Systemic Approach to Elevation Data Acquisition for Geophysical Survey Alignments in Hilly Terrains Using UAVs

Fully-automated estimation of snow depth in near real time with the use of unmanned aerial vehicles without utilizing ground control points

The Digital Elevation Model (DEM) contains elevation and slope information, making interpretation easierso that it is a fundamental element of geospatial data and can be used as a mapping source. The use oftechnology in the field of photogrammetric mapping is demonstrated by the use of Unmanned Aerial Vehicle(UAV) or drones in mapping and Geodetic GPS tied to benchmarks to obtain Ground Control Point (GCP)coordinates as ground control points. This research aims to make the Palangka Raya University DEM usingUAV and Geodetic GPS. In processing aerial photo data, the photogrammetric method is used. The time fortaking aerial photo data begins on 14-21 October 2022 which is divided into 10 flying missions with a flightaltitude of 100 m, overlap and sidelap of 75%, and camera angle of 90 with a total of 7,935 photos. GCP dataretrieval using the Real Time Kinematic (RTK) method with Geodetic GPS was carried out on October 14,2022 with a total of 33 coordinate points. The DEM that has been formed can be seen that mapping usingUAVs/drones and Geodetic GPS produces high-resolution photo data that can be used for making DigitalElevation Models (DEMs) with the highest altitude at Palangka Raya University, namely 90 meters and thelowest altitude at 50 meters. The DEM resolution obtained is 18.1 cm/pixel and the interpolation point densityis 30.7 points/m2.

Abstract. The rapid development of unmanned aerial vehicles is a challenge for applied research. Many technologies are developed and then researcher are looking up for their application in different sectors. Therefore, we decided to verify the use of the unmanned aerial vehicle for wood chips pile monitoring. We compared the use of GNSS device and unmanned aerial vehicle for volume estimation of four wood chips piles. We used DJI Phantom 3 Professional with the built-in camera and GNSS device (geoexplorer 6000). We used Agisoft photoscan for processing photos and ArcGIS for processing points. Volumes calculated from pictures were not statistically significantly different from amounts calculated from GNSS data and high correlation between them was found (p = 0.9993). We conclude that the use of unmanned aerial vehicle instead of the GNSS device does not lead to significantly different results. Tthe data collection consumed from almost 12 to 20 times less time with the use of UAV. Additionally, UAV provides documentation trough orthomosaic.

In recent years, low-cost unmanned aerial vehicles (UAVs) photogrammetry and terrestrial laser scanner (TLS) techniques have become very important non-contact measurement methods for obtaining topographic data about landslides. However, owing to the differences in the types of UAVs and whether the ground control points (GCPs) are set in the measurement, the obtained topographic data for landslides often have large precision differences. In this study, two types of UAVs (DJI Mavic Pro and DJI Phantom 4 RTK) with and without GCPs were used to survey a loess landslide. UAVs point clouds and digital surface model (DSM) data for the landslide were obtained. Based on this, we used the Geomorphic Change Detection software (GCD 7.0) and the Multiscale Model-To-Model Cloud Comparison (M3C2) algorithm in the Cloud Compare software for comparative analysis and accuracy evaluation of the different point clouds and DSM data obtained using the same and different UAVs. The experimental results show that the DJI Phantom 4 RTK obtained the highest accuracy landslide terrain data when the GCPs were set. In addition, we also used the Maptek I-Site 8,820 terrestrial laser scanner to obtain higher precision topographic point cloud data for the Beiguo landslide. However, owing to the terrain limitations, some of the point cloud data were missing in the blind area of the TLS measurement. To make up for the scanning defect of the TLS, we used the iterative closest point (ICP) algorithm in the Cloud Compare software to conduct data fusion between the point clouds obtained using the DJI Phantom 4 RTK with GCPs and the point clouds obtained using TLS. The results demonstrate that after the data fusion, the point clouds not only retained the high-precision characteristics of the original point clouds of the TLS, but also filled in the blind area of the TLS data. This study introduces a novel perspective and technical scheme for the precision evaluation of UAVs surveys and the fusion of point clouds data based on different sensors in geological hazard surveys.

