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Published byOswald O’Neal’ Modified over 2 years ago

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Clipless Dual-Space Bounds for Faster Stochastic Rasterization Samuli Laine Timo Aila Tero Karras Jaakko Lehtinen NVIDIA Research

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(x,y)

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(x,y,u,v,t)

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Motion Blur

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t=0t=1

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Motion Blur

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t Accumulation Buffer [Haeberli ‘90]

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t InterleaveUVT [Fatahalian ‘09]

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t

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t

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t

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4 samples/pixel (16 UVT triples)16 samples/pixel (64 UVT triples) Scene: Assassin’s Creed, courtesy of Ubisoft InterleaveUVT [Fatahalian ‘09]

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Unique UVTs 4 samples/pixel, unique UVTs16 samples/pixel, unique UVTs Scene: Assassin’s Creed, courtesy of Ubisoft

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5D Rasterization t=0t=1 t

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5D Rasterization t=0t=1 t

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5D Rasterization t=0t=1 t

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5D Rasterization t

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t=0t=1 t ?

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5D Rasterization t=0t=1 t

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5D Rasterization t=0t=1 t ?

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5D Rasterization t=0t=1 t ?

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Pixar Algorithm t=0t=1 t t=.5

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Pixar Algorithm t=0t=1 t t=.5 XX

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Pixar Algorithm t=0t=1 t t=.5 XX

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Our Method t=0t=1 t

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Our Method t=0t=1 t

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Our Method t=0t=1 t XXX t range computed for pixel

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Our Method Determine pixels potentially covered by triangle For each pixel Compute time bounds t min,t max Enumerate samples where t min ≤ t ≤ t max For each such sample, perform 5D coverage test Same for lens bounds u min,u max and v min,v max

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Bound Computation Lens bounds computed in screen space Time bounds computed in dual space

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Lens Bounds x y u=0u= –1u= +1 film lens focal plane u screen-space x is linear with u

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Lens Bounds x y u= –1u= +1 screen-space x is linear with u

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Lens Bounds x y u=au=b screen-space x is linear with u u a b

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Time Bounds World-space affine motion Not affine in screen space, but affine in clip space Perspective causes singularities in screen space Operate in dual space

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Clip Space and Dual Space x w t=0 t=1

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Clip Space and Dual Space x w γ δ γ= –1 γ= +1

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Clip Space and Dual Space x w γ δ δ { γ= –0.5

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Clip Space and Dual Space x w γ δ

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x w γ δ

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x w γ δ

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x w γ δ δ is linear in x and w δ = x – wγ x and w are linear in t δ is linear in t t=0 t=1 t=0 t=1

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Clip Space and Dual Space x w γ δ t=0 t=1 t=0 t=1

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Clip Space and Dual Space x w γ δ t=0 t=1 t=0 t=1

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Clip Space and Dual Space x w γ δ t=0 t=1 t=0 t=1 t=a t

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Clip Space and Dual Space x w γ δ t=0 t=1 t=0 t=1 t=a t a

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Time Bounds Compute separately for x and y Intersect resulting spans If intersection is empty, skip pixel

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Recap For each triangle For each pixel Compute t, u, v bounds Cull samples outside bounds Profit

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Results Measure sample test efficiency (STE) Compare against methods that allow arbitrary sampling patterns # samples tested with full 5D test # samples hit STE =

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Results Scene: Age of Conan PC MMO, courtesy of Funcom Bbox scan Pixar Our method 41664 static23.6 motion2.79.517.721.923.7 motion x 21.36.014.620.924.0 defocus1.74.48.813.923.1 defocus x 20.71.84.48.821.9 both0.71.22.64.35.6 both x 20.40.61.12.02.9 STE in %, scene Conan

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Results Scene: Assassin’s Creed, courtesy of Ubisoft Bbox scan Pixar Our method 41664 static23.2 motion10.819.522.423.123.4 motion x 24.314.821.223.023.6 defocus9.515.119.021.123.2 defocus x 24.39.515.119.023.0 both4.56.87.210.114.1 both x 21.32.13.96.76.9 STE in %, scene Assassin

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Results Bbox scan Pixar Our method 41664 static8.598.608.598.608.59 motion0.502.976.438.028.63 motion x 20.141.274.707.408.69 defocus0.190.591.533.138.57 defocus x 20.050.190.591.538.51 both0.120.250.491.084.51 both x 20.030.070.160.392.42 STE in %, scene Cars

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Conclusions Each triangle processed once Arbitrary sampling patterns High STE Future work Combined motion + defocus case

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Thank You

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