(I've not fully read the paper properly yet by the way, but I work on 3d global image based localisation professionally for the last 4 years) Compared to doing

(I've not fully read the paper properly yet by the way, but I work on 3d global image based localisation professionally for the last 4 years) Compared to doing this for photos of buildings its simpler, as you know what direction the camera is pointing. This means instead of having to reconstruct a 3d point cloud, you can just keep a 2d image and have done with it. So at worst you'll need to keep an image of the entire area you want to position against on disk. But, you shouldn't need to keep it all in ram. as you're not flying, you can make the assumption that you're never going to jump from one corner of the place to another. So you can have you current location and an area big enough to buffer against SSD access. update They have photographed the floor, and pre-computed a map by extracting SIFT descriptors, which from memory are 128*32bits. They throw most of these descriptors away and keep only ~50 per "image". To answer your question directly, an entire warehouse would probably be less than 1 gigabyte.