Large maps are possible but you have to plan a lot for how they will grow. I am not sure about the 30Mb BSP limit, but I have hit a lot of other limits. My latest project 'Map on the edge of forever' is about 23K brushes and still growing, got 2 more areas to complete yet. Here is a quick image from the editor to show the scale of the thing.
[lvlshot]http://www.simonoc.com/images/design/maps_q3/moteof1ef_editor1.jpg[/lvlshot]
Key: Blue is grouped brushwork, Orange is ASE models.
The number one killer of file size is lightmaps and how you scale them. Personally I would recommend you only add the lightmapscale key to things that really need it (angled architecture, stuff close to the player, special vista areas) and then always try and start with high values (0.5) and go towards (0.125) low values when you really need it.
Make sure your architecture is as modular as possible and use ASE models where ever possible, because they are perfect for good texture alignment and individual lightmap tweaking. Never get too attached to any one area because when you deal with huge maps you may have to cut sections because of engine limitations.
Do not use any ambient lighting because it just creates flat and pointless lighting! (bad lighting joke
) Sort out your sky sunlight angles very early on because changing it later will cause you a lot of pain, especially if you have setup all the lightmapscale keys for maximum visual impact on light angles.
Hint and portal your map very early on because once the detail is added it will be awkward to fix later. Always do a full compile of your map at least once a week to check that the whole map can load into the engine without any errors. I know it is handy to work on region/sections of a map especially when tweaking lightmaps, but it is always wise to know if everything still works.
Everytime you work on the map create a new revision and if you are experimenting with different architectural detail styles save them off into seperate map revision. This has saved me so many times that I have lost count. I often find that I can go back to later revisions and grab stuff that did not work at the time and re-use it elsewhere. Multiple revisions are also handy for comparing how lightmaps look and are a good indication of how fast the map is growing in size.
Start with high resolution textures (512x512) for your basic block sizes and scale stuff up or down depending on how close the player is to the surface. Textures are loaded seperately to the BSP file so it does not affect that limit. Set up your Q3 engine to the default com_hunkmegs so that you got an idea of what limits you are hitting and when. Try to squash all your texture trims on to single large image, because it will make the map more efficient at loading and help with video card memory texture swapping.
Hope that helps and good luck with your new project.
Well he was evil, but he did build alot of roads. - Gogglor
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