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

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.

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

ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ◽

10.5194/isprs-archives-xliii-b1-2020-507-2020 ◽

2020 ◽

Vol XLIII-B1-2020 ◽

pp. 507-514 ◽

Cited By ~ 2

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?

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DIRECTIONS OF LINE CONSTRAINTS DILEMMA IN PARAMETRIC LINEAR REGRESSION

Journal of Southwest Jiaotong University ◽

10.35741/issn.0258-2724.56.5.50 ◽

2021 ◽

Vol 56 (5) ◽

pp. 552-562

Author(s):

Mohd Azwan Abbas ◽

Norshahrizan Mohd Hashim ◽

Mohamad Faiz Mohd Zaim ◽

Muhammad Husaini Ya’cob ◽

Ahmad Azmi Hashim ◽

...

Keyword(s):

Linear Regression ◽

Satellite System ◽

Control Points ◽

Process Data ◽

Network Adjustment ◽

Positional Accuracy ◽

Rigorous Approach ◽

Adjustment Procedure ◽

Global Navigation Satellite

The demand for positional accuracy and multi-dimensional data have demonstrated drastic changes in the geomatics data adjustment approach. Furthermore, the capability of modern sensors to provide high accuracy data (i.e., global navigation satellite system) has caused the crucial requirement for a rigorous adjustment that can process data from multi-sensors. Geomatics practitioners have gradually transformed the adjustment procedure to the most rigorous approach (i.e., parametric linear regression) to adapt to current demand. However, legacy datasets that utilize independent line constraint in the traditional adjustment approach have caused significant uncertainties in parametric linear regression (LR) adjustment. To resolve this dilemma, this research has designed robust experiments using closed traverse types: single-line constraint, multi-line constraints, and sub-network line constraint. Through errors trend and network form deterioration analyses, the outcomes have visually and numerically verified the insignificant of independent line constraints in parametric LR. However, the establishment of control points at the beginning or end of lines could solve the limitation of the abovementioned issue. In both analyses, control points at initial lines have demonstrated the best solution for constrained adjustment. The obtained results have exemplified the appropriate implementation of network adjustment in the presence of line constraints. As positional accuracy becomes the main priority, it can be concluded that points-based constraints are more advisable in preserving the quality of cadastral network adjustment.

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

Sensors ◽

10.3390/s20082318 ◽

2020 ◽

Vol 20 (8) ◽

pp. 2318 ◽

Cited By ~ 5

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.

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Geometric Accuracy of 3D Reality Mesh Utilization for BIM-Based Earthwork Quantity Estimation Workflows

ISPRS International Journal of Geo-Information ◽

10.3390/ijgi10060399 ◽

2021 ◽

Vol 10 (6) ◽

pp. 399

Author(s):

Paulius Kavaliauskas ◽

Daumantas Židanavičius ◽

Andrius Jurelionis

Keyword(s):

Process Management ◽

Satellite System ◽

Control Points ◽

Ground Sample ◽

Ground Control Points ◽

Volume Measurements ◽

Efficient Construction ◽

Global Navigation Satellite ◽

The Relationship ◽

Efficiency And Reliability

Current surveying techniques are typically applied to survey the as-is condition of buildings, brownfield sites and infrastructure prior to design. However, within the past decade, these techniques evolved significantly, and their applications can be enhanced by adopting unmanned aerial vehicles (UAVs) for data acquisition, up-to-date software for creating 3D reality mesh, which in turn opens new possibilities for much more efficient construction site surveying and constant updating and process management. In this study the workflows of three UAV-based photogrammetry techniques: Real Time Kinematic (RTK), Post-Processing Kinematic (PPK) and Global Positioning System (GPS) based on control points were analyzed, described, and compared to conventional surveying method with Global Navigation Satellite System (GNSS) receiver. Tests were performed under realistic conditions in 36 ha quarry in Lithuania. The results of the relationship between ground sample distance (GSD) and the comparison of volume measurements under each technique, including conventional method were analyzed. The deviation of data collected on field vs. generated in reality mesh, including ground control points (GCPs) and check points (CHPs) with different configurations, was investigated. The research provides observations on each workflow in the terms of efficiency and reliability for earthwork quantity estimations and explains processing schemes with advanced commercial software tools.

