What I think (PSP version of LCS):
dtz - Core files (Used for naming the entries in all other files, a change in the img means a change in the game.dtz)
lvz* - Filetable for compressed img files
dir* - Filetable for uncompressed img files
img* - Package files
chk* - Package files
tex* - Texture archives
wrld - World files (Placement and models, some parts look similar to the mdl files)
mdl - Model files (New format, replacing dff - used for scripted and dynamic objects, vehicles and actors)
col2 - Collision files (Changed col2 format from PS2 San Andreas)
*Cracked in most parts
I could be wrong, but atleast thats what I came accross so far. I noticed that it is probably easier to documentate the col2 files for now, then go over to the wrld files, and then to the mdl files again. Once thats done I should have a closer look at the game.dtz
Somehow I remember that there were some VC models for games like Re-Volt when it wasn't out for PC.
I looked for a few minutes a few hours ago, but couldn't find any good information. It might be usefull to read through the GTAModding pages and the RenderWare documentation though.
This is some progress on my LCS mdl loader by the way
The box is from -143 to +143 on the x axis, and from -211 to +211 on the y axis. Its supposed to be an object which uses the texture inddoor1 so i was expecting to see a door in a MUCH smaller format. Actually every model I loaded so far turns out as a box. Some objects have multiple boxes though, I thought it would be the vertex data - but it looks like I was wrong. Makes me wonder why the UV,XYZ is correct - its a trianglestrip straight from the files (Only rescaled by doing: X /= 128 (As suggested in the renderware docs, the pspsdk and on gtamodding about col files) I still have around 100 bytes without comments and it looks like those are responsible for the real data in that model - maybe I can finish it tomorrow (I still hope I can find the correct model data inside that area).
Another problem is, that I finished documentating some sections (Each byte makes sense to me) - but I have no clue how to sort them or how to detect which section does what. Most sections start with data without any prefix or anything. The order of those sections is also different in each file - REALLY WEIRD...
//Edit: The box I found is the collision model or the clipping object! I m 99.99% sure, I just wrote some handy tool which is able to copy one file into another (replacing sections only) which also works over usb - I changed the model data over and over again and wrote it to the iso again (only takes a few seconds now): I was able to turn the door into a ramp and make it unsolid (only collision! - the model was the same as before). My second guess would be, that those triangles are used for clipping and orientating the collision, because the renderer is a bitchy about where i look now
The model I use for testing is: ldm-282 in the gta3.img, 0x023A in the memory (for CheatDevice construction mode), a green door - only half texture visible