scholarly journals ARE MEASURED GROUND CONTROL POINTS STILL REQUIRED IN UAV BASED LARGE SCALE MAPPING? ASSESSING THE POSITIONAL ACCURACY OF AN RTK MULTI-ROTOR PLATFORM

2020 ◽  
Vol XLIII-B1-2020 ◽  
pp. 507-514 ◽  
Author(s):  
L. Teppati Losè ◽  
F. Chiabrando ◽  
F. Giulio Tonolo
Keyword(s):  
Large Scale ◽  
Control Point ◽  
Satellite System ◽  
Added Value ◽  
Ground Control ◽  
Positional Accuracy ◽  
Ground Control Points ◽  
Aerial Vehicle ◽  
Global Navigation Satellite ◽  
The Impact

Abstract. The estimate of External Orientation (E.O.) parameters for a block of images is a crucial step in the photogrammetric pipeline and the most demanding in terms of required time and human effort, both during the fieldwork and post-processing phases. Different researchers developed strategies to minimize the impact of this phase. Despite the achievement of good results, it was not possible until now to completely cancel the effect of this step. However, the efforts of the researchers in these years have also been devoted to the implementation of direct photogrammetry strategies, in order to almost completely automate the E.O. of the photogrammetric block. These new approaches were made possible also thanks to the latest developments of commercial UAVs, especially in terms of the installed GPS/GNSS (Global Positioning System/Global Navigation Satellite System) hardware. The aim of this manuscript is to evaluate the different perspectives and issues connected with the deployment of a UAV (Unmanned Aerial Vehicle) equipped with a multi-frequency GPS/GNSS receiver. Starting from the considerations mentioned above and leveraging previous works based on a fixed-wing platform, the focus of this contribution is the assessment of the real performances of an RTK multi-rotor platform addressing several questions. Is it possible to generate added-value products with centimetre 3D accuracies without measuring any ground control point? Which are the operational requirements to be taken into account in the planning phase? Are consolidated UAV mapping operational workflows already available to enable a robust direct georeferencing approach?

scholarly journals Photogrammetric 3D Model via Smartphone GNSS Sensor: Workflow, Error Estimate, and Best Practices

2020 ◽  
Vol 12 (21) ◽  
pp. 3616
Author(s):  
Stefano Tavani ◽  
Antonio Pignalosa ◽  
Amerigo Corradetti ◽  
Marco Mercuri ◽  
Luca Smeraglia ◽  
...  
Keyword(s):  
3D Model ◽  
Model Building ◽  
Satellite System ◽  
Test Case ◽  
Digital Terrain ◽  
Ground Control Points ◽  
Terrain Models ◽  
Aerial Vehicle ◽  
Global Navigation Satellite ◽  
The Impact

Geotagged smartphone photos can be employed to build digital terrain models using structure from motion-multiview stereo (SfM-MVS) photogrammetry. Accelerometer, magnetometer, and gyroscope sensors integrated within consumer-grade smartphones can be used to record the orientation of images, which can be combined with location information provided by inbuilt global navigation satellite system (GNSS) sensors to geo-register the SfM-MVS model. The accuracy of these sensors is, however, highly variable. In this work, we use a 200 m-wide natural rocky cliff as a test case to evaluate the impact of consumer-grade smartphone GNSS sensor accuracy on the registration of SfM-MVS models. We built a high-resolution 3D model of the cliff, using an unmanned aerial vehicle (UAV) for image acquisition and ground control points (GCPs) located using a differential GNSS survey for georeferencing. This 3D model provides the benchmark against which terrestrial SfM-MVS photogrammetry models, built using smartphone images and registered using built-in accelerometer/gyroscope and GNSS sensors, are compared. Results show that satisfactory post-processing registrations of the smartphone models can be attained, requiring: (1) wide acquisition areas (scaling with GNSS error) and (2) the progressive removal of misaligned images, via an iterative process of model building and error estimation.

scholarly journals Unmanned Aerial Vehicle Surveying For Monitoring Road Construction Earthworks

2019 ◽  
Vol 14 (1) ◽  
pp. 1-17 ◽  
Author(s):  
Kalev Julge ◽  
Artu Ellmann ◽  
Romet Köök
Keyword(s):  
Unmanned Aerial Vehicle ◽  
Road Construction ◽  
Point Clouds ◽  
Satellite System ◽  
Ground Control Points ◽  
Surface Models ◽  
Aerial Vehicle ◽  
Global Navigation Satellite ◽  
Sand And Gravel ◽  
The Impact

Unmanned aerial vehicle photogrammetry is a surveying technique that enables generating point clouds, 3D surface models and orthophoto mosaics. These are based on photos captured with a camera placed on an unmanned aerial vehicle. Within the framework of this research, unmanned aerial vehicle photogrammetry surveys were carried out over a sand and gravel embankment with the aim of assessing the vertical accuracy of the derived surface models. Flight altitudes, ground control points and cameras were varied, and the impact of various factors on the results was monitored. In addition, the traditional real-time-kinematic Global Navigation Satellite System surveys were conducted for verifications. Surface models acquired by different methods were used to calculate volumes and compare the results with requirements set by Estonian Road Administration. It was found that with proper measuring techniques an accuracy of 5.7 cm for the heights were achieved.

