Amortized supersampling

Amortized supersampling
Lei Yang, Diego Nehab, Pedro Sander, Pitchaya Sitthi-amorn, Jason Lawrence, Hugues Hoppe.
ACM Trans. Graphics (SIGGRAPH Asia), 28(5), 2009.
Adaptive reuse of pixels from previous frames for high-quality antialiasing.
Abstract: We present a real-time rendering scheme that reuses shading samples from earlier time frames to achieve practical antialiasing of procedural shaders. Using a reprojection strategy, we maintain several sets of shading estimates at subpixel precision, and incrementally update these such that for most pixels only one new shaded sample is evaluated per frame. The key difficulty is to prevent accumulated blurring during successive reprojections. We present a theoretical analysis of the blur introduced by reprojection methods. Based on this analysis, we introduce a nonuniform spatial filter, an adaptive recursive temporal filter, and a principled scheme for locally estimating the spatial blur. Our scheme is appropriate for antialiasing shading attributes that vary slowly over time. It works in a single rendering pass on commodity graphics hardware, and offers results that surpass 4x4 stratified supersampling in quality, at a fraction of the cost.
Hindsights: Some related work is being pursued in the CryEngine 3 game platform, as described by Anton Kaplanyan in a SIGGRAPH 2010 course. It also seems related to the temporal reprojection in NVIDIA TXAA, although there are few details on its technology.
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