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Schlick's approximation 173 Schlick's approximation In 3D computer graphics, Schlick's approximation is a formula for approximating the bidirectional reflectance distribution function (BRDF) of metallic surfaces. It was proposed by Christophe Schlick to approximate the contributions of Fresnel terms in the specular reflection of light from conducting surfaces. According to Schlick's model, the specular reflection coefficient R is given by where is half the angle between the incoming and outgoing light directions, and is the reflectance at normal incidence (i.e. the value of the Fresnel term when ). References • Schlick, C. (1994). "An Inexpensive BRDF Model for Physically-based Rendering". Computer Graphics Forum 13 (3): 233. doi:10.1111/1467-8659.1330233. Screen Space Ambient Occlusion Screen Space Ambient Occlusion (SSAO) is a rendering technique for efficiently approximating the well-known computer graphics ambient occlusion effect in real time. It was developed by Vladimir Kajalin while working at Crytek and was used for the first time in a video game in the 2007 PC game Crysis made by Crytek. Implementation The algorithm is implemented as a pixel shader, analyzing the SSAO component of a typical game scene. scene depth buffer which is stored in a texture. For every pixel on the screen, the pixel shader samples the depth values around the current pixel and tries to compute the amount of occlusion from each of the sampled points. In its simplest implementation, the occlusion factor depends only on the depth difference between sampled point and current point. Without additional smart solutions, such a brute force method would require about 200 texture reads per pixel for good visual quality. This is not acceptable for real-time rendering on modern graphics hardware. In order to get high quality results with far fewer reads, sampling is performed using a randomly rotated kernel. The kernel orientation is repeated every N screen pixels in order to have only high-frequency noise in the final picture. In the end this high frequency noise is greatly removed by a NxN post-process blurring step taking into account depth discontinuities (using methods such as comparing adjacent normals and depths). Such a solution allows a reduction in the number of depth samples per pixel to about 16 or less while maintaining a high quality result, and allows the use of SSAO in soft real-time applications like computer games. Compared to other ambient occlusion solutions, SSAO has the following advantages: • Independent from scene complexity. • No data pre-processing needed, no loading time and no memory allocations in system memory. • Works with dynamic scenes. • Works in the same consistent way for every pixel on the screen. • No CPU usage – it can be executed completely on the GPU.
Screen Space Ambient Occlusion 174 • May be easily integrated into any modern graphics pipeline. Of course, it has its disadvantages, as well: • Rather local and in many cases view-dependent, as it is dependent on adjacent texel depths which may be generated by any geometry whatsoever. • Hard to correctly smooth/blur out the noise without interfering with depth discontinuities, such as object edges (the occlusion should not "bleed" onto objects). Games using SSAO • Crysis (2007) (Windows) [1] • Gears of War 2 (2008) (Xbox 360) [2] • S.T.A.L.K.E.R.: Clear Sky (2008) (Windows) [3] • Crysis Warhead (2008) (Windows) [1] • Bionic Commando (2009) (Windows and Xbox 360 versions) [4] • Burnout: Paradise the Ultimate Box (2009) (Windows) [5] • Empire: Total War (2009) (Windows) [6] • Risen (2009) (Windows and Xbox 360 versions) [7] • BattleForge (2009) (Windows) [8] • Borderlands (2009) (Windows and Xbox 360 versions) [9] • F.E.A.R. 2: Project Origin (2009) (Windows) [10] • Fight Night Champion (2011) (PlayStation 3 and Xbox 360) [11] • Batman: Arkham Asylum (2009) (Windows and Xbox 360 versions) [12] • Uncharted 2: Among Thieves (2009) (PlayStation 3) [13] • Shattered Horizon (2009) (Windows) [14] • NecroVision (2009) (Windows) • S.T.A.L.K.E.R.: Call of Pripyat (2009) (Windows) [15] • Red Faction: Guerrilla (2009) (Windows) [16] • Napoleon: Total War (2010) (Windows) [17] • Star Trek Online (2010) (Windows) • Just Cause 2 (2010) (Windows) [18] • Metro 2033 (2010) (Windows and Xbox 360 versions) [19] • Dead to Rights: Retribution (2010) (PlayStation 3 and Xbox 360) • Alan Wake (2010) (Xbox 360) [20] • Toy Story 3: The Video Game (2010) (PlayStation 3 and Xbox 360) [21] • Eve Online (Nvidia GPUs only) [22] [23] [24] • Halo: Reach (2010) (Xbox 360) • Transformers: War for Cybertron (2010) (PlayStation 3 and Xbox 360) [25] • StarCraft II: Wings of Liberty (2010) (Windows) (after Patch 1.2.0 released 1/12/2011) [26] • City of Heroes (2010) (Windows) [27] • ArmA 2: Operation Arrowhead (2010) (Windows) [28] • The Settlers 7: Paths to a Kingdom (2010) (Windows) [29] [30] [31] • Mafia II (2010) (Windows and Xbox 360) • Amnesia: The Dark Descent (2010) (Windows) [32] • Arcania: A Gothic Tale (2010) (Windows) [33] • Assassin's Creed: Brotherhood (2010) (PlayStation 3 and Xbox 360) [34] • Battlefield: Bad Company 2 (2010) (Windows) (uses HBAO - improved form of SSAO) [35] • James Bond 007: Blood Stone (2010) (PlayStation 3, Xbox 360 and Windows) [36]
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3D Rendering PDF generated using th
