![]() Thus you cannot closely examine reflection-map images to make accurate inferences about a surface or its reflected environment.Ī lighting geometry made of a spherical or cylindrical roomĪ local environment: The radius of the room is finite reflections do not depend solely on the direction of the reflection angle. Furthermore, the texture image is usually blurred to avoid problems that occur when the curvature of a surface can cause two points that are close together to reflect widely separated points on the texture map, an effect called aliasing. Notice that the shading for all points on each face of the cube is determined by one point on the texture image, which is determined by the normal to each surface. This effect is illustrated in Figure 8-1, where collimating “lenses” indicate the effects of the remote viewer and remote source approximations. For example, the algorithm yields the same image point for every point on a large, flat surface. However, reflection angles are not exact. You can simulate complex lighting environments at low computational cost with a simple reflection map. As an object rotates, the directions of the normal vectors completely determine texture coordinates you do not have to calculate a new mapping from the surface to the texture image. For a tessellated surface, which includes correct surface-normal vectors only at vertices, the rendering algorithm calculates the texture coordinates for a point inside a triangular surface tile by interpolating the coordinates of the triangle's three vertices. These three assumptions imply that the texture coordinates for any point on a surface are determined by the viewing angle to the center of the scene and the vector normal to the surface. The direction of the rays is from the viewpoint to the center of the scene. Effectively the viewpoint is infinitely far away. ![]() ![]() Effectively, the texture map is infinitely far away.Ī remote viewer: The reflection geometry is further simplified by assuming that all rays are parallel between the viewpoint and object's surface. An image that lies on a sphere surrounding the scene.Ī remote environment: The reflection geometry is simplified, so that only the direction of the reflection vector determines texture coordinates. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |