Semi-automated topographic mapping of fracture surfaces through stereo-photogrammetry

By equipping a standard Hilger-Watts stereo-photogrammetry viewer with transducers, sets of (X, Y, Z) coordinates corresponding to features within fracture surfaces can be obtained. Transducers mounted so as to monitor the the X and Y translations of the viewing tray, when incorporated with a third transducer to measure the rise and fall of the light spot used to measure apparent height changes, supply three voltage signals corresponding to the coordinates of any feature within the fracture surface. These signals are then processed through an analog/digital converter and the digitized signals stored on diskette on an ATT 6300 computer. The voltage files can then be converted to calibrated, normalized files of (X, Y, Z) coordinates using a menu-driven program. Inexpensive commercially available software is then incorporated to use this data to generate calibrated topographic maps. In this way, detailed contour maps, as well as carpet plots and line profiles, can be generated from any fracture surface.