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Stainless Steel

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SSGGMM
Stainless Steel
on Aug 31, 2006 at 2:01:49 am

Help needed. I've been trying to do a plain old kitchen sink, to no avail. I've tried every plausible material: Phong, DGS, Env. Chrome. Either it looks like bright polished chrome, or like plastic. I've tried to plug in all kinds of maps (motion blurred or not) into all kinds of channels, nothing seems to work. I'm working with a simple ambient light up by the ceiling, 4 walls and a ceiling.

Could anyone recommend a good tutorial, or at least start me off in the right direction?

Warmest regards,
SGM


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Steve Sayer
Re: Stainless Steel
on Aug 31, 2006 at 5:25:37 am

A couple quick suggestions.

First, Anisotropic might be the shader for you. It is designed to simulate 'brushed metal' types of surfaces (among others).

Second, the key to any kind of reflective surface is getting the environment right. By the sound of it you have this object in a very simple environment, and that's probably part of the problem. We never see "plain old" kitchen sinks in super-clean, sterile, flat-colour environments with a single light source. You will either need to complicate your environment OR simulate a more complex and rich environment using a reflection map image.

Beyond that, realism will be added with a specular map to break up the shininess, and possibly also with bump (for water droplets--or you could model them!) and colour (for stains).

Post some screenshots if you want more detailed direction.

Good luck!

-Steve


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SSGGMM
Re: Stainless Steel
on Aug 31, 2006 at 1:44:29 pm

Yes, anisotropic. Tried that. With the default "anisotropic reflectivity" box checked, it looks mat. With the box unchecked, it looks like Phong (too shiny). How exactly do you get those tiny "brushed metal" grooves, anyway? If I could get these somehow, I think I'd be on my way to a good-looking sink. Anisotropic doesn't do it by default, regardless of that attributes you punch in it seems. And once I get going on those sliders, well, there's no end in sight.

About maps, I'm confident that I can dirty it all up afterwards. I'd like to get a relatively clean one going first. It's all about that "brushed metal" look, first and foremost.

BTW, I'm new here. How do you post an image?

Warm regards,
Serge


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Steve Sayer
Re: Stainless Steel
on Aug 31, 2006 at 3:13:22 pm

Anisotropic reflectivity, I believe, only works with Raytracing... I might be wrong. But in any case, while it is more physically correct, it is often less appealing. What it does is scale the reflectivity automatically as a function of the anisotropic properties (Spread X and Spread Y). I think--it's been a while since I looked it up, so check the Maya docs for a definitive answer.

The main use of the anisotropic shader is to create highlights that are asymmetrical; i.e. they spread out in one direction or another. This property is distinct from the overall shininess, which can be controlled by simply changing the specular colour of the material (as with all specular materials).

I'm sure there are plenty of brushed metal tutorials out there. You might want to look into using a very fine bump map (with long skinny grooves), and/or texture-mapping the anisotropic properties themselves to exert more control over the appearance of your object.

Good luck,

-Steve


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SSGGMM
Re: Stainless Steel
on Aug 31, 2006 at 3:45:15 pm

"This property is distinct from the overall shininess, which can be controlled by simply changing the specular colour of the material (as with all specular materials)."

Yes, but by, say, reducing the specular colour, you also reduce those bright white highlights I need. Specularity here seems to effect the entire surface. (My cinematography background tells me that specularity refers to the blown-out white highlights - and only the highlights - you get on curved metallic surfaces - does it mean something else in Maya?)

Changing the "spread x" and "spread y" sliders has no effect whatsoever using MR with default raytracing.

As far as brushed metal turorials are concerned, they're all aimed at Max users. Haven't found one for Maya.

Regards - Serge


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SSGGMM
Re: Stainless Steel (solved)
on Sep 1, 2006 at 7:16:51 pm

RE my problems with brushed metal (or any other metal for that matter): I was in the habit of using a single ambient light as an all-purpose rendering work light (Mr. Sayer touched on this). Changing it to an area light seemed to help in getting those blown-out highlights I couldn't seem to control under an ambient light. Don't ask why.

Warm regards,
Serge


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Steve Sayer
Re: Stainless Steel (solved)
on Sep 1, 2006 at 7:45:46 pm

Oh! Yikes. Yeah, that would explain it.

In CG, unlike in the real world, light sources can cast different 'kinds' of light. Ambient lights actually do not cast 'specular' light at all, so they will never cause 'sheen,' much less blown-out hotspots.

Sorry for the miscommunication!

-Steve


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SSGGMM
Re: Stainless Steel (solved)
on Sep 1, 2006 at 10:04:07 pm

Indeed, putting in another light seems to have solved everything. And I'm finally starting to get Maya's definition of specular and reflectivity, which is in no significant way all that different than in reality. Thanks for helping to clear it all up.

This may be for another thread, but I'm wondering if anyone can recommend a general-purpose lighting setup; something that can help you gauge how your shading is coming along in MR, without having to worry about the scene's lighting "style" (which, I can't help but think, should come a bit later in the process.)

Regards,
Serge


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Steve Sayer
Re: Stainless Steel
on Sep 1, 2006 at 7:30:13 pm

Hi Serge.[SSGGMM] "reducing the specular colour, you also reduce those bright white highlights I need."

Hmm. You mentioned earlier that unchecking the Anisotropic Reflectivity attribute left your surfaces 'too shiny,' which made me think you wanted the highlights dimmed. Did you mean the surface was too reflective? If so, then you want to turn down the 'reflectivity' slider instead--that will leave the highlights as-is, while reducing the reflections.

Specularity in Maya is similar to the blown-out 'hotspots' you are familiar with, but it also affects regions of the surface surrounding those hotspots. It affects a general 'sheen' to the surface, and controls how the hotspots blend into the rest of the surface. Each specular shader has its own way of controlling this--for better or worse, anisotropic is the most complex (and therefore also the most powerful).

[SSGGMM] "hanging the "spread x" and "spread y" sliders has no effect whatsoever using MR with default raytracing."

Are you sure? It works for me: changing the ratio between these two values changes the shape of specular highlights. Oh, one thing: this property depends on the surface having properly-mapped UV coordinates. Are you using a poly surface without good UVs? If so, that might be the cause of your problems.

You asked earlier about screenshots--unfortunately you can't attach them to messages on the COW. You'll have to post them elsewhere and include a link in your post. If you don't have access to web hosting, feel free to email me.

-Steve



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jaideep singh
Re: Stainless Steel
on Aug 19, 2010 at 4:12:09 am

please tell me how to create a realstic chrome shader in maya


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