But with low_error_factor, it lowers the error_bound
during the pretrace. In effect, when using low_error_factor
0.125 with error_bound 0.8, it should be doing the same
as using error_bound 0.1 in the first place. The only
difference is that it will interpolate amongst more samples
in the final trace, as a higher error_bound has a larger
gathering radius for the samples.

If my two-pass method uses error_bound 0.1 in the
first pass, and 0.8 in the second, it should theoretically
be the same as using error_bound 0.8 with low_error_factor
0.125.

-- 
Tim Nikias v2.0
Homepage: http://www.digitaltwilight.de/no_lights


> > I've made a quick test with a scene :
> >
> > 1st render :
> > pretrace_start 0.08
> > pretrace_end 0.02
> > error_bound 0.1
> > low_error_factor 1
> > always_sample off
> > save_file "rad1.data"
> >
> > and 2nd render :
> > pretrace_start 0.08
> > pretrace_end 0.02
> > error_bound 0.8
> > low_error_factor .125
> > always_sample off
> > save_file "rad2.data"
> >
> > and rad1.data is 3 times bigger than rad2.data.. !
>
> Ok, I think this is because in the 1st render, even with "always_sample
off"
> we can have new gather locations on the final trace, when povray don't
find
> *any* samples to reuse (For "always_sample on" we have more gathering if
the
> number of samples to reuse is < nearest_count). With an error_bound of 0.1
> it's not surprising that it finds places with no samples to reuse,
compared
> to error_bound 0.8 for which it has probably at least 1 sample it can
reuse
> from pretrace and so don't need more gathering.
>
> M
>
>


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