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TLS MODELS GENERATION ASSISTED BY UAV SURVEY

ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ◽

10.5194/isprsarchives-xli-b5-413-2016 ◽

2016 ◽

Vol XLI-B5 ◽

pp. 413-420 ◽

Cited By ~ 3

Author(s):

F. Chiabrando ◽

V. Di Pietra ◽

A. Lingua ◽

P. Maschio ◽

F. Noardo ◽

...

Keyword(s):

Laser Scanning ◽

Large Scale ◽

Control Points ◽

Survey Techniques ◽

Multi Scale ◽

Ground Control Points ◽

Initial Stage ◽

Registration Number ◽

Aerial Vehicle ◽

Gps Rtk

(TLS, Terrestrial Laser Scanning), and large scale mapping derived by UAV (Unmanned Aerial Vehicle) survey. This paper refers an example of 3D survey and reality based modelling applied on landscape and architectural assets. The choice of methods for documentation, in terms of survey techniques, depends primarily on issues and features of the area. <br><br> The achieved experience, allow to consider that the easy handling of TLS has enabled the use in limited spaces among buildings and collapsed roofs, but the topographic measure of GCPs (Ground Control Points), neither by total station nor by GPS/RTK technique, was easily feasible. Even more than proving the ability of the integration of TLS and UAV photogrammetry to achieve a multi-source and multi-scale whole model of a village, the experience has been a test to experiment the registration of terrestrial clouds with the support of control points derived by UAV survey and finally, a comparison among different strategies of clouds registration is reported. Analysing for each approach a number of parameters (number of clouds registration, number of needed points, processing time, overall accuracy) the further comparisons have been achieved. <br><br> The test revealed that it is possible to decrease the large number of terrestrial control points when their determination by topographical measures is difficult, and it is possible to combine the techniques not only for the integration of the final 3Dmodel, but also to solve and make the initial stage of the drafting process more effective.

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THEORETICAL ANALYSIS OF POSITIONAL UNCERTAINTY IN DIRECT GEOREFERENCING

ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ◽

10.5194/isprs-archives-xli-b1-1221-2016 ◽

2016 ◽

Vol XLI-B1 ◽

pp. 1221-1226

Author(s):

Ali Coskun Kiraci ◽

Gonul Toz

Keyword(s):

Graphical User Interface ◽

Inertial Navigation System ◽

Satellite System ◽

Ground Control ◽

Control Points ◽

Positional Uncertainty ◽

Ground Control Points ◽

Field Works ◽

Global Navigation Satellite ◽

Orientation Parameters

GNSS/INS system composed of Global Navigation Satellite System and Inertial Navigation System together can provide orientation parameters directly by the observations collected during the flight. Thus orientation parameters can be obtained by GNSS/INS integration process without any need for aero triangulation after the flight. In general, positional uncertainty can be estimated with known coordinates of Ground Control Points (GCP) which require field works such as marker construction and GNSS measurement leading additional cost to the project. Here the question arises what should be the theoretical uncertainty of point coordinates depending on the uncertainties of orientation parameters. In this study the contribution of each orientation parameter on positional uncertainty is examined and theoretical positional uncertainty is computed without GCP measurement for direct georeferencing using a graphical user interface developed in MATLAB.

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TLS MODELS GENERATION ASSISTED BY UAV SURVEY

ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ◽

10.5194/isprs-archives-xli-b5-413-2016 ◽

2016 ◽

Vol XLI-B5 ◽

pp. 413-420 ◽

Cited By ~ 1

Author(s):

F. Chiabrando ◽

V. Di Pietra ◽

A. Lingua ◽

P. Maschio ◽

F. Noardo ◽

...

Keyword(s):

Laser Scanning ◽

Large Scale ◽

Control Points ◽

Survey Techniques ◽

Multi Scale ◽

Ground Control Points ◽

Initial Stage ◽

Registration Number ◽

Aerial Vehicle ◽

Gps Rtk

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Performance of UAV-Based Digital Orthophoto Generation for Emergency Response Applications

TEM Journal ◽

10.18421/tem104-31 ◽

2021 ◽

pp. 1721-1727

Author(s):

Burak Akpınar

Keyword(s):

Emergency Response ◽

Satellite System ◽

Ground Control ◽

Control Points ◽

Earthquake Hazards ◽

Emergency Situations ◽

Ground Control Points ◽

Digital Orthophoto ◽

Global Navigation Satellite ◽

Gnss Observations

Unmanned Aerial Vehicles (UAVs) have been used for accurate orthophoto generation based on advanced Global Navigation Satellite System (GNSS) techniques. In recent years, the UAV systems have become an effective tool for fast monitoring of damages caused by disasters such as the earthquake hazards. The conventional orthophoto generation based on ground control points takes too much time during emergency situations. In the study, different methodologies for the processing of the acquired GNSS Positioning data for direct georeferencing of UAVs were investigated in terms of various orbit products. Evaluating the fitness for emergency response applications, the ground control points (GCPs) also used for validation of the generated orthophoto without using GCPs and based on Precise Point Positioning (PPP) approach. In this study, Ultra-Rapid, Rapid and Final PPP methods based on GNSS observations were used for direct geo-referencing. Thirteen GCPs were located at the study area for the validation of the orthophoto accuracy generated by direct geo-referencing.

