Arnold is not calculating specular indirect of normal and bump ?

[lcollod]

So i've been trying to create recently some materials using normal and bumps map but after some test i found that my materials didn't have the same look with displace or with bump/nomal, especially for metal materials.

So i tried some test render and i found that they was no specular indirect calculated when i was using normal or bump maps, so it creates black areas (where it supposed to have reflections).

So did i change a setting somewhere i didn't have to change ?

Version with displacement only:
screenshot-543.png

version with bump only:

screenshot-544.png

specular indirect pass from the displaced version:

screenshot-545.png

So as you can see if i just overlay the specular indirect pass on the bump version render i get almost the same result as the displaced version.

Thank you for reading me.

[maxtarpini]

It's not that arnold isn't calculating this or that .. it's that if you crank up too much bump it eats everything from diffuse to specular etc. and this happens in any render engine. however arnold has displacement+autobump feature that should be just perfect for this kind of stuff (ie. the first image you posted may have already autobump if you did not unchecked it in the arnold displacement rollout.

[lcollod]

The first image don't have autobump.
Here is a comparison blender cycles and arnold, same mesh, same hdri, both use the same normal map (i used ai_normal_map node for arnold).

And here is the specular indirect pass for the same render:

Also my specular raydepth in arnold is set to 8 so that's not the problem.

Maybe displacement is a solution but this is an expensive one, i don't want to have thousands of poly for that kind of materials.
And using a lower strength for teh normal map is not a solution cause you lose all the" crushed effect".

[maxtarpini]

Ok the black you see in the Arnold image ain't nothing to do with specular indirect .. it's that too much bump corrupts normals and so your reflections ain't shining as they should. btw did you try to increase specular bounces to see if you get better reflections ?

That said, the default specular indirect pass in Arnold is for when an object is reflecting other stuff other than lights (like the ibl you probably use to light up the scene) .. ie. if you use a green ball side by side with your aluminum ball .. you'll see that green ball in the indirect specular.