Why does all the major renderer use path tracing?

Practical and theoretical implementation discussion.
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Why does all the major renderer use path tracing?

Post by shiqiu1105 » Wed Oct 29, 2014 5:17 am

I am just curious. Why does algorithms based on density estimation like photon mapping weren't as favored by all the major renderers? not to mention metropolis methods.
I know the latest renderman has VCM, but still path tracing is most used algorithm, despite it's noise and deffieiency at caustics.

Is it because it's dead simple to implement and maintain? or the market doesn't require more fancy algorithm?

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Re: Why does all the major renderer use path tracing?

Post by MohamedSakr » Wed Oct 29, 2014 5:50 am

in my personal opinion, path tracing suits commercial rendering for 1 main reason, it is more controllable!!, it can work in very dense scenes "where photon mapping and final gather fails" like hair rendering

VCM should give better results, more accurate light transport, but it has 2 main disadvantages, in complex interior scenes you will find good artifacts!! , and it is more difficult to extend like path tracing

path tracing enhances anti-aliasing and lens effects faster than all other methods "DoF and motion blur" , because all of paths are requiring the Camera, other methods like photon mapping are relying on the light sampling

edit: the artist doesn't know how the "correct" result will be :D , so if you tell him PT is an unbiased light transport algorithm, he will be happy with the noise :lol: and he will never understand that PT will never give him correct results "PT alone can't get full caustics, difficult light transport paths, fails in most difficult scenes"

what commercial render engines do is simple materials , like architectural glass, etc..

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Re: Why does all the major renderer use path tracing?

Post by Tristan » Thu Oct 30, 2014 12:07 am

Despite the new Renderman also supporting VCM it will still be more common to use its uni-directional path tracing mode (at least for film VFX work) simply because it's faster for most lighting situations. It's certainly nice to have alternative options in those cases where it's beneficial, but if you could only have one or the other uni-directional path tracing would be the preference.

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