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SIGGRAPH 97. Rendering With Coherent Layers. Jed Lengyel John Snyder Microsoft Research. Traditional Pipeline. Renders 3D scene to an image. Traditional Pipeline. Traditional Pipeline. Problems Does not exploit temporal coherence Spatial and temporal resolutions are global
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SIGGRAPH 97 Rendering With Coherent Layers Jed Lengyel John Snyder Microsoft Research
Traditional Pipeline • Renders 3D scene to an image.
Traditional Pipeline • Problems • Does not exploit temporal coherence • Spatial and temporal resolutions are global • Limited integration of 2D elements in 3D
Traditional Pipeline • How can we improve this?
Layered Pipeline • Add a 2D image warp.
Layered Pipeline • A sprite is a warped image with alpha. Sprite
Layered Pipeline • Each layer produces a sprite. Layer
Layered Pipeline • The scene is factored into layers.
Previous Work • Image-caching [Shade96, Schaufler96] • Composition architectures (with z per pixel) [Duff85, Molnar92, Regan94, Mark97] • Image-based rendering [Chen93, Chen95, McMillan95] • Regulation [Funkhouser93, Maciel95] • Shading factorization [Cook84, Hanrahan90, Segal92, Dorsey95, Guenter95, Meier96]
2D Image Transform • T is 3D transform to screen coordinates.
2D Image Transform • Extra degrees of freedom
2D Image Transform • Composition maps to same screen point.
2D Image Transform • Spatial resolution
2D Image Transform • Temporal resolution
Factoring Geometry • Good
Factoring Geometry • Good
Factoring Geometry • Good
Factoring Geometry • Good
Factoring Geometry • Poor
Factoring Geometry • Poor
Factoring Geometry • Poor
Factoring Geometry • Poor
Factoring Geometry • Poor
Depth Sorting of Layers • Depth sorting in software is effective. • Relatively small number of primitives • Exploits temporal coherence
Multipass Shading [Segal92]
Warp Choice • Accuracy of image interpolation through time • Efficient hardware implementation • Ease of computing the warp parameters
Characteristic Points • Track 3D motion projected to 2D
Warp Calculation • Characteristic points are matched
Warp Calculation W P0= P1
Warp Calculation W P0= P1
Warps Considered • Pure translation • Translation with isotropic scale • Translation with independent scale in x and y • Affine • Perspective
Image Interpolation • Warping intermediate images is effective • Triple- or quadruple-framing • Warp calculated with a small set of points • Decouples 3D rendering from display
Regulation • Set independent layer quality parameters
Regulator • Maximize fidelity, balance resources
Fiducials • Measure fidelity of approximation • Geometric • Photometric • Sampling • Visibility
Geometric Fiducial • Compares warped and current points
Photometric Fiducial • Samples lighting at characteristic points
Photometric Fiducial 2 • Measures change in light position
Sampling Fiducial • Measures distortion of image samples
Visibility Fiducial • Counts back-to-front transitions Frame 0 Frame 1