Dynamic Indirect Illumination in Real-Time Ray Tracing using Lightcuts

This thesis describes a system that adds plausible indirect illumination to the Arauna real-time ray tracer. Only the first diffuse reflection of light on static geometry is simulated. Light sources are allowed to be dynamic. Virtual point lights (VPLs) are used to simulate the reflection of light by surfaces. Their contribution to the final shading is stored in a sparse point set distributed randomly over the surfaces. During rendering the direct light is obtained through ray tracing and the indirect light from the VPLs is interpolated from the nearby points of the point set. When light sources are dynamically changed, the VPLs are updated and the indirect shading at the point set is updated. To avoid having to calculate the contribution of all VPLs (which may be thousands) for each point of the point set, the Lightcuts algorithm is used to approximate the illumination from the VPLs for each point. This sublinear scaling algorithm first creates clusters of lights which are adaptively selected during run-time while maintaining an upper bound on the approximation error. We describe bounding spheres as an alternative to the bounding boxes used in the original Lightcuts algorithm and derive new formulae for the error upper bounds. The system is tested with three different scenes. Our bounding sphere alternative is on average 1.3× faster than the box variant. In the tested scenes, plausible indirect illumination is obtained at interactive frame rates on commodity hardware.

Subject

computer graphics
real-time ray tracing
indirect illumination

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http://resolver.tudelft.nl/uuid:641d573e-18bb-45d9-bb74-4fc55c479757

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Student theses

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master thesis

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