Cloud Screening From Aerial Photography Applying Coherent Optical Pattern Recognition Techniques

The challenge facing the mapping community today is the effective utilization of increasingly large volumes of aerial photography and other data to provide topographic information in the form of line maps, orthophotomaps, specialized products or individual responses to decision makers and other users in a timely manner. Automation of rapid screening techniques to determine the suitability of aerial photography for further processing represents an important aspect of this problem. This paper discusses the use of data from the optical power spectrum for cloud screening of aerial photography with emphasis on the computer processing of signals from a segmented spatial frequency plane detector in a coherent optical system. It is assumed that optical samples from aerial photographic patterns will have optical power spectra with attributes representitive of the patterns which can be electronically detected and classified by statistical pattern recognition techniques. This hybrid approach provides an advantageous combination of the speed of the optical Fourier transform with the flexibility of digital processing which leads to a simple, efficient system with the potential for screening aerial photography at very rapid rates.