Precision Value
In direct simulation, the displayed precision value corresponds to the pixel having the highest number of integrated
rays.
Precision formula is the following. Precision = 1/sqrt(N) With N the number of rays integrated by the pixel.
Warning: When no
rays are integrated on a pixel, the error is infinite. The precision value is one hundred percent. In direct simulation using radiance luminance sensor with activated gathering, precision does
not have any meaning. Precision value is also one hundred percent.
Note: In inverse simulation using the Monte-Carlo algorithm, a number of pass has to
be specified as 100 passes = 100 rays per pixel (not necessary effective rays). Precision formula is the following. Precision = 1/sqrt(N) With N the number of passes.
Warning: In inverse simulation using deterministic or photon map algorithms, precision does not have any meaning. Precision value is also one hundred
percent.
Warning: Higher is the precision percent, lower is the image quality. Be aware that one pixel which has not received any rays or which has
received only one has a one hundred percent precision.
More rays or passes there are, lower is the statistical noise. A direct correlation between this number and
the error (or variance, standard deviation) is not possible.
For systems under weighted Monte-Carlo algorithms, the only way to compute error (variance) is to launch the
same simulation several times and to calculate the standard deviation of specific pixels.
Note: The statistical error is always less important for pixels with
more integrated rays.
Precision Map
For direct simulation, you can click Tools, Precision map... to
display the precision map.
Warning: The precision map is only validate for all sources set at one hundred percent when there is no any separation by
sources.
The precision is displayed in percent and is saved in rays number in the map. You can then generate precision calculation with the Measures analysis tool.
