jagged reflection of hdr environment map

[robert-then]

When using Arnold with material with high reflection roughness=0 the image of the environment map becomes jagged. Problem does not occur using art renderer. I have experimented with settings but it still happens. Changing roughness to .03 or greater changes result but puts blur over entire background.
Any Suggestions?

[aaronfross]

This is because the Resolution is too low. Default is only 1000 pixels. Go into Render Setup > Arnold Renderer tab > Environment, Background, & Atmosphere. Set Mode to Advanced. Enable Custom Resolution and increase it as needed. For bulletproof results, you can use the horizontal resolution of the environment map.

[aaronfross]

You can also use an Arnold Skydome light if that's your pleasure... the Resolution field is a little easier to get to, and manipulating the backdrop placement is as easy as rotating the light. But with a Skydome, you won't have the option for a backdrop/backplate separate from the lighting.

[madsd]

You could map the inside of a sphere with the map and make sure it was filtered out from all scene light and feed it through emission color at 1.0 I guess.

[aaronfross]

If you needed a separate background you could use a geometric sphere with an Arnold Flat map into a Map to Material shader... then an Arnold Properties modifier with all visibility and shadows disable except Camera and Transmission rays. You wouldn't want any Emission if you're trying to separate the lighting from the backdrop. The point of the separate backdrop is that it does NOT contribute to lighting. And anyway, Emission is super grainy, requiring massive camera samples to fight the grain. For glowing objects, the Arnold Mesh light is the way to go. But NOT for backdrops.

[robert-then]

Aaron

Thank you very much for the information

Adjusted resolution to 3000 and image is fine

Increasing resolution seems to have minimal effect on rendering time

Tried at 500 and it really shows the effect of that resolution setting

[robert-then]

Another question

Would using a skydome light for the environment be the same as the material reflection map in mental ray?