scholarly journals UAV PHOTOGRAMMETRY AND VHR SATELLITE IMAGERY FOR EMERGENCY MAPPING. THE OCTOBER 2020 FLOOD IN LIMONE PIEMONTE (ITALY)

2021 ◽  
Vol XLIII-B3-2021 ◽  
pp. 727-734
Author(s):  
L. Teppati Losè ◽  
F. Chiabrando ◽  
F. Giulio Tonolo ◽  
A. Lingua
Keyword(s):  
Data Processing ◽  
Large Scale ◽  
Heavy Rain ◽  
Satellite System ◽  
Control Points ◽  
Positional Accuracy ◽  
Multi Scale ◽  
Ground Control Points ◽  
Processing Strategies ◽  
Global Navigation Satellite

Abstract. Heavy rain between the 2nd and 3rd of October 2020 severely affected the area of Limone Piemonte, Piemonte Region (Italy). The consequence of those two days of rain was a flood that, starting from the hamlet of Limonetto severely damaged the areas close to the riverbed of the Vermegnana river and the related hydrographyc network. A synergistic multi-sensor and multi-scale approach for documenting the affected areas using VHR satellite images and UAVs (Uncrewed Aerial Vehicles) is presented. The pro and cons in terms of level of detail and processing strategies are reviewed with a focus on the workflows adopted for processing large UAV datasets. A thorough analysis of the 3D positional accuracy achievable with different georeferentation strategies for UAVs data processing is carried out, confirming that if an RTK (Reale Time Kinematic)-enabled GNSS (Global Navigation Satellite System) receiver is available on the UAV platform and proper acquisition guidelines are followed, the use of GCPs (Ground Control Points) is not impacting significantly on the overall positional accuracy. Satellite data processing is also presented, confirming the suitability for large scale mapping.

scholarly journals Evaluation of the Georeferencing Accuracy of a Photogrammetric Model Using a Quadrocopter with Onboard GNSS RTK

Sensors ◽  
2020 ◽  
Vol 20 (8) ◽  
pp. 2318 ◽  
Author(s):  
Martin Štroner ◽  
Rudolf Urban ◽  
Tomáš Reindl ◽  
Jan Seidl ◽  
Josef Brouček
Keyword(s):  
Vertical Component ◽  
Satellite System ◽  
Bundle Adjustment ◽  
Ground Control ◽  
Control Points ◽  
Ground Sample ◽  
Ground Control Points ◽  
Aerial Vehicle ◽  
Global Navigation Satellite ◽  
Orientation Parameters

Using a GNSS RTK (Global Navigation Satellite System Real Time Kinematic) -equipped unmanned aerial vehicle (UAV) could greatly simplify the construction of highly accurate digital models through SfM (Structure from Motion) photogrammetry, possibly even avoiding the need for ground control points (GCPs). As previous studies on this topic were mostly performed using fixed-wing UAVs, this study aimed to investigate the results achievable by a quadrocopter (DJI Phantom 4 RTK). Three image acquisition flights were performed for two sites of a different character (urban and rural) along with three calculation variants for each flight: georeferencing using ground-surveyed GCPs only, onboard GNSS RTK only, and a combination thereof. The combined and GNSS RTK methods provided the best results (at the expected level of accuracy of 1–2 GSD (Ground Sample Distance)) for both the vertical and horizontal components. The horizontal positioning was also accurate when georeferencing directly based on the onboard GNSS RTK; the vertical component, however, can be (especially where the terrain is difficult for SfM evaluation) burdened with relatively high systematic errors. This problem was caused by the incorrect identification of the interior orientation parameters calculated, as is customary for non-metric cameras, together with bundle adjustment. This problem could be resolved by using a small number of GCPs (at least one) or quality camera pre-calibration.

An Analysis of Alternatives for the COSMIC-2 Constellation in the Context of Global Observing System Simulation Experiments

2020 ◽  
Vol 35 (1) ◽  
pp. 51-66 ◽  
Author(s):  
L. Cucurull ◽  
M. J. Mueller
Keyword(s):  
System Simulation ◽  
Three Dimensional ◽  
Lower Troposphere ◽  
Weather Forecast ◽  
Satellite System ◽  
Forecast Skill ◽  
Added Value ◽  
Simulation Experiments ◽  
Global Navigation Satellite ◽  
The Impact

