dirt map?

indian_boy

hey guys...
i was just wondering wat a dirtmap is and what it does. i've seen it being referred to in one or two threads, and in one of Pior's tutorials... and i was just wondering about it...

thanks

malcolm

There are a few definitions to what it means so undoubtedly you will get a few answer in here. My definition below.

Dirty map: baked out ambient occlusion map used to mask ares of the model to make them look dirty in the cracks and corners. You can use this to dirty the diffuse texture if you have unwrapped the model in the 0-1 uv range or make a second uv set and blend your dirty map on top of the diffuse texture similar to a light map, again you need the 0-1 uv map. I used a dirty map when I textured my panzer tank on my website, a quick way to get dirt in all the recessed areas as well as the treads.

Husch

You can also use a RGB Multiply Shader with a tiling texture which you can use as a dirt map. Dark pixels of the texture will be multiplied with the texture below and make them look "dirty".
If the engine supports a second uv channel, you can use this channel for the dirt texture, using uv scaling for tiling the dirt map. But please be careful, a second uv channel will increase the number of vertices of the model.

fritz

hey malcolm....can't you just composite your dirt map into your diffuse in Pshop just like a shadow map? or do you have to do a texture blend?

poopinmymouth

A real dirtmap is a map that works based on the angle of the surface. Completely planar surfaces will have no dirt, and the more angled the crevice, the more dirt it will have. It won't shadow two objects who happen to be close to one another like an ambient occlusion map will.

Max doesn't have an easy way of making it, so I just use an AO pass with the photoshop high pass filter to take out the larger shadow areas. However you can also render a crevice map in zbrush onto a lower poly version of your model and then texture bake that in max.

rooster

was blurs dirtmap like that or did it work like AO?
I think I tried to use it a while ago but either it didnt work in latest max or I couldnt find it, I forget

malcolm

Fritz you can do either, if you composite you are limiting yourself to not tiling your diffuse texture and having extra work to mirror it. But yes that is what I did on my tank model as I stated above.

StefanH

I also use the term dirmapping in something like this.





I don't know if its the right terminology though. Blending textures should work too

Apart from that. A dirt map is an AO bake with low distance and spread that can be used as a mask for dirtying up stuff.

Eric Chadwick

That's usually called vertex blending.

SouL

Hahahaha
Technology is growing so fast that it can't even keep it's terminology straight.