- Q3 maxes out texture/lightmap page sizes at 1024x1024 (1024x2048 textures work, but 2048x2048 crashes the game. Lightmap pages must be square).
- Q3's default texture resolution is 2x2 texels/game unit.
- At a 1:1 texel to luxel density, that means that the maximum surface size allowed is 512x512.
- External lightmaps have an issue with mipmapping, causing what looks a bit like light bleeding on edges when viewed from a distance.
- Besides, a large part of what makes Doom3 and newer engines look significantly different is the use of specular maps, which Q3 can't fake in the same way.
Sure it's all possible (I've tried it), but there are all sorts of limitations and the effect in most cases is hard to notice compared to say, just a well lit map with soft shadows, blurring, and maybe some faked light effects. You can build a little test map as an academic experiment as I did, but for an actual playable map, it's just not particularly practical.
I'd say that the most interesting thing about the whole effect is the generated lightmaps, which makes for some pretty cool looking abstract art...
[lvlshot]https://farm9.staticflickr.com/8240/8510544241_e16000eae6_b.jpg[/lvlshot]
[lvlshot]https://farm9.staticflickr.com/8248/8511656848_ac89904d4b_o.png[/lvlshot]
Doesn't id Tech 5 do a significant amount of precalculated lighting? IIRC, it's baked into the megatextures.
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