I’m in the process of downloading each USGS 7.5 minute topographic map for the entire state of Utah. I’ve been doing it in my spare time during the past week or so, and I’ve got eight degree blocks finished so far, with fifteen remaining. That’s about 500 maps out of almost 1500 total. They average about one meg apiece, so I’ll probably end up using three CDs when I burn them. I’d like to eventually buy all the paper quads for the state, but that would be pretty costly. Someday, though…
For some reason, the site I’ve been leeching these off of doesn’t have a high-res image for the Price and Pinnacle Peak quads, so I decided to piece my own together using TerraServer. I viewed the topo maps as large as I could on TerraServer, then copied each image and pasted it into a 4000 X 4000 pixel image in Photoshop. When I got done with each one, I had over 40 layers, and Photoshop was using up over 300 megs worth of scratch disk space. Since TerraServer serves its images up as JPGs, I had to change the image mode to indexed color, using the exact same color table as the PNGs that I was downloading, but they still didn’t come out right–the images I created had a lot of dark purple where they should have been black. Anyway, after all that work, I found out that a different site has all the Utah quads in GIF format–they’re of a slightly worse quality than the PNGs I’ve been downloading, but it would have been better to use one of those GIFs than making my own images from scratch.