Warning! You will find major spoilers here if you haven't completed these games yet!
Maps from Ultima VI
Britannian surface
Dungeon level 1
Dungeon level 2
Dungeon level 3
Dungeon level 4
Gargoyle surface
Maps from Savage Empire
Eodon Valley surface
Myrmidex caves
Surface level caves
Underground city of Kotl
Maps from Martian Dreams
Mars surface
Mines
Dream World
Dream World
Mine and underground parts of Martian city
Coal mine and power plant
About the maps
The scale of these maps is 1 pixel per step. The data is stored in the files MAP and CHUNKS and isn't too difficult to decode, but colouring is fiddly. To colour these maps I modified the MAP and CHUNKS files to find out what tile each number corresponds to. The tiles are as follows:
Ultima VI (left), Savage Empire (centre), Martian Dreams (right)
Note that these aren't all the graphics from the games because there are two types of tile. The other tiles are object tiles, the positions and types of which are stored in the files in the SAVEGAME folder. Going to a finer scale would be rather pointless without deciphering this data. For example, you can see even at this scale that the buildings are empty.
It would be really cool to make a 1:1 scale map including all the objects, equivalent to the Eagle Eye spell. Unfortunately it would be a bit too large for your web browser - stored as a GIF file each large map would take up at least 70Mb! However, it would look nice scaled down (even better than these maps at the same scale) and it would be good to have a program that would let you scroll around and zoom into/out of the map. It would also be nice to create a census of all the characters in the games and find out the purpose (if any) of the message "Winona Ryder is a really hot babe" in Savage Empire and Martian Dreams. I may do these things someday.
Surprising stuff the maps revealed
I was surprised that the maps in Ultima VI actually form a three dimensional structure - if you scale up the small maps to the size of the large one then all the cave entrances, holes and ladders line up. The same is not true of Savage Empire and Martian Dreams. In fact, in Savage Empire the "level" isn't even related to the 3 dimensional configuration of the world.
The authors embedded hidden information into the maps as you can see - SMB (Stephen Beeman) in Savage Empire and Gryphon (Philip Brogden) in Martian Dreams. There are also some hidden areas in the poles of Mars. I don't know if these have any purpose in the game or not - I'll tell you when I've completed it.
Although the "shape of the world" is supposed to be flat in Ultima VI and Savage Empire and spherical in Martian Dreams, the true shape of each world is a torus or doughnut. If you could walk off the left you would reappear at the same place on the right, and if you could walk off the top you would reappear at the same place on the bottom. In fact you can see this effect in the Savage Empire maps: there is a river which disappears off the top and reappears on the bottom on the surface, and the rightmost walls of the underground city are on the left. This is used in Martian Dreams to create a cylindrical (okay, spherical...) world rather than a flat one.
Savage Empire uses only 4 of the 6 levels. Level 5 is empty but level 6 contains the gargoyle world straight out of Ultima VI! It doesn't quite make sense because some of the chunks (8x8 blocks of tiles) are different, but it's clearly the same map.
Links
These maps were inspired by those of Otmar Lendl. Check them out, he's got some of Ultima IV and Ultima V as well.
Mobygames entries for Ultima VI, Savage Empire and Martian Dreams.
Bartholomew Melnicki has gone much further and started plotting objects on the maps. Check it out!