Single Dirt Map over multiple groups & materials

[mayfield_uk]

I have drawn a tiled pathway. Each tile is a grouped object which then has the corresponding material applied. I would now like to add extra details to the path, specifically a Dirt Map. I am currently unable to think of a way to do this, given that each tile is an individual group/material - If I add a dirt map to the black/white tile material it will appear on every instance which is not what I would like.

I would like the 'dirt' to appear along the outer edges of the path as a whole. Is there a way of having a transparent material with dirt mapping applied. This is the only way I can think of adding these details, i.e. laying a piece of nonreflective transparent material ontop of the whole path which would then correctly apply the dirt map.

I hope that makes sense.

Thanks!

[mayfield_uk]

Ok, have found a solution.

Have just created a dirt map in photoshop which is the same size/ proportions as the area I want to cover on the path. Black area where I want the dirt, white areas where I don't. Have then created a material and used the dirtmap image in the opacity/transparency modifier. Added a dirt/soil image for the diffuse layer and then added a refraction layer with clear settings (IOR: 1.0). Also used the dirt map as a bump map. Has worked really nicely. Once I got the texture placed correctly in the model I just need to paint dirt onto the file in photoshop where necessary.

If there are any other solutions to this I'd be very interested to hear them.

[peerman]

Hi, You could also use a texture with the tilingpattern. If you use a texture instead of real geometry the dirtmap could be painted on the texture (as well as other stains for example). In combination with a displacement and bumpmap you could achieve the same look as the "full geometry" one. And you only need one rectangular plane.

Best,