Texture-Based Photogrammetry Accuracy on Curved Surfaces

Abstract

Photogrammetry is a preferred technique for noncontact measurement of flexible structures, such as large membranes and flapping-wing vehicles. Traditionally, discrete features are triangulated between photos. New techniques use the local texture of a surface to match random speckle among images. Texture-based photogrammetry allows for higher resolution surfaces, and this paper tests if the precision is similar to traditional photogrammetry. Test surfaces provide known, rounded profiles used to compare surface reconstructions. Many images are taken of an object with a projected texture, and the depth error is used to quantify the accuracy of the results. Results on surfacemeshes from800 to 2500 points show accuracy on the order of 1:2000, or nearly that of one pixel. Camera locations had a surprisingly minor effect on surface quality. There is a slight correlation of more parallel views tomore points on the surface. To show that the technique extends to practical use, results are shown for aflapping cycle of amembranewing.Dense surfacemeshes are important for higherfidelitymodels in computational fluid dynamics and finite element analysis.