A Survey on Temporal Coherence Methods in Real-Time Rendering

Daniel Scherzer, Lei Yang, Oliver Mattausch, Diego Nehab, Pedro V. Sander, Michael Wimmer, Elmar Eisemann
A Survey on Temporal Coherence Methods in Real-Time Rendering
In EUROGRAPHICS 2011 State of the Art Reports, pages 101-126. 2011.
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Information

Abstract

Nowadays, there is a strong trend towards rendering to higher-resolution displays and at high frame rates. This development aims at delivering more detail and better accuracy, but it also comes at a significant cost. Although graphics cards continue to evolve with an ever-increasing amount of computational power, the processing gain is counteracted to a high degree by increasingly complex and sophisticated pixel computations. For real-time applications, the direct consequence is that image resolution and temporal resolution are often the first candidates to bow to the performance constraints (e.g., although full HD is possible, PS3 and XBox often render at lower resolutions).

In order to achieve high-quality rendering at a lower cost, one can exploit emph{temporal coherence} (TC). The underlying observation is that a higher resolution and frame rate do not necessarily imply a much higher workload, but a larger amount of redundancy and a higher potential for amortizing rendering over several frames. In this STAR, we will investigate methods that make use of this principle and provide practical and theoretical advice on how to exploit temporal coherence for performance optimization. These methods not only allow us to incorporate more computationally intensive shading effects into many existing applications, but also offer exciting opportunities for extending high-end graphics applications to lower-spec consumer-level hardware.

To this end, we first introduce the notion and main concepts of TC, including an overview of historical methods. We then describe a key data structure, the so-called emph{reprojection cache}, with several supporting algorithms that facilitate reusing shading information from previous frames. Its usefulness is illustrated in the second part of the STAR, where we present various applications. We illustrate how expensive pixel shaders, multi-pass shading effects, stereo rendering, shader antialiasing, shadow casting, and global-illumination effects can profit from pixel reuse. Furthermore, we will see that optimizations for visibility culling and object-space global illumination can also be achieved by exploiting TC.

This STAR enables the reader to gain an overview of many techniques in this cutting-edge field and provides many insights into algorithmic choices and implementation issues. It delivers working knowledge of how various existing techniques are optimized via data reuse. Another goal of this STAR is to inspire the reader and to raise awareness for temporal coherence as an elegant tool that could be a crucial component to satisfy the recent need for higher resolution and more detailed content.

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BibTeX

@inproceedings{scherzer2011c,
  title =      "A Survey on Temporal Coherence Methods in Real-Time
               Rendering",
  author =     "Daniel Scherzer and Lei Yang and Oliver Mattausch and Diego
               Nehab and Pedro V. Sander and Michael Wimmer and Elmar
               Eisemann",
  year =       "2011",
  abstract =   "Nowadays, there is a strong trend towards rendering to
               higher-resolution displays and at high frame rates. This
               development aims at delivering more detail and better
               accuracy, but it also comes at a significant cost. Although
               graphics cards continue to evolve with an ever-increasing
               amount of computational power, the processing gain is
               counteracted to a high degree by increasingly complex and
               sophisticated pixel computations. For real-time
               applications, the direct consequence is that image
               resolution and temporal resolution are often the first
               candidates to bow to the performance constraints (e.g.,
               although full HD is possible, PS3 and XBox often render at
               lower resolutions).  In order to achieve high-quality
               rendering at a lower cost, one can exploit emph{temporal
               coherence} (TC). The underlying observation is that a higher
               resolution and frame rate do not necessarily imply a much
               higher workload, but a larger amount of redundancy and a
               higher potential for amortizing rendering over several
               frames. In this STAR, we will investigate methods that make
               use of this principle and provide practical and theoretical
               advice on how to exploit temporal coherence for performance
               optimization. These methods not only allow us to incorporate
               more computationally intensive shading effects into many
               existing applications, but also offer exciting opportunities
               for extending high-end graphics applications to lower-spec
               consumer-level hardware.  To this end, we first introduce
               the notion and main concepts of TC, including an overview of
               historical methods. We then describe a key data structure,
               the so-called emph{reprojection cache}, with several
               supporting algorithms that facilitate reusing shading
               information from previous frames. Its usefulness is
               illustrated in the second part of the STAR, where we present
               various applications. We illustrate how expensive pixel
               shaders, multi-pass shading effects, stereo rendering,
               shader antialiasing, shadow casting, and global-illumination
               effects can profit from pixel reuse. Furthermore, we will
               see that optimizations for visibility culling and
               object-space global illumination can also be achieved by
               exploiting TC.  This STAR enables the reader to gain an
               overview of many techniques in this cutting-edge field and
               provides many insights into algorithmic choices and
               implementation issues. It delivers working knowledge of how
               various existing techniques are optimized via data reuse.
               Another goal of this STAR is to inspire the reader and to
               raise awareness for temporal coherence as an elegant tool
               that could be a crucial component to satisfy the recent need
               for higher resolution and more detailed content. ",
  booktitle =  "EUROGRAPHICS 2011 State of the Art Reports",
  location =   "Llandudno UK",
  publisher =  "Eurographics Association",
  pages =      "101--126",
  URL =        "https://www.cg.tuwien.ac.at/research/publications/2011/scherzer2011c/",
}