Hi!

I have just discovered how to UV map my whole game-level by using unwrap and then Blender creates a texturelayout that i can fill in with my textures. This is soooooooo coool, and makes it easy for me to texture. It means only one big texture-file for my whole scene.

How is this performance wise?

I plan to UV-Map an entire FPS level and make three big textures:
1 Textures
2 Bump Map
3 Specular Map

Is this a good way to do it?

With the areas i dont want to bump-map will just be solid and the areas i will create some bumping i create bump-color.
Same with specular, where no specular i leave out from the layout texture.

any ideas?

Is this a good way to do it?

In common: no

The reason is, that the hardware only support certain max texture resolutions, older hardware only 8192x8192 or even 4096x4096 and this is not much if you unwrap your whole level automatically.

The other issue is, that environment art often reuse texture extensively to keep a good level of texel density.

But there are always exceptions,i.e IdTech5 has mega textures support, which could be used to do it this way. But this is the only game engine which comes to mind using this technique in games and the engine is not available (only to bethesda).