3D MODELING OF OUTCROP SCALE FEATURES IN THE BIG BEND RANCH STATE PARK USING STRUCTURE FROM MOTION PHOTOGRAMMETRY TECHNIQUES

We are pursuing the use of Structure from Motion techniques in an educational setting to better illustrate geologic processes on an outcrop scale. Two geologic structures in Big Bend Ranch State Park, a laccolith and a flower structure, have been digitally photographed at multiple angles according to photogrammetric guidelines. The corresponding imagesets have been processed using Agisoft ImageScan Pro (software which utilizes the Structure from Motion technology) in order to produce two 3D models from the 2D images. Still images taken from a drone or a camera phone can be transformed into accurate orthomosaics or DEM’s (Digital Elevation Models). These models, when used in a classroom setting, are able to better convey the geologic processes involved in their formation than traditional 2D teaching techniques. 3D models can provide students with a clear representation of exposed geologic structures. Our area of interest is in Big Bend Ranch State Park, dominated by Tertiary volcanics and Cretaceous carbonate facies.

Our procedure begins with flying a drone equipped with a gyroscopically mounted camera in a planned route, capturing images in controlled intervals. After data collection, images were inspected for quality. Any images with resolution or coloration issues were discarded or corrected. The remaining images were uploaded into AgiSoft ImageScan Pro for processing. Reference markers were used to stitch the images together to create a point cloud, a dense point cloud, and a textured 3D mesh. Agisoft ImageScan Pro is capable of exporting the model in multiple formats. The resulting products are two 3D models that can be uploaded to a 3D model hosting site and then used in a classroom setting.