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Lecture Computer graphics - Chapter 6: Texture

This chapter presents the following content: Texture mapping, adding visual detail, parameterization, varieties of projections, opengl texture mapping, how to map object to texture? Texture mapping and the opengl pipeline,. | Texture Mapping 1 An Interactive Introduction to OpenGL Programming 1 Texture Mapping Important topic: nearly all objects textured Wood grain, faces, bricks and so on Adds visual detail to scenes Meant as a fun and practically useful lecture Polygonal model With surface texture 2 Adding Visual Detail Basic idea: use images instead of more polygons to represent fine scale color variation 3 Parameterization Q: How do we decide where on the geometry each color from the image should go? 4 geometry + = image texture map Option: Varieties of projections [Paul Bourke] 5 Option: unfold the surface [Piponi2000] 6 Option: make an atlas [Sander2001] charts atlas surface 7 Option: it’s the artist’s problem 8 OpenGL Texture Mapping 9 OpenGL Texture Mapping Apply a 1D, 2D, or 3D image to geometric primitives Uses of Texturing Simulating materials Reducing geometric complexity Image warping Reflections 10 An Interactive Introduction to OpenGL Programming 10 In this section, we’ll discuss texture ( . | Texture Mapping 1 An Interactive Introduction to OpenGL Programming 1 Texture Mapping Important topic: nearly all objects textured Wood grain, faces, bricks and so on Adds visual detail to scenes Meant as a fun and practically useful lecture Polygonal model With surface texture 2 Adding Visual Detail Basic idea: use images instead of more polygons to represent fine scale color variation 3 Parameterization Q: How do we decide where on the geometry each color from the image should go? 4 geometry + = image texture map Option: Varieties of projections [Paul Bourke] 5 Option: unfold the surface [Piponi2000] 6 Option: make an atlas [Sander2001] charts atlas surface 7 Option: it’s the artist’s problem 8 OpenGL Texture Mapping 9 OpenGL Texture Mapping Apply a 1D, 2D, or 3D image to geometric primitives Uses of Texturing Simulating materials Reducing geometric complexity Image warping Reflections 10 An Interactive Introduction to OpenGL Programming 10 In this section, we’ll discuss texture ( sometimes also called image ) mapping. Texture mapping augments the colors specified for a geometric primitive with the colors stored in an image. An image can be a 1D, 2D, or 3D set of colors called texels. 2D textures will be used throughout the section for demonstrations, however, the processes described are identical for 1D and 3D textures. Some of the many uses of texture mapping include: simulating materials like wood, bricks or granite reducing the complexity (number of polygons ) of a geometric object image processing techniques like image warping and rectification, rotation and scaling simulating reflective surfaces like mirrors or polished floors How to map object to texture? To each vertex (x, y, z in object coordinates), must associate 2D texture coordinates (s, t) So texture fits “nicely” over object s t x y z image geometry screen 11 Idea: Use Map Shape Map shapes correspond to various projections Planar, Cylindrical, Spherical First, map (square) texture to basic map .