, when the viewpoint 10 does not exist in the non-intersection area A, the process proceeds to S320.
[0045]
In S320, the inclusion determination is performed. This is whether or not the viewpoint 10 is included in the region B (FIG. 6 (4)), which is a product set of the Bx region, the By region, and the Bz region shown in FIGS. 6 (1), (2), and (3). judge. The Bx region is a region on the bounding box 4 side (including the x = Xmin plane) among regions divided by the x = Xmin plane. The By region is a region on the bounding box 4 side (including the y = Ymin plane) among regions divided by the y = Ymin plane. The Bz region is a region (including the z = Zmax plane) on the bounding box 4 side among the regions divided by the z = Zmax plane.
[0046]
Since it is known from the above-described non-crossing determination that the viewpoint 10 does not exist in the non-crossing area A (that is, the viewpoint exists in the area of FIG. 6 (5)), the viewpoint is in the area B shown in FIG. 6 (4). By determining whether or not 10 is included, it can be determined whether or not the viewpoint 10 is included in the bounding box 4 (see FIG. 6 (6)).
[0047]
Returning to FIG. 4, the process branches in S330 depending on the result of the inclusion determination in S320. When it is determined that the viewpoint 10 is included in the bounding box 4, it is determined that the bounding box 4 and the viewpoint 10 intersect, and the process returns to the image generation process. On the other hand, if it is determined that the viewpoint is not included in the bounding box 4, the process proceeds to S340.
[0048]
In S340, a surface intersection determination is performed to determine whether or not the surface and the light ray 12 intersect. From the progress so far, it can be seen that the existence region of the viewpoint 10 is a region obtained by removing the bounding box 4 from the region that is not the non-crossing region A (see FIG. 7A). Further, the region can be divided into three groups depending on how many of the three faces that the ray 12 shares the negative vertex 8 of the bounding box 4 may intersect. That is, a group in which the ray 12 may intersect only one surface (see FIG. 7 (2)), a group in which the ray 12 may intersect two surfaces (see FIG. 7 (3)), a ray 12 is divided into three groups of groups (see FIG. 7 (4)) that may intersect three faces. Further, which of the three groups has the viewpoint 10 is known when the inclusion determination in S320 is performed. For this reason, according to which group the viewpoint 10 belongs to, the plane intersection determination is performed only with the minimum necessary plane.
[0049]
Subsequently, in S350, the process branches according to the result of S340. When the surface and the light beam 12 intersect, the bounding box 4 and the light beam 12 intersect, and when the surface and the light beam 12 do not intersect, the bounding box 4 and the light beam 12 do not intersect. Then, the process returns to the image generation process while holding the respective determination results.
[0050]
In addition, the plane crossing determination in S340 is performed by the following method.
For example, when the target surface is a surface having a large X component among surfaces parallel to the yz plane (a surface indicated by reference numeral 40 in FIG. 8), the intersection point is expressed by the following formula 1.
[0051]
[Expression 2]

A determination formula for determining whether or not the target surface exists is expressed by the following formula 2.
[0052]
[Equation 3]

Here, when each element of the target surface and the intersection point coordinates are multiplied by the X component of the vector representing the light ray, the following Expression 3 or Expression 4 is obtained.
[0053]
[Expression 4]

When the X component of the vector representing the light ray 12 is positive, the result is as in Expression 3, and when it is negative, as in Expression 4. By performing the surface intersection determination using Equation 3 or Equation 4, the number of multiplications is increased compared to the case where Equation 2 is used, but there is no division. FIG. 9 shows the experimental results comparing the execution times of multiplication and division. The outline of the experiment is that a random number is generated on a computer, two arbitrary numbers are selected from them, and a process of performing multiplication (0 to 32 times) is executed 10 million times. Of this process, the time taken for multiplication was measured. The same processing was performed for division instead of multiplication.
[0054]
According to this experiment, the execution time of division takes approximately 18 times the execution time of multiplication. Therefore, it can be said that if plane crossing determination is performed using Equation 3, the execution time of plane crossing determination is reduced.
