1. One or more computer storage media comprising computer-readable instructions that when executed, perform acts comprising: acquiring an image of a current location; iteratively comparing the image in a plurality of different formats with two or more previously stored images in corresponding formats to identify a subset of potential matches using a first of a plurality of different image analysis techniques, and to identify one or more matching images of the subset using a second of the plurality of different image analysis techniques; prompting a user to input location information; and assigning to the image the location information.