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Should Rendering be slower with Instances?
Posted: Wed Dec 22, 2010 7:22 pm
by brodie_geers
I'm testing a simple scene with a small grass bush made of a number of instances with clipmaps.
Instancing OFF: Voxelization takes 1 second and it gets to SL 3 in 1m49s
Instancing ON: Voxelization takes 1 second and it gets to SL 3 in 6m17s
Not only that but the images look quite different...
Any ideas? The instances do intersect with eachother and the ground plane, but my understanding was that intersecting issues were solved back in 2.0.
-Brodie
Re: Should Rendering be slower with Instances?
Posted: Wed Dec 22, 2010 11:31 pm
by Mihai
Perhaps it's all the clipmaps and instances that are the cause. Is it possible to model something similar but with real geometry for the strand, and instanced? To see if it's caused by instances and clipmaps...
Re: Should Rendering be slower with Instances?
Posted: Thu Dec 23, 2010 12:16 am
by brodie_geers
Did some quick tests, just to SL 2
Clip maps OFF, Instances OFF: 3s (separate test to SL 5: 14s)
Clip maps OFF, Instances ON: 6s (separate test to SL 5: 27s)
Clip maps ON, Instances OFF: 16s
Clip maps ON, Instances ON: 43s
So clip maps certainly make a difference (as you'd expect) but turning instances ON is still slowing the rendering down by 50% as well as making significant changes to the shading, which was also noticeable in my non-clipmapped tests.
-Brodie
Re: Should Rendering be slower with Instances?
Posted: Thu Dec 23, 2010 12:23 am
by Richard
Wow - well that might explain a lot Brodes! I've been whinging (like always) about increased emitter materials slowing my renders to all buggery and it may well be the instancing is the cause.
I have that same plant so will test a scene this end too and check results. And yes certainly a lot of intersecting geometry, sorry!
Re: Should Rendering be slower with Instances?
Posted: Thu Dec 23, 2010 12:30 am
by Richard
BTW your tests there have highlighted the issue I've been having where the centre core of the plant is SO dark and never cleans up, I figured it was simply not enough light getting in but the non instanced version shows this not to be the case.