I've spent a few hours tonight giving it a go making this plugin.
It was inspired by this article at Garage Games.
An adventure singleplayer game using multiple missions
http://www.garagegames.com/index.php?sec=mg&mod=resource&page=view&qid=11672
If you don't have a license to view the content, the quote that got me started down this path was this, "Create a height map (source 3DGPAi1) using a large greyscale bitmap at the desired size in pixels. Divide this large bitmap into 256 by 256 pixels with overlaping of 64 pixels."
The idea is that as your moving accros the game, you're automatically warped to a new mission area, to a position that like like the one you just came from. By overlapping pixels between zones, it appears like a seamless transition from mission area to mission area.
If you play Everquest, the effect is like going from North Karana to West Karana.
I've started with the atGrowTilesByOne sample.
(http://www.bundysoft.com/L3DT/downloads/zeolite/atGrowTilesByOne.zip)
I think I'm beginning to get a handle on how things work. I have the opening setup dialogue started. From there, I have subdialogs that load the HeightField map and then allows edtiting of the export type and options.
That all works. I can drill into the HeightField, set for BMP export and flip the invert flag or change the greyscale limits, in dialogues that look like the L3DT dialogues.
I've tried to stay true to the look and feel of L3DT.
Tomorrow I'm going to try to get it to actually export a Heightfield Mosaic.
I believe I can expand this to create entire project arrays easily enough, so that mission areas can be individually tweaked and edited after being split.
Off to get some sleep.