USING DRONE TECHNOLOGY, PHOTOGRAMMETRY, AND VIRTUAL REALITY IN THE ANALYSIS OF REMOTE AND INACCESSIBLE CLASSIC LOCALITIES: THE VERTEBRATE-DEFINED PERMIAN–TRIASSIC SECTION ON THE BETHEL FARM, FREE STATE PROVINCE, SOUTH AFRICA

Vertebrates recovered on the Bethel Farm and adjacent properties (Heldenmoed 677 and Donald [Fairydale] 207 farms), account for nearly 75% of fossils that have been used to construct a model for the terrestrial response to the end-Permian crisis. The stratigraphic sections on which this model is based are exposed on these farms in the Free State Province, South Africa. Rock exposures are restricted to erosional gullies (dongas) that traverse prominent escarpments and buttes, as well as resistant sandstone bodies that can be traced for several kilometers along strike. These sites, though, are difficult to find and access without knowledge of their location, permission of the land owner, and a 4x4 vehicle because they are positioned several kilometers off road from any tar or gravel route. And, once there, two-dimensional photographic or digital images taken from ground level do not provide the visual coverage or context of the sites. We have employed drone technology to acquire geospatially referenced digital images of the Bethel Farm which, in turn, are processed using photogrammetric software to reconstruct both 3d models and an open-sourced software package to create a virtual reality tour of the classic locality.

To create this virtual representation, digital images were imported from our South African drone flights into Agisoft Photoscan. The software processes images using photogrammetry by creating a point cloud of overlapping features which, then, are connected into a 3-dimensional solid mesh and, finally, wrapped in a photo-stitched texture. This resulting model (*.obj), which can be viewed using freely-available software, was imported into Unity 3D — a 3D game engine with built-in physics and interactivity features. Using a popular open-source plugin called VRTK, we allow the user to virtually fly around the Photoscan models, approaching them as if they were actually at the site. The application is optimized for use on an HTC Vive headset, which will be available on site for demonstration purposes.