A New Fast and Low-Cost Photogrammetry Method for the Engineering Characterization of Rock Slopes

Abstract

Digital photogrammetry (DP) represents one of the most used survey techniques in engineering geology. The availability of new high-resolution digital cameras and photogrammetry software has led to a step-change increase in the quality of engineering and structural geological data that can be collected. In particular, the introduction of the structure from motion methodology has led to a significant increase in the routine uses of photogrammetry in geological and engineering geological practice, making this method of survey easier and more attractive. Using structure from motion methods, the creation of photogrammetric 3D models is now easier and faster, however the use of ground control points to scale/geo-reference the models are still required. This often leads to the necessity of using total stations or Global Positioning System (GPS) for the acquisition of ground control points. Although the integrated use of digital photogrammetry and total station/GPS is now common practice, it is clear that this may not always be practical or economically convenient due to the increase in cost of the survey. To address these issues, this research proposes a new method of utilizing photogrammetry for the creation of georeferenced and scaled 3D models not requiring the use of total stations and GPS. The method is based on the use of an object of known geometry located on the outcrop during the survey. Targets located on such objects are used as ground control points and their coordinates are calculated using a simple geological compass and trigonometric formula or CAD 3D software. We present three different levels of survey using (i) a calibrated digital camera, (ii) a non-calibrated digital camera and (iii) two commercial smartphones. The data obtained using the proposed approach and the three levels of survey methods have been validated against a laser scanning (LS) point cloud. Through this validation we highlight the advantages and limitations of the proposed method, suggesting potential applications in engineering geology.

Geotechnical Study of Raspadalica Cliff Rockfall, Croatia

“…In recent years, unmanned aircraft vehicle (UAV) photogrammetry has been developed to collect spatial data. This very popular subject has found wider application in geomatics [16][17][18][19][20][21], engineering geology [21][22][23][24][25][26], and geotechnical engineering [27][28][29][30][31][32][33]. The products generated from UAV photogrammetry are usually datasets, such as point clouds, high-resolution digital surface models, high resolution digital orthophotos, and photorealistic 3D models and visualizations [16,17].…”

Applications of 3D Paleontological Data at the Florida Museum of Natural History

“…Photogrammetry also has the unique benefit of reproducing 3D models of objects or scenes at various scales. This scalability makes photogrammetry particularly useful for the geoscience because research objects often range in size from single fossil specimens only visible under a scanning electron microscope (Eilitz and Reiss, 2015) to entire geologic localities (Becker et al, 2018;Francioni et al, 2019). Advancements in complementary image capturing equipment (e.g., affordable digital cameras and drones) make image capturing of vast areas more efficient and the ability to generate photogrammetric 3D models of geologic outcrops possible.…”

3D Thermal Monitoring of Jointed Rock Masses through Infrared Thermography and Photogrammetry

“…Recent developments in commercial Structure from Motion (SfM) software paved the way for the possibility to create dense point clouds starting directly from unordered and uncalibrated thermal infrared (TIR) and RGB optical images [18]. While RGB image-based terrestrial and aerial DP represents a well-established methodology for the engineering geological characterization of jointed rock masses [19][20][21], the creation of 3D TIR models represents an almost unexplored frontier. Several studies that mainly focused on the analysis of energy performances of historical buildings and industrial plants [8,22,23] proposed different approaches to fuse thermal attributes derived from IR cameras with geometrical and geospatial data obtained through the generation of 3D point clouds from Total Laser Scanner (TLS) and terrestrial or aerial photogrammetric surveys.…”