USING CLOSE-RANGE PHOTOGRAMMETRY TO ANALYZE PALEONTOLOGICAL EXCAVATIONS

Close-range photogrammetry (CRP) produces three-dimensional digital models of surfaces or objects using photographs taken at distances less than 300 m from the photographed target. These products can then be used to determine the size and shape of those objects through the analysis of their images and may be useful when studying areas that are not easily accessible. Although introduced to paleontology as a means of recording fossil trackways, CRP has yet to be extensively employed to document fossil excavations. Three-dimensional models of excavations will enable scientists to quantitatively analyze the visible morphology and orientation of a specimen, as well as document the history of excavation itself. Photographs of the summer 2012 excavation at the Mammoth Site of Hot Springs, South Dakota, Inc. were taken on a weekly basis with a consumer-grade digital camera and used to build models in AgiSoft Photoscan Professional. Photographs of a second excavation along the Missouri River near Chamberlain, South Dakota were also taken to assess the viability of this technique in a less controlled setting. Initial models have either been scaled to lengths of known objects within the study area or referenced with GPS coordinates, producing bone measurements accurate within 2 to 50 cm depending on the object-to-camera distance. Future work will include statistically analyzing and comparing specimen measurements made from models to those made by hand and evaluating the models for use in taphonomic studies.