UTILIZING SFM PHOTOGRAMMETRY TO BUILD A FULL TRACKSITE MODEL IN SUPPORT OF RESEARCH AND EDUCATIONAL OUTREACH AT DINOSAUR STATE PARK, CT

SfM photogrammetry from the air and ground is well suited to detailed mapping and modeling of geologic artifacts including dinosaur tracksites. For indoor museum settings, however, lighting conditions and physical constraints are challenging, making ground-based imaging preferable to UAV capture. Originally intended for the Covid-cancelled 2020 meeting in Reston, this presentation summarizes imaging and SfM modeling techniques used to construct a 350 million-point model of the entire 335 m² tracksite within the interpretive center at Dinosaur State Park. We utilize Metashape SfM software to analyze >2100 full-frame images from 12 subsections of the tracksite that were georeferenced and reassembled to a single point cloud using laser survey/scan ground control points. Geospatial analysis of this sub-mm resolution model includes areas under walkways and viewing platforms that are not visible to the public. Visualizations and height maps, many of which are shared with DSP for educational use, optimize topographic detail by detrending the slope of track-bearing sandstone surface for individual tracks, as well as the entire tracksite. We inventory ≈751 Eubrontes, ≈89 swim tracks, and 2 varieties of unidentified enigmatic structures at the site. Our tracksite height map also identifies a previously undescribed topographic arch on the main track surface, although its relationship to track microtopography is not understood. We use our model to present new depth and volume data for most tracks. In addition, by georeferencing previous trace maps into our survey space we can select tracks within individual dinosaur trackways (sequential footprints made by one dinosaur) for geospatial analysis. Consistent with previous work, we do not identify a preferred travel direction, but we recognize groups of trackways that display broadly parallel paths, albeit dispersed widely in compass direction. Many of these trackways have prints registered on the 3 main track-bearing sedimentary beds. On average, tracks within trackways (and for the entire tracksite) are largest for prints registered in the lowest sedimentary layer. Further analysis is required to identify which sedimentary bed was trod upon (is primary). The results of these analyses are part of a multi-authored book that is under contract.