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Diffuse reflection 39 Interreflection Diffuse interreflection is a process whereby light reflected from an object strikes other objects in the surrounding area, illuminating them. Diffuse interreflection specifically describes light reflected from objects which are not shiny or specular. In real life terms what this means is that light is reflected off non-shiny surfaces such as the ground, walls, or fabric, to reach areas not directly in view of a light source. If the diffuse surface is colored, the reflected light is also colored, resulting in similar coloration of surrounding objects. In 3D computer graphics, diffuse interreflection is an important component of global illumination. There are a number of ways to model diffuse interreflection when rendering a scene. Radiosity and photon mapping are two commonly used methods. References [1] Scott M. Juds (1988). Photoelectric sensors and controls: selection and application (http:/ / books. google. com/ ?id=BkdBo1n_oO4C& pg=PA29& dq="diffuse+ reflection"+ lambertian#v=onepage& q="diffuse reflection" lambertian& f=false). CRC Press. p. 29. ISBN 9780824778866. . [2] P.Hanrahan and W.Krueger (1993), Reflection from layered surfaces due to subsurface scattering, in SIGGRAPH ’93 Proceedings, J. T. Kajiya, Ed., vol. 27, pp. 165–174 (http:/ / www. cs. berkeley. edu/ ~ravir/ 6998/ papers/ p165-hanrahan. pdf). [3] H.W.Jensen et al. (2001), A practical model for subsurface light transport, in ' Proceedings of ACM SIGGRAPH 2001', pp. 511–518 (http:/ / www. cs. berkeley. edu/ ~ravir/ 6998/ papers/ p511-jensen. pdf) [4] Only primary and secondary rays are represented in the figure. [5] Or, if the object is thin, it can exit from the opposite surface, giving diffuse transmitted light. [6] Paul Kubelka, Franz Munk (1931), Ein Beitrag zur Optik der Farbanstriche, Zeits. f. Techn. Physik, 12, 593–601, see The Kubelka-Munk Theory of Reflectance (http:/ / web. eng. fiu. edu/ ~godavart/ BME-Optics/ Kubelka-Munk-Theory. pdf) [7] Kerker, M. (1909). The Scattering of Light. New York: Academic. [8] Mandelstam, L.I. (1926). "Light Scattering by Inhomogeneous Media". Zh. Russ. Fiz-Khim. Ova. 58: 381. Displacement mapping Displacement mapping is an alternative computer graphics technique in contrast to bump mapping, normal mapping, and parallax mapping, using a (procedural-) texture- or height map to cause an effect where the actual geometric position of points over the textured surface are displaced, often along the local surface normal, according to the value the texture function evaluates to at each point on the surface. It gives surfaces a great sense of depth and detail, permitting in particular self-occlusion, self-shadowing and silhouettes; on the other hand, it is the most costly of this class of techniques owing to the large amount of additional geometry. For years, displacement mapping was a peculiarity of high-end rendering systems like PhotoRealistic RenderMan, while realtime APIs, like OpenGL and DirectX, were only starting to use this feature. One of the reasons for this is that the original implementation of displacement mapping required an adaptive tessellation of the surface in order to obtain enough micropolygons whose size matched the size of a pixel on the screen. Displacement mapping
Displacement mapping 40 Meaning of the term in different contexts Displacement mapping includes the term mapping which refers to a texture map being used to modulate the displacement strength. The displacement direction is usually the local surface normal. Today, many renderers allow programmable shading which can create high quality (multidimensional) procedural textures and patterns at arbitrary high frequencies. The use of the term mapping becomes arguable then, as no texture map is involved anymore. Therefore, the broader term displacement is often used today to refer to a super concept that also includes displacement based on a texture map. Renderers using the REYES algorithm, or similar approaches based on micropolygons, have allowed displacement mapping at arbitrary high frequencies since they became available almost 20 years ago. The first commercially available renderer to implement a micropolygon displacement mapping approach through REYES was Pixar's PhotoRealistic RenderMan. Micropolygon renderers commonly tessellate geometry themselves at a granularity suitable for