White dot syndrome

[z1pp3r]

stuff id correct : some more realistic mapping on wooden shelf on the right, maybe also add vray edges tex in bump slot to get fillet feel for edges because its too sharp now., add some bump to towel material, maybe add some contrast in post? try changing white balance in vray camera, as its overally to yellowish for my taste but thats just me

[Buck]

putting your materials (the ones that get the sparkles, which should be pretty much any material with a blurry reflection) inside of a color clamp material. Set the color clamp anywhere from 600 and up, that should take care of it.

[stage36]

is my post invisible ?

[Clifton Santiago]

I read your post, but its not the solution to my problem. I don't want to disable specular in the material.

Of course, if clamp+subpixel solved the problem for WWX, then my problem is completely different. I should start a new thread and post an example.

@Buck: what's a color clamp material?

[WWX]

I agree with Clifton, I wish there was away these dots can be solved without resorting to the work around I ended up with, to me it seems like treating the symptoms and not the problem.

As if one is using a physical incorrect material or solution, or am I misunderstanding these options?

[Da_elf]

yes

[vlado]

The dots are reflective caustics, caused by glossy reflections of (glossy) reflections of bright light sources.

These are cases that are difficult to solve in general, other than with a lot of samples or some other cheats. This is because the chance that a ray starts out from the camera, reflects twice and hits a small light source are quite small. Starting from the light, this is also true - the chance that a ray starts from the light, reflects twice and hits the camera are also small, so methods like bi-directional path tracing also are not too helpful...

Best regards,
Vlado

[Clifton Santiago]

How can that be when I have reflective caustics disabled?

[WWX]

Glad you asked that Clifton, because I was wondering the same, but always feel that with VRay its a cause of a little know is dangerous (with reference to me) so I didn't asked the question

I would seem as if I am having to much (unwanted) caustic in one scene and none in the scene I long for it But sure I will get there in the end with this great knowledge and support base

[vlado]

The reflective caustics under the GI settings only refer to caustics on diffuse surfaces caused by GI (e.g. a mirror reflects light onto a diffuse surface), not to caustics on glossy surfaces (e.g. a mirror reflects light onto another mirror), as technically, this is also perfectly normal reflection. It is these reflective caustics that cause the problem. They will be there even if you do not use GI at all, just reflections (because they are just reflections).

One work-around is to set the "Treat glossy rays as GI rays" option for the dotted materials to "Always". In this case, the paths that lead to the dots will be considered GI caustics and will not be traced if the "Reflective GI caustics" option is off.

Another work-around is to reduce the reflection depth for material causing the caustics (not the one visible by the camera, but the one visible in the reflections). Alternatively, one can use the VRayOverride material to replace that material with a diffuse one in reflections only.

Yet another work-around is to make the light invisible in reflections and specular.

Another option, currently not implemented in V-Ray though, would be to disable secondary speculars/reflections from the light.

Best regards,
Vlado

[WWX]

Thanks Vlado - very help full and informative post.

[priad]

Indeed great input there, the dots pbl is my worst enemy.
Thanks again master Vlado

[Clifton Santiago]

Thanks Vlado. You are awesome. I will give some of these options a try. Cheers.

(Imagine how much easier our jobs would be if 3dsMax developers and programmers would answer questions on The Area, like Vlado does here... )