If you do this:
tesannwyn -c -T 5 -h 18040 -w Tamriel Skyrim.esm
It will give you the 16-bit image of the landscape in "tesannwyn.bmp". The vertex colour map is in "tesannwyn-vclr.bmp". If you then do:
tesannwyn -c -T 5 -x -57 -y -43 -w MySkyrim tesannwyn.bmp
You can load the generated ESP (tesannwyn.esp) as a plugin into Skyrim, load up the game, type "COW MySkyrim 0 0" and it will take you to cell 0,0 in a cloned worldspace, which will contain the fully textured Skyrim landscape - no objects or LOD. Each cell position will be the same as that in the Tamriel worldspace. You can do a similar thing with Oblivion and import the Oblivion landscape straight in to Skyrim - but don't use the "-T 5" option as the texturing FormIDs won't match. Without "-T 5" it'll be an untextured world, using the default brown textured landscape, and the vertex colour map.
If you wanted an 8-bit black and white heightmap (which is of poor quality for importing, but easy to interpret with the eye):
tesannwyn -r -p 2 -b 8 -w Tamriel Skyrim.esm
If you wanted a 16-bit RAW (the best format if you have photoshop and want to things like scaling up the landscape):
tesannwyn -p 1 -b 16 -w Tamriel Skyrim.esm
Couldn't get this working at all when attempting to get the morrowind map exported from TES3. Is there something I'm missing? It exports the heightmap from morrowind with no apparent issues and it's viewable as a .bpm, and following instead your instructions in the tesannwyn release notes for exporting to skyrim .esp -
TESAnnwyn -i Skyrim -o -2048 Morrowind01.bmp
This got it opening in the Creation Kit, I can wander about the awesome brownness of it all, but entering the command
"COW Morrowind01 0 0" just came up with an error saying "Item 'Morrowind01' not found for parameter worldspace - compiled script not saved!"
Not sure if I'm making some foolish error here so apologies - I'm new to heightmapping and world space creation and have been running in circles trying to find out various things about it. The "morrowind01.esp" file is in Skyrim's data directory with all the other mods though, and is activated in Skyrim's Data Files option on startup, with no other plugins enabled. I should note that the worldspace only seems to show up as a small corner in the Creation Kit's heightmapping view too - I'm really not sure what this means, whether it's a problem or how to get the rest of it to display. Seems OK in CK's normal 3D render window, I've heard the heightmap editor is a broken piece of **** anyway so I'm assuming this is just normal. Other than that though, any thoughts on what I'm doing wrong?