1. Texture Mapping
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2. 3D Rendering Pipeline Texture Mapping 3D Primitives
3D Modeling Coordinates
Model Transformation
3D World Coordinates
Lighting
3D World Coordinates
Viewing Transformation
3D Viewing Coordinates
Projection Transformation
2D Projection Coordinates
Clipping
Texture
Mapping
2D Projection Coordinates
Viewport Transformation
2D Device Coordinates
Scan Conversion
2D Device Coordinates
Image
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3. Textures Color variation in interior of 3D polygon
When scan converting a polygon
Vary pixel colors according to values fetched from a texture y s ys x t xs
Texture
Image
Surface z
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4. Texture Surface Add Visual Detail to Surfaces of 3D Objects
With Surface Texture
Polygonal Model
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5. Overview Texture mapping methods Texture mapping applications Mapping
Filtering
Texture mapping applications
Modulation textures
Illumination mapping
Bump mapping
Environment mapping
Image-based rendering
Non-photorealistic rendering
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6. Texture Mapping Steps: Define texture
Specify mapping from texture to surface
Lookup texture values during scan conversion
(0,1)
(1,0) s v y t u
(0,0) x
Texture
Coordinate
System
Modeling
Coordinate
System
Device
Coordinate
System
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7. Texture Mapping When scan converting Device coordinate system (x,y)
Modeling coordinate system (u,v)
Texture image (t,s)
(0,1)
(1,0) s v y t u
(0,0) x
Texture
Coordinate
System
Modeling
Coordinate
System
Device
Coordinate
System
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8. Texture Mapping 2D projective transformation
Texture coordinate system (t,s) to
Device coordinate system (x,y)
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9. Texture Mapping Scan conversion Interpolate texture coordinates
Distortion due to bilinear interpolation approximation
Cut polygons into smaller ones, or
Perspectively divide at each pixel
(u1, v1) α β γ
(u2, v2)
(u3, v3)
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10. Texture Mapping Corrected Interpolation Linear Interpolation
of Texture Coordinate
Corrected Interpolation
with Perspective Divide
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11. Texture Mapping Texture mapping methods Texture mapping applications
Filtering
Texture mapping applications
Modulation textures
Illumination mapping
Bump mapping
Environment mapping
Image-based rendering
Non-photorealistic rendering
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12. Texture Filtering
Must sample texture to determine color at each pixel in image y s ys x t xs z
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13. Texture Filtering Aliasing is a problem Point Sampling Area Filtering
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14. Texture Filtering Ideally, use elliptically shaped convolution filters
In practice, use rectangles
Texture
Screen
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15. Texture Filtering Size of filter depends on projective warp
Prefiltering images
Mip maps
Summed area tables s ys s ys
Texel
Texel
Pixel
Pixel t xs t xs
Magnification
Minification
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16. Mip Maps Keep textures prefiltered at multiple resolutions
For each pixel, linearly interpolate between two closest levels (e.g., trilinear filtering)
Fast and easy for hardware
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17. Overview Texture mapping methods Texture mapping applications Mapping
Filtering
Texture mapping applications
Modulation textures
Illumination mapping
Bump mapping
Environment mapping
Image-based rendering
Non-photorealistic rendering
cgvr.korea.ac.kr

18. Modulation Texture Map Texture Values to Scale Factor Wood Texture
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19. Illumination Mapping Map Texture Values to Surface Material ParameterKA KD KS KT n
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20. Bump Mapping Map Texture Values to Perturbations of Surface Normals
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21. Bump Mapping
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22. Environmental Mapping
Map Texture Values to the Environment Map
Surface
Pixel Projection
onto Environment
Map
Pixel Area
Projection
Reference Point
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23. Image-Based Rendering
Map Photographic Textures to Provide Details for Coarsely Detailed Polygonal Model
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24. Nonphotorealistic Rendering
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25. Summary Texture mapping methods Texture mapping applications Mapping
Filtering
Texture mapping applications
Modulation textures
Illumination mapping
Bump mapping
Environment mapping
Image-based rendering
Non-photorealistic rendering
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26. Thanks…
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