1. A method performed at least in part by a computer processor, said method comprising: determining a plurality of image frustums having an approximate point of origin and an approximate direction, each of said image frustums being determined from data derived from each of an individual image and representing a geographic area covered by said individual image; arranging said plurality of image frustums based on said approximate point of origin and said approximate direction relative to one another in a geographic representation to form a relevance map showing one or more densities of coverage by said plurality of image frustums; determining a first area of relevance from said relevance map based on said one or more densities of coverage of said relevance map; and identifying a first group of images that include said first area of relevance.