Combining Nadir, Oblique, and Façade Imagery Enhances Reconstruction of Rock Formations Using Unmanned Aerial Vehicles

Developments in computer vision, such as structure from motion and multiview stereo reconstruction, have enabled a range of photogrammetric applications using unmanned aerial vehicles (UAV)-based imagery. However, some specific cases still present reconstruction challenges, including survey areas composed steep, overhanging, or vertical rock formations. Here, the suitability geometric accuracy four UAV-based image acquisition data processing scenarios for topographic surveying complex terrain are assessed compared. The include use of: 1) nadir imagery; 2) oblique 3) façade 4) nadir, oblique, imagery to reconstruct topographically natural surface. Results illustrate that supplement more traditional collections significantly improves point cloud by approximately 35% when against terrestrial laser scanning near-vertical walls. Most points (99.41%) had distance errors less than 50 cm between clouds derived nadir–oblique–façade Apart delivering enhanced spatial resolution details, improvements achieved integrating provide value applications, geotechnical geohazard investigations. Such gains particularly relevant studies assessing integrity stability, engineering design, planning, construction, where information on position cracks, joints, faults, shears, bedding planes may be required.