Nivedita Goswami

Spherical Harmonic Lighting

Thesis

This project is about the efficient rendering of objects under low frequency illumination by transforming the
lighting into spherical harmonics. RenderMan has been the choice of platform for the implementation.
Results of spherical harmonic lighting have been compared against standard ray-tracing in terms of both quality
and efficiency. The contribution Directional Ambient Occlusion for better image integration has been demonstrated.

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Sponza Atrium renders. Left: Ray traced shadows from a spot light. Right: Spherical Harmonic Approximation of the same light.

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The raw shadow layers. Left: Standard spot light shdows. Right:Shadows from the custom Spherical Harmonic Light.

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An example showing the use of directional ambient occlusion for better image integration.
Top Left: Original photograph. Top Right: CG Setup. Bottom Left: Composited with standard AO. Bottom Right: Composited with directional AO.

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A comparison of the raw ambient occlusion layers and the render time for each of the layers

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A comparison between standard ambient occlusion and directional occlusion. Graph shows render performance
with both the methods over 70 frames. SH stands for Spherical Harmonic and RT stands for Ray Trace