Possibilities for Using Lidar and Photogrammetric Data Obtained With an Unmanned Aerial Vehicle for Levee Monitoring

Abstract

Commission I, ICWG I/VbKEY WORDS: UAV, UAS, LiDAR, ultra-light, accuracy, DTM ABSTRACT:This paper presents the possibilities for using an unmanned aerial system for evaluation of the condition of levees. The unmanned aerial system is equipped with two types of sensor. One is an ultra-light laser scanner, integrated with a GNSS receiver and an INS system; the other sensor is a digital camera that acquires data with stereoscopic coverage. Sensors have been mounted on the multirotor, unmanned platform the Hawk Moth, constructed by MSP company. LiDAR data and images of levees the length of several hundred metres were acquired during testing of the platform. Flights were performed in several variants. Control points measured with the use of the GNSS technique were considered as reference data. The obtained results are presented in this paper; the methodology of processing the acquired LiDAR data, which increase in accuracy when low accuracy of the navigation systems occurs as a result of systematic errors, is also discussed. The Iterative Closest Point (ICP) algorithm, as well as measurements of control points, were used to georeference the LiDAR data. Final accuracy in the order of centimetres was obtained for generation of the digital terrain model. The final products of the proposed UAV data processing are digital elevation models, an orthophotomap and colour point clouds. The authors conclude that such a platform offers wide possibilities for low-budget flights to deliver the data, which may compete with typical direct surveying measurements performed during monitoring of such objects. However, the biggest advantage is the density and continuity of data, which allows for detection of changes in objects being monitored.

Evaluation of Photogrammetry and Inclusion of Control Points: Significance for Infrastructure Monitoring

“…Overall, the agreement between the results from both software packages is high, and we can consider the differences to be less than 1 cm in general. Figure 5b presents similar results to those shown in Figure 5a 10 cm [46]. A greater optimal accuracy, near 5 cm, was captured when an iterative control point 189 method was deployed [46].…”

“…Figure 5b presents similar results to those shown in Figure 5a 10 cm [46]. A greater optimal accuracy, near 5 cm, was captured when an iterative control point 189 method was deployed [46]. Udin and Ahmad (2014) also presented submeter accuracies using UAV 190 photogrammetry for large-scale stream mapping [36].…”

The Potential of Light Laser Scanners Developed for Unmanned Aerial Vehicles – The Review and Accuracy

“…The average distance value was 0.90 m. According to the accuracy resulting from the mathematical model, after considering the components errors used by Jozkow et al, is up to 2 m. A quite big difference between the mathematical model used in this article and experimental results obtained by Bakuła et al (2016) is noticed. In this case, according to the mathematical model, the measurement accuracy could even reach 0.20 m, contrary to the 0.09 obtained in Bakuła et al experiment. In the last example (Gallay et al, 2016), the most accurate modules, both laser scanner and GNSS/IMU, were used.…”

“…In order to analyse if the mathematical model can be applied properly to estimate the ULS accuracy, the results obtained by Jozkow et al (2016), Bakuła et al (2016) and Gallay et al (2016) are discussed. It is worth highlighting that these articles were published in 2016, which shows the recently growing interest in light laser scanners.…”

“…Moreover, only a few articles regarding the measurement accuracy using experimental data from light laser scanners can be found (Bakuła et al, 2016;Jozkow et al, 2016), and because of the different laser scanners used in the experiments, the results are on divergent levels. On the contrary, many publications refer to the accuracy of airborne laser scanning, but airborne scanning differs from UAV scanning; therefore, in this article the theoretical measurement accuracy of light laser scanners is analysed.…”