Please ask the satellite map so clear, but also mapping topographic maps for what?

One of the guidance methods used for ground-based missiles, such as Tomahawk cruise missiles, is terrain-matching guidance, where high-precision mapping of the terrain ensures efficient guidance. Satellite mapping accuracy is not high, that is, the use of software to solve the curvature of the earth caused by image distortion, the highest is only 0.5m/pixel, of course, for daily life this accuracy has been satisfied, for military purposes appears to be very low. Only the use of traditional mapping means of field mapping, in order to ensure the accuracy of mapping.