Geological applications of optical data processing

A recently developed method for the optical processing of seismic data is applicable to the study of some common types of geological data, such as the orientation and spacing of rock fractures recorded in aerial photographs and of grain boundaries recorded in photomicrographs of thin sections. Fractures, cleavage, grain orientation, and drainage can be studied in this way. In this method a photograph, map, or drawing is reproduced as a reduced transparency through which laser light is passed. The diffraction pattern or Fourier transform thus produced provides a display of the statistical distribution of directional and spatial frequencies associated with all elements in the photograph, map, or drawing. The blocking of parts of the pattern and subsequent reconstruction of the remaining part into an image makes it possible to filter out lineations of any desired direction or spatial frequency. Thus the effects of dominant features can be eliminated so that the weakly developed features they conceal can be observed. Preliminary experiments show this method to be promising also for grainsize analysis and comparison of contour patterns.