Abstract Observing system simulation experiments (OSSEs) were conducted to evaluate the potential impact of the six Global Navigation Satellite System (GNSS) radio occultation (RO) receiver satellites in equatorial orbit from the initially proposed Constellation Observing System for Meteorology, Ionosphere, and Climate-2 (COSMIC-2) mission, known as COSMIC-2A. Furthermore, the added value of the high-inclination component of the proposed mission was investigated by considering a few alternative architecture designs, including the originally proposed polar constellation of six satellites (COSMIC-2B), a constellation with a reduced number of RO receiving satellites, and a constellation of six satellites but with fewer observations in the lower troposphere. The 2015 year version of the operational three-dimensional ensemble–variational data assimilation system of the National Centers for Environment Prediction (NCEP) was used to run the OSSEs. Observations were simulated and assimilated using the same methodology and their errors assumed uncorrelated. The largest benefit from the assimilation of COSMIC-2A, with denser equatorial coverage, was to improve tropical winds, and its impact was found to be overall neutral in the extratropics. When soundings from the high-inclination orbit were assimilated in addition to COSMIC-2A, positive benefits were found globally, confirming that a high-inclination orbit constellation of RO receiving satellites is necessary to improve weather forecast skill globally. The largest impact from reducing COSMIC-2B from six to four satellites was to slightly degrade weather forecast skill in the Northern Hemisphere extratropics. The impact of degrading COSMIC-2B to the COSMIC level of accuracy, in terms of penetration into the lower troposphere, was mostly neutral.

scholarly journals Ground Control Point Distribution for Accurate Kilometre-Scale Topographic Mapping Using an RTK-GNSS Unmanned Aerial Vehicle and SfM Photogrammetry

Drones ◽  
2020 ◽  
Vol 4 (3) ◽  
pp. 55 ◽  
Author(s):  
Eilidh Stott ◽  
Richard D. Williams ◽  
Trevor B. Hoey
Keyword(s):  
Low Cost ◽  
Control Point ◽  
Systematic Errors ◽  
Satellite System ◽  
Ground Control ◽  
Check Point ◽  
Point Distribution ◽  
Check Points ◽  
Spatially Distributed ◽  
Global Navigation Satellite

Unmanned Aerial Vehicles (UAVs) have revolutionised the availability of high resolution topographic data in many disciplines due to their relatively low-cost and ease of deployment. Consumer-grade Real Time Kinematic Global Navigation Satellite System (RTK-GNSS) equipped UAVs offer potential to reduce or eliminate ground control points (GCPs) from SfM photogrammetry surveys, removing time-consuming target deployment. Despite this, the removal of ground control can substantially reduce the georeferencing accuracy of SfM photogrammetry outputs. Here, a DJI Phantom 4 RTK UAV is deployed to survey a 2 × 0.5 km reach of the braided River Feshie, Scotland that has local channel-bar relief of c.1 m and median grain size c.60 mm. Five rectangular adjacent blocks were flown, with images collected at 20° from the nadir across a double grid, with strips flown in opposing directions to achieve locally convergent imagery geometry. Check point errors for seven scenarios with varying configurations of GCPs were tested. Results show that, contrary to some published Direct Georeferencing UAV investigations, GCPs are not essential for accurate kilometre-scale topographic modelling. Using no GCPs, 3300 independent spatially-distributed RTK-GNSS surveyed check points have mean z-axis error −0.010 m (RMSE = 0.066 m). Using 5 GCPs gave 0.016 m (RMSE = 0.072 m). Our check point results do not show vertical systematic errors, such as doming, using either 0 or 5 GCPs. However, acquiring spatially distributed independent check points to check for systematic errors is recommended. Our results imply that an RTK-GNSS UAV can produce acceptable errors with no ground control, alongside spatially distributed independent check points, demonstrating that the technique is versatile for rapid kilometre-scale topographic survey in a range of geomorphic environments.

scholarly journals UAV ONBOARD GPS IN POSITIONING DETERMINATION

2016 ◽  
Vol XLI-B1 ◽  
pp. 1037-1042
Author(s):  
K. N. Tahar ◽  
S. S. Kamarudin
Keyword(s):  
Coordinate System ◽  
Global Positioning System ◽  
Large Scale ◽  
Control Point ◽  
Critical Issue ◽  
Ground Control ◽  
Positioning System ◽  
Ground Control Points ◽  
Global Positioning ◽  
Point Positioning

The establishment of ground control points is a critical issue in mapping field, especially for large scale mapping. The fast and rapid technique for ground control point’s establishment is very important for small budget projects. UAV onboard GPS has the ability to determine the point positioning. The objective of this research is to assess the accuracy of unmanned aerial vehicle onboard global positioning system in positioning determination. Therefore, this research used UAV onboard GPS as an alternative to determine the point positioning at the selected area. UAV is one of the powerful tools for data acquisition and it is used in many applications all over the world. This research concentrates on the error contributed from the UAV onboard GPS during observation. There are several points that have been used to study the pattern of positioning error. All errors were analyzed in world geodetic system 84- coordinate system, which is the basic coordinate system used by the global positioning system. Based on this research, the result of UAV onboard GPS positioning could be used in ground control point establishment with the specific error. In conclusion, accurate GCP establishment could be achieved using UAV onboard GPS by applying a specific correction based on this research.

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 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 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.

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