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Image-based lighting 64 Image plane
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References Article Sources and Cont
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3D rendering 2 Non real-time Animat
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3D rendering 4 The shaded three-dim
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Ambient occlusion 6 ambient occlusi
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Ambient occlusion 8 • ShadeVis (h
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Anisotropic filtering 10 will only
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Beam tracing 12 Beam tracing Beam t
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Bilinear filtering 14 Are all true.
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Binary space partitioning 16 togeth
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Binary space partitioning 18 Other
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Binary space partitioning 20 [1] Bi
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Bounding interval hierarchy 22 Prop
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Bounding volume 24 bounding boxes b
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Bump mapping 26 Bump mapping Bump m
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CatmullClark subdivision surface 28
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CatmullClark subdivision surface 30
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Conversion between quaternions and
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Cube mapping 34 Advantages Cube map
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Cube mapping 36 Related A large set
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Diffuse reflection 38 2), or, of co
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Displacement mapping 40 Meaning of
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DooSabin subdivision surface 42 Ext
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False radiosity 44 False radiosity
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Geometry pipelines 46 Geometry pipe
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Global illumination 48 Rendering wi
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Gouraud shading 50 Gouraud shading
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Graphics pipeline 52 Graphics pipel
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Graphics pipeline 54 References 1.
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Hidden surface determination 56 imp
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High dynamic range rendering 58 Hig
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High dynamic range rendering 60 Ton
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High dynamic range rendering 62 Fro
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High dynamic range rendering 64 •
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Irregular Z-buffer 66 Applications
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Lambert's cosine law 68 than would
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Lambertian reflectance 70 Lambertia
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Level of detail 72 Well known appro
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Level of detail 74 Hierarchical LOD
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Newell's algorithm 76 Newell's algo
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Non-uniform rational B-spline 78 Us
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Non-uniform rational B-spline 80 of
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Non-uniform rational B-spline 82 ar
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Non-uniform rational B-spline 84 Ex
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Normal mapping 86 How it works To c
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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
Page 127 and 128: Procedural texture 122 Self-organiz
Page 129 and 130: Procedural texture 124 References [
Page 131 and 132: 3D projection 126 The distance of t
Page 133 and 134: Quaternions and spatial rotation 12
Page 145 and 146: Radiosity 140 Overview of the radio
Page 147 and 148: Radiosity 142 This is sometimes kno
Page 149 and 150: Radiosity 144 References [1] " Mode
Page 151 and 152: Ray casting 146 the light will reac
Page 153 and 154: Ray tracing 148 Typically, each ray
Page 155 and 156: Ray tracing 150 independence of eac
Page 157 and 158: Ray tracing 152 On June 12, 2008 In
Page 159 and 160: Reflection 154 Reflection Reflectio
Page 161 and 162: Reflection 156 Glossy Reflection Fu
Page 163 and 164: Reflection mapping 158 Cube mapping
Page 165 and 166: Render Output unit 160 Render Outpu
Page 167 and 168: Rendering 162 • indirect illumina
Page 169 and 170: Rendering 164 Ray tracing Ray traci
Page 171 and 172: Rendering 166 Academic core The imp
Page 173 and 174: Rendering 168 • 1984 Distributed
Page 175 and 176: Retained mode 170 Retained mode In
Page 177: Scanline rendering 172 Comparison w
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 and 228: 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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