Using a texture for dirt falloff?!?

[MoGrafik]

Hey everyone,
I was hoping someone might be able to help out:
I'm drying to find away to use a texture to determine the falloff for dirt. I tried searching the forum and it pointed towards it being possible in this post:

http://render.otoy.com/forum/viewtopic. ... t=dirt+map

However I'm not really too familiar with the standalone application, and I need to do my rendering inside of Cinema 4D.

(as a note, the same kind of dirt texture map looks like it is used on the image of Ironman on the otoy homepage:http://render.otoy.com/)

If anyone can please help me out I'd be really grateful.
Thanks

[FooZe]

Hi MoGrafik,

Hopefully i am understanding what you want correctly...

I'm not sure a dirt map would be any easier than just a mix material where the amount is controlled by a texture.
If you need to make a texture to control the falloff then you may as well bypass the dirt texture altogether and just control the material mix with a texture.

It is quite possible that this is how iron man was done (a texture to map where to control where worn vs clean metal is used).

Or is there something i'm missing?

Thanks
Chris

[djart]

Hi, i just started a thread for worn edges/ paint here:
http://render.otoy.com/forum/viewtopic.php?f=30&t=36833

Maybe this helps a little bit.

[MoGrafik]

Hey guys, thanks so much for getting back to me!
Fooze, I thought about using the mix material, but I wasn't sure how I could tell it to use one material just on the edges of an object. Or would just loading in an Imagetexture do it?
And Djart, that looks great! Thanks for the link!
I'm away from my work computer at the moment, but will try using the mix material, and using that download!
Thanks very much for your help!

[FooZe]

Hi MoGrafik,

Yes. Create the mix material assign the two materials (clean and worn) to the two material inputs, then load an octane imagetexture into the amount pin.

Thanks
Chris.

[MoGrafik]

Hey Chris,
thanks so much for getting back to me!
Had a go at doing this, but it didn't quite give the result I'm after. It blends the two materials based on the luminance of the imagetexture you load in, however it does not pick up the edges of an object, as the dirt shader will.

The DJart method (above) can work pretty well, the only drawback being it seems to be reliant on having two quite contrasting textures in the materials (ie: a clean metal material and a VERY dirty metal material) however the falloff in this method is still uniform.

The effect I am trying to achieve is similar to in vray, how you can load an occluded colour, a unoccluded colour, and then a texture map that determines the falloff between them. I've had some cool results using the dirt as the amount in a blend material, but still not quite what I'm after.
Thanks so much for all your help and suggestions!