crazy out of control artifacts...

[shadevfx]

weve seen NaN pixels and super bright white pixels a bunch, but this is a totally new one for us.

Any thoughts on what might cause this?

Pretty standard settings, all IBL driven lighting from the environment... irradiance map and brute force.

[instinct]

As a first thought i'd say check the HDR you're using for crazy pixel values. Can happen during HDR creation / stitching...and can be a bitch. Try clamping to some sane levels and see if it goes away.

Regards,
Thorste

(Max here, but seems like a platform independent issue :P )

[shadevfx]

highest value in the map is 2.7... not crazy at all.

weird huh?

[cdavis]

do you have "force colour clamping" off in the buffer?

[shadevfx]

clamp output is set to 5

[jensl]

That is odd. It almost looks like the light is getting magnified as it refracts - there's no shaders with reflection/refraction color values above 1? Sub-pixel mapping and clamp output always seem to take care of any over-brights for me. If you test with just rectangular V-Ray lights or a different IBL, the problems go away?

[instinct]

How did you check for the brightest value ? I had some HDRIs that were only diagnosable using a tool like Nuke's maxlumapixel wich will give you the brightest pixel (trying to eyeball overbrights didnt work)

Regards,
Thorsten

[vlado]

Which build is this? A similar effect could happen in older versions if there are perfectly black regions in the HDR map (as would happen if the lower half is black for example). This should be fixed in the latest nightly builds though.

Best regards,
Vlado

[shadevfx]

V-Ray: V-Ray for Maya version 1.50.00 from Sep 4 2009, 19:04:36
V-Ray: V-Ray core version is 1.80.01

we've emailed a couple of times to get on the nightly builds with no success..

can you sign us up?

Thanks
Bryan

[vlado]

Yep, I've just sent you the info.

Best regards,
Vlado