• Korean Journal of Remote Sensing
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• v.37 no.5_1
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• pp.1071-1081
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• 2021

Remote Sensing using unmanned aerial vehicles(UAV) can acquire images with higher time resolution and spatial resolution than aerial and satellite remote sensing. However, UAV images are photographed at low altitude and the area covered by one image isrelatively narrow. Therefore multiple images must be processed to monitor large area. Since UAV images are photographed under different exposure conditions, there is difference in brightness values between adjacent images. When images are mosaicked, unnatural seamlines are generated because of the brightness difference. Therefore, in order to generate seamless mosaic image, a radiometric processing for correcting difference in brightness value between images is essential. This paper proposes a relative radiometric calibration and image blending technique. In order to analyze performance of the proposed method, mosaic images of UAV images in agricultural and mountainous areas were generated. As a result, mosaic images with mean brightness difference of 5 and root mean square difference of 7 were avchieved.

• Proceedings of the Korea Water Resources Association Conference
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• 2016.05a
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• pp.249-249
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• 2016

무인항공기(UAV)는 군사적 목적으로 개발되었지만, 최근 다양한 분야에서 활용되고 있다. 수자원 관리를 위해서도 시대적 흐름에 따라 드론과 관련된 많은 연구가 진행되고 있다. 이수임 등(2015)은 UAV영상을 활용한 수변구조물의 DSM 생성 및 정확도 연구를 통해 지상 LIDAR와 같은 수준의 DSM 및 더욱 정확한 GCP 취득의 필요성을 제시했다. 이용창(2015)은 회전익 UAS 영상기반 고밀도 측점자료의 위치 정확도를 평가하였다. 이인수 등(2013)은 초경량 고정익무인항공기 사진측량기법의 정사영상 정확도 평가를 수행하였다. 또한 김민규 등(2010)은 풍수해 모니터링을 위한 UAV 적용성 분석을 실시하였고, 김홍래 등(2014)은 UAV를 활용한 감시정보정찰 임무분석 및 설계도구 개발을 위한 연구를 수행하였다. 상기와 같이 수자원 분야 활용을 위한 많은 연구가 보고 되고 있으나, 아직까지 드론 활용의 대부분은 항공영상 취득 및 분석기술 개발에 집중되어 있다. 본 연구에서는 무인항공기를 수재해 감시 및 관리 기술에 적용하기 위해 수행되었다. 수재해 감시 및 관리를 위한 방법으로 NIR(Near Infrared) 센서를 부착한 '재해관리용 드론'을 개발하고 현장실험을 수행하였다. 실험결과 NIR센서를 탑재한 드론은 수재해 관리에 매우 유용하게 활용될 수 있을 것으로 판단되었다.

• Journal of Aerospace System Engineering
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• v.17 no.6
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• pp.9-15
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• 2023

In order to effectively prevent and respond to disasters, several techniques have been developed in which the pilot wearing a see-through Head Mounted Display (HMD) performs disaster-related rescue activities using images transmitted from an Unmanned Aerial Vehicle (UAV). However, these techniques have limitations in quickly determining and executing tasks appropriate to the on-site situation because the pilot cannot recognize the entire field in an integrated manner. In order to overcome these problems, we propose an AR based-interface technique that allows the rescuer wearing a see-through HMD to operate a UAV efficiently. Simulation results show that the proposed interface technique allows the rescuer wearing a see-through HMD to control the gimbal and flight of the UAV at a high speed based on finger gestures in a visibility situation.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.47 no.6
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• pp.10-18
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• 2010

This paper proposes an image stabilization algorithm for close watching UAV(Unmanned Aerial Vehicle) using motion separation and stabilization mode. The motion of UAV is composed of its actual navigating motion and unwanted vibrating motion so that image sequences obtained from UAV are shaken randomly. In order to stabilize these images we separate the vibrating motion component from UAV motion and remove the effect caused by it from image sequences. In the proposed algorithm the motion and global intensity change of two consecutive images are modeled with 6 motion parameters and 2 intensity change parameters respectively. These modeled parameters are estimated by non-linear least square method based on Gauss-Newton algorithm. The vibrating motion component is separated from the estimated motion using IIR filtering and the geometric deformation caused by it is removed from image sequences. In order to apply the proposed method to real aerial image sequences with many abrupt changes of camera view, we proposed a stabilizing method using two different modes named as stabilizing and non-stabilizing mode. Experimental results show that the accuracy of motion estimation is 99% and the efficiency of removing the vibrating motion component is 90%. We apply the proposed method to real aerial image sequences and verified its stabilizing performance.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.12
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• pp.1115-1123
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• 2011

