struggling with metals

[dubcat]

I wanted to keep conversion errors to a minimum, this is what I did.

- Used the same HDRi in every application.
- Made a quick material in "Substance Painter 2", keeping everything PBR.
- Used the same "Physical Camera" with same "Physical Camera DOF" settings (I wanted to test DOF too).
- Kept all the renders Linear.

The V-Ray render is 0.3 RGB darker.
Some V-Ray people actually lower the GI Contrast to around 0.75 to mimic Corona/Octane.

Everything is controlled with maps, so there was no reason to show the material settings.

[romullus]

I wonder what's causing those artefacts in Corona?

[Juraj]

The bump is done with procedural noise. But yes, Vray doesn't have it. Hmm, no idea. Could be some form of terminator ? (despite having no diffuse). It's super contrasty HDRi (Chelsea stairs from HDR-labs)

[4b4]

There's a checkbox in Arnold called smooth subdivision tangents that deals with this faceting effect that occurs with anisotropy. Not sure if that gives a steer towards a solution in Corona?

[Nekrobul]

Lowering bump value might help. to sth like .05-.03

[freeflow]

i'm getting the same artifact even with no bump, didnt find a walkaround still
i noticed that is somehow related to the anisotropy of a material and it occures both in uvw and in local normal orientation, if it's set to 0 the facets disappear

[DarcTheo]

Thanks for the replies and thanks dubcat & juraj for showing your examples.

I will try setting up a new test scene and try again using your inputs. You both use HDRIs, does this make a big difference on metals? My studio tend to use just the sun&sky as the images get a style in photoshop, so its not aiming for photorealism. I did try use an HDRI for reflection override but the scene was being lit with sun & sky still.

It's clearly possible to get very similar results, just frustrating that i'm doing something wrong. perhaps I need to convince the use of HDRIs in our work flow.

I also noticed those artifacts appearing on my corona shader, not sure what caused it, will try lower bump values again.

[Juraj]

i'm getting the same artifact even with no bump, didnt find a walkaround still
i noticed that is somehow related to the anisotropy of a material and it occures both in uvw and in local normal orientation, if it's set to 0 the facets disappear

Correct. I did another test and it's because of ano not bump :- ).

[Juraj]

Thanks for the replies and thanks dubcat & juraj for showing your examples.

I will try setting up a new test scene and try again using your inputs. You both use HDRIs, does this make a big difference on metals? My studio tend to use just the sun&sky as the images get a style in photoshop, so its not aiming for photorealism. I did try use an HDRI for reflection override but the scene was being lit with sun & sky still.

It's clearly possible to get very similar results, just frustrating that i'm doing something wrong. perhaps I need to convince the use of HDRIs in our work flow.

I also noticed those artifacts appearing on my corona shader, not sure what caused it, will try lower bump values again.

Well, in this small example, I needed contrasty environment for metals to truly look like metal :- ).

HDRi or Sun/Sky is just type of light, it doesn't dictate reflections but with Sun/Sky, you need geometry to complete the environment, while HDRi can already have on.

I use Sun/Sky 90perc. of time :- )

[DarcTheo]

Well, in this small example, I needed contrasty environment for metals to truly look like metal :- ).

HDRi or Sun/Sky is just type of light, it doesn't dictate reflections but with Sun/Sky, you need geometry to complete the environment, while HDRi can already have on.

I use Sun/Sky 90perc. of time :- )

Good to know its not sun & sky then, I quite like this simple way of setting up the base lighting. Haven't had time to try any tests again yet but hopefully I can get similar results soon.

[freeflow]

did anybody find a workaround or a way to fix the facets appearing when using anisotropy?