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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