View Full Version : vray - does caustics need GI?

04 April 2006, 03:21 PM
I'm making this bathroom that I'll post soon, and I'll have Swarovski lights on the ceiling. Rarely I need Caustics, and every time I use it, it doesn't work. Usually you need really strong multipliers, more than 100.0, but this time nothing helped. So every time I need to use it, I got to blank scene and teach myself how to use it all over and over again.

Now, does anyone else have problems with caustics not showing up, and has any ideas on what to do? This time, I realized I need to turn on GI in order for caustics to show up. Is this really necesary?

Oh and, everything is turned on, lights generate it, objects too, and other objects recieve it, so that's not the issue.

Thanks for help

04 April 2006, 06:11 PM
yes, caustics are a GI related effect... so you will need to use gi to have any caustics in the scene.

04 April 2006, 10:32 PM
No it is not necessary for GI to be on. I was having the same problem with caustics a while back and found out that caustics require a decay (I used inverse square, not sure if that's necessary or not) on your light sources. If you're using a VRayLight, this is built in. Standard Max lights have decay turned off by default, so you'll have to do this yourself. Also make sure that your shadows are set to VRay shadows and transparent shadows is clicked on.

On the other hand, for GI caustics, GI has to be on for them to work. But it sounds like you're going for direct refracted caustics.

04 April 2006, 10:48 AM
Ok, I'll try that also. I found out one more thing, the object that will recieve caustics must have a material (so no default object with no material) and I think it should be vray material.

Nope, nothing we thought is necesary. You need vray shadows and the object that recieves caustics needs to be vray. That's it!!! :-)

04 April 2006, 04:39 AM
However, if you plan on using rendered layers of the caustics, reflections, refractions, GI, diffusion, shadow, etc. you must be using Vray materials.

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04 April 2006, 04:39 AM
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