High-Speed Radiosity Method in Animation Environments

High-Speed Radiosity Method in Animation Environments

       Disclosed is a high-speed radiosity method, which reduces
the computational cost of generating images in animation environments
with changes in geometry or topology, without sacrificing image
quality.

      There has been a rapid growth in the popularity of the
radiosity method, which provides limited global illumination effects,
but produces very realistic images. The basic radiosity procedure for
image generation is based on methods from thermal engineering, and is
suitable for environments composed of ideal diffuse emitters and
reflectors. The procedure determines surface intensities for diffuse
environments. It computes form-factors, which represent the
geometrical relationship between any two surfaces, on the basis of
the shape, area, and orientation of each surface, the distance
between them, and the portion of each patch visible to the others.

      Computing the form-factors involves a large computational cost.
Some approaches have been formulated to reduce this expense without
sacrificing the image quality, but they are still inadequate in
animation environments with changes in geometry or topology.

      The new method focuses on patches where the luminous intensity
is affected strongly by changes in geometry or topology.

      The conditions for the strongly affected patches are as
follows:
1) The ratio (Ri) of the energy of patch-i received by some moving
objects to the total energy of patch-i received by all objects is
high.
     The Ri of patch-i is given by
        Ri = Sum of (Fim * Lim) / Sum of (Fin * Lin)
     Fim : Form-factor of patch-i for moving objects (1 < m < M)
     Fin : Form-factor of patch-i for all objects (1 < n < N)
     Lim : Luminous intensity of patch-i for moving objects
     Lin : Luminous intensity of patch-i for all objects
     M   : the number of patches for moving objects
     N   : the number of patches for all objects
2) The luminous intensity of patch-i is newly affected by moving
objects.

      When an object is moved to a new place, the form-factors of the
patches surrounding the new place should be calculated, because the
ratio Ri may be low...