the image being rendered. That is: the modeling application delivers high-level primitives to the renderer. Examples include true NURBS- or subdivision surfaces. The renderer then tessellates this geometry into micropolygons at render time using view-based constraints derived from the image being rendered. Other renderers that require the modeling application to deliver objects pre-tessellated into arbitrary polygons or even triangles have defined the term displacement mapping as moving the vertices of these polygons. Often the displacement direction is also limited to the surface normal at the vertex. While conceptually similar, those polygons are usually a lot larger than micropolygons. The quality achieved from this approach is thus limited by the geometry's tessellation density a long time before the renderer gets access to it. This difference between displacement mapping in micropolygon renderers vs. displacement mapping in a non-tessellating (macro)polygon renderers can often lead to confusion in conversations between people whose exposure to each technology or implementation is limited. Even more so, as in recent years, many non-micropolygon renderers have added the ability to do displacement mapping of a quality similar to what a micropolygon renderer is able to deliver, naturally. To distinguish between the crude pre-tessellation-based displacement these renderers did before, the term sub-pixel displacement was introduced to describe this feature. Sub-pixel displacement commonly refers to finer re-tessellation of geometry that was already tessellated into polygons. This re-tessellation results in micropolygons or often microtriangles. The vertices of these then get moved along their normals to archive the displacement mapping. True micropolygon renderers have always been able to do what sub-pixel-displacement achieved only recently, but at a higher quality and in arbitrary displacement directions. Recent developments seem to indicate that some of the renderers that use sub-pixel displacement move towards supporting higher level geometry too. As the vendors of these renderers are likely to keep using the term sub-pixel displacement, this will probably lead to more obfuscation of what displacement mapping really stands for, in 3D computer graphics. In reference to Microsoft's proprietary High Level Shader Language, displacement mapping can be interpreted as a kind of "vertex-texture mapping" where the values of the texture map do not alter pixel colors (as is much more common), but instead change the position of vertices. Unlike bump, normal and parallax mapping, all of which can be said to "fake" the behavior of displacement mapping, in this way a genuinely rough surface can be produced from a texture. It has to be used in conjunction with adaptive tessellation techniques (that increases the number of rendered polygons according to current viewing settings) to produce highly detailed meshes.
Page 1 and 2: 3D Rendering PDF generated using th
Page 3 and 4: Image-based lighting 64 Image plane
Page 5 and 6: References Article Sources and Cont
Page 7 and 8: 3D rendering 2 Non real-time Animat
Page 9 and 10: 3D rendering 4 The shaded three-dim
Page 11 and 12: Ambient occlusion 6 ambient occlusi
Page 13 and 14: Ambient occlusion 8 • ShadeVis (h
Page 15 and 16: Anisotropic filtering 10 will only
Page 17 and 18: Beam tracing 12 Beam tracing Beam t
Page 19 and 20: Bilinear filtering 14 Are all true.
Page 21 and 22: Binary space partitioning 16 togeth
Page 23 and 24: Binary space partitioning 18 Other
Page 25 and 26: Binary space partitioning 20 [1] Bi
Page 27 and 28: Bounding interval hierarchy 22 Prop
Page 29 and 30: Bounding volume 24 bounding boxes b
Page 31 and 32: Bump mapping 26 Bump mapping Bump m
Page 33 and 34: CatmullClark subdivision surface 28
Page 35 and 36: CatmullClark subdivision surface 30
Page 37 and 38: Conversion between quaternions and
Page 39 and 40: Cube mapping 34 Advantages Cube map
Page 41 and 42: Cube mapping 36 Related A large set
Page 43: Diffuse reflection 38 2), or, of co
Page 47 and 48: DooSabin subdivision surface 42 Ext
Page 49 and 50: False radiosity 44 False radiosity
Page 51 and 52: Geometry pipelines 46 Geometry pipe
Page 53 and 54: Global illumination 48 Rendering wi
Page 55 and 56: Gouraud shading 50 Gouraud shading
Page 57 and 58: Graphics pipeline 52 Graphics pipel
Page 59 and 60: Graphics pipeline 54 References 1.
