First off I have to say I know i'm possibly comparing apples and pears but in trying to learn mantra i'm comparing it with my experience of redshift and arnold (in softimage). Sphere on a grid lit with the equivalent of a domelight with the same hdr hdr, and a peak white plaster style shader, very simple. Arnold and redshift look prety near identical but mantra has a completely different hue. I have to ask why is there a difference? I'm not saying mantra is right or wrong but i would like to know what's in control of the difference.

cheers,

A.

Hi. Do you also have the HDR image you used for these renders?

apologies, i was having trouble getting stuff uploaded yesterday

Hmmm seems like environment light is either downsampling hdri incorrectly or picking sampling directions that are slightly off. You can alleviate this issue by increasing “Light Importance Levels” (add it to ROP or envlight from edit parameter interface) but that's just a temporary workaround that may be limited to this particular hdr image.

I'll file a bug.

This issue is addressed in upcoming daily build.