The path to path-traced movies

1Pixar Animation Studios 2Dartmouth College

In Foundations and Trends in Computer Graphics and Vision, 2016

An illustration of the paths traced by path tracing (left) and bidirectional path tracing (right) in a Cornell box scene with two light sources, two teapots and a scattering medium. Eye sub-paths are shown in black, light sub-paths in orange, and potential shadow connections are drawn with dashed red lines.


Path tracing is one of several techniques to render photorealistic images by simulating the physics of light propagation within a scene. The roots of path tracing are outside of computer graphics, in the Monte Carlo simulations developed for neutron transport. A great strength of path tracing is that it is conceptually, mathematically, and often-times algorithmically simple and elegant, yet it is very general. Until recently, however, brute-force path tracing techniques were simply too noisy and slow to be practical for movie production rendering. They therefore received little usage outside of academia, except perhaps to generate an occasional reference image to validate the correctness of other (faster but less general) rendering algorithms. The last ten years have seen a dramatic shift in this balance, and path tracing techniques are now widely used. This shift was partially fueled by steadily increasing computational power and memory, but also by significant improvements in sampling, rendering, and denoising techniques. In this survey, we provide an overview of path tracing and highlight important milestones in its development that have led to it becoming the preferred movie rendering technique today.



Per H. Christensen, Wojciech Jarosz. The path to path-traced movies. Foundations and Trends in Computer Graphics and Vision, 10(2):103–175, October 2016.
    author   = {Christensen, Per H. and Jarosz, Wojciech},
    title    = {The Path to Path-Traced Movies},
    journal  = {Foundations and Trends in Computer Graphics and Vision},
    volume   = {10},
    number   = {2},
    year     = {2016},
    month    = oct,
    doi      = {10/gfjwjc},
    issn     = {1572-2740},
    pages    = {103--175},
    keywords = {special effects, animated films, industry, rendering}