Want to acheive this look...

[Matt Sugden]

Hi all, I'm wanting to try and emulate this look on a metal cladded building I'm working on. I'm using vray as my renderer and I wondered if anyone could give me some good points for getting that great large broken up specular reflection. I'm talking about the upper part of the building.

 

http://www.tropolism.com/shiny2.jpg

 

is it just down to choice of HDRI perhaps? and adjusting the glossiness of the relection? I can never seem to get these really strong sun reflections.

 

Cheers.

[mattclinch]

slightly anisotropic metal with a noise bump uv mapped per face, possibly with 5 or 6 variations of the noise in a multi-sub with material by element on the metal facade, assuming ther metal panels are individual elements.

[Matt Sugden]

Cheers, getting the radomness the faces isn't what I'm struggling with. It's getting the blown out sunshine reflection is where I'm having difficulty.

[spanish pants]

I was struggling with a similar problem but on a glass facade. After pulling out what little hair i had, i tried adding a little Hilight glossiness to my v-ray material and it worked.

I don´t know if there is another method but it worked for me.

 

Hope this helps you out.

[Fran]

I also notice that the panels are slightly pillowed. That is contributing the most to the broken-up reflection.

[Nic H]

if you have a decent bump and spec map (like matt said would prob do a face mapped UVW, or maybe a material by element modifier with a few differing versions of you base mat)

 

on your material id unlock highlight glossiness from reflect glossiness (use a falloff map) to something like 0.5 / 0.6.

 

I would even put in a specular only omni that affects only the wall. i do this alot to get more specular on specific objects like water and metal.

 

then in post use the spec pass and blur / screen a few versions over your diffuse pass

[FlytE]

Its hard to give you an exact solution to this as there are lots of variations but off the top of my head I would say to try keeping your Reflection IOR low (1.6), but putting your refraction IOR high (say 16.0). Also set your material BRDF to ward and make sure your sun is not invisible.

 

Hope this helps, if not maybe try posting your material settings

[Nic H]

metal isn't refractive though.

[FlytE]

Its not see through, but the refraction value can still affect surface reflection.

[mattclinch]

i'm intrigued.. how?

[AndyC]

i'm intrigued.. how?

 

Erm, I would love to know also. Isn't reflection a surface effect?

[FlytE]

Im not really sure what to say other than to suggest that you try it for yourself. Open a simple relfective material and watch the change when you bump the refraction IOR from 1.6 to 16.0

 

Im not saying it is THE solution in your case, perhaps its not, but it in certain circumstances it can make a difference to your metal.

[Matt Sugden]

I would even put in a specular only omni that affects only the wall. i do this alot to get more specular on specific objects like water and metal.

 

This did it, great idea, I'd would have never thought of setting up a light for a single object in a scene just to 'fake' a highlight.

 

Must remember this in the future... thanks

[Justin Hunt]

http://mentalraytips.blogspot.com/2007_10_01_archive.html

 

Master Zap gives a bit of info about metals here.

 

Vray doesn't really give direct access to the diffuse level (or amount the suface absorbs light) so by changing the refractive values simulates the absorbtion that metals have.

 

This is also true for Glass. By dropping the diffuse level of the glass eliminates "Milkyness", making the reflections crisper and more contrasty.

 

jhv

[FlytE]

Thanks for that Justin, in the time I had I couldnt find a decent resource to explain myself.

[mattclinch]

that shows how the fresnel curve of the fresnel falloff of reflection can be linked (as it is in most physical cases where a materials surface is composed of the same material as the innards) to the index of refraction - especially in the case of metal materials where the reflection fresnel curve adjusts to simulate the reflection falloff caused by the anisotropy of metals at higher viewing angles when the two are linked.

 

however i cannot understand how you can "keep your Reflection IOR low (1.6), but putting your refraction IOR high (say 16.0)"?

Edited October 30, 2009 by mattclinch

[FlytE]

I know what you mean, I think what I was trying to emphasize was to put the refraction higher and use that to boost the reflection a bit. In hindsight he probably does want to keep his refl IOR fairly high too, but either way its a moot point as he has found his solution.

[Nic H]

weirdnessssss