With the advent of:
a.) The Internet
b.) Terrabyte (and larger) sized databases, and the means to manage them
c.) Commercially available Hi Res Satellite images
there has been a growth of folks that are out there looking for specific things, and doing an (apparently) good job of analyzing their findings. I give you “Planeman’s” analysis of Pyongyang’s Air Defense (ADA) capabilities. It is a nice piece. I ran down a couple of the GPS coordinates on Google Earth and came back with the same images. I just didn’t have the ability to validate some of his interpretations and conclusions.
If you go deeper into the thread you will see some additional data on underground air bases in North Korea as well.
I know it has been said before, but this calls into question what else you can locate and find on the internet. It is also a good example of what someone with the interest, reference material, patience, and intelligence can do with a few photos.