3D graphics eBook - Course Materials Repository
3D graphics eBook - Course Materials Repository 3D graphics eBook - Course Materials Repository
UV mapping 223 UV mapping UV mapping is the 3D modeling process of making a 2D image representation of a 3D model. UV mapping This process projects a texture map onto a 3D object. The letters "U" and "V" are used to describe the 2D mesh [1] because "X", "Y" and "Z" are already used to describe the 3D object in model space. UV texturing permits polygons that make up a 3D object to be painted with color from an image. The image is called a UV texture map, [2] but it's just an ordinary image. The UV mapping process involves assigning pixels in the image to surface mappings on the polygon, usually done by "programmatically" copying a triangle shaped piece of the image map and pasting it onto a triangle on the object. [3] UV is the alternative to XY, it only maps into a texture space rather than into the geometric space of the object. But the rendering computation uses the UV texture coordinates to determine how to paint the three dimensional surface. In the example to the right, a sphere is given a checkered texture, first without and then with UV mapping. Without UV mapping, the checkers tile XYZ space and the texture is carved out of the sphere. With UV mapping, the The application of a texture in the UV space related to the effect in 3D. A checkered sphere, without and with UV mapping (3D checkered or 2D checkered). A representation of the UV mapping of a cube. The flattened cube net may then be textured to texture the cube. checkers tile UV space and points on the sphere map to this space according to their latitude and longitude. When a model is created as a polygon mesh using a 3D modeler, UV coordinates can be generated for each vertex in the mesh. One way is for the 3D modeler to unfold the triangle mesh at the seams, automatically laying out the triangles on a flat page. If the mesh is a UV sphere, for example, the modeler might transform it into a equirectangular projection. Once the model is unwrapped, the artist can paint a texture on each triangle individually, using the unwrapped mesh as a template. When the scene is rendered, each triangle will map to the appropriate texture from the "decal sheet".
UV mapping 224 A UV map can either be generated automatically by the software application, made manually by the artist, or some combination of both. Often a UV map will be generated, and then the artist will adjust and optimize it to minimize seams and overlaps. If the model is symmetric, the artist might overlap opposite triangles to allow painting both sides simultaneously. UV coordinates are applied per face, [3] not per vertex. This means a shared vertex can have different UV coordinates in each of its triangles, so adjacent triangles can be cut apart and positioned on different areas of the texture map. The UV Mapping process at its simplest requires three steps: unwrapping the mesh, creating the texture, and applying the texture. [2] Finding UV on a sphere UV coordinates represent a projection of the unit space vector onto the xy-plane. References [1] when using quaternions (which is standard), "W" is also used; cf. UVW mapping [2] Mullen, T (2009). Mastering Blender. 1st ed. Indianapolis, Indiana: Wiley Publishing, Inc. [3] Murdock, K.L. (2008). 3ds Max 2009 Bible. 1st ed. Indianapolis, Indiana: Wiley Publishing, Inc. External links • LSCM Mapping image (http:/ / de. wikibooks. org/ wiki/ Bild:Blender3D_LSCM. png) with Blender • Blender UV Mapping Tutorial (http:/ / en. wikibooks. org/ wiki/ Blender_3D:_Noob_to_Pro/ UV_Map_Basics) with Blender
- Page 177 and 178: Scanline rendering 172 Comparison w
- Page 179 and 180: Screen Space Ambient Occlusion 174
- Page 181 and 182: Screen Space Ambient Occlusion 176
- Page 183 and 184: Shadow mapping 178 Algorithm overvi
- Page 185 and 186: Shadow mapping 180 Drawing the scen