As described above, in the bounding box intersection determination process, it is possible to determine whether or not the bounding box 4 and the light ray 12 intersect by performing the non-intersection determination and the inclusion determination, which have a smaller calculation amount than the plane intersection determination. . Even if it is not possible to determine whether or not the bounding box 4 and the light beam 12 intersect with each other by the non-intersection determination and the inclusion determination, by performing the intersection determination only on the minimum surface, the bounding box 4 and the light beam 12 are determined. It can be determined whether or not.
[0055]
Therefore, according to the present image generation apparatus 2, it can be determined with a small amount of calculation whether or not the bounding box 4 and the light beam 12 intersect, and the time required for the image generation processing can be shortened.
[Second Embodiment]
The image generation apparatus according to the second embodiment performs a bounding box intersection determination process using a method different from the bounding box intersection determination process according to the first embodiment. Note that the configuration of the apparatus and other processes are the same as those in the first embodiment, and thus description thereof is omitted.
[0056]
FIG. 10 is a bounding box intersection determination process according to the second embodiment. First, non-crossing determination is performed in S400. This non-crossing determination is the same as the non-crossing determination (S300 in FIG. 4) in the first embodiment. Subsequently, the process branches in S410 according to the result of S400. When the viewpoint 10 exists in the non-intersection area, it is determined that the bounding box 4 and the viewpoint 10 do not intersect, and the process returns to the image generation process. On the other hand, when the viewpoint 10 does not exist in the non-intersection area, the process proceeds to S420.
[0057]
In S420, a surface intersection determination is performed to determine whether or not the surface of the bounding box 4 and the light ray 12 intersect. This plane crossing determination is performed on three planes sharing the normal vertex 6. At this time, one end opposite to the vertex of the two sides including the vertex located diagonally to the normal vertex 6 on the target surface is extended, and the plane including the target surface is divided into two partial planes. The partial plane that does not include the target surface of the two partial planes is defined as a non-intersecting partial plane 42 (see FIG. 11). When the intersection of the light ray 12 and the plane including the target surface exists in the non-intersecting partial plane 42, it is determined that the bounding box 4 and the light ray 12 do not intersect without performing subsequent surface intersection determination.
[0058]
Subsequently, in S430, the process branches according to the result of S420. When the surface and the light beam 12 intersect, the bounding box 4 and the light beam 12 intersect, and when the surface and the light beam 12 do not intersect, the bounding box 4 and the light beam 12 do not intersect. Then, the process returns to the image generation process while holding the respective determination results.
[0059]
In this way, in the bounding box intersection determination process, it can be determined whether or not the bounding box 4 and the light beam 12 intersect by non-intersection determination, which has a smaller calculation amount than the surface intersection determination. Even if it is not possible to determine whether or not the bounding box 4 and the light beam 12 intersect by these non-intersection determinations, it is only necessary to perform the three planes without performing the plane intersection determination for all the six planes. Furthermore, even during the execution of the plane intersection determination with the three surfaces, the intersection between the light beam 12 and the plane including the corresponding surface may be obtained, and the subsequent surface intersection determination may be omitted depending on the location of the intersection.
[0060]
Therefore, according to the present image generation apparatus 2, it can be determined with a small amount of calculation whether or not the bounding box 4 and the light beam 12 intersect, and the time required for the image generation processing can be shortened.
[Third Embodiment]
The image generation apparatus according to the third embodiment executes a bounding box intersection determination process that is different from the bounding box intersection determination process according to the first embodiment and the second embodiment. Note that the configuration of the apparatus and other processes are the same as those in the first embodiment and the second embodiment, and a description thereof will be omitted.
[0061]
FIG. 12 is a bounding box intersection determination process according to the third embodiment. First, in S500, it is determined whether any two components of the direction vector 14 are zero. If any two components are 0, the process proceeds to S510, and if not, the process proceeds to S530.
[0062]
In S510, non-crossing determination is executed. Of the surfaces constituting the bounding box 4, one surface that is located most in the negative infinity direction is selected. Then, for the five planes including each of the five planes excluding the selected one plane, the union of the areas that do not include the plane itself and are not on the bounding box 4 side among the areas divided into two by each plane (See FIG. 13), and it is determined whether or not the viewpoint 10 is included in the non-crossing region C.
