Occlusion Preprocessing slow-ow-ow

Fax · March 30, 2011, 2:42pm

Hi guys,

Suddenly my render times increased a lot - it takes a long long time in a step called “Occlusion Preprocessing”. I don’t know what I did to “turn this on”, I’m pretty sure the scene I’m working on used to render much faster. I can only associate this with Ambient Occlusion but it is turned off, so…

I’m using a more or less recent build from graphicall, 35739 with bundled luxrender, but I tried falling back to the official 2.56a (in which I started the scene) and had the same problem. Windows7 64bit.

Any ideas?

arexma · March 30, 2011, 3:25pm

You have environmental lighting turned on.
It basically is just another occlusion pass that brightens the scene instead of the darkening of the occlusion.

Both need Occlusion Preprocessing

Fax · March 30, 2011, 11:23pm

Indeed I do, thanks arexma. Then I’d say it’s probably the environmental lighting + SSS that suddenly slowed things down (EL was there before but SSS just recently). Guess I’ll have to live with it!

Fax · March 31, 2011, 1:56am

Or was it? As soon as I made the hair material for my character NOT cast shadows, times are back to normal. Makes sense, calculating shadows for 37500 hairs must be somewhat time consuming Solved!