Experiments in Map-Guided Photo Interpretation

Introduction A central scientific goal of image understanding research is to investigate ways of bringing diverse sources of knowledge to bear on the problem of interpreting images. An important source of knowledge used by humans in the interpretation of aerial photographs is the topographic map. This paper describes some initial experiments in the use of map knowledge to automate an important class of photo-interpretation tasks involving monitoring and change detection. This work is part of a larger image understanding research program aimed at developing collaborative aids for photo interpreters and cartographers [Barrow 1977a]. Photo interpreters spend a significant proportion of their time in routine monitoring tasks such as counting box cars stored in railyards or keeping track of the ships berthed in a harbor. A major difficulty in automating such tasks is locating the monitoring sites in sensed imagery, which may be taken from arbitrary viewpoints. Once the location is known many monitoring tasks are reduced to simpler detection problems that can be solved by straightforward techniques such as template matching.