Metric capabilities of low-cost digital cameras for close range surface measurement

This paper examines the potential of low cost digital cameras for close-range surface measurement using feature based image matching methods. This is achieved through extracting digital elevation models (DEMs) and comparing accuracies between three low-cost consumer grade digital cameras (Sony DSC-P10, Olympus C3030, Nikon Coolpix 3100) and the proven Kodak DCS460. Surprisingly, the tests revealed that the highest accuracies were achieved using the Sony DSC-P10, not the Kodak DCS460, whilst the other two cameras certainly proved suitable for most close-range surface measurement tasks. Lens modelling was found to provide a limiting constraint on final accuracies, with very small systematic error surfaces caused by residual imperfections in lens modelling. The IMAGINE OrthoBASE Pro software and an independent self-calibrating bundle adjustment were used to process these data. These tests identified an inaccuracy in the self-calibrating capability of IMAGINE OrthoBASE Pro version 8.6 and Leica Geosystems LPS 8.7, which will be rectified in subsequent software releases. The study has demonstrated that cheaper consumer grade digital cameras have potential for routine surface measurement provided lens modelling is considered. The lead author is maintaining a web based repository for camera calibration data, which may assist other users.