第03章视觉和OpenGL建模光照和纹理映射-d.ppt

OpenGL纹理映射 Bump mapping James F. Blinn 1978 (1983, SIGGRAPH Computer Graphics Achievement Award.) Inexpensive way of simulating wrinkles and bumps on geometry James F. Blinn: Simulation of Wrinkled Surfaces. Siggraph, 1987. OpenGL纹理映射 Bump mapping Let a texture modify the normal at each pixel, and then use this normal to compute lighting geometry Bump map Stores heights: can derive normals + Bump mapped geometry = n t b n t b 在游戏中的应用。 OpenGL纹理映射 Multitexturing More than one set of texture coords per vertex OpenGL纹理映射 Multitexturing GLSL (OpenGL Shading Language) OpenGL纹理映射 Volume texture OpenGL纹理映射 Texture tutorial 实习 Shading vase with texture 训练题目 任务III：基于Bump mapping的3D目标真实感绘制 Generate normals from height map/geometry Align normal map with the specified viewpoint geometry Compute surface shade * * * Texel sampling: Point sampling (nearest filtering)---aliasing Interpolation * Multum In Parvo: much in a small space. * target:纹理对象维度,GL_TEXTURE_1D, GL_TEXTURE_2D, GL_TEXTURE_3D; level：要Mipmap的等级; components:internalformat,内部存储格式，GL_ALPHA, GL_LUMINANCE, GL_LUMINANCE_ALPHA, GL_RGB, GL_RGBA * * * /bumpMapping/index.php / * * rmatik.uni-stuttgart.de/~engel/pre-integrated/data.html rmatik.uni-erlangen.de/External/vollib/ / * * Northwest AF University 虚拟现实技术 视觉系统 OpenGL建模 OpenGL光照 OpenGL纹理映射 第三章 视觉与OpenGL建模、光照、纹理映射(4) 视觉系统 OpenGL建模 OpenGL光照 OpenGL纹理映射 第三章 视觉与OpenGL建模、光照、纹理映射(4) Bump mapping effect of a chameleon in “Real-time Rendering” OpenGL纹理映射 What is texturing? Glue n-dimensional images onto geometric objects. + = OpenGL纹理映射 Why use texturing? More realism with a cheap way. + = (0,0) (1,0) (1,1) (0,1) (u,v) in [0,1] (u0,v0) (u1,v1) (u2,v2) OpenGL纹理映射 Texture coordinates (0,0) (1,0) (1,1) (0,1) (u,v) in [0,1] (u0,v0) (u1,v1) (u2,v2) OpenGL纹理映射 What if (u,v) 1.0 or 0.0 ? Repeat, mirror, clamp, border (-1,-1) (2,2) OpenGL纹理映射 Texture magnification Box filter (nearest-neighbor) → poor quality OpenGL纹理映射 Texture magnification Bilinear interpolation OpenGL纹理映射 Texture