The Direct Georeferencing Application and Performance Analysis of Uav Helicopter in GCP-Free Area

Lo, Cheng Fang; Tsai, Meng Lun; Chiang, Kai-Wei; Chu, Chih‐Ping; Tsai, Guang-Je; Cheng, Chaoyi; El‐Sheimy, Naser; Ayman, Hussein

doi:10.5194/isprsarchives-xl-1-w4-151-2015

Cited by 17 publications

(14 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…In this case, the orthophoto accuracy of 11 cm (mean) was reached. The differential GNSS receiver was further employed by Lo et al (2015); the approach enables carrier phase measurement, but the reached object accuracy is in the order of meters when flying at 100 m AGL. Contrariwise, the superior ground accuracy values of 0.9, 0.6, and 0.9 cm RMS for the X, Y , and Z axes, respectively, are presented in a relevant study by Eling et al (2015).…”

Section: Introductionmentioning

confidence: 99%

Calibration and accuracy assessment in a direct georeferencing system for UAS photogrammetry

Gábrlík

Cour-Harbo

Kalvodova

et al. 2018

International Journal of Remote Sensing

View full text Add to dashboard Cite

Unmanned aerial systems (UAS) have already proven useful in fields and disciplines such as agriculture, forestry, or environmental mapping, and they have also found application during natural and nuclear disasters. In many cases, the environment is inaccessible or dangerous for a human being, meaning that the widely used technique of aerial imagery georeferencing via ground control points cannot be employed. The present paper introduces a custom-built multi-sensor system for direct georeferencing, a concept that enables georeferencing to be performed without an access to the mapping area and ensures centimetre-level object accuracy. The proposed system comprises leading navigation system technologies in the weight category of micro and light UASs. A highly accurate global navigation satellite system receiver integrating the real time kinematic technology supports an inertial navigation system where data from various sensors are fused. Special attention is paid to the time synchronisation of all sensors, and a method for the field calibration of the system is designed. The multi-sensor system is completely independent of the used UAS.The authors also discuss the verification of the proposed system's performance on a real mission. To make the results credible, a high number of test points are used, with both the direct and the indirect georeferencing techniques subjected to comparison, together with different calibration methods. The achieved spatial object accuracy (about 4 cm RMSE) is sufficient for most applications.

show abstract

Section: Introductionmentioning

confidence: 99%

Calibration and accuracy assessment in a direct georeferencing system for UAS photogrammetry

Gábrlík

Cour-Harbo

Kalvodova

et al. 2018

International Journal of Remote Sensing

View full text Add to dashboard Cite

show abstract

“…The main aim of this paper is that of showing the possibility of obtaining 3D metric reconstruction without using control points from UAV aerial imagery (similarly to direct georeferencing [25,28]), by exploiting a UWB positioning system: the possibility of using UWB positioning when GNSS is not available (e.g., in tunnels, indoors, close to high buildings or mountains, in critical environments) could make it an attractive solution in such operating conditions. UWB ranging characterization of Section 2 shows that the Pozyx UWB system is characterized by a quite complex systematic error (Figure 3).…”

Section: Discussionmentioning

confidence: 99%

“…The use of control points can be extremely useful to improve the reconstruction and georeferencing accuracy of aerial photogrammetry; however, their use is difficult in certain cases, e.g., surveys during natural disasters in areas difficult to reach on the ground. In these cases, Direct Georeferencing (DG) is typically considered instead [25][26][27][28][29][30], i.e., the direct estimation of camera position and orientation with sensors mounted on the UAV (e.g., GNSS and INS). Motivated by the above considerations, DG has attracted the attention of several research groups in the last few years: inexpensive and lightweight sensor solutions are typically considered [25,28], where DG positioning accuracy is usually mainly related to the performance of the consumer-grade GNSS receiver in the integrated Position and orientation System (PoS) (e.g., ∼5 m [6,28]), whereas higher grade GNSS receivers can allow better positioning accuracy [31]).…”

Section: Introductionmentioning

confidence: 99%

A Low Cost UWB Based Solution for Direct Georeferencing UAV Photogrammetry

2017

View full text Add to dashboard Cite

Thanks to their flexibility and availability at reduced costs, Unmanned Aerial Vehicles (UAVs) have been recently used on a wide range of applications and conditions. Among these, they can play an important role in monitoring critical events (e.g., disaster monitoring) when the presence of humans close to the scene shall be avoided for safety reasons, in precision farming and surveying. Despite the very large number of possible applications, their usage is mainly limited by the availability of the Global Navigation Satellite System (GNSS) in the considered environment: indeed, GNSS is of fundamental importance in order to reduce positioning error derived by the drift of (low-cost) Micro-Electro-Mechanical Systems (MEMS) internal sensors. In order to make the usage of UAVs possible even in critical environments (when GNSS is not available or not reliable, e.g., close to mountains or in city centers, close to high buildings), this paper considers the use of a low cost Ultra Wide-Band (UWB) system as the positioning method. Furthermore, assuming the use of a calibrated camera, UWB positioning is exploited to achieve metric reconstruction on a local coordinate system. Once the georeferenced position of at least three points (e.g., positions of three UWB devices) is known, then georeferencing can be obtained, as well. The proposed approach is validated on a specific case study, the reconstruction of the façade of a university building. Average error on 90 check points distributed over the building façade, obtained by georeferencing by means of the georeferenced positions of four UWB devices at fixed positions, is 0.29 m. For comparison, the average error obtained by using four ground control points is 0.18 m.

show abstract

“…Recent advances in a UAV's low cost direct georeferencing utilizing a navigational grade of a GPS/GNSS board mounted on the aerial platform [25] provides additional 3D information about geographical coordinates encoded in an EXIF format [26] on each captured images. This low level accuracy of coordinates in geotagged images gives a baseline vector b between two successive overlapping images.…”

Section: Introductionmentioning

confidence: 99%

A Relative Rotation between Two Overlapping UAV's Images

Tjahjadi

Agust

2018

EECSI

View full text Add to dashboard Cite

In this paper, we study the influence of varying baseline components on the accuracy of a relative rotation between two overlapping aerial images taken form unmanned aerial vehicle (UAV) flight. The case is relevant when mosaicking UAV's aerial images by registering each individual image. Geotagged images facilitated by a navigational grade GPS receiver on board inform the camera position when taking pictures. However, these low accuracies of geographical coordinates encoded in an EXIF format are unreliable to depict baseline vector components between subsequent overlapping images. This research investigates these influences on the stability of rotation elements when the vector components are entered into a standard coplanarity condition equation to determine the relative rotation of the stereo images. Assuming a nadir looking camera on board while the UAV platform is flying at a constant height, the resulted vector directions are utilized to constraint the coplanarity equation. A detailed analysis of each variation is given. Our experiments based on real datasets confirm that the relative rotation between two successive overlapping images is practically unaffected by the accuracy of positioning method. Furthermore, the coplanarity constraint is invariant with respect to a translation along the baseline of the aerial stereo images.

show abstract

The Direct Georeferencing Application and Performance Analysis of Uav Helicopter in GCP-Free Area

Cited by 17 publications

References 8 publications

Calibration and accuracy assessment in a direct georeferencing system for UAS photogrammetry

Calibration and accuracy assessment in a direct georeferencing system for UAS photogrammetry

A Low Cost UWB Based Solution for Direct Georeferencing UAV Photogrammetry

A Relative Rotation between Two Overlapping UAV's Images

Contact Info

Product

Resources

About