scholarly journals DEM Generation from Fixed-Wing UAV Imaging and LiDAR-Derived Ground Control Points for Flood Estimations

Sensors ◽  
2019 ◽  
Vol 19 (14) ◽  
pp. 3205 ◽  
Author(s):  
Jairo R. Escobar Villanueva ◽  
Luis Iglesias Martínez ◽  
Jhonny I. Pérez Montiel
Keyword(s):  
Unmanned Aerial Vehicle ◽  
Structure From Motion ◽  
Local Level ◽  
Control Point ◽  
Ground Control ◽  
Control Points ◽  
Ground Control Points ◽  
Digital Elevation ◽  
Elevation Data ◽  
Aerial Vehicle

Geospatial products, such as digital elevation models (DEMs), are important topographic tools for tackling local flood studies. This study investigates the contribution of LiDAR elevation data in DEM generation based on fixed-wing unmanned aerial vehicle (UAV) imaging for flood applications. More specifically, it assesses the accuracy of UAV-derived DEMs using the proposed LiDAR-derived control point (LCP) method in a Structure-from-Motion photogrammetry processing. Also, the flood estimates (volume and area) of the UAV terrain products are compared with a LiDAR-based reference. The applied LCP-georeferencing method achieves an accuracy comparable with other studies. In addition, it has the advantage of using semi-automatic terrain data classification and is readily applicable in flood studies. Lastly, it proves the complementarity between LiDAR and UAV photogrammetry at the local level.

scholarly journals PRECISION POTENTIAL OF UNDERWATER NETWORKS FOR ARCHAEOLOGICAL EXCAVATION THROUGH TRILATERATION AND PHOTOGRAMMETRY

2019 ◽  
Vol XLII-2/W10 ◽  
pp. 175-180 ◽  
Author(s):  
D. Skarlatos ◽  
F. Menna ◽  
E. Nocerino ◽  
P. Agrafiotis
Keyword(s):  
Standard Deviation ◽  
Structure From Motion ◽  
Control Point ◽  
Archaeological Site ◽  
3D Models ◽  
Ground Control ◽  
Control Points ◽  
Archaeological Excavation ◽  
Control Networks ◽  
Ground Control Points

<p><strong>Abstract.</strong> Given the rise and wide adoption of Structure from Motion (SfM) and Multi View Stereo (MVS) in underwater archaeology, this paper investigates the optimal option for surveying ground control point networks. Such networks are the essential framework for coregistration of photogrammetric 3D models acquired in different epochs, and consecutive archaeological related study and analysis. Above the water, on land, coordinates of ground control points are determined with geodetic methods and are considered often definitive. Other survey works are then derived from by using those coordinates as fixed (being ground control points coordinates considered of much higher precision). For this reason, equipment of proven precision is used with methods that not only compute the most correct values (according to the least squares principle) but also provide numerical measures of their precisions and reliability. Under the water, there are two options for surveying such control networks: trilateration and photogrammetry, with the former being the choice of the majority of archaeological expeditions so far. It has been adopted because of ease of implementation and under the assumption that it is more reliable and precise than photogrammetry.</p><p>This work aims at investigating the precision of network establishment by both methodologies by comparing them in a typical underwater archaeological site. Photogrammetric data were acquired and analysed, while the trilateration data were simulated under certain assumptions. Direct comparison of standard deviation values of both methodologies reveals a clear advantage of photogrammetry in the vertical (Z) axis and three times better results in horizontal precision.</p>

scholarly journals OPTIMIZATION OF GROUND CONTROL POINT (GCP) CONFIGURATION FOR UNMANNED AERIAL VEHICLE (UAV) SURVEY USING STRUCTURE FROM MOTION (SFM)

2019 ◽  
Vol XLII-4/W12 ◽  
pp. 167-174 ◽  
Author(s):  
J. K. S. Villanueva ◽  
A. C. Blanco
Keyword(s):  
Structure From Motion ◽  
Reference Data ◽  
Control Point ◽  
Ground Control ◽  
Ground Control Point ◽  
Center Configuration ◽  
Digital Elevation ◽  
Aerial Vehicle ◽  
Elevation Model ◽  
The Impact