[0063]
Subsequently, in S520, the process branches according to the result of S510. When the viewpoint 10 exists in the non-crossing region C, it is determined that the bounding box 4 and the light ray 12 do not intersect. When the viewpoint 10 does not exist in the non-crossing region C, it is determined that the bounding box 4 and the light ray 12 intersect. . Then, the process returns to the image generation process while holding the respective determination results.
[0064]
On the other hand, in S530, plane crossing determination is executed. This determines whether each surface of the bounding box 4 and the light ray 12 intersect. In S540, the process branches according to the result of S530. If the ray 12 has an intersection with any surface of the bounding box 4, the determination result that the bounding box 4 and the ray 12 intersect is held, and the process returns to the image generation process. On the other hand, if the ray 12 has no intersection with any surface of the bounding box 4, the determination result that the bounding box 4 and the ray 12 do not intersect is held, and the process returns to the image generation process.
[0065]
As described above, when any two components of the direction vector 14 are zero, it is possible to determine whether or not the bounding box 4 and the light ray 12 intersect with each other only by executing the non-intersection determination. Therefore, according to the present image generation device 2, the time required for the image generation processing can be shortened.
[0066]
Although the present embodiment has been described above, the present invention is not limited to the above-described embodiment, and can take various forms. For example, in the third embodiment, the coordinate system may be set so that any one of the coordinate axes is parallel to the direction vector 14. In this way, any two components of the direction vector 14 are always zero, and the non-crossing determination can always be executed.
[0067]
In the first embodiment, the bounding box intersection determination process is performed in the order of non-intersection determination, inclusion determination, and plane intersection determination, but may be performed in the order of inclusion determination, non-intersection determination, and plane intersection determination. Furthermore, it is possible to perform only the inclusion determination and the surface intersection determination. Even in this case, the time required for the image generation process can be shortened compared to the conventional image generation apparatus.
[0068]
The inclusion determination may be executed only when the bounding box 4 is larger than a predetermined size. For this predetermined size, the probability that the viewpoint 10 is contained in the bounding box 4 (the volume of the area occupied by the bounding box 4 divided by the volume of the area where the viewpoint 10 may exist) and the plane intersection A method for calculating the amount of calculation for determination and inclusion determination and determining during the image generation process so that the most efficient determination of inclusion determination can be determined is conceivable.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of a three-dimensional model of a ray tracing method using a bounding box.
FIG. 2 is a block diagram of an image generation apparatus.
FIG. 3 is a flowchart illustrating image generation processing according to the first embodiment.
FIG. 4 is a flowchart showing bounding box intersection determination processing according to the first embodiment.
FIG. 5 is a three-dimensional model for explaining non-intersection determination according to the first embodiment.
FIG. 6 is a three-dimensional model for explaining inclusion determination according to the first embodiment.
FIG. 7 is a three-dimensional model for explaining plane crossing determination according to the first embodiment.
FIG. 8 is a three-dimensional model for explaining an example of plane intersection determination according to the first embodiment.
FIG. 9 is a summary and results of an experiment comparing execution times of multiplication and division.
FIG. 10 is a flowchart illustrating a bounding box intersection determination process according to the second embodiment.
FIG. 11 is a three-dimensional model for explaining plane crossing determination according to the second embodiment.
FIG. 12 is a flowchart illustrating a bounding box intersection determination process according to the third embodiment.
FIG. 13 is a three-dimensional model for explaining non-intersection determination according to the third embodiment.
[Explanation of symbols]
2 ... 3D space, 4 ... Bounding box, 6 ... Positive vertex, 8 ... Negative vertex, 10 ... Viewpoint, 12 ... Ray, 14 ... Direction vector, 22 ... Image generator, 24 ... CPU, 26 ... ROM, 28 ... RAM, 30 ... VRAM, 32 ... IF, 34 ... bus, 36 ... display device, 38 ... connection cable.

