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sammael
04-01-2009, 12:15 AM
Hey
I have been experimenting with blending materials, on the upside you can get some interesting results on the downside... render times.

For example I blended a skin shader 50/50 with sigma 2.
render with aa on 1 no as took about an hour. I turned up the aa a little and rendered overnight, the image was still not completed after 11 hours. I cancelled at 71%

You would think it would take a bit longer but is this normal?

I'm just blending 50% with no alpha image.

sammael
04-01-2009, 12:34 AM
I should add, I'm using radiosity Monte Carlo 3 bounces as well. Preprocess and GI alone takes about 40 mins for a 640x480 frame. With either of the blended materials by itself its around 1-2 minutes.
Radiosity has 3 bounces otherwise default settings.

Sensei
04-01-2009, 05:43 AM
Blending materials 50% mean that both materials are evaluated. If you don't need material in GI pre-process stage you can experiment with Logic/Mixer node (Opacity) and Spot Info > Radiosity/Preprocess flags.. and turn them off calculation at this stage.. You can also try LightWolf's Cache node..

Another thing is Render Global > Bounces.. If you didn't touch it, it's very high value like 16.. Lower it to 1, render, increase to 2, render, increase to 3, render.. And compare results/times.. :)

RebelHill
04-01-2009, 05:47 AM
Ive done blending of materials before...

yes... it does rocket your rendertimes way beyond the additive time of rendering each material separately, which seems weird... but check the results...

No artifacting, u can blend interpolated with non interpolated materials, and it jsut works...

it may not be great time wise, but its a great testament to the quality and capability of the LW renderer... it amazes me it works at all.

Sensei
04-01-2009, 05:52 AM
it amazes me it works at all.

Why it should not work?

sammael
04-01-2009, 06:01 AM
Blending materials 50% mean that both materials are evaluated. If you don't need material in GI pre-process stage you can experiment with Logic/Mixer node (Opacity) and Spot Info > Radiosity/Preprocess flags.. and turn them off calculation at this stage.. You can also try LightWolf's Cache node..

Another thing is Render Global > Bounces.. If you didn't touch it, it's very high value like 16.. Lower it to 1, render, increase to 2, render, increase to 3, render.. And compare results/times.. :)


Thanks Sensei I will try the things you suggest and see how it goes.


RebelHill - yeah its cool that you can do it, I just didnt expect such a jump in render times... you would assume maybe 3,4,5 times longer given the extra calculations but its somewhere between 10 and 20 times longer to render which seems to increase more as you crank up the aa a little :S
Very cool results though, I hope they can optomise the performance a bit. Great reel btw.

RebelHill
04-01-2009, 05:17 PM
Why it should not work?

its not that it shouldnt work at all... its just pretty impressive that u can take materials/shaders that work in very different ways and get them to blend properly with no artifacting, especially the like of subsurface materials where the "internal" parts are rendered very differntly from one another... Ive seen where folks have tried to do it with other renderers, in other apps, and there've been gotchas where certain thigns cant be mixed in render without aritifacting and its had to be done with work arounds of passes and alphas, etc.