How to add a "dirt map" to a painted surface?

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derei
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How to add a "dirt map" to a painted surface?

Post by derei » Tue Feb 10, 2015 11:02 pm

I need to make a surface looking like a (matte) paint, but with some tearing on the surface, some less-reflective areas, like dust, or fingerprints, or scratches...
I tried this:
1.From Deep Editor I made a Satin Paint template
2.under Diffuse, I added under Reflection a grayscale image representing my "dirt map" - I just ended up with perfectly reflecting patches, not good.
3. I added the dirt map under Specular Map, again in Diffuse chanel - nothing happened this time
4. I tried 2-3 under Reflection Channel, the same... no good result.

If you can make such material, please tell me how I can reproduce it.
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Fletch
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Re: How to add a "dirt map" to a painted surface?

Post by Fletch » Wed Feb 11, 2015 11:04 am

Do you have an example image of the material you would like to create?

derei
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Re: How to add a "dirt map" to a painted surface?

Post by derei » Wed Feb 11, 2015 12:32 pm

I don't have, but try to imagine this:
A egg-shell paint (doesn't matter the color), and that paint would have some less-shiny areas (like fatigue or friction marks) and even brighter areas (like dust/fingerprints - dust makes the surface to look a bit white-ish, brighter and not shiny), that are consistent with the pattern provided from a "dirt map", for example this one: http://www.3dmir.ru/files_store/upload/large/11546.jpg
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Chris
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Re: How to add a "dirt map" to a painted surface?

Post by Chris » Thu Feb 12, 2015 5:06 am

You absolutely can. There are 2 ways to go about this. You can use the standard paint template and give it a Specular map, or you can mask together two materials.

Lets look at the first way.
e.png
e.png (11.48 KiB) Viewed 15030 times
Just replace the Specular element, which by default is a solid color, with your specular map (which can be a procedural or texture). The advantage of this method is that it is simple. You will get variations in shininess/reflection corresponding to your map. However, you won't get variations in color, your shininess is limited, and the material is not as realistic as it could be.

Now lets look at the second.
a.png
a.png (7.67 KiB) Viewed 15030 times
Here you see we have two "complete" materials layered together. While it's not show in depth, the first material is a shiny paint (IOR 1.4), the second a very flat paint (1.05). The key to this material setup is the Mask.
b.png
b.png (16.99 KiB) Viewed 15030 times
The key to ALL complex materials is masking separate materials together. For the Twilight Render material system, the mask is referred to as the Weight. Here you can see that the two layers each have a "weight" or mask. What is key for this material is that both masks are identical with one exception: the second mask is Inverted.
c.png
c.png (16.74 KiB) Viewed 15030 times
With this method, though it's more complicated, you can mask together any two materials (metal, glass, wood, paint). Your materials will also be realistic (assuming you create realistic layers in the first place ;) ).

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Re: How to add a "dirt map" to a painted surface?

Post by Fletch » Thu Feb 12, 2015 10:20 am

I would import a library material and then edit the pieces, it's much easier than trying to start from scratch.

derei
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Re: How to add a "dirt map" to a painted surface?

Post by derei » Thu Feb 12, 2015 5:57 pm

thank you, this explanation actually helped more than you think ;) ... i understood a bit about "layered materials" ... so, now I can be one step closer in making some more complex materials (can't wait to need them :D )
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Fletch
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Re: How to add a "dirt map" to a painted surface?

Post by Fletch » Thu Feb 12, 2015 6:33 pm

Maybe try to Import on of Majid's Car Paint materials and start from there.

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