Andrey Platonov nous apporta ses lumieres en ce 2005-09-16 15:57:
> Hi
> 
> Could someone please explain, how pretrace_start affects the quality of the
> final image? Radiosity pretrace phase is mentioned quite shortly in
> documentation and tutorials, and only pretrace_end gets explained. As far
> as I understand, the difference between pretrace_start and pretrace_end
> specifies the number of pretrace steps. E.g if I specify pretrace_start
> 0.08 and pretrace_end 0.01 there will be 4 steps. But will there be any
> difference if I e.g. specify pretrace_start the same as pretrace_end, and
> there will be only one step?
> 
> --------------------------
> Andrey
> 
> 
> 
> 
In some cases where you get artefacts near corners, a slight change in pretrace_start
may supress 
those. Changing the pretrace_start value cause the location of the samples to shift
slightly and 
possibly miss the problem pixel(s).
Using smaller pretrace_end can realy help improve the quality of the radiosity while
still using 
lower, and faster, parameters.
I like to use a variable to set my pretrace, by itself for _start, divided by a power
of 2 for the _end.

Alain

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