Validation of lighting simulation in the game engine Unity

To utilise virtual reality in lighting research, realistic simulations of lighting conditions are essential. Game engines could play a vital role in this, as they enable stereoscopic visualisation, immersive experiences and real-time rendering. This paper evaluates the lighting simulation quality of Unity’s High Definition Render Pipeline (HDRP) Lightmapper for electric lighting conditions using the test cases defined in the technical report CIE 171:2006 ‘Test cases to assess the accuracy of lighting computer programs’. The authors provide adjustments to light colour, IES profiles and global illumination to enhance and in some cases correct the simulation. To assess the simulated illuminance in Unity scenes, a coordinate-driven measurement toolbox ( PhotoProbe ) was developed based on Unity’s Rendering Debugger. Without adjustments to the HDRP, high error rates were observed for most of the test cases. With the adjustments specified in this paper, the mean absolute percentage error was below 3% for all analytical test cases and the simulated illuminances for the six experimental test cases were within the global limit threshold defined in CIE 171:2006. For one test case, the average room illuminance limit was not met.