Weird pattern reflection in V-Ray glass

[Streetwise]

Nothing special about this glass - it's a standard vray material, black glass. I'm sure it something with my render settings, but am unsure what to check.

Thanks

Dave

[joconnell]

Could be the cutoff parameter in the material? Go To the options rollout of your glass material and check to see if the cuttoff parameter under trace reflections is at the default of 0.01, it can often cut off reflections early and cause this type of banding.

[Streetwise]

Cutoff is at 0.01. Are you then saying that it should be set lower, like .005?

[Morbid Angel]

yes, its an optimization feature but on low light reflections it can get cut off. You also need to render in float format to make sure the whole range is preserved.

[Streetwise]

.005 seemed to take care of the issue, but you lost me with the Float Format thing. I'm saving as 32-bit. Is that the same thing?

Thanks for your quick responses and help! Much appreciated!

Dave

[Morbid Angel]

yeah like an exr or any image that has high range otherwise you may get banding or other 8 bit artifacts.

[Streetwise]

Hmmm.... I'm at .001 now for the cutoff, and I'm still seeing artifacts. Anything else to try?

Thanks.

[Morbid Angel]

that to me looks like low irradience map

[joconnell]

Yep - looks like the type of shape you get with light cache samples like here - http://www.spot3d.com/vray/help/200R...half_scale.png

[zeronove]

are you using the lightcache for glossy ray? if yes, try unchecking it or switching to fixed filter

[Streetwise]

I think that fixed it! unchecked the lightcache for glossy and switched to fixed filter. Glass looks really clean now!

So basically, anytime that I have glass shelving in a shot, I need to do that? or perhaps just see how it's looking first?

[Morbid Angel]

no, using light cache for glossy is good for rendering/speed improvement, but if your lc settings are low, it will produce this kind of artifact.