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Pan3sar
08-09-2011, 04:24 PM
Does anyone know how to get this type of effect using mental ray shaders, where the specular light hits, the swirls form around it. I thought about texturing the car using scratches as a specular map with falloff, however, the scratches do not form a circular shape as in real life.

http://www.elitedetail.co.uk/userimages/ba3aeswirls7qc.jpg
http://cpdetailing.com/pix/before_swirls.jpg

littledevil
08-11-2011, 01:07 PM
aren't these anisotropic highlights (reflections) ? i am not using mr , so i cannot help you, but in c4d you can change the anisotropic frequency / scale / projection of the highlight to get this scratchy effect.

soulburn3d
08-11-2011, 05:33 PM
It is an anisotropic effect, but it's not the standard effect where the entire surface has scratches in a single direction, it has circular type scratches all over the place. I assume this comes mostly from people rubbing the car, like using a rag to dry it, or buffing caused by multiple applications of wax.

Finding a good map that simulates this will be tough. I can suggest maybe a non digital method to create on, go to your local art store, buy some scratch board (a large piece), get a brush, and replicate the same motion you'd get by buffing the car, except do it on the scratch board strong enough to remove some of the black covering, revealing the white below. Then scan the scratchboard, and make a tilable map in photoshop. You can also experiment with custom brushes in pshop to produce the map.

You can then use this map as a soft bump, and you could probably modify the map too be used as an anisotropic direction map. This will be a tough effect to achieve, but it'll be very cool if you pull it off.

- Neil

Pan3sar
08-11-2011, 09:09 PM
I think it is caused by washing the car, sponges, and just day to day wear and tear. The only thing is the scratches are random and there are hundreds of them, however (I don't know why) they are only visible like at a tangent to the specular light beam, it might be possible if I added a scratch map to specular, combined with a falloff map.

thats some good advice, will give it a go and post back if I can make it work

Thanks for the advice!

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