Claims (15)

3D using a ray tracing method that obtains an intersection of a light beam extending further from a viewpoint through a point on the screen and a three-dimensional object, calculates a light state at the intersection, and determines a color of the point on the screen. When generating a two-dimensional image of an object, a surface intersection determination is performed to determine whether any of the six surfaces constituting the bounding box made up of a rectangular parallelepiped including the three-dimensional object intersects the ray. Control means for selecting the bounding box having a surface determined to intersect with the ray and performing intersection calculation for obtaining an intersection with the ray only for the three-dimensional object included in the bounding box; In the image generating apparatus provided,
Furthermore, it comprises an inclusion determination means for executing an inclusion determination for determining whether or not the viewpoint is included in the bounding box according to a command of the control means,
The control means first causes the inclusion determination means to execute the inclusion determination, and when it is determined by the inclusion determination that the viewpoint is included in the bounding box, the bounding box is not executed without performing the plane intersection determination. And the ray intersect, and if it is determined by the inclusion determination that the viewpoint is not included, the plane intersection determination is executed to determine whether the bounding box and the viewpoint intersect An image generation apparatus characterized by the above. The image generation apparatus according to claim 1,
Prior to causing the inclusion determination means to execute the inclusion determination, the control means determines whether or not the bounding box is larger than a predetermined size. If it is determined that the bounding box is larger, the control means determines the inclusion determination to the inclusion determination means. An image generation apparatus characterized by executing the surface intersection determination without causing the inclusion determination unit to execute the inclusion determination when it is determined that the value is small. 3D using a ray tracing method that obtains an intersection of a light beam extending further from a viewpoint through a point on the screen and a three-dimensional object, calculates a light state at the intersection, and determines a color of the point on the screen. When generating a two-dimensional image of an object, a surface intersection determination is performed to determine whether any of the six surfaces constituting the bounding box made up of a rectangular parallelepiped including the three-dimensional object intersects the ray. Control means for selecting the bounding box having a surface determined to intersect with the ray and performing intersection calculation for obtaining an intersection with the ray only for the three-dimensional object included in the bounding box; In the image generating apparatus provided,
Further, of the bounding box vertices of interest, the three infinite planes each including three faces sharing the following normal vertex are included in the area divided into two by each infinite plane itself. A non-crossing region is defined as a non-crossing region, and a non-crossing determination for determining whether or not the viewpoint is included in the non-crossing region is executed according to a command from the control unit. With non-intersection judging means,
The control means first causes the non-intersection determining means to execute the non-intersection determination, and executes the surface intersection determination only when the determination determines that the viewpoint is not included in the non-intersection area. It is determined whether a box and the viewpoint intersect, and if it is determined by the non-intersection determination that the viewpoint is included in the non-intersection area, the bounding box and the viewpoint are not performed without performing the plane intersection determination. An image generation apparatus, characterized in that it is determined that it does not intersect with a ray.
When the infinity of the vector direction of the light ray is set to positive infinity and the infinity of the opposite direction is set to negative infinity when viewed from the viewpoint with respect to the straight line including the light ray, a perpendicular is dropped on the straight line from each vertex of the bounding box. In this case, the vertex where the intersection point is located in the most positive infinity direction is the positive vertex, and the vertex located in the most negative infinity direction is the negative vertex. The image generation apparatus according to claim 3.
And an inclusion determination means for executing an inclusion determination for determining whether or not the viewpoint is included in the bounding box according to a command of the control means,
The control means causes the inclusion determination means to execute the inclusion determination prior to causing the non-crossing determination means to execute the non-crossing determination, and determines that the viewpoint is included in the bounding box by the determination. If it is determined that the bounding box and the ray intersect without performing another intersection determination, and if it is determined by the inclusion determination that the viewpoint is not included in the bounding box, the non-intersection is continued. When the determination means performs the non-crossing determination, and it is determined by the determination that the viewpoint is included in the non-crossing determination region, it is determined that the ray and the bounding box do not cross, and the non-crossing determination If it is determined that the viewpoint is not included in the non-intersection area, the bounding determination is performed and the bounding is performed. Image generating apparatus wherein the grayed box viewpoint and is characterized by determining whether the intersection. The image generation apparatus according to claim 3.
