The URL links to a blank page. I guess you could say there're indeed lots of missing features (j/k).
Edited the link; hopefully this one's not blank. Actually the lem3edit code in the repository is missing a few essential level-editing features that a previous version had since I reworked a bunch of the code. You can drag and drop pieces around the level, but that's about all there is.
Any chance you can document some of your knowledge of image formats? I actually remember the fact that there's lem3edit, but never having used it (I haven't even played the official levels yet), hearing that it has lots of missing features, and not finding any documentation on image formats, I didn't know for sure whether it can even display the level, so I didn't mention it.
I know it's lame, but I'm going to have to claim the code as my documentation. <_< It's been so long since I've worked on it, I remember next to nothing about the formats. It should be pretty clear where the code to load the different formats is if you happen to want to take a stab at it.
It probably also won't help if Jason's looking for things like animation frames, especially for things like the actual lemmings themselves. But at least it'll be easier to get the graphics for all terrain pieces (say) with just a few screenshots and a single specially edited level.
The lemming animation frames should be among the formats I reverse-engineered. (Recall the ninja lemming seppuku avatar I had a while back.)
Perhaps I can hack together a dumper quick. We'll see.
Edit: Here's some of the
Lemmings 3 tribe graphics.