Abstract. This paper looks into the latest achievement in the low-cost Unmanned Aerial Vehicle (UAV) technology in their capacity to map the semi-development areas. The objectives of this study are to establish a new methodology or a new algorithm in image registration during interior orientation process and to determine the accuracy of the photogrammetric products by using UAV images. Recently, UAV technology has been used in several applications such as mapping, agriculture and surveillance. The aim of this study is to scrutinize the usage of UAV to map the semi-development areas. The performance of the low cost UAV mapping study was established on a study area with two image processing methods so that the results could be comparable. A non-metric camera was attached at the bottom of UAV and it was used to capture images at both sites after it went through several calibration steps. Calibration processes were carried out to determine focal length, principal distance, radial lens distortion, tangential lens distortion and affinity. A new method in image registration for a non-metric camera is discussed in this paper as a part of new methodology of this study. This method used the UAV Global Positioning System (GPS) onboard to register the UAV image for interior orientation process. Check points were established randomly at both sites using rapid static Global Positioning System. Ground control points are used for exterior orientation process, and check point is used for accuracy assessment of photogrammetric product. All acquired images were processed in a photogrammetric software. Two methods of image registration were applied in this study, namely, GPS onboard registration and ground control point registration. Both registrations were processed by using photogrammetric software and the result is discussed. Two results were produced in this study, which are the digital orthophoto and the digital terrain model. These results were analyzed by using the root mean square errors and mean absolute error to determine the level of accuracy and the precision of photogrammetric products. It can be concluded that the new method of image registration by using the GPS onboard of the UAV produces medium accuracy result compared to the method that uses the ground control point. This new method can be used for the medium accuracy requirements. Unmanned Aerial Vehicle can be used for several applications, which requires a medium accuracy.

This paper demonstrates the performance of a fixed-wing unmanned aerial vehicle in mapping semi-undulated area. Current practices incur huge cost and time consuming. The aim of this study is to evaluate photogrammetric technique for mapping slope. Fixed-wing unmanned aerial vehicle (UAV) was employed as a tool for image acquisition at the height of 300m. This unit is a complete package that includes low cost digital camera, autonomous chip, global positioning system (GPS), gyro and electronic speed controller. This study was conducted at Skudai, Johor, which is located approximately at latitude 1°33'24.49N and longitude 103°39'4.30E. All the acquired images were processed using photogrammetric technique which comprise of aerial triangulation and bundle adjustment. There are two main photogrammetric products produced from this study known as digital orthophoto and digital elevation model (DEM). Both products were analyzed to determine accuracy of the results. Ground control points and check points were distributed randomly at the study area and all the points were established using GPS Real Time Kinematic (RTK) technique. Based on the results, it was found that root mean square error for slope analysis is +1.169m and length analysis is +0.259m.

Detailed documentation of historical and cultural heritage is a necessity for further analysis, interpretation, and physical reconstruction. Usage of The Unmanned Aerial Vehicles (UAVs) in this role have been increasing day by day. As a result of its important contributions to the production of three-dimensional (3D) terrain models, it has reached an important point in the discipline of surveying engineering. Especially in 3D modeling and documentation of historical and cultural heritage, UAVs are advantageous tools in terms of time and cost when compared to the classical methods. The aim of this study is to generate a 3D model of the Kurtkulağı Caravanserai, located in the Kurtkulağı town of Ceyhan District of Adana, using UAV (DJI Phantom 4 RTK) and to reveal the importance of UAV in the documentation of this historical structure. In this context, according to a planned flight on the UAV, following the capture of the images of the caravanserai in a multiview aspect, a metric 3D model was produced using photogrammetric methods. Root Mean Square Errors (RMSEs) in X, Y, Z coordinates were calculated based on the Ground Control Points (GCPs) and corresponding model coordinates. The RMSEs for X, Y, Z coordinates were calculated 0.019m, 0.025m, and 0.033m, respectively.