Furthermore, it comprises an inclusion determination means for executing an inclusion determination for determining whether or not the viewpoint is included in the bounding box according to a command of the control means,
The control means first causes the non-crossing determination means to execute the non-crossing determination, and when the determination determines that the viewpoint is included in the non-crossing area, the light ray and the bounding box do not cross each other. And when the non-intersection determination determines that the viewpoint is not included in the non-intersection area, the inclusion determination unit continuously performs the inclusion determination, and the viewpoint is included in the bounding box by the determination. If it is determined that the bounding box and the light ray intersect without performing the plane intersection determination, and if it is determined by the inclusion determination that the viewpoint is not included in the bounding box, An image generation apparatus that performs a plane intersection determination. The image generation apparatus according to claim 5,
The inclusion determination executed by the inclusion determination means is performed on a region that is on the bounding box side among two regions divided by each infinite plane, with respect to three infinite planes each including three surfaces sharing the negative vertex. If the viewpoint is included in an area represented by a product set of the three target areas, it is determined that the viewpoint is included in the bounding box, and the viewpoint is expressed by a product set of the three target areas. If the viewpoint is not included in the area to be processed, it is determined that the viewpoint is not included in the bounding box. The image generation apparatus according to claim 6.
The control means selects a target area that does not include the viewpoint from the three target areas used by the inclusion determination means in the inclusion determination, and applies to a plane included in an infinite plane that divides the target area The image generation apparatus is characterized in that the plane intersection determination is executed. In the image generation device according to claim 1 or any one of claims 4 to 6,
When the infinity of the vector direction of the light ray is set to positive infinity and the infinity of the opposite direction is set to negative infinity when viewed from the viewpoint with respect to the straight line including the light ray, a perpendicular is dropped on the straight line from each vertex of the bounding box. When the vertex located in the most positive / infinity direction is the positive vertex and the vertex located in the most negative infinity direction is the negative vertex,
The image generating apparatus according to claim 1, wherein the control unit selects and determines three surfaces sharing a negative vertex in the surface intersection determination. 3D using a ray tracing method that obtains an intersection of a light beam extending further from a viewpoint through a point on the screen and a three-dimensional object, calculates a light state at the intersection, and determines a color of the point on the screen. When generating a two-dimensional image of an object, a surface intersection determination is performed to determine whether any of the six surfaces constituting the bounding box made up of a rectangular parallelepiped including the three-dimensional object intersects the ray. Control means for selecting the bounding box having a surface determined to intersect with the ray and performing intersection calculation for obtaining an intersection with the ray only for the three-dimensional object included in the bounding box; In the image generating apparatus provided,
When the infinity of the vector direction of the light ray is set to positive infinity and the infinity of the opposite direction is set to negative infinity when viewed from the viewpoint with respect to the straight line including the light ray, a perpendicular is dropped on the straight line from each vertex of the bounding box. In this case, the vertex located at the most positive infinity direction is the positive vertex, the vertex located at the most negative infinity direction is the negative vertex,
The image generating apparatus according to claim 1, wherein the control unit selects and determines three surfaces sharing a normal vertex in the surface intersection determination. The image generation apparatus according to claim 9.
Further, for three infinite planes each including three faces sharing the positive vertex among the vertices of the bounding box of interest, the infinite plane itself is not included in the region divided into two by each infinite plane, and A non-crossing determination in which a region represented by a union of regions not on the bounding box side is defined as a non-crossing region, and a non-crossing determination is performed based on a command from the control unit to determine whether the viewpoint is included in the non-crossing region With means,
The control means first causes the non-intersection determining means to execute the non-intersection determination, and executes the surface intersection determination only when the determination determines that the viewpoint is not included in the non-intersection area. It is determined whether a box and the viewpoint intersect, and if it is determined by the non-intersection determination that the viewpoint is included in the non-intersection area, the bounding box and the viewpoint are not performed without performing the plane intersection determination. An image generation apparatus, characterized in that it is determined that it does not intersect with a ray. The image generation device according to any one of claims 1 to 10,
The control means obtains an intersection with an infinite plane including the target surface when performing the plane intersection determination, determines whether the intersection exists in a non-intersection partial plane shown below, and the intersection is The image generating apparatus according to claim 1, wherein if the plane exists in the non-intersecting partial plane, the bounding box and the light ray are determined not to intersect without performing the subsequent plane intersection determination on the bounding box.
