Methodology for Accuracy Assessments and Verifications in Digital Photogrammetry

摘要

This paper describes a new methodology verifying the accuracy of photogrammetric networks by known distances between imaged points on scale bars. The analysis presents three issues of photogrammetric accuracy (point, distance, and scale accuracy) together with the issue of scale-bar length accuracy. The latter, in turn, involves the uncertainty in reference length, measured temperature, coefficient of thermal expansion, and centering of targets. The methodology is based on a one-time determination of photogrammetric point accuracy using statistics generated by discrepancies between points in a photogrammetric network and their counterparts determined very reliably by other means. It focuses on geometrically strong networks, where the coordinate standard error is approximately the same for all three coordinates of a typical point. This methodology replaces much lengthier and more expensive numerical procedures, such as a Monte-Carlo technique, by a straightforward statistical analysis. Under stipulated conditions, it can assist users of digital photogrammetry in verifying the performance of their system(s) after each survey.