Page 61 and 62: Hidden surface determination 56 imp
Page 63 and 64: High dynamic range rendering 58 Hig
Page 65 and 66: High dynamic range rendering 60 Ton
Page 67 and 68: High dynamic range rendering 62 Fro
Page 69 and 70: High dynamic range rendering 64 •
Page 71 and 72: Irregular Z-buffer 66 Applications
Page 73 and 74: Lambert's cosine law 68 than would
Page 75 and 76: Lambertian reflectance 70 Lambertia
Page 77 and 78: Level of detail 72 Well known appro
Page 79 and 80: Level of detail 74 Hierarchical LOD
Page 81 and 82: Newell's algorithm 76 Newell's algo
Page 83 and 84: Non-uniform rational B-spline 78 Us
Page 85 and 86: Non-uniform rational B-spline 80 of
Page 87 and 88: Non-uniform rational B-spline 82 ar
Page 89 and 90: Non-uniform rational B-spline 84 Ex
Page 91 and 92: Normal mapping 86 How it works To c
Page 93 and 94: OrenNayar reflectance model 88 Oren
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OrenNayar reflectance model 90 , ,
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Painter's algorithm 92 The algorith
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Parallax mapping 94 • Parallax Ma
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Particle system 96 A cube emitting
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Path tracing 98 History Further inf
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Path tracing 100 Scattering distrib
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Phong reflection model 102 Visual i
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Phong reflection model 104 Because
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Phong shading 106 Visual illustrati
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Photon mapping 108 Rendering (2nd p
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Photon tracing 110 Advantages and d
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Potentially visible set 112 • Can
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Potentially visible set 114 Externa
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Procedural generation 116 increases
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Procedural generation 118 • Softi
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Procedural generation 120 Reference
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Procedural texture 122 Self-organiz
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Procedural texture 124 References [
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3D projection 126 The distance of t
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Quaternions and spatial rotation 12
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Radiosity 140 Overview of the radio
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Radiosity 142 This is sometimes kno
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Radiosity 144 References [1] " Mode
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Ray casting 146 the light will reac
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Ray tracing 148 Typically, each ray
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Ray tracing 150 independence of eac
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Ray tracing 152 On June 12, 2008 In
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Reflection 154 Reflection Reflectio
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Reflection 156 Glossy Reflection Fu
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Reflection mapping 158 Cube mapping
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Render Output unit 160 Render Outpu
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Rendering 162 • indirect illumina
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Rendering 164 Ray tracing Ray traci
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Rendering 166 Academic core The imp
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Rendering 168 • 1984 Distributed
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Retained mode 170 Retained mode In
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Scanline rendering 172 Comparison w
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Screen Space Ambient Occlusion 174
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Screen Space Ambient Occlusion 176
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Shadow mapping 178 Algorithm overvi
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Shadow mapping 180 Drawing the scen
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Shadow mapping 182 Further reading
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Shadow volume 184 There is also a p
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Shadow volume 186 The depth fail me
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Silhouette edge 188 Silhouette edge
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Specular highlight 190 Specular hig
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Specular highlight 192 normalized o
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Sphere mapping 194 Sphere mapping I
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Stencil codes 196 Stencil codes Ste
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Stencil codes 198 Stencils The shap
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Stencil codes 200 [7] Wellein, G et
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Subdivision surface 202 used a four
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Subsurface scattering 204 Subsurfac
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Subsurface scattering 206 External
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Surface normal 208 If a (possibly n
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Surface normal 210 Normal in geomet
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Texture filtering 212 Texture filte
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Texture mapping 214 Texture mapping
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Texture mapping 216 constant distan
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Texture synthesis 218 • Structure
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Texture synthesis 220 Pattern-based
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Texture synthesis 222 • Micro-tex
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UV mapping 224 A UV map can either
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Vertex 226 Polytope vertices are re
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Vertex Buffer Object 228 //Make the
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Vertex Buffer Object 230 GLuint sha
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Vertex Buffer Object 232 vertexes *
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Virtual actor 234 Virtual actor A v
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Virtual actor 236 exercises, and ev
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Volume rendering 238 Volume ray cas
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Volume rendering 240 Maximum intens
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Volume rendering 242 Image-based me
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Volumetric lighting 244 References
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Voxel 246 • Outcast, a game made
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Z-buffering 248 Z-buffering In comp
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Z-buffering 250 } } display COLOR a
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Z-fighting 252 Z-fighting Z-fightin
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Appendix 3D computer graphics softw
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3D computer graphics software 256
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3D computer graphics software 258
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3D computer graphics software 260 2
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Article Sources and Contributors 26
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Article Sources and Contributors 26
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Image Sources, Licenses and Contrib
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Image Sources, Licenses and Contrib
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