Anisotropic Chrome

[JayH]

Hi,

I've been looking at this for a while, but I'm starting to think it's not possible, or is it?

How do you create chrome like surface material with anisotropic reflections? All the examples I can find are for brushed metal, but all metals, and mirrors produce anisotropic reflections if they are say on a hand rail, drinks can etc. It just doesn't appear to work in Vray.

Thanks, Jay.

[super gnu]

do you have some examples? im not sure what doesnt work in vray.. you seem to be describing reflections being stretched in one direction when reflective surfaces are curved in one direction, which, most definitely, vray does the vray material also has full control over anisotropy.

[JayH]

Hi,

Someone else was discussing this, but didn't go into much detail:
http://forums.chaosgroup.com/showthr...8-steel-shader

I've tried doing something similar, but can't get it to work. Plus the reflections on clean chrome, such as I mentioned don't really have any visible scratches and have very sharp reflections. Altering the Anisotropic setting and the angle appears to do nothing without a texture - 'm probably missing something.

If anyone has an example material/scene I can pick apart, that'd work

[JayH]

I forgot the example:

[super gnu]

anisotropic settings work just fine without maps.. you do need some glossiness to see the result however.


im not the hugest expert on totally accurate materials, grant warwick might contradict me totally here, but id say your example is entirely possible with just a normal reflective cylinder.. the stretching of the reflections is caused by the curvature of the surface. all depends on the environment its reflecting.


on a related note, -everything- has small scratches if you want to get picky

[JayH]

Hi,

I've tried changing the settings to no avail, I can't get the reflections to alter:



Do you have an example?

Yes I know that nothing is perfect

[JayH]

As nobody is answering, maybe I'm talking out of my bottom.

I still think you can have clean reflective surfaces, from chrome to glass all having stretched reflections - the reflections are stretched, but I don't think enough. It seems that Vray produces more Anisotropy the more blurry the surface is, here's an example.



If anyone can say different, I'd love to know

[mrG_Grm]

Maybe u should change brdf type to ward or ggx, it is more suitable for metals.

[dlparisi]

@JayH: I've never seen a chrome material behave like the way you think it should. Chrome is usually pretty much a mirror finish except for minor surface imperfections. The "stretching" you're describing is just from the curvature of the tube as super gnu mentioned. In your first test image (with the tube) if you simply made the light longer it would look nearly identical to the sample image, no?

[Rens]

Hi Jay, anisotropic reflections are caused by (micro)grooves in the surface running roughly in the same direction. A fully clean chrome material meaning a fully smooth surface would by definition not have anisotropic reflections. I think what you're looking for is the effect caused by a curved surface, as mentioned before. Hope this helps.

[JayH]

I have a drinks can, Pepsi, which has a silver/metal finish. The can is polished smooth on the side, and the reflection is really stretched. But I couldn't find anything else as an example. I think that due to the vertical reflections from my monitor and various other things around my desk - all vertical, they've been giving me an impression that isn't accurate. On closer inspection they sort of match Vray.

So I think I'm wrong. Cheers for the comments though

[Rens]

Ah, there it might be the ink or sealing layer on top you're seeing, like a clearcoat. : )