Hi,

I want to point out an issue with overbright dots when rendering reflective surfaces with Mantra.
I'm working on Houdini 17.0.x.

Here is an example of the problem I have :




I can't find a way to clamp these white values when rendering.

I tried :
- to increase Pixel Sample (even with 20x20 values, I've got the same result)
- to turn the Color Limit in the Limits Tab from 10 to 0, or lower values (same result)

I have to mention that I don't use a HDRI (in other tests, I thought that the hotspot value was too high) but I'm using the default Sky Light rig (environment light + Sun).

I'm using Principled Shader, with basic setup.

So my question is :
how can you avoid these very bright dots ? Is there a way to clamp white values when rendering (as well as VRay does, for example) ? Is there a hidden option in Mantra parameters ? Is there an option in shaders ?

Thx !

Maybe if I join the scene it's better

The bright spots are because of how bright the sun actually is.

Primary rays are not clamped, as it causes energy loss. Clamping them requires either modifying the pathtracer, or if not using pbr, clamping the ‘Cf’ output of the materials.

Increasing the roughness slightly will cause the bright spots to be more smudged.

Using a proper color space with highlight compression the hot spots will not look as clipped.