I've uploaded a world map viewer application to my website; download it from
http://www.ficedula.co.uk/f2k3/ as per normal (under "FF7 Programs", "Reeve").
See;
...it's not perfect yet, but I reckon about 90% of the textures are correct now. Controls are as per Zangan and my other 3d apps; right click to turn viewpoint around, hold left mouse button to fly forwards, press A/Z to increase or decrease height.
Essentially the entirety of the 3d mesh format is already documented
here; I've just added on textures. Additional information on the file format:
In the triangle data, Unknown1 (1byte) seems to be walkmap status; I haven't investigated thoroughly, but the following values I've observed:
$23 = Deep sea (can't land highwind, water spray when flying low)
$22 = No sea spray from highwind, still can't land
$21 = No sea spray from highwind, still can't land
$20 = No sea spray, can land & walk
It may not be a simple bitmask, since $22 and $21 give the same results (I'd hoped that the lowest bit was "show spray", but apparently not.) I rather suspect at least some bits in this variable will control which chocobos can traverse the tile, too (which means figuring this out could be tedious, you might have to fudge some values, and then try every chocobo types plus vehicle type over that tile...)
The second Unknown field (2 bytes) is texture; the lower 9 bits contain a texture number (0-511, but only 0-281 appear to be used). The text files in the Reeve download show how each number maps to one (or more) .TEX files within WORLD_US.LGP. The upper bits are something to do with texture coordinate mapping; 90% of the textures work fine if you ignore them, but I'm hoping the ones that look wrong in my viewer will be due to these bits, which I don't do anything with, yet. It's most obvious on the "rocky" tiles, such as around Mideel and Midgar, which look rubbish and have muddy green patches on them.
(The viewing distance is currently rubbish in my app; this I know about.)