Accuracy of Earthwork Calculations From Digital Elevation Data

Abstract

Recent developments in photogrammetric methods, in general, and orthophoto mapping in particular, have resulted in the increasing availability of digital elevation data. The accuracy of digital elevation data generated from the orthophoto scanning process is usually below the level normally needed for earthwork calculations. However, the density and quantity of the elevation data from this source usually exceeds by many folds the coverage used in the conventional method of field or photogrammetric method of cross-section leveling. An investigation aimed at studying the effects of accuracy, density and distribution of gridded elevation data on the accuracy of earthwork calculations had been conducted.

Results from this investigation had clearly demonstrated that in earthwork calculations, the density and quantity of the data base can compensate for the decrease in data accuracy. More specifically, the elevation data generated from the orthophoto scanning process, can potentially be used to provide accurate volume measurements. Quantitative approach and general prediction formulas were developed to relate the reliability of volume determination with elevation accuracy, data spacing along the cross-section profile, distance between cross-sections, and the type of topography.