Some recent developments in photographic interpretation

Abstract

This paper has attempted to summarize, and to place in proper focus, the major developments of significance that recently have occurred in photographic interpretation and related fields, ’with special reference to the inventory and management of earth resources. To the extent that the announced objective has been realized, the following conclusions seem warranted. (i) Just as in the past 100 years or so, photo interpretation can continue to provide significant amounts of useful information even in those instances wherein only one conventional black-and-white aerial photograph (or perhaps a stereoscopic pair of photos) is available for the area of interest and when the interpretation is performed by only one photo interpreter, using only one technique and aided with only one type of equipment such as the conventional stereoscope. (ii) In the future, however, photo interpretation is likely to provide vastly increased amounts of useful information, if what might be termed the “multi” approach as developed and illustrated in this paper, is exploited. Specifically, much more useful results almost certainly will be obtained if, istead of one photograph or stereo pair of photographs, many are available of the same area, including multiband, multidate and multistage photographs. Further gains usually can be made if certain of these images are multienhanced by being suitably combined in various ways, both optically and electronically, and are then subjected to hiultidisciplinary analysis by a team of photo interpreters, including for example a geologist, a hydrologist and a vegetation analyst. Finally, the effectiveness of photo interpretation can be further increased if human information extraction efforts are augmented by machines which, when properly programmed, can accomplish part of the photo interpreter’s task through a process known as automatic data processing. (iii) As the various elements of this “multi” approach are intelligently used, each adding to the information previously obtainable, a cost-effectiveness threshold is likely to be crossed, below which the amount of useful information derivable is so slight that one cannot afford to use photo interpretation techniques, but above which the amount eventually becomes so great that one cannot affordnot to use such techniques.