GI method and dielectric materials

[simmsimaging]

Unfortunately Paul was not able to check the scene because it was done in Max2008. Does anyone have an idea what might be causing this odd band of sharp/softness in the caustics?

Thanks!

b

[zeronove]

@ simmsimaging

how did u render that direct caustics map?

i've done a little search for the script u mentioned but I didn't find it; any chances to have more info from u?

thanx

[simmsimaging]

@ simmsimaging

how did u render that direct caustics map?

i've done a little search for the script u mentioned but I didn't find it; any chances to have more info from u?

thanx

It's from a thread started by Vlado - I don't have the link handy but here is the line of script though:

renderers.current.caustics_showCalcPhase=true

Just paste that into the maxscript listener and hit enter and it should work.

b

[zeronove]

I see, I missed that post

now I get it, thanx

[crazy homeless guy]

are dielectrics considered more accurate than using Vray materials for things like glass? what is the advantage? sorry if it sounds like a newbie question.

[simmsimaging]

I am using Vray materials - I just used the term to refer to the type of material I was setting up with it, sorry if that was confusing. Right now I am trying to make everything I can with VrayMat and VrayBlendMat to ensure the most compatibility.

[simmsimaging]

bump

Still haven't figured out what is going on with the caustics here - anyone else have any thoughts?

Thanks!
b

[MoonDoggie]

I still can't get the damn things to render on a simple scene here! heh, I'll figure it out later.

[vlado]

Still haven't figured out what is going on with the caustics here - anyone else have any thoughts?

If you are using the direct caustics method, the only way to clear the noise is to shoot more caustic photons from your lights (from the Light settings dialog). You might also want to increase the Max. density parameter for the caustics to some non-zero value so that you don't run out of RAM.

Best regards,
Vlado

[simmsimaging]

If you are using the direct caustics method, the only way to clear the noise is to shoot more caustic photons from your lights (from the Light settings dialog). You might also want to increase the Max. density parameter for the caustics to some non-zero value so that you don't run out of RAM.

Best regards,
Vlado

Thanks Vlado -I have been trying that but that leads to the other problem I posted about earlier in #13 of this thread - have a look at the attached shots there and you will see where part of the caustics are blurred and part are not. That's what I'm trying to get around at the moment.

Thanks,
b

[vlado]

Caustics that are directly visible by the camera will not be blurred, but any caustics visible through reflections/refractions will use the normal interpolated caustics method as they cannot be calculated directly. So in that case, you will have to play a bit with the search distance/max photons/max. density parameters to get similar results.

On the other hand, if you are using area lights, those caustics can be calculated exactly with the brute force GI method, instead of actual photon-mapped caustics.

Best regards,
Vlado

[simmsimaging]

Caustics that are directly visible by the camera will not be blurred, but any caustics visible through reflections/refractions will use the normal interpolated caustics method as they cannot be calculated directly. So in that case, you will have to play a bit with the search distance/max photons/max. density parameters to get similar results.

On the other hand, if you are using area lights, those caustics can be calculated exactly with the brute force GI method, instead of actual photon-mapped caustics.

Best regards,
Vlado

Ah - now I see why the difference. Thanks!

I'm pretty confused about a clear-cut workflow for using caustics though. I can't seem to get clear on whether to use only GI caustics, or direct as well, and whether to use that script you gave or not. I thought that script just made the caustic "pass" visible - but perhaps it changes how it works too? Also, do you mean literally that I should use Brute Force GI to get proper caustics?

I generally do use area lights (vray lights) so would my best bet be to turn off direct caustics and just use GI caustics? Time is not my bigger concerns here, but rather getting good quality results - then time

Could you recommend the simplest workflow for rendering good fluids with caustics?

Sorry for all the questions, but I have been through all the threads I could find, googled tutorials, and read the manual and I'm just not getting very far with this.

Thank you for the help!
b

[vlado]

The answer to that would depend on how you are lighting the scene. But in general, I myself would use just the normal caustics (not the directly visible ones), max. photons set to 0, and max. density locked to 1/3rd to 1/4th of the search distance. Then I would play with the Search distance to reach the amount of blurriness that can be tolerated, and then its just a matter of shooting more photons until they become relatively noise-free. Also, I would try to use relatively small light sources or point light sources (large area lights might take a very long time to clear up the caustics in this way).

Best regards,
Vlado