Thursday, May 31, 2012

Procedural Dents 'n' Dirt / Downward Drips (Part 3)

AO based weathering featuring DDD (Dents, Dirt, Drips)

Lately I've been working on trying to get some directionality into an AO weathering type shader. A problem with my previous shader was that the streaks weren't just dripping down from surfaces, but also dripping up. The current solution is to pipe the Out Colour of a Maya snow texture into both the bright and dark inputs of an AO node. Adjusting the 'depth decay' of the snow as well as the 'threshold' seem to be the main tweakable parameters here, along with AO spread.

I'm attaching an .ma scene file + shader if anyone would like to experiment (12 mb)

Just the DDD shader


  1. Looks great! Definitely worth a look. The new version of KludgeCity is going to be all procedurally-shaded, so I'll definitely be borrowing some of these techniques.

    1. No worries Ed ;) I'm very keen to see what you come up with for Kludge City.

      Happy tweaking :)

  2. Great shader. I am trying to figure out how to correctly bake out just a dirt/weathered pass. Can you maybe stear me in the right direction? Thanks in advance.

  3. Hi Stuart, I would like to apply the same technique for a model I'm working currently on,but don't know how to connect this shader into my base material which is mia_x_passes material and to get the effect of the durt and the drips.

  4. Thank you very much Stuart, it's really great! I think I read something about inverse ambient occlusion on mental ray 3.10? Could be an alternative to roundcorner combination?

  5. Hi Marc - that would be great if true, I haven't checked it out yet though. Report back if you discover anything :)

  6. Hi once i add this shader to the buildings i have.. How do i add the textures which i have created into this shader or is there any other way.. please help me

  7. Hi Praveen -

    You could try feeding the drips/grunge output into the color gain of your diffuse texture. Look for the 'Color Balance' menu in the texture node you want to add the grime to. Within the Color Balance menu you'll see 'Color Gain'. Connect the output of the drips/grunge into the Color Gain of your other texture, that will multiply the grime over your other texture - hope this helps! :)

    This will multiply the grime over your other texture - hope this helps! :)

  8. Hi Stuart, could you please explain once more how to add a texture to the existing shader? I am trying to add a layered texture in order to input an AO baked by me + a Diffuse map but it does not seem to work. I don't understand which is the "drips/grunge"output node. I've tried to have a look at the image you've posted but it's not available anymore. Many thanks !

  9. Hi Raphael - sorry for the delayed reply. Did you bake the AO (the grunge/drips) yet, or are you having trouble layering your maps? If you want to add a baked AO to your diffuse map- if it's a file texture (maybe some bricks) then in the file node there's a subsection there called 'Color Balance'- open that up and you'll see a parameter called 'Color Gain'. Putting anything in this slot is just like multiplying a layer in photoshop. Put your baked AO in there and see how you go.

    I will need to revisit this shader sometime. It seems overly complicated and the creative crash download scene has extra stuff in it such as a physical sun and sky which people may not want (I didn't realise it was there until tonight).


  10. Hi Stuart, Thanks for your reply. I've managed to create a more complex shader by combining my texture/other shader with a Layered Texture node. I'm using a diffuse map as a base and on top I add your entire shader (multiply). I'm not baking the AO from the shader to a map, I'm rendering it as it is. regards,

  11. Good morning Stuart, I guess I'm a bit confused as to which file node to plug the texture into. is it the color gain of one of the ramp textures?