Thomas wrote:

> Is there somewhere some information on how to change settings (even the
> 3.1 settings in 3.5 are dead slow) and how to get some decent speed.

I think that it's better to forget about 3.1 radiosity settings and start
anew. There are various examples in the current distribution (see the
rad_def2.inc), including in the advanced scenes (see for instance the
stackerday.pov and stackernight.pov scenes). Right now, it seems that
people who have experimented with it have their own preferred methods. Kari
Kivisalo, for instance, has done a lot of work about matching the settings
with real-life lighting parameters (see his posts in povray.binaries) with
good results. Other people have an approach based on trial-and-error. For
me, presently, the setting up of radiosity involves three basic (almost
independent) steps :

- a quality/speed/memory optimisation where I try to find the optimal count
and error_bound combination, both for testing and for final renders. I
usually end up with high count (>300) and low error_bound (<0.05) values,
but it heavily depends on the scene. Particularly, scenes involving large
expanses of flat, non-varying colours mixed with more complex material are
still a problem. AFAIK, small error_bound are the only way to get proper
shadows in the corners.

- a colour intensity optimisation where the brilliance/assumed_gamma/light
intensity (if any)/environment colour intensity come into play.

- a "colour bleed" optimisation where the gray_threshold/light colour (if
any)/environment colour(s) are tuned

I barely touch the other parameters, using pretrace values = 1 and
recursion = 1. Higher recursion values give more realistic results but I
find the render times and the artefacts unbearable.

And yes, render times can be incredibly long and the memory use can be
extremely high. Some of the new images done for my website took several
weeks to render and ate more than 700 Mb of RAM.

G.


--

**********************
http://www.oyonale.com
**********************
Graphic experiments
Pov-ray gallery

Post a reply to this message