When the infinity of the vector direction of the light ray is set to positive infinity and the infinity of the opposite direction is set to negative infinity when viewed from the viewpoint with respect to the straight line including the light ray, a perpendicular is dropped on the straight line from each vertex of the bounding box. In this case, when the vertex located at the most positive infinite direction is the positive vertex and the vertex located at the most negative infinite direction is the negative vertex, the intersection point is located diagonally to the positive or negative vertex on the target surface of the bounding box. For two sides including the vertex, one end opposite to the vertex is extended, the infinite plane including the target surface is divided into two partial planes, and the partial plane that does not include the target surface of the partial planes is a non-intersecting portion A plane. The image generation device according to any one of claims 1 to 10,
The image generation apparatus according to claim 1, wherein the control unit sets the bounding box so that each side of the bounding box is parallel to a coordinate axis, and determines the plane intersection determination as follows.
(1) When the plane including the target plane is parallel to the yz plane, each element and intersection coordinates of the target plane are multiplied by the x component of the direction vector of the light beam.
(2) When the plane including the target plane is parallel to the xz plane, each element and intersection coordinates of the target plane are multiplied by the y component of the direction vector of the light beam.
(3) When the plane including the target surface is parallel to the xy plane, each element and intersection coordinates of the target surface are multiplied by the z component of the direction vector of the light beam. 3D using a ray tracing method that obtains an intersection of a light beam extending further from a viewpoint through a point on the screen and a three-dimensional object, calculates a light state at the intersection, and determines a color of the point on the screen. When generating a two-dimensional image of an object, a surface intersection determination is performed to determine whether any of the six surfaces constituting the bounding box made up of a rectangular parallelepiped including the three-dimensional object intersects the ray. Control means for selecting the bounding box having a surface determined to intersect with the ray and performing intersection calculation for obtaining an intersection with the ray only for the three-dimensional object included in the bounding box; In the image generating apparatus provided,
The image generation apparatus according to claim 1, wherein the control unit sets the bounding box so that each side of the bounding box is parallel to a coordinate axis, and determines the plane intersection determination as follows.
(1) When the plane including the target plane is parallel to the yz plane, each element and intersection coordinates of the target plane are multiplied by the x component of the direction vector of the light beam.
(2) When the plane including the target plane is parallel to the xz plane, each element and intersection coordinates of the target plane are multiplied by the y component of the direction vector of the light beam.
(3) When the plane including the target surface is parallel to the xy plane, each element and intersection coordinates of the target surface are multiplied by the z component of the direction vector of the light beam. 3D using a ray tracing method that obtains an intersection of a light beam extending further from a viewpoint through a point on the screen and a three-dimensional object, calculates a light state at the intersection, and determines a color of the point on the screen. When generating a two-dimensional image of an object, a surface intersection determination is performed to determine whether any of the six surfaces constituting the bounding box made up of a rectangular parallelepiped including the three-dimensional object intersects the ray. Control means for selecting the bounding box having a surface determined to intersect with the ray and performing intersection calculation for obtaining an intersection with the ray only for the three-dimensional object included in the bounding box; In the image generating apparatus provided,
Further, for five infinite planes each including five surfaces except for one surface designated by the control means, an area that does not include the infinite plane itself and is not on the bounding box side among the areas divided into two by each infinite plane A non-crossing determination unit that executes a non-crossing determination according to a command of the control unit to determine whether or not the viewpoint is included in the non-crossing region.
The control means sets the bounding box so that each side of the bounding box is parallel to the coordinate axis, and only when any two of the components of the direction vector of the ray are zero: If the non-crossing determining means executes the non-crossing determination by designating one surface located in the negative infinity direction, and the non-crossing determination determines that the viewpoint is included in the non-crossing region, It is determined that the bounding box and the light ray do not intersect, and when it is determined by the non-intersection determination that the viewpoint is not included in the non-intersection area, it is determined that the bounding box and the light beam intersect. An image generating apparatus.
With respect to the straight line including the light ray, infinity in the direction opposite to the vector direction of the light ray as viewed from the viewpoint is defined as negative infinity. The program for functioning a computer as each means which comprises the image generation apparatus in any one of Claims 1-14.

Images