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CSE 681 Texture mapping - other methods Environmental mapping Bump mapping

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CSE 681 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

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

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

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

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CSE 681 Environmental Mapping table construction by projection

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CSE 681 Hemi-cube projection construction method

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

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CSE 681 Hemi-cube reflectance look-up

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CSE 681 Examples

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CSE 681 Examples

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CSE 681 Examples

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CSE 681 Examples

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CSE 681 Examples

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CSE 681 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

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CSE 681 Bump Mapping 1.Use grey-scale image to define height field 2.Compute gradient of height field 3.Use gradient vectors to modify normal Don’t really modify surface geometry – just pretend we do by modifying normal

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CSE 681 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) + =

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

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CSE 681 Bump Mapping

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Bump Mapping Normal Vector

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

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

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CSE 681 Bump mapping examples

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CSE 681 Bump Mapping Example

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