> All this seems logical. More samples and more time with the 2-pass method
> because it takes sample locations at full res. with error_bound 0.1 (even
> with "always_sample off", see my previous post). For the low_error_factor
> there is only gathering at error_bound 0.1 during pretrace (and i've not
> used a small mosaic) (and maybe some more samples for error_bound 0.8 for
> final), so less samples, less time.

I can't follow you here.
If always_sample is off, radiosity will only calculate samples during the
pretrace,
right? So, for the two-pass method, I'm pretracing with error_bound 0.1, and
for the one-pass method, I'm pretracing at error_bound 0.8*0.125, which is
0.1.
Unless the radiosity takes into account that it's actually tracing with 0.1
error_bound,
but pretracing with 0.1 when using low_error_factor, it shouldn't have much
different
numbers of samples. If it does, to me this clearly indicates that
low_error_factor
has some other side-effects which aren't mentioned in the docs.
After all, the using always_sample off should switch off sampling during the
final
trace, and then its all pretrace that matters.

Additionally, have you checked if the resulting images were of same quality?
Of
course they aren't, if the one-pass uses less samples. But the question to
me is,
why ARE there less samples?!

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

> done your test with the cornell scene
>
> 2-pass method :
> radiosity{
> #if (frame_number=1)
>       pretrace_start 0.08
>       pretrace_end 0.02
>       error_bound 0.1
>       save_file "rad.data"
> #else
>       pretrace_start 1
>       pretrace_end 1
>       error_bound 0.8
>       always_sample off
>       load_file "rad.data"
> #end
> low_error_factor 1
> count 100
> recursion_limit 3
> nearest_count 10
> }
>
> Stats : 47411 samples , 1-pass in 4'18 total 6'52 (0 samples in 2-pass)
> and the same but with "always_sample off" for the 1st pass
> Stats : 20714 samples , 1-pass in 1'32 total 1'59 (0 samples in 2-pass)
>
> Method with low_error_factor :
> radiosity{
>     pretrace_start 0.08
>     pretrace_end 0.02
>     error_bound 0.8
>     low_error_factor .125
>     count 100
>     recursion_limit 3
>     nearest_count 10
> }
>
> Stats : 6655 samples 1'06
>
> All this seems logical. More samples and more time with the 2-pass method
> because it takes sample locations at full res. with error_bound 0.1 (even
> with "always_sample off", see my previous post). For the low_error_factor
> there is only gathering at error_bound 0.1 during pretrace (and i've not
> used a small mosaic) (and maybe some more samples for error_bound 0.8 for
> final), so less samples, less time.
>
>
> Finally note that when you save radiosity data in a file you don't save
all
> the information (gradient are not saved, and only locations at bounce
depth
> = 1 are saved)
>
> M
>
>


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