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Abstract:
We present a new, real-time method for rendering diffuse and glossy
objects in low-frequency lighting environments that cap-tures soft
shadows, interreflections, and caustics. As a preprocess, a novel
global transport simulator creates functions over the object s surface
representing transfer of arbitrary, low-frequency incident lighting
into transferred radiance which includes global effects like shadows
and interreflections from the object onto itself. At run-time, these
transfer functions are applied to actual incident lighting. Dynamic,
local lighting is handled by sampling it close to the object every
frame; the object can also be rigidly rotated with respect to the
lighting and vice versa. Lighting and transfer functions are
represented using low-order spherical harmonics. This avoids aliasing
and evaluates efficiently on graphics hardware by reducing the shading
integral to a dot product of 9 to 25 element vectors for diffuse
receivers. Glossy objects are handled using matrices rather than
vectors. We further introduce functions for radiance transfer from a
dynamic lighting environment through a preprocessed object to
neighboring points in space. These allow soft shadows and caustics
from rigidly moving objects to be cast onto arbitrary, dynamic
receivers. We demonstrate real-time global lighting effects with this
approach.