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Inventory of Locations of Old Mining Works Using LiDAR Data: A Case Study in Slovakia

Sustainability ◽

10.3390/su13126981 ◽

2021 ◽

Vol 13 (12) ◽

pp. 6981

Author(s):

Marcela Bindzarova Gergelova ◽

Slavomir Labant ◽

Jozef Mizak ◽

Pavel Sustek ◽

Lubomir Leicher

Keyword(s):

Satellite System ◽

Precise Determination ◽

Lidar Data ◽

Positional Accuracy ◽

Current Form ◽

Mining History ◽

Mining Works ◽

Gnss Measurements ◽

Global Navigation Satellite

The concept of further sustainable development in the area of administration of the register of old mining works and recent mining works in Slovakia requires precise determination of the locations of the objects that constitute it. The objects in this register have their uniqueness linked with the history of mining in Slovakia. The state of positional accuracy in the registration of objects in its current form is unsatisfactory. Different database sources containing the locations of the old mining works are insufficient and show significant locational deviations. For this reason, it is necessary to precisely locate old mining works using modern measuring technologies. The most effective approach to solving this problem is the use of LiDAR data, which at the same time allow determining the position and above-ground shape of old mining works. Two localities with significant mining history were selected for this case study. Positional deviations in the location of old mining works among the selected data were determined from the register of old mining works in Slovakia, global navigation satellite system (GNSS) measurements, multidirectional hill-shading using LiDAR, and accessible data from the open street map. To compare the positions of identical old mining works from the selected database sources, we established differences in the coordinates (ΔX, ΔY) and calculated the positional deviations of the same objects. The average positional deviation in the total count of nineteen objects comparing documents, LiDAR data, and the register was 33.6 m. Comparing the locations of twelve old mining works between the LiDAR data and the open street map, the average positional deviation was 16.3 m. Between the data sources from GNSS and the registry of old mining works, the average positional deviation of four selected objects was 39.17 m.

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TDMA Datalink Cooperative Navigation Algorithm Based on INS/JTIDS/BA

Electronics ◽

10.3390/electronics10070782 ◽

2021 ◽

Vol 10 (7) ◽

pp. 782

Author(s):

Shuo Cao ◽

Honglei Qin ◽

Li Cong ◽

Yingtao Huang

Keyword(s):

Distribution System ◽

Large Scale ◽

Satellite System ◽

Time Of Arrival ◽

Military Operations ◽

Position Information ◽

Cooperative Navigation ◽

Navigation Algorithm ◽

Geometric Dilution Of Precision ◽

Global Navigation Satellite

Position information is very important tactical information in large-scale joint military operations. Positioning with datalink time of arrival (TOA) measurements is a primary choice when a global navigation satellite system (GNSS) is not available, datalink members are randomly distributed, only estimates with measurements between navigation sources and positioning users may lead to a unsatisfactory accuracy, and positioning geometry of altitude is poor. A time division multiple address (TDMA) datalink cooperative navigation algorithm based on INS/JTIDS/BA is presented in this paper. The proposed algorithm is used to revise the errors of the inertial navigation system (INS), clock bias is calibrated via round-trip timing (RTT), and altitude is located with height filter. The TDMA datalink cooperative navigation algorithm estimate errors are stated with general navigation measurements, cooperative navigation measurements, and predicted states. Weighted horizontal geometric dilution of precision (WHDOP) of the proposed algorithm and the effect of the cooperative measurements on positioning accuracy is analyzed in theory. We simulate a joint tactical information distribution system (JTIDS) network with multiple members to evaluate the performance of the proposed algorithm. The simulation results show that compared to an extended Kalman filter (EKF) that processes TOA measurements sequentially and a TDMA datalink navigation algorithm without cooperative measurements, the TDMA datalink cooperative navigation algorithm performs better.

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