Unmanned aerial vehicles (UAVs) are an emerging technology for 3D Earth modelling and mapping. UAVs collect aerial images that are used to generate orthophotos with the assistance of navigation systems such as the Global Positioning System (GPS) and telemetry monitors at the Ground Control Station (GSC) for monitoring and controlling the UAV in autonomous flight. However, precision is critical in UAV photogrammetry mapping (PMg) to present acceptable precision measurements of the captured images that closely related to Ground Sample Distance (GSD) as most survey works are gradually shifting away from conventional surveying equipment such as total station and theodolite which has good precision measurement. This study focuses on the application of UAVs at close-range topography and mapping of land slope. Flight through the slope will vary in terms of flying altitude, affecting the GSD’s value for each slope height. The accuracy of PMg for land slope is subsequently assessed by evaluating the accuracy of slope mapping, particularly the slope height derived from Digital Elevation Model (DEM), Digital Surface Model (DSM) of orthophotos and Global Navigation Satellite System (GNSS) survey. This is due to the fact that most PMg is done on almost exclusively horizontal areas, and the GSD change value acquired remains the same. The purpose of this study is to analyze the accuracy of PMg of land slope by land slope mapping at 100m flight high above ground level. the RMSE recorded for x and y coordinate were (RMSEx = 0.654198cm) and (RMSEy = 0.668516cm) while for elevation error was (RMSEz = 0.512062cm). This study’s output is to help and assist authorities in construction planning, particularly during the cutting and filling process; to determine the precise amount of earth required for construction; and control the cost of earthwork.

This study investigates the optimisation of Unmanned Aerial Vehicle (UAV) photogrammetry and Global Positioning System Real-Time Kinematic (GPS-RTK) technologies for volume calculation in complex terrains, using the hillside of Universiti Teknologi MARA (UiTM) Perak as a case study. Although UAV photogrammetry is increasingly applied in topographic modelling, few studies have empirically compared its volumetric accuracy at different flight altitudes against GPS-RTK benchmarks in undulating landscapes. In this study, two UAV flight altitudes (80m and 100m) were evaluated to determine their impact on measurement precision, with results benchmarked against ground-truthed GPS RTK data. Processing through Pix4Dmapper and ArcGIS Pro revealed that UAV-based surveys achieved 91.87% accuracy at 80m compared to 87.57% at 100m, demonstrating the critical role of flight altitude in terrain modelling. The higher accuracy at lower altitudes is attributed to enhanced image resolution and improved capture of terrain details, despite marginally increased operational time. These findings position UAV technology as a viable, cost-efficient complement to traditional GPS RTK surveys, particularly for large-scale or inaccessible terrain mapping. For projects requiring sub-decimetre accuracy in undulating landscapes, an 80m flight altitude is recommended as the optimal balance between data quality and survey efficiency. This research provides empirically validated guidelines for integrating UAV photogrammetry into geospatial workflows across construction, environmental management, and land development sectors.

Chapter 18 - GNSS and UAV in archeology: high-resolution mapping in Cephalonia Island, Greece

The conventional methods of aerial photogrammetry using helicopters or airplanes are costly and challenging for small areas. For a developing country like Nepal, where Geospatial data is in high demand, a new competitive approach is essential for rapid spatial data acquisition at a low cost and time. This article demonstrates how this can be achieved using one of the evolving remote sensing technology, Unmanned Aerial Vehicles (UAVs). The application of UAVs is rapidly increasing in Nepal due to its capability of acquiring images remotely and the potential to provide data with a very high spatial and temporal resolution even in inaccessible terrain at a relatively low cost. Here, the performance of UAVs for topographical surveying and mapping has been investigated, along with the comparison between orthophoto obtained using GCPs, and without using GCPs. For this study, a DJI Phantom 3 Advanced quadcopter collected about 700 images at a flying height of 50 m above the settlement area. An orthophoto of 3.78 cm GSD covering 40.83 hectares of area was produced. With appropriate ground control points, an absolute positional accuracy of 0.035 m RMSE was achieved, whereas the output obtained without using GCPs was satisfactory. This study also highlights the use of a High-Performance Computing (HPC) system and open-source platform for rapid image processing.

