Knowledge Bank

This report pertains to research conducted in the applications of large scale analytical aerial photogrammetry to surveying for transportation systems. A demonstration of the improvement in accuracies of measurement of terrain elevation after special calibration is presented. New specialized hardware interfaced with a simple micro-computer for measurement of cross-sections is discussed and its performance is presented. An improved version of a field deployable comparator is also discussed. After implementing the aerial calibration procedure the analytical photogrammetric method using 1:3000 scale photography produces elevation values on targeted but withheld check points. The standard deviation (1σ) of elevation discrepancies ls 0.5 inches (14mm) corresponding to a proportional error of one part in 27,000. The cross-section device produces a standard deviation in plan of 0.003 inches (0.076mm and provides a real time edit of observations in accordance with the criteria contained in the ROAD's program. The comparator development is only partially successful. Recommendations are made for improvement of the calibration procedure, the cross- section digitizer, the comparator and for implementation of results of this research.