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キーワード:
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要旨:
Lighting simulations obtained using hierarchical radiosity with clustering can
be very slow when the computation of fine and
artifact-free shadows is needed. To avoid the high cost of mesh refinement
associated with fast variations of visibility across
receivers, we propose a new hierarchical algorithm in which partial visibility
maps can be computed on the fly, using a
convolution technique, for emitter-receiver configurations where complex
shadows are produced. Other configurations still
rely on mesh subdivision to reach the desired accuracy in modeling the energy
transfer. In our system, radiosity is therefore
represented as a combination of textures and piecewise constant or linear
contributions over mesh elements at multiple
hierarchical levels. We give a detailed description of the gather, push/pull
and display stages of the hierarchical radiosity
algorithm, adapted to seamlessly integrate both representations. A new
refinement algorithm is proposed, that chooses the most
appropriate technique to compute the energy transfer and resulting radiosity
distribution for each receiver/emitter
configuration. Comprehensive error control is achieved by subdividing either
the source or receiver in a traditional manner, or
by using a blocker subdivision scheme that improves the quality of shadow masks
without increasing the complexity of the
mesh. Results show that high-quality images are obtained in a matter of seconds
for scenes with tens of thousands of polygons.
