RTK GNSS-Assisted Terrestrial SfM Photogrammetry without GCP: Application to Coastal Morphodynamics Monitoring

Abstract

The present article describes a new and efficient method of Real Time Kinematic (RTK) Global Navigation Satellite System (GNSS) assisted terrestrial Structure-from-Motion (SfM) photogrammetry without the need for Ground Control Points (GCPs). The system only requires a simple frame that mechanically connects a RTK GNSS antenna to the camera. The system is low cost, easy to transport, and offers high autonomy. Furthermore, not requiring GCPs enables saving time during the in situ acquisition and during data processing. The method is tested for coastal cliff monitoring, using both a Reflex camera and a Smartphone camera. The quality of the reconstructions is assessed by comparison to a synchronous Terrestrial Laser Scanner (TLS) acquisition. The results are highly satisfying with a mean error of 0.3 cm and a standard deviation of 4.7 cm obtained with the Nikon D800 Reflex camera and, respectively, a mean error of 0.2 cm and a standard deviation of 3.8 cm obtained with the Huawei Y5 Smartphone camera. This method will be particularly interesting when simplicity, portability, and autonomy are desirable. In the future, it would be transposable to participatory science programs, while using an open RTK GNSS network.

Using Geomatic Techniques to Estimate Volume–Area Relationships of Watering Ponds

“…The first was that, even at the end of the summer, watering ponds usually show a thick layer of water at the bottom, which is usually turbid [70] and makes unsuitable underwater photo-reconstructions such as those carried out successfully in other environments [71]. The second reason was that the photogrammetric model needed to be (at least) scaled using GCPs (or GNSS RTK systems connected to the camera instead of GCPs; e.g., [72]), while the GNSS allowed the survey of additional CCPs to independently quantify the accuracy of the model. In recent years, affordable (or low-cost) GNSS survey-grade devices have been available in the market [73] to carry out this task.…”

Monitoring the Coastal Changes of the Po River Delta (Northern Italy) since 1911 Using Archival Cartography, Multi-Temporal Aerial Photogrammetry and LiDAR Data: Implications for Coastline Changes in 2100 A.D.

“…In this case, these methodologies can provide useful data in the study of planimetric changes: along the coastal area, with low elevations compared to the mean sea level, low subsidence rates can provide high planimetric changes of the coastline, with submersion of large areas that can be evaluated using photogrammetric and LiDAR data. For more limited areas, unmanned aerial vehicle (UAV) [14,15] and terrestrial laser scanning (TLS) [16][17][18] systems can also be used successfully.…”

Virtual Outcrops in a Pocket: The Smartphone as a Fully Equipped Photogrammetric Data Acquisition Tool

“…For many geoscience applications, it is necessary to register 3D rock-surface reconstructions within a local or global coordinate frame. The use of survey-grade total stations and/or real-time kinematic (RTK) differential global navigation satellite system (GNSS) antennas permit both terrestrial (Jaud et al, 2020) and aerial (Rieke et al, 2012) image data and/or ground control points (GCPs) to be georeferenced within the mapped scene with centimeter to millimeter accuracy (Bemis et al, 2014). Those survey tools are, however, bulky and expensive, and are not standard tools for geoscientists engaged in fieldwork.…”