Because someone asked if it was possible: (no infringement intended...)





Here's what I did - I took a scan of the map - copied it on a much larger blank page in GIMP - before anchoring the image I rotated it -30 degrees.

I couldn't get the image to measure perfectly - and what appear to be the same size corridors can vary in width by a dozen pixels - so I just picked a measurement to be 10' and lined it up wih what corridors/rooms I could (not too many).

I used the "Filters" "Pattern" "Grid" to set up the grid. I had sized the original image to 1700 x2200 (well, 2206) pixels.  You know, 100 pixels per inch... Yeah, still didn't work that well...

I used 34 pixels for the grid layer.

Then I erased the grid that was outside the rooms.  I created a garbage matte, selected it, inverted the selection, selected the grid layer, and cut everything outside the garbage matte.  It would be nearly as easy to simply erase the lines I didn't want :)

All in all it took about 20 minutes (including some false starts...