<p><strong>Abstract.</strong> This research presents a method in assessing the impact of Ground Control Point (GCP) distribution, quantity, and inter-GCP distances on the output Digital Elevation Model (DEM) by utilizing SfM and GIS. The study was carried out in a quarry site to assess the impacts of these parameters on the accuracy of accurate volumetric measurements UAV derivatives. Based on GCP Root Mean Square Error (RMSE) and surface checkpoint error (SCE), results showed that the best configuration is the evenly distributed GCP set (1.58&amp;thinsp;m average RMSE, 1.30&amp;thinsp;m average SCE). Configurations clumped to edge and distributed to edge follow suit with respective RMSE (SCE) of 2.53&amp;thinsp;m (2.13&amp;thinsp;m) and 3.11&amp;thinsp;m (2.54&amp;thinsp;m). The clumped to center configuration yielded 6.23&amp;thinsp;m RMSE and 4.66&amp;thinsp;m SCE. As the number of GCPs used increase, the RMSE and SCE are observed to decrease consistently for all configurations. Further iteration of the best configuration showed that from RMSE of 4.11&amp;thinsp;m when 4 GCPs are used, there is a drastic decrease to 0.86&amp;thinsp;m once 10 GCPs are used. From that quantity, only centimeter differences can be observed until the full set of 24 GCPs have been used with a 0.012&amp;thinsp;m error. This is reflected in the stockpile measurement when the iteration results are compared to the reference data. The dataset processed with a minimum of 4 GCPs have a 606,991.43&amp;thinsp;m<sup>3</sup> difference, whereas the dataset processed with 23 out of 24 has a 791.12&amp;thinsp;m<sup>3</sup> difference from the reference data. The accuracy of the SfM-based DEM increases with the quantity of the GCPs used with an even distribution.</p>

scholarly journals The Evaluation of GPS techniques for UAV-based Photogrammetry in Urban Area

2016 ◽  
Vol XLI-B1 ◽  
pp. 1079-1084 ◽  
Author(s):  
M. L. Yeh ◽  
Y. T. Chou ◽  
L. S. Yang
Keyword(s):  
Land Use ◽  
Unmanned Aerial Vehicle ◽  
Three Dimensional ◽  
High Mobility ◽  
Urban Land Use ◽  
Ground Control ◽  
Surface Model ◽  
Control Points ◽  
Ground Control Points ◽  
Aerial Vehicle

The efficiency and high mobility of Unmanned Aerial Vehicle (UAV) made them essential to aerial photography assisted survey and mapping. Especially for urban land use and land cover, that they often changes, and need UAVs to obtain new terrain data and the new changes of land use. This study aims to collect image data and three dimensional ground control points in Taichung city area with Unmanned Aerial Vehicle (UAV), general camera and Real-Time Kinematic with positioning accuracy down to centimetre. The study area is an ecological park that has a low topography which support the city as a detention basin. A digital surface model was also built with Agisoft PhotoScan, and there will also be a high resolution orthophotos. There will be two conditions for this study, with or without ground control points and both were discussed and compared for the accuracy level of each of the digital surface models. According to check point deviation estimate, the model without ground control points has an average two-dimension error up to 40 centimeter, altitude error within one meter. The GCP-free RTK-airborne approach produces centimeter-level accuracy with excellent to low risk to the UAS operators. As in the case of the model with ground control points, the accuracy of x, y, z coordinates has gone up 54.62%, 49.07%, and 87.74%, and the accuracy of altitude has improved the most.

scholarly journals Pemanfaatan Unmanned Aerial Vehicle (UAV) Jenis Quadcopter untuk Percepatan Pemetaan Bidang Tanah (Studi Kasus: Desa Solokan Jeruk Kabupaten Bandung)

2019 ◽  
Vol 2018 (1) ◽  
Author(s):  
Dhiky Hartono ◽  
Soni Darmawan
Keyword(s):  
Unmanned Aerial Vehicle ◽  
Control Point ◽  
Ground Control ◽  
Ground Control Point ◽  
Land Registration ◽  
Ground Control Points ◽  
Stop And Go ◽  
Aerial Vehicle ◽  
First Time ◽  
The Village

ABSTRAKPendaftaran Tanah Sistematik Lengkap (PTSL) merupakan kegiatan pendaftaran tanah untuk pertama kali yang dilakukan secara serentak di Indonesia. Program PTSL dimulai pada tahun 2016 dan ditargetkan selesai pada tahun 2025. Dengan luas darat Indonesia mencapai 2,01 juta km2, dibutuhkan teknologi yang dapat mempercepat program PTSL, di antaranya menggunakan pesawat tanpa awak (drone). Tujuan dari penelitian ini adalah untuk mengetahui sejauh mana kemampuan unmanned aerial vehicle (UAV) jenis Quadcopter untuk pemetaan bidang tanah yang ditinjau dari ketelitian, biaya, dan kecepatan. Daerah yang akan dikaji merupakan daerah yang sedang melaksanakan program PTSL yaitu Desa Solokan Jeruk Kecamatan Solokan Jeruk Kabupaten Bandung. Metodologi penelitian terdiri atas akuisisi data menggunakan UAV jenis Quadcopter dan proses pengolahan foto menggunakan perangkat lunak Agisoft Photoscan yang digeoreferensikan dengan ground control points (GCP) yang didapat dari pengamatan GPS Stop and Go. Hasil penelitian ini menunjukkan UAV jenis Quadcopter dapat mempercepat program PTSL dengan tingkat akurasi 96%, kecepatan penyediaan peta kerja atau peta dasar untuk program PTSL kurang dari 5 hari untuk luasan 1000 Ha, namun dengan biaya yang cukup tinggi.Kata Kunci: PTSL, UAV jenis Quadcopter, Ground Control Point (GCP) ABSTRACTComplete Systematic Land Registration (CSLR) is a land registration activity for the first time that is carried out simultaneously in Indonesia. The PTSL program was started in 2016 and targeted for completion by 2025. With Indonesia's land area reaching 2.01 million km2, technology is needed that can accelerate the CSLR program, one of which is using a drone. The purpose of this research is to know the extent of Unmanned Aerial Vehicle (UAV) capability of Quadcopter type for mapping of plot of land in terms of accuracy, speed, and economics. The study area is area that is being implemented the program, which located in the village of Solokan Jeruk, Solokan Sub-District, Bandung Regency. The research methodology consists of data acquisition by using UAV type Quadcopters and photo processing using Agisoft Photoscan software that will be georeferenced to the Ground Control Point (GCP) that is obtained from the GPS Real Time Kinematic observation using the Stop and Go method. The results of this study indicate that the UAV type Quadcopter can accelerate the CSLR program by providing 96% accuracy, and the speed of providing a work map or base map for CSLR program of less than 5 days for 1000 Ha, but at a high cost.Keywords: CSLR, UAV type Quadcopter, Ground Control Point (GCP)

