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Texture mapping - other methods Environmental mapping Bump mapping

Texture mapping - other methods Environmental mapping Bump mapping. Review Surface Texturing. u,v mapping: map 3D point within 3D surface Quadrilateral: inverse bi-linear mapping Spherical: e.g. lattitude-longitude Triangulated: barycentric coordinates Mip-mapping: pre-filter texture map

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Texture mapping - other methods Environmental mapping Bump mapping

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  1. Texture mapping - other methodsEnvironmental mappingBump mapping CSE 681

  2. Review Surface Texturing • u,v mapping: map 3D point within 3D surface • Quadrilateral: inverse bi-linear mapping • Spherical: e.g. lattitude-longitude • Triangulated: barycentric coordinates • Mip-mapping: pre-filter texture map • Average texels, reduce resolution • Index into appropriate map based on projected pixel size CSE 681

  3. Environmental Mapping Reflect the environment off an object Use normal to index into texture that represents the environment • Procedurally • Reflection_color = f(R(u,v)) • Table look-up • Reflection_color = table(Rq(u,v),Rf (u,v)) CSE 681

  4. Procedural Environmental Mapping • Simple: ray up is blue, ray down is brown • Medium: use sinusoidals to interpolate between gray and silver for a chrome effect • Complex: compute fractal intersection CSE 681

  5. Environmental (table-based) Mapping • Use pre-constructed enclosing volume containing projected environment • Hemi-cube or hemisphere • Mip-mapping possible CSE 681

  6. Environmental Mappingtable construction by projection CSE 681

  7. Hemi-cube projection construction method CSE 681

  8. Hemi-cube image construction method Use pictures - of sky, mountains, buildings, etc. CSE 681

  9. Hemi-cube reflectance look-up CSE 681

  10. Examples CSE 681

  11. Examples CSE 681

  12. Examples CSE 681

  13. Examples CSE 681

  14. Examples CSE 681

  15. Bump Mapping • Modulate normals over surface to create visual effect of geometric detail http://www.mpi-inf.mpg.de/departments/irg3/ws0506/cg/slides/13-Texturing.pdf CSE 681

  16. Bump Mapping • Use grey-scale image to define height field • Compute gradient of height field • Use gradient vectors to modify normal • Don’t really modify surface geometry – just pretend we do by modifying normal CSE 681

  17. Bump Mapping Surface is displaced in direction of normal according to displacement in bump table, B(u,v) = + O’(u,v) B(u,v) O(u,v) CSE 681

  18. Bump Mapping Normal Vector = + O’(u,v) B(u,v) O(u,v) Display: CSE 681

  19. Bump Mapping CSE 681

  20. Bump Mapping Normal Vector

  21. Bump Mapping Normal Vector

  22. Bump Mapping Normal Vector Assume B is small - too small to deal with CSE 681

  23. Bump Mapping Normal Vector = N = D(u,v) = 0 CSE 681

  24. Bump mapping examples CSE 681

  25. Bump Mapping Example CSE 681

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