compute_rasterizer

About

This repository contains the source code for our papers about real-time software rasterization of point clouds, which can be 10 to 100 times faster than GL_POINTS. This is possible because GL_POINTS is built upon the triangle-oriented rendering pipeline that is not optimal for pixel-sized points.

The basic idea is to spawn a compute shader that transforms points to screen space, encodes depth and color into a single 64 bit integer, and uses atomicMin to compute the closest point for each pixel. The color value is then extracted from the interleaved depth+color buffer and converted into a regular OpenGL texture for display.

The latest improvement also groups about 10k points into batches, and each compute workgroup(128 threads) renders a batch(10k points), i.e., each thread renders about 80 points. This allows several batch-level optimizations such as frustum culling, LOD rendering, and adaptive precision. Adaptive precision picks a sufficient coordinate precision (typically just 10 bit per axis) depending on the projected batch size, which boosts brute-force performance due to lower memory bandwidth requirements.

The main branch is a slightly more user friendly version that allows loading LAS files via drag&drop. Other branches contain snapshots of the code made after evaluations for specific paper submissions:

• "Software Rasterization of 2 Billion Points in Real-Time"

In branch compute_rasterizer_2022

paper - video

• "Rendering Point Clouds with Compute Shaders and Vertex Order Optimization"

In branch compute_rasterizer_2021

Features and Limitations

• Renders up to one billion points in about 8 milliseconds (hence 2 billion points in real-time, 60fps) on an RTX 3090.
• You need to make sure not to load more than your GPU memory can handle. You'll need about 1.6GB for every 100 million points, plus 1GB or 2GB overhead.
• Drag & Drop a LAS or LAZ files into the window to load it. Only RGB attributes are displayed.
• Requires Windows and NVIDIA GPUs. Pull requests for AMD support are welcome.

Building

• Clone the repository

• Compile build/ComputeRasterizer.sln with Visual Studio 2022.

• Run (ctrl + f5)

  复制

    Method
    Location
    
  
  
  
  
    basic
    ./modules/compute_loop_las
    
  
  
  
  
    prefetch
    ./modules/compute_loop_las2
    fastest, each thread fetches 4 points at a time
  
  
  
  
    hqs
    ./modules/compute_loop_las_hqs
    High-Quality Shading
  
  
  
  
    LOD
    ./modules/compute_loop_nodes
    Support for the Potree LOD format
  
  
  
  
    LOD hqs
    ./modules/compute_loop_nodes_hqs

Citing

@article{SCHUETZ-2022-PCC, title = "Software Rasterization of 2 Billion Points in Real Time", author = "Markus Sch"{u}tz and Bernhard Kerbl and Michael Wimmer", year = "2022", month = jul, journal = "Proc. ACM Comput. Graph. Interact. Tech.", volume = "5", pages = "1--16", URL = "https://www.cg.tuwien.ac.at/research/publications/2022/SCHUETZ-2022-PCC/", }

@article{SCHUETZ-2021-PCC, title = "Rendering Point Clouds with Compute Shaders and Vertex Order Optimization", author = "Markus Sch"{u}tz and Bernhard Kerbl and Michael Wimmer", year = "2021", month = jul, doi = "10.1111/cgf.14345", journal = "Computer Graphics Forum", number = "4", volume = "40", pages = "115--126", keywords = "point-based rendering, compute shader, real-time rendering", URL = "https://www.cg.tuwien.ac.at/research/publications/2021/SCHUETZ-2021-PCC/", }