Brushed stainless material does not look right

Started by JST, September 15, 2015, 07:47:46 PM

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JST

I am having trouble getting a brushed pattern to look right.   Bump does not do it, and the rendering looks more like sand than brushing.  Renders as dots, not streaks, and does not catch light like brushing.

Heavy is not better, and light is looking just polished.  My attempts to fix this are not making it better.

Any suggestions as to parameters to fiddle with?

Keyshot 5, recently updated, I think 5.3.  Using it with Geomagic Design, if it makes any difference.

INNEO_MWo

Hello.
In KeyShot Cloud you will find several solutions. I've pushed an example tagged with INNEO. This solution works for big sheets.
And there is an impressive tutorial from Richard Funnel that explains all about lighting for stainless steel.

JST

#2
Where is that tutorial?  I thought I had seen all of the relevant tutorials.

Also, since the lighting is known, it isn't arbitrary, I'm not sure how much I can change it just to suit the rendering.  It's an indoor scene, with lights in certain places, so....

Chad Holton

I'm guessing you may need to bump the roughness samples up a bit. Can you share a screenshot of the brushed stainless result?

JST

#4
Quote from: MWo on September 15, 2015, 11:12:14 PM
Hello.
In KeyShot Cloud you will find several solutions. I've pushed an example tagged with INNEO. This solution works for big sheets.
And there is an impressive tutorial from Richard Funnel that explains all about lighting for stainless steel.

Unable to register with the cloud.  After many tries, still get "could not open socket".  Some other time, I guess. 

The best version I found was the "radial brushed" material, although even it is not quite there.

Attached is the sink basin only, currently set up as radial brushed.

INNEO_MWo

(I reply your post via mobile phone. So I can't open your ksp file)

In KS cloud you will find two different materials from me. One is this made with anisotropic mat. type with a ten times larger roughness scale in x to y. Plus a small procedural brushed texture with similar scale factor like roughness. That will give a smooth reflection of lights and shadows, just like a linear brushed steel.
The second mat example is made with metal paint instead of metal (type).

I've looked in the learning section as well in the YouTube channel, but I can't find the tutorial I have in mind.

@ a Luxion member.
Is it allowed to upload a movie in here?
Perhaps I find the video in my old podcast backup. This one was recorded by Richard Funnel.
So let me know and I'll post it.

So now my kids are ready for dreaming time

See ya

INNEO_MWo


jhiker

Yeah, but he's having trouble registering with the cloud, it seems.

JST

Yes, it took 20+ tries to even register here.  same deal, socket problem.

Chad Holton

Quote from: JST on September 17, 2015, 10:58:36 AM
Yes, it took 20+ tries to even register here.  same deal, socket problem.

Try flushing your cookies for keyshot.com

If that doesn't help, please contact our support team: support@luxion.com

richardfunnell

I hope that you were able to sort out the issues with the cloud! Sorry for the long explanation, but I wanted to chime in on this topic :)

When working with stainless steel and many other materials, there are two main factors for getting what I would call good results. I started with your BIP file and created 2 material variations with your scene.
First, the environment will have a big effect since metals are so reflective. My suggestion is to start with an environment that you like and build your materials to suit that environment. Environments with high contrast will work better, and I also try not to have pure black in the environment since those black reflections will always show up. I tend to use the HDR Editor to slightly blur an environment and try to lighten some of the darker areas. An example environment is in the attached KSP.

The second main factor is the material itself which has a few key variables. I generally use the Metal material for chrome and simpler material finishes, and I make a lot of metals from scratch using either the Metallic Paint or Anisotropic material (95% of the time with Metallic Paint). The reason to use these materials is that they give you control over the specularity of the material which the Metal material does not do. I've made a brushed stainless material using both in the KSP file, you can toggle them on and off in the scene tree.

It's equally important to stress that there is no "perfect" stainless steel that can be used every time. It's going to depend on your geometry, lighting environment, and render intent. The final material appearance itself is very subjective depending on material grade, nickel/chrome content, brush number, and surface finishes. Add on render time (and how much time you have to fine tune all the variables) and your results will vary :)

Since I mostly use the Metallic Paint, I can give you some pointers on that. I start from scratch by selecting any Metallic Paint in the library and dragging it to my part.
- Use a dark Base Color. This is where I add a little bit of warm/cool hue depending on the chrome/nickel content. Usually very dark grey colors here with 2-5% color saturation.
- Use a light color for the Metal Color, we'll change this anyway.
- Increase Metal Coverage to .8 or .9, this slider caps out at 1.
- Reduce both Metal Roughness & Clear-coat roughness to 0. You should have something like a chrome material :)
- Move to textures tab, and select Specular. I completely ignore Color, and only rarely add bump. We're going to get control over the reflections by defining a brushed Specular texture, which is the Metal color in Metallic Paint. Try Brushed (2D) and scale it up or down and use the Mapping Tool to position it. What's important to know here is that we're defining our reflections with this texture, so dark=no reflections & white=very reflective. I usually use lighter grey colors with about 10-30% between them, like 70% for one and 90% for the other. Again, your geometry & environment will make a difference.
- Now go back to your Properties tab and add in a little bit of Metal Roughness and Clear-coat Roughness. You should see a material that's brushed metal, but hopefully doesn't blow out.
- After that, it's just tweaking to get the results. I may increase the Clear-coat Refraction Index, add a *slight* bump if I want to see the brush texture more.

For the Anisotropic material the technique is similar, but that material includes independent X/Y roughness control which will give you streaky reflections which are more accurate (but harder to control) for brushed metals. It will give you a more accurate appearance but can be tricky to get right. For more info on Anisotropic, check the KeyShot Manual under Help>Manual..., then Materials > Material Types > Anisotropic.

I hope this helps, let me know if you have any further questions!

JST

That IS helpful.  Thank you.

Now I see a bit more about how the parameters work.  And I see how the brushed was made-up.  I didn't understand it to begin with.

I didn't really get it from the manual, it gives the information, but I think a hands-on tutorial walk through would be good.  Maybe there is one, I didn't see any.  The Geomagic folks, and Solidworks,  have them, as do others.  They make you run through various operations and commands to accomplish a task.  In the process you start to see how things are done in the program.

richardfunnell

Awesome, glad to help! Can you post your results when you've had a chance to try this method out?

Yes, our "how to do/get xxx" could sometimes be better, brushed stainless is a good example of a common but complex material. Hopefully next time someone has a question about it they'll find this thread :)

JST

OK.  I probably can.

I did notice that lighting makes a huge difference.  Most of the material looked good, but the sloping stove hood was just as bad, even with a modified material.  Must be the lighting angle.   Since it isn't actually critical to the rendering, I may just alter the angle along with some other scene changes.  That may fix it.

Metal is a problem.  I have some chromate dipped aluminum to deal with next, which is a bit blotchy and sorta dull.  I'm thinking that scaling a suitable map and messing with the colors might do it.  But I'm not sure I understand the maps, quite.

More fun.....

jhiker

Quote from: richardfunnell on September 19, 2015, 09:38:16 AM
Awesome, glad to help! Can you post your results when you've had a chance to try this method out?

Yes, our "how to do/get xxx" could sometimes be better, brushed stainless is a good example of a common but complex material. Hopefully next time someone has a question about it they'll find this thread :)
That's a really useful little tutorial there - many thanks!