| Abstract: | In attempting to assess the possibilities of mapping from earth satellites, various factors which do not occur with aerial photography must be considered. The orbital characteristics of satellites are discussed from the point of view of their effects on photographic scale and coverage and the problems of taking and retrieving photography from satellites are outlined. An evaluation of the possibilities and limitations of mapping from both single and stereoscopic television pictures and normal frame photography is made and the tentative conclusion reached that topographic mapping from earth satellite photography may only be considered seriously for the scales 1 : 250 000 to 1 : 1 000 000 and for a minimum contour interval of 100 m. The economy of this very small-scale mapping is at present very doubtful in view of the current costs of building and launching a suitable satellite. Any extensive programme of satellite photography for mapping purposes could pose some difficult legal and political problems if the photography was made freely available. |
