Basic idea of Irradiance Gradients

The idea of irradiance gradients is, to calculate diffuse lighting with ray tracing in an
efficient way. Because of the irradiance normally changing slowly over surfaces, it is
mostly not necessary, to calculate a new irradiance value at every point of the scene,
because it is possible to interpolate already calculated irradiance values not far away
from the requested point to get this new irradiance value.

Position of irradiance values

Here you can see the positions of the calculated irradiance values at the different
recursion levels.
The main reason for these pictures was to examine wheather there is some other
information included in these gradients in addition to using them for the
interpolation of the irradiance values. Unfortunately there is not enough information
included in the spacing and size of the gradients to use them for more than
interpolation.

The different colors show the different recursion levels.
To improve the visibility of the spheres, there are no
shadows calculated in this image.


The position of the calculated irradiance values of the first recursion level	The position of the caluclated irradiance values of the first three recursion levels

The result of a hemicube sampling (about 120 divisions), used to
calculate the gradients

Rotational and translational Gradients


The rotational gradients of the first recursion level	Thes rotational gradients of the first three recursion levels


The translational gradients of the first recursion level	The translationsal gradients of the first three recursion levels

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