Photon problem in mtor


:lightbulb problem
i’m using rat6 on maya5, i just finished textureing my set, i kept a spot light and switched on emit photons, i checked the rays in globals also, but it dosen’t emit photons, there’s no bounce at all. 1. why i’m not getting photons( render looks the same as emit photons of )?
2. is there any other way i can light my set with one light with bounce etc. ?


You need to have an ensemble on yuor surface with the surface type set. There are only a few presets to choose from. To be honest photons in prman are rubbish - save your time and ue Mental Ray if you can - it is a lot better in this case.



Thank u very much Simon…i’ve planned to go to mental ray after trying my stint in this. i read about the ensemble thing, but if i want light bounces all over the scene should i have ensemble on all the surfaces? that would make me change shaders for most of the objects, but isn’t there any other way? what about indirect illumination?


Simon’s right. Don’t ever use photons in prman.

For indirect illumination you can use the IndirectLight. But it’s not quick.


“it” can display photon maps.
You can use that for debugging your scene.



now i’m using indirect light and it is slow as u said. but without ensemble for the object can’t we map a photon node to light to get bounce( i just want to try out all the options i don’t care if it’s slow)


You may be able to light link the indirect light if you don’t mind some inacuracy. The real problem with photon maps in prman is that surfaces either reflect or collect photons - there is nowhere inbetween. And you have absolutely no shader control over it. In the RenderMan globals Rays > Photon Map settings you can set an overall shader for all surfaces, but it’s not very useful unless you have a combination of reflective and diffuse photon surfaces.

Also the way photon maps are generated is just weird. There should be just a photon map display driver, but instead you have to use a null display driver and use an attribute to set the output path.



Thank u ver much simon…that was quiet an indepth explanation on photons.


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