so lately i've been trying to figure out if it's possible to fix the lightmaps for Quake Arena Arcade's maps to make them playable on PC Quake 3 / Live.
for reference, these maps are IBSP version 47 (the same as Quake Live) and can be loaded into the PC versions (easily converted to IBSP 46 for Quake 3) without changes.
the main issue being the lightmaps are very messy- striped and not algined with anything properly.
after exporting the lightmaps via Q3Map2 and messing around with the resulting .TGA files in ImageHeat, i found that all i needed to do was change the dimensions of each file to 512x32 and add an offset of 18- no unswizzling involved!
as theres no way to work on multiple files at once, i then flipped + appended 200 files together at a time via ImageMagick (nearing the size limit), fixed them all in ImageHeat, and appended them together.
the result was the complete undistorted lightmap for Crossed Off (qaactf02).
while i now had the full 512x17408 lightmap, the .bsp still expects 544 128x128 .TGA files.
i've tried many different orientations and ways of splitting it up, but nothing looks correct.
my guess is that QAA has some kind of extra code for unscrambling and processing these files as 512x512 lightmaps.
a bit more than a month later...
after giving this some more testing, i found out that only the first 34 lightmap .TGAs are actually visible on the map (amount equal to the amount of 512x512 lightmaps, varies by map).
scaling down the original 34 512x512 lightmap .TGAs to 128x128 and using those in place of the first 34 lightmap files seems to work as a workaround to all this (the rest being just black squares).
it's not perfect as without editing theres going to be downscaling artifacts (bits of other parts of the lightmap) visible in certain areas, usually on stairs and corners and such.
i also realised at this point that the maps are also missing some kind of "fx_heatHaze" entities (seemingly exclusive to these maps), but i'll ignore this for now.
as far as i know there's no way to make Quake 3 / q3map2 use 512x512 lightmap files without using shaders for external lightmaps, and that would require decompiling the map which defeats the original purpose here- trying to use the original compiled .bsp files with minimal changes (IBSP version, fixing entities).
if such a way appears before me i'll definitely update this post, but for now the maps are very playable~