Render types

General questions about Indigo, the scene format, rendering etc...
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BluShift
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Render types

Post by BluShift » Mon Aug 31, 2009 7:34 pm

I don't know if this has been answered, but I certainly couldn't find it anywhere; what is the advantages/drawbacks/differences between the different "types" of rendering? Like MLT, Bidir MLT, Alpha render, etc. I've always used Bidir MLT because it sounded the coolest, and because I actually know what MLT means. :lol: But other than that, I don't know what they all mean and what separates one from another :?

Can anyone "shed some light?" (Sorry :wink: )

remus
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Re: Render types

Post by remus » Tue Sep 01, 2009 4:19 am

What ive managed to glean over the years:

MLT is the only one which can do caustics.
Path tracing is slightly faster (although i could be wrong, its just a feeling.)
Alpha render is for creating clip masks, so you its not overly important for actually rendering your scenes.

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PureSpider
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Re: Render types

Post by PureSpider » Tue Sep 01, 2009 4:21 am

remus wrote:MLT is the only one which can do caustics.
No, it just does caustics faster in certain scenes.
MLT "remembers" the valid paths while PT is pure brute forcing :)

remus
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Re: Render types

Post by remus » Tue Sep 01, 2009 4:38 am

That makes sense :)

neo0.
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Re: Render types

Post by neo0. » Tue Sep 01, 2009 5:00 pm

It would be very nice if there was a sticky with common info about the various render types..

remus
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Re: Render types

Post by remus » Tue Sep 01, 2009 6:40 pm

A little snippet from the manual about hybrid:
"hybrid
If true, direct illumination is sampled with QMC sampling, and indirect illumination with Metropolis-
Hastings sampling."

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benn
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Re: Render types

Post by benn » Wed Sep 02, 2009 9:05 am

Like PureSpider said - Metropolis light transport finds paths that the light goes along and then send more rays along them (imagine you were looking down a telescope in the scene, it'd be unlikely for light to go through the telescope, but you want Indigo to send more rays down the telescope so that it will resolve faster).

Bi-directional Path Tracing is usually fastest, but if you're scene is complex and is taking far too long -then it's worth going to Metropolis Light Transport, hybrid is usually only used by advanced users, as I'm not too sure of the use-cases myself.

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