Spotlight specular affecting VRay Lighting pass

[DaveKW]

I'm using the Vray Carpaint shader and I've got an issue where the specular component from a standard spotlight is introducing artifacts/noise in the VRay Lighting pass, with the noise being the shape of the bright specular highlight. If I untick the specular option, the lighting pass looks correct but then the RGB render isn't how we want it. I've attached a zip file with the issue.

Any help would be great.

Cheers

[AbeMata]

Turn off your clamping, or set it to something like 5. This cleared it up for me. The same issue happens with a vray light as well with clamping set to 1.

[kosso_olli]

This also happens when clamping is off entirely, or when very bright reflections are on the object. To me, this behavior is somewhat expected. I mean, the more the speculars or reflections are sampled, the less samples are available for the lighting below. The rgb result is what matters to me, as long as that it clean, I am happy.

[svetlozar.draganov]

Which Vray version is that, I got completely different result with the attached scene:

The noise in the Lighting element exists because the contribution of that area to the final RGB pass is too small and Vray is optimized to not spend too much time calculating things that will be invisible in the final-pixel. If you want to clear that pass you could increase the light-subdivisions.

[DaveKW]

We're on 3.00.02. That attached image looks like the rgb channel with specular disabled and the sRGB shift turned off in the VFB. Increasing the light subdivisions doesn't have any effect

UPDATE: I've sorted it...I think. The issue seems to go away when I increase the subdivs on the VRay light and not the spotlight.

[svetlozar.draganov]

Yes - the specular was disabled, thanks for the confirmation.
The Light Subdivisions doesn't work because for SpotLight they only affects the Shadows not the Specular - sorry about that.
Increase Min Shading Rate value inside Image Sampler Rollout to 10 or 20 and the noise will disappear.