scholarly journals Structure-from-Motion on shallow reefs and beaches: potential and limitations of consumer-grade drones to reconstruct topography and bathymetry

Coral Reefs ◽  
2021 ◽  
Author(s):  
C. Gabriel David ◽  
Nina Kohl ◽  
Elisa Casella ◽  
Alessio Rovere ◽  
Pablo Ballesteros ◽  
...  
Keyword(s):  
Shallow Water ◽  
Structure From Motion ◽  
Water Levels ◽  
Aerial Photographs ◽  
Ground Control ◽  
Control Points ◽  
Ground Control Points ◽  
Digital Elevation ◽  
Nonlinear Distortions ◽  
Elevation Model

AbstractReconstructing the topography of shallow underwater environments using Structure-from-Motion—Multi View Stereo (SfM-MVS) techniques applied to aerial imagery from Unmanned Aerial Vehicles (UAVs) is challenging, as it involves nonlinear distortions caused by water refraction. This study presents an experiment with aerial photographs collected with a consumer-grade UAV on the shallow-water reef of Fuvahmulah, the Maldives. Under conditions of rising tide, we surveyed the same portion of the reef in ten successive flights. For each flight, we used SfM-MVS to reconstruct the Digital Elevation Model (DEM) of the reef and used the flight at low tide (where the reef is almost entirely dry) to compare the performance of DEM reconstruction under increasing water levels. Our results show that differences with the reference DEM increase with increasing depth, but are substantially larger if no underwater ground control points are taken into account in the processing. Correcting our imagery with algorithms that account for refraction did not improve the overall accuracy of reconstruction. We conclude that reconstructing shallow-water reefs (less than 1 m depth) with consumer-grade UAVs and SfM-MVS is possible, but its precision is limited and strongly correlated with water depth. In our case, the best results are achieved when ground control points were placed underwater and no refraction correction is used.

scholarly journals Improving the Accuracy of Aerial Photography Using Ground Control Points

2021 ◽  
Vol 15 (4) ◽  
pp. 42-47
Author(s):  
R. K. Kurbanov ◽  
N. I. Zakharova ◽  
D. M. Gorshkov
Keyword(s):  
Data Processing ◽  
Unmanned Aerial Vehicle ◽  
High Precision ◽  
Aerial Photography ◽  
Ground Control ◽  
Control Points ◽  
Post Processing ◽  
Standard Data ◽  
Ground Control Points ◽  
Aerial Vehicle

The authors showed that it is possible to quickly collect up-to-date information on the agricultural land condition using an unmanned aerial vehicle. It was noted that the use of ground control points increases the accuracy of project measurements, helps to compare the project post-processing results with the real measurements. (Research purpose) To compare the results of standard and high-precision post-processing of aerial survey data using ground control points. (Materials and methods) Aerial photography was carried out on a 1.1- hectare breeding field. The authors used DJI Matrice 200 v2 unmanned aerial vehicle with a GNSS L1/L2 receiver and a modified DJI X4S camera, five control points sized 50 × 50 centimeters and an EMLID Reach RS2 multi-frequency GNSS receiver. The results of scientific research into the use of ground control points during aerial photography were studied. (Results and discussion) It was found out that the error of georeferencing images obtained by an unmanned aerial vehicle without control points is significantly higher during the standard data processing compared to the high-precision one. The project error when using five control points is 3.9 times higher during the standard data processing. (Conclusions) It was shown that using ground control points it is possible to improve the project measurement accuracy, as well as compare the project post-processing results with the measurements on the ground. It was detected that the high-precision monitoring enables the use of fewer ground control points. It was found out that in order to obtain data with the accuracy of 2-4 centimeters in plan and height, at least 3 ground control points need to be used during the high-precision post-processing.

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