This is a simple multithreaded spectral pathtracer implementing the algorithm (linear combination of bases) described in our EGSR 2019 paper "Spectral Primary Decomposition for Rendering with sRGB Reflectance". Also implemented are [Meng et al. 2015], [Jakob and Hanika 2019], and a classic RGB renderer.

The spectral rendering uses hero-wavelength sampling on a simple pathtracer. Our implementation supports both the CIE 1931 and 2006 standard observers.

Dependencies are intended to be minimal and easy: • GLM (required) • GLFW (optional, adds windowing support) • lodepng (required, included) • Meng et al. 2015 (required, included) • Jakob and Hanika 2019 (required, included)

Setup is basic CMake: (1) "cd <path/to/>simple-spectral/" (2) "mkdir build" (3) "cd build/" (4) "cmake .." (3) "cmake --build ."

There are some handy options in "simple-spectral/src/stdafx.hpp" near the top of the file.
Some parameters are only exposed this way for simplicity or performance.

Usage, including command-line options, can be found by simply running the binary with no arguments.

However, for convenience, basic usage looks something like:

<binary> --scene=cornell-srgb -w=1024 -h=1024 -spp=64 --output=output.png --window

The available scenes are "cornell" (original Cornell box), "cornell-srgb" (adjusted materials), and "plane-srgb", which is the plane setup in Figure 1.

We would like to thank [Meng et al. 2015] and [Jakob and Hanika 2019], both of which make their code easy to use. Also lodepng, for existing. More acknowledgments can be found within the paper.