In the scene there are a lot of materials ( 60 ), which I created out of two kind of maps: procedurals and bitmaps (what is already known). Many people think that procedurals (also known as shaders, although this is not the right meaning of the word) are not good for achieving a real look in their models; and there are a lot of artists that use procedurals exclusively. Well, I think we need to get a balance.

I think that, as visual artists, we have more participation in the final result using bitmaps, because we can choose the image we use as raw material (an illustration, a photograph, a drawing, a painting) and because we can manipulate them as we want in an external software (Photoshop, Painter, PSP, Gimp and so on). The outcome is an image created specially for mapping a specific object.

Of course that procedurals are very useful maps, because they are parametric; they have features easily animatable; and we don't need to work hard to achieve a right 3D space mapping projection, as we sometimes need to do with bitmaps.

In this scene I used mainly bitmaps, because the old architectural look requires the features that bitmap mapping offers. Fortunately, I have a very powerful and useful tool that helped me a lot in this part of the project: the 3D Total textures collection. All bitmaps I used in this scene are from 3D Total CD's.

I prefer to edit bitmaps, composing, mixing, and modifying them as I wish till I get the needed goal, but you can also use the bitmaps directly from the CD's because of their quality and because they're prepared for tiling.

At first, I define the kind of mapping for each object in the scene. I use mainly planar and cylindrical mapping (of course it depends on the geometry). For objects with high complexity, the Unwrap modifier is very useful, because you can unfold the geometry and paint the map in a planar projection.
I usually work with "Texporter", a plugin for Max highly suitable to export mapping projections as bitmap images, and work later in an image-processing software like Photoshop. Once I set the mapping coordinates, the next step is the bitmap editing process.

In this part of the process we need to use an image processing software, like Photoshop, PSP, Fireworks, Gimp, or whatever you want. This software lets us manipulate bitmap images, and then export them as bitmap files (JPEG, GIF, TIFF, PNG, etc.) and include them as maps in the materials we are gonna use in the 3D model.

The first thing I do, is open the bitmap file exported through "texporter". I use that image as background layer, to create a texture using this as a reference to paint it correctly. The lines from the geometry structure help me to know where I have to paint, and where not to.

Once I've got the background I go to the 3D Total textures collection and I choose the map I'm gonna use as base material. In this case, a brick wall.

I choose textures for diffuse and bump channels. All textures in 3D total collection are available with diffuse and bump channels version. This is really useful to avoid painting the bump textures by myself.

After that, I tile the textures in the image processing software. These textures are tileable by default (directly from 3DTotal collection), but I usually tile them by myself because after that I modify some areas to avoid an even look.

Then I get the borders dark (burn) , to achieve a rusty and worn look. There are many tools to get this. For example, the Burn Tool in Photoshop.

Following, I add layers using masks. I usually use several dirty maps, and combine them into only one. This is the real power of a good bitmap collection, the possibility to keep creating new images every time we need. In the image on the right, I added some kind of moss using the technique explained above.