Hi,
The scene I am using requires me to use some blurry refractions. As you can see in the image. Turning the glas from a refraction-glossiness from 1,0 to 0,97 turns the refraction really dark. Using interpolation or not makes no difference.
Where is the Problem ?
The scene contains one direct light, and some simple environment light, GI: Irradiance Map, Brute Force secondary, Regular camera, …
are refractive caustics turned on?
Is “affect shadow” turned on in the glass material?
Affect Shadows is on (has been before as well)
Caustics for refraction ?!? Well, I do not use caustics so far … did not think, it would matter in a scene like that ( and actually it did not matter as long as I do not use glossy refraction ..)
where can I find the button you are talking about ?
Cheers, Peter
under indirect illumination- there are 2 options for caustics.
The refractive caustics option needs to be checked if light is to go through any transparent object.
Is transparent shadows turned on in the direct light you are using for the sun?
Yes
Hi, Jack. Thanx for your will to help, BUT:
Yes, the GI caustics button ist turned on ( If not, then it would not work in non-blurry mode as well, would it ?!?).
Transparent shadows are fine as well …
Hmmm :?: Help !
I recognise the problem. Your refraction depth might be too low, but what I usualy do is go to Vray properties and up the “recieve GI” section, sometimes to 1.8 to get it looking good. To make diffuse glass in a right way you probably would also need to use translucency, but keeping in mind the rendertimes I allways go for the increase GI solution.
One day when I have the time I’ll dive into it and solve it.
Marc
Done !
Solved, just change “Treat glossy rays as GI rays” to “Always”.
Puh, 
, Peter