- Page 187 and 188: Shadow mapping 182 Further reading
- Page 189 and 190: Shadow volume 184 There is also a p
- Page 191 and 192: Shadow volume 186 The depth fail me
- Page 193 and 194: Silhouette edge 188 Silhouette edge
- Page 195 and 196: Specular highlight 190 Specular hig
- Page 197 and 198: Specular highlight 192 normalized o
- Page 199 and 200: Sphere mapping 194 Sphere mapping I
- Page 201 and 202: Stencil codes 196 Stencil codes Ste
- Page 203 and 204: Stencil codes 198 Stencils The shap
- Page 205 and 206: Stencil codes 200 [7] Wellein, G et
- Page 207 and 208: Subdivision surface 202 used a four
- Page 209 and 210: Subsurface scattering 204 Subsurfac
- Page 211 and 212: Subsurface scattering 206 External
- Page 213 and 214: Surface normal 208 If a (possibly n
- Page 215 and 216: Surface normal 210 Normal in geomet
- Page 217 and 218: Texture filtering 212 Texture filte
- Page 219 and 220: Texture mapping 214 Texture mapping
- Page 221 and 222: Texture mapping 216 constant distan
- Page 223 and 224: Texture synthesis 218 • Structure
- Page 225 and 226: Texture synthesis 220 Pattern-based
- Page 227: Texture synthesis 222 • Micro-tex
- Page 231 and 232: Vertex 226 Polytope vertices are re
- Page 233 and 234: Vertex Buffer Object 228 //Make the
- Page 235 and 236: Vertex Buffer Object 230 GLuint sha
- Page 237 and 238: Vertex Buffer Object 232 vertexes *
- Page 239 and 240: Virtual actor 234 Virtual actor A v
- Page 241 and 242: Virtual actor 236 exercises, and ev
- Page 243 and 244: Volume rendering 238 Volume ray cas
- Page 245 and 246: Volume rendering 240 Maximum intens
- Page 247 and 248: Volume rendering 242 Image-based me
- Page 249 and 250: Volumetric lighting 244 References
- Page 251 and 252: Voxel 246 • Outcast, a game made
- Page 253 and 254: Z-buffering 248 Z-buffering In comp
- Page 255 and 256: Z-buffering 250 } } display COLOR a
- Page 257 and 258: Z-fighting 252 Z-fighting Z-fightin
- Page 259 and 260: Appendix 3D computer graphics softw
- Page 261 and 262: 3D computer graphics software 256
- Page 263 and 264: 3D computer graphics software 258
- Page 265 and 266: 3D computer graphics software 260 2
- Page 267 and 268: Article Sources and Contributors 26
- Page 269 and 270: Article Sources and Contributors 26
- Page 271 and 272: Image Sources, Licenses and Contrib
- Page 273 and 274: Image Sources, Licenses and Contrib
UV mapping 224<br />
A UV map can either be generated automatically by the software application, made manually by the artist, or some<br />
combination of both. Often a UV map will be generated, and then the artist will adjust and optimize it to minimize<br />
seams and overlaps. If the model is symmetric, the artist might overlap opposite triangles to allow painting both<br />
sides simultaneously.<br />
UV coordinates are applied per face, [3] not per vertex. This means a shared vertex can have different UV coordinates<br />
in each of its triangles, so adjacent triangles can be cut apart and positioned on different areas of the texture map.<br />
The UV Mapping process at its simplest requires three steps: unwrapping the mesh, creating the texture, and<br />
applying the texture. [2]<br />
Finding UV on a sphere<br />
UV coordinates represent a projection of the unit space vector onto the xy-plane.<br />
References<br />
[1] when using quaternions (which is standard), "W" is also used; cf. UVW mapping<br />
[2] Mullen, T (2009). Mastering Blender. 1st ed. Indianapolis, Indiana: Wiley Publishing, Inc.<br />
[3] Murdock, K.L. (2008). 3ds Max 2009 Bible. 1st ed. Indianapolis, Indiana: Wiley Publishing, Inc.<br />
External links<br />
• LSCM Mapping image (http:/ / de. wikibooks. org/ wiki/ Bild:Blender<strong>3D</strong>_LSCM. png) with Blender<br />
• Blender UV Mapping Tutorial (http:/ / en. wikibooks. org/ wiki/ Blender_<strong>3D</strong>:_Noob_to_Pro/ UV_Map_Basics)<br />
with Blender
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