Approximate Dynamic Global Illumination for VR

Convincing illumination is a major component of visual immersion in virtual worlds. For dynamic environments, the direct and indirect scattering of light must adapt to changes in both the geometry and the light sources, a computationally demanding task for typical untethered VR systems or mobile platforms. In this paper we explore a simple yet effective approach to generate real-time, responsive illumination effects due to the indirect scattering of light in the virtual space, based on the well-studied approach of instant radiosity and the notion of virtual point lights (VPLs), which simulate global illumination via direct lighting. However, contrary to the instant radiosity method, where VPLs are spawned on demand by tracing photons from the light sources, here the VPLs are statically defined and represent the geometric and material properties of the underlying environment. Dynamic updates to the VPLs intensity allow for fast reflected light estimation, taking into account light source visibility. We provide a full details and evaluation of the methodology and easy-to-use source code to apply the technique in the Unity game engine.