Recent technological innovations have led to the available of lightweight Unmanned Aerial Vehicle (UAV) and Structure-from-Motion (SfM) photogrammetry that are successfully applied for 3D topographic surveys. However, application of UAV and SfM for complex topographic areas i.e. open-pit mine areas is still poorly understood. This paper aims to investigate and verify potential application of these techniques for generating Digital Surface Model (DSM) at open-pit coal mine area and assessing its accuracy. For this purpose, the Nui Beo open-pit coal mine located in northeast Vietnam is selected as a case study. Accordingly, a total of 206 photos were captured using DJI Phantom 3 Professional. In addition, 19 ground control points (GCPs) were established using Leica TS09 total station. The accuracy of DSM was assessed using root-mean-square error (RMSE) in X, Y, Z, XY, and XYZ components. The result showed that the DSM model has high accuracy, RMSE on the 12 calibrated GCPs for X, Y, Z, XY, XYZ is 1.1 cm, 1.9 cm, 0.8 cm, 2.2 cm, and 2.3 cm, respectively, whereas RMSE on the 7 checked GCPs is 1.8 cm, 2.4 cm, 3.2 cm, 3.0 cm, and 4.4 cm for X, Y, Z, XY, XYZ components, respectively. We concluded that small UAV and SfM are feasible and valid tools for 3D topographic mapping in complex terrains such as open-pit coal mine areas.

The use of unmanned aerial vehicles (UAVs) is becoming increasingly widespread in many areas of human life every year. Not only military, but also civilian use of UAVs in various fields of science, industry, forestry, agronomy, cartography, ecology, and space research is hard to overestimate. For this reason, the use and development of UAVs in various fields remains extremely promising in the near future. Compared to manned vehicles, UAVs have the following advantages: no crew and no need for life support systems, large airfields; lower cost and low expenses for their development, production and operation; better weight and dimensions; high reliability and maneuverability; a wide range of specialized equipment for placement on board. UAVs are being introduced into all spheres of human life, even those where UAVs have no manned alternative. Some models of multicopters are already being used to deliver goods and extinguish fires. UAVs of new designs continue to be developed.In all areas of UAV application, the task of increasing autonomy remains relevant and important. The duration of con-tinuous operation and flight range directly affect the capabilities of the UAV, its ability to perform tasks and efficiency.UAV power consumption depends on the weight of the payload, weather conditions and drone speed. Energy consumption is a critical criterion for a drone to perform its missions and needs to be further studied. Many studies have been conducted to increase flight time by improving energy efficiency or reducing the energy consumed by the drone.Study the influence of battery parameters (capacity and weight) and propeller group (number of propellers and their diameter) on the maximum possible flight duration of UAVs of different masses.The main factors affecting the maximum flight duration of a UAV are considered. A model for calculating the power consumed by the device in the hover mode is presented. The maximum flight duration of a UAV is calculated depending on the battery capacity and weight, the number of propellers, and the diameter of the propellers for vehicles of different masses.It is shown that there is no point in increasing the battery capacity indefinitely, and there is an optimum point that depends on the ratio of the battery mass to the mass of the vehicle. It is also shown that increasing the diameter of the propellers significantly increases the flight time, while increasing their number is not as effective.

This study aims to measure the overburden volume at Pit 3HWE, PT. Indominco Mandiri using Unmanned Aerial Vehicle (UAV) technology. The use of UAV for volume measurement offers a more efficient and accurate alternative compared to conventional methods. In this research, aerial images were captured using a UAV and processed with photogrammetry software to generate a digital surface model (DSM) and 3D maps. The overburden volume calculations were analyzed and compared with manual measurement data as a reference. The results indicate that UAV usage provides accurate results with higher time efficiency, making it a viable method for mining operations. Factors affecting the measurement results, such as weather conditions and image resolution, were also analyzed in this study.

In this study, we generated Digital Elevation Model (DEM) from Unmanned Aerial Vehicle (UAV) to confirm the suitability of UAV to the tidal flat study. The DEMs were generated from aerial triangulation method using rotary-wing UAV. For the accurate generation of mosaic images and DEM, the distorted images occurred by interior and exterior orientation were corrected using camera calibration. In addition, we set up a Ground Control Points (GCPs) in order to correct of the UAV position error. Therefore, the DEM was obtained with geometric error less than 30 cm. The height of generated DEM by UAV was compared with the levelled elevation by RTK-GPS and TanDEM-X radar satellite DEM. From this study, we could confirm that accurate DEM of the tidal flat can be generated using UAV and these detailed spatial information about tidal flat will be widely used for tidal flat management.