This paper proposes an image processing algorithms for detection and tracking of aerial vehicles in short-range. Proposed algorithm detects moving objects by using image homography calculated from consecutive video frames and determines whether the detected objects are approaching aerial vehicles by the Probabilistic Multi-Hypothesis Tracking method(PMHT). This algorithm can perform better than simple color-based detection methods since it can detect moving objects under complex background such as the ground seen during low altitude flight and consider the characteristics of vehicle dynamics. Furthermore, it is effective for the flight test due to the reduction of thresholding sensitivity against external factors. The performance of proposed algorithm is verified by applying to the onboard video obtained by flight test.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.6
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• pp.600-607
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• 2008

Reliable wireless transmission of data generated by the flight critical subsystems or mission equipments of the unmanned aerial system is critical for mission success. As the UAS system becomes more sophisticated, its dependency on a reliable high rate radio communication system also increases. This requirement is applied not only during the operation phase but also in the early development test phase. This paper introduces a practical cost-effective communication system for a UAS. The downlink module combines analog NTSC video signal with onboard data, and send them using 2.4 GHz carrier wave. The uplink system has less a severe requirement on the bandwidth, and thus uses 430 MHz signal. This paper also presents a sample packet structure which can be adopted for many UAS of similar class.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.10
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• pp.893-901
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• 2014

UAS and related technology have been mainly developed for military use but, in recent years, various types of civil UAS have been using in a variety of applications. For example, there are multicopters to shoot aerial photography, pesticide spraying unmanned helicopter, and in addition there are radio control (R/C) aircraft to be used for hobbyists. UAV has spread rapidly enough that permitted experts as well as the public can use it but the related safety regulations are not properly equipped. We investigated the status of domestic and international UAS certification system and airworthiness standards. And the trends in research for the development and modification of the certification system were studied in this paper. As a result, most countries have studied to develop the related regulations and especially ICAO has tried to develop RPAS manual, standards and recommended plans and modify the related ICAO annex through the research group, ICAO UASSG. Based on the manual and SARPs, authorities, related organizations and companies have prepared to develop and modify regulations in accordance with the actual situation of each country.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.6
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• pp.594-599
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• 2008

Image data produced from ADD water-tunnel test are currently analyzed manually. The accuracy and elapsed time of this process can be determined by observers. In this paper, the algorithm based on MATLAB for improved image data processing and analysis is proposed. This algorithm consists of camera calibration, gray-level transformation, noise filtering and binarization in image preprocessing, vortex trajectory measurement in image analysis. Experimental results show that the proposed algorithm has better accuracy and execution speed than those of the existing methods.

• Journal of Advanced Navigation Technology
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• v.25 no.6
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• pp.485-492
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• 2021

Vision-based autonomous precision landing technology for UAVs requires precise position estimation and landing guidance technology. Also, for safe landing, it must be designed to determine the safety of the landing point against ground obstacles and to guide the landing only when the safety is ensured. In this paper, we proposes vision-based navigation, and algorithms for determining the safety of landing point to perform autonomous precision landings. To perform vision-based navigation, CNN technology is used to detect landing pad and the detection information is used to derive an integrated navigation solution. In addition, design and apply Kalman filters to improve position estimation performance. In order to determine the safety of the landing point, we perform the obstacle detection and position estimation in the same manner, and estimate the speed of the obstacle using LSM. The collision or not with the obstacle is determined based on the CPA calculated by using the estimated state of the obstacle. Finally, we perform flight test to verify the proposed algorithm.

• Journal of Digital Convergence
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• v.17 no.2
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• pp.201-206
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• 2019

Korea is constructing geospatial information application system for geospatial information utilization, but it is trying to establish a system for joint use of geospatial information system centering on Ministry of Land Transport and Transport due to the problem of sharing. The purpose of this study is to investigate and analyze the geospatial information application system operated by local governments, and to suggest the application of geospatial information application system using unmanned aerial images. As a result of the research, it was found that the functions of existing spatial information application system are concentrated on the public services and it is difficult to share and utilize data between administrative departments. In addition, the utilization of the system using unmanned aerial image has been suggested, and additional functions such as vector display, area calculation, and report generation have been derived to improve the usability of geospatial information application system. If additional functions of spatial information application system are added through further studies in the future, it will be possible to use it as a basic data of field survey and policy decision in related fields. And non-experts will be able to improve the efficiency of work by utilizing highly accurate geospatial information in various fields.