Xplo Eristotle wrote:

> It's been a while since I actually messed with pretrace parameters, but
> IIRC, error_bounds > .1 benefit visually from a really precise pretrace
> (although above .4 or so, the benefit may not be worth the time anyway),
> whereas smaller error_bounds don't, so pretrace should be set to 1 to
> save time. Don't take this as absolute gospel, though; these are
> approximations off the top of my head, and not based on extensive testing.

My feeling too. My rule of thumb would be like this:
[1] test renders with no quality requirement : pretrace 1 (saves time)
[2] final renders with error_bound < 0.1 : pretrace 1 (saves time)
[3] all other types of radiosity renders  : small pretrace values may save time
and improve quality

BTW, I was too optimistic about my current test renders as the first one (with
pretrace<1) is crawling at 150 points per minute. No answers (checking rule [2])
until next Monday at best.

> It's worth pointing out that the messier your scene naturally is (due to
> texturing, or objects casting a lot of small shadows, or something), the
> less perfect your radiosity has to be.

This is true, and particularly for flat surfaces. However, in my experience, small
error_bound values are always needed to get accurate shadows below objects placed
in radiosity-lit areas.

G.



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