This repository contains example materials for Weta Digital's PhysLight system as presented in the Siggraph 2020 Talk PhysLight: An End-to-End Pipeline for Scene-Referred Lighting. Slides can be found here.
The documentation in docs contains the foundational mathematics
In the usd folder are a set of schema that can be used to apply to lights and cameras in USD to store and carry necessary information to implement a system that communicates lights and camera data necessary to implement a PhysLight compliant render chain.
data directory contains the spectral sensitivity curves of a number of cameras as measured with our 'lightsaber' system. It also contains a notebook that loads the data and plots the curves for visual inspection.
The imaging notebook shows a simple example of calculating the imaging ratio and checking that it gives the correct response for an idealized camera system.
The physlight camera model notebook shows how to use the curves to convert from spectral radiance to Camera RGB, solve matrices to go from Camera RGB to XYZ, and compares different approaches for handling white balance.