Journal of KIISE:Computer Systems and Theory (한국정보과학회논문지:시스템및이론)

Korean Institute of Information Scientists and Engineers (한국정보과학회)
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Real-Time Rendering of a Displacement Map using an Image Pyramid

이미지 피라미드를 이용한 변위 맵의 실시간 렌더링

  • Published : 2007.06.15
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Abstract

displacement mapping enables us to add realistic details to polygonal meshes without changing geometry. We present a real-time artifacts-free inverse displacement mapping method. In each pixel, we construct a ray and trace the ray through the displacement map to find an intersection. To skip empty regions safely, we traverse the image pyramid of displacement map in top-down order. Furthermore, when the displacement map is enlarged, intersection with bilinear interpolated displacement map can be found. When the displacement map is at distance, our method supports mipmap-like prefiltering to enhance image quality and speed. Experimental results show that our method can produce correct images even at grazing view angles. Rendering speed of a test scene is over hundreds of frames per second and the influence of resolution of displacement map to rendering speed is little. Our method is simple enough to be added to existing virtual reality systems easily.

역변위 매핑은 기하정보를 증가시키지 않고, 모델에 상세함을 더하는데 사용된다. 우리는 부드럽고 정확한 굴곡을 표현할 수 있는 GPU 기반의 실시간 역변위 매핑 기법을 제안한다. 이를 위하여, 렌더될 각 픽셀에서 광선을 만들고 이를 전진시켜 나가며 변위 맵과의 교차점을 찾는다. 광선 추적을 안전하고 효율적으로 수행하기 위하여, 변위 맵을 쿼드트리 형태의 이미지 피라미드로 만들고, 이 트리를 하향식으로 탐색하며 전진해 나간다. 나아가, 변위 맵이 화면에서 확대되었을 때 선형 보간을, 그리고 화면에서 멀어져 작게 보일때는 때는 밉맵 필터링을 통해 화질을 향상시키고 렌더링을 가속화한다. 실험을 통해, 기존의 GPU 기반의 기법들과는 달리 날카로운 변위 맵에 대해 예각에서도 깨끗한 이미지를 생성하는 것을 확인하였다. 초당 수 백 프레임의 빠른 속도로 렌더링할 수 있었으며, 변위 맵의 해상도가 커져도 렌더링 속도의 저하가 적었다. 우리의 기법은 구현이 간단하고 수행속도가 빠르기 때문에 현존하는 게임이나 가상 현실 시스템 등에 쉽게 적용할 수 있다.

Keywords

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