• Journal of Korean Society for Geospatial Information Science
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• v.21 no.2
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• pp.117-123
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• 2013

This study focuses on the determination of optimal photographing angle and overlapping ratio for automatic image stitching system using a non-metric camera module with motorized head. Photographing overlap was calculated considering the angle of view on different kinds of lenses and moving angle of motorized head per each option, and optimal photographing angle and overlapping ratio could be determined through the experimental result using the operating time, data volume and performance of image stitching. Through this experiment, we could find that it was effective to take a picture with $36^{\circ}$ of interval(33.82% of overlap) in vertical direction and $24^{\circ}$ or $30^{\circ}$ of interval(36.51% or 20.63% of overlap) in horizontal direction using 35mm lens for automatic image stitching system.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.38 no.6
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• pp.645-653
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• 2020

Recently studies on how to use the UAV (Unmanned Aerial Vehicle) are actively being conducted, and the National Geographic Information Institute published the 『Work Guidelines for Public Surveying of Unmanned Aerial Vehicles』. However, the guidelines do not provide the optimum shooting conditions required for each application. In this study, we tried to find the suitable shooting conditions for the production of 3D (Three-dimensional) spatial information and orthophoto. To this end, 45 experiments were conducted by various altitudes, overlaps, and camera angles within an above ground level of 150m. For evaluating the 3D modeling by shooting conditions, point densities of 9 verification areas were analyzed, and to evaluate the orthophotos, 1/1,000 digital maps were compared. Considering the quality of the output and the processing time for precise 3D construction, an altitude of 50m, an overlap of 70~80%, and a camera angle of 80~90° are suitable as shooting conditions, and an altitude of 100m and camera angle of 80~90° are suitable for orthophoto generation.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.6 no.2
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• pp.10-18
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• 1988

In the three-dimensional analysis and deformation analysis of large structures, efficient is the use of the multiple method of close range photogrammetry which approaches the object distance. This study analyzes the influence of errors according to the overlap, the control points, and the object distance, to solve the problems which are raised in the multiple method. A wall-board, 7 meters by 3 meters, was used as a test field on which a total of 225 unknown points were equally disposed. The photographs with changing the overlap and object distance were taken by P-31 camera system. a total of 143 negatives are used in this study for computing 3-dimensional coordinates and its standard errors, and bundle adjustment of strips and blocks developed with on-line system is applied. In case of decreasing the number of control points, simulation error increases but actual error decreases and increases again. Due to the changed of object distances Z error represents largely compared to X, Y error, but good results in Z can be obtained by increasing the redundancy. And simulation error or actual error shows best results at the endlap of about 70%. To sum up this study, approprate arrangement of control points and overlap is meaningful, and multiple method by short object distance will be widely used to precision and deformation analysis of critical structures.

• Proceedings of the Korea Contents Association Conference
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• 2018.05a
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• pp.117-118
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• 2018

드론의 활용은 점점 더 다양해지며 소규모지역에 대한 정밀 지도제작방법으로 자리매김하고 있다. 그러나, 결과물의 요구정확도의 예측이 불가능하므로 종종 촬영계획을 수정하여 재촬영할 경우가 종종있다. 촬영지역의 면적, 기준점 수 및 배치, 촬영고도 및 중복도에 대한 다양한 정확도 분석이 이루어진다면 사전 시뮬레이션을 통하여 원하는 정확도의 결과물을 얻을 수 있다. 본 연구에서는 드론측량 시 정확도에 영향을 주는 다양한 요소들을 추출하고 정확도 분석을 위한 테스트필드를 설계하고자 한다.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2009.04a
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• pp.91-94
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• 2009

The Aerial photographic mission is working of taking picture at appropriate point at operating aircraft. Specially, because multi-looking camera system for 3D spatial data construction don't use large size CCD camera, do use middle size or small size CCD camera, Exterior parameter can't be calculated because of not enough overlap, if taking picture at inappropriate position. Therefore, we can construct 3D spatial modeling data by taking picture at planned points using GPS Positioning information

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2010.04a
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• pp.53-56
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• 2010

An aerial multi-looking camera system equips itself with five separate cameras which enables acquiring one vertical image and four oblique images at the same time. This provides diverse information about the site compared to aerial photographs vertically. However, multi-looking Aerial Camera for building a 3D spatial information don't use a large-size CCD camera, do uses a medium-size CCD camera, if acquiring forward, backward, left and right imagery of Certain objects, Aerial photographing set overlap and sidelap must be considered. Especially, Sideward-looking camera set up by the sidelap to determine whether a particular object can be acquisition Through our research we analyzed of sideward footprint and aerial photographing efficiency of Multi-view imagery by sidelap changing.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 2008.10a
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• pp.358-363
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• 2008

최근 아날로그 항공사진카메라는 디지털방식으로 급속히 변화하고 있어 이에 따른 다양한 실험연구가 수행되고 있다. 디지털 카메라는 CCD의 구조와 촬영방식에 따라 크게 면형방식(area array)과 선형방식(line array)으로 구분되며 기술적으로 서로 상이한 원리로 영상을 취득하고 있다. 본 논문에서는 블록 조정에 횡스트립을 추가하여 블록 조정하였을 때 안정성에 얼마나 큰 영향이 있는지 알아보았다. 본 논문은 촬영시 추가한 횡스트립이 블록기하의 안정성에 미치는 영향을 검증하기 위하여 블록조정 결과에 따른 외부표정요소의 정확도를 비교 분석하였다. 연구결과 횡스트립을 추가하였을 때는 외부표정요소의 정확도가 크게 향상됨을 알 수 있었다. 향후 디지털 카메라에 의한 촬영시 적절한 중복도와 횡스트립의 배치간격 등에 대한 연구가 계속해서 이루어져야 될 것으로 판단된다.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.40 no.2
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• pp.69-77
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• 2022

The 3D spatial model is an analysis framework for solving urban problems and is used in various fields such as urban planning, environment, land and housing management, and disaster simulation. The utilization of drones that can capture 3D images in a short time at a low cost is increasing for the construction of 3D spatial model. In terms of building a virtual city and utilizing simulation modules, high location accuracy of aerial survey and precision of 3D spatial model function as important factors, so a method to increase the accuracy has been proposed. This study analyzed location accuracy of aerial survey and precision of 3D spatial model by each condition of aerial survey for urban areas where buildings are densely located. We selected Daerim 2-dong, Yeongdeungpo-gu, Seoul as a target area and applied shooting angle, shooting altitude, and overlap rate as conditions for the aerial survey. In this study, we calculated the location accuracy of aerial survey by analyzing the difference between an actual survey value of CPs and a predicted value of 3D spatial Model. Also, We calculated the precision of 3D spatial Model by analyzing the difference between the position of Point cloud and the 3D spatial Model (3D Mesh). As a result of this study, the location accuracy tended to be high at a relatively high rate of overlap, but the higher the rate of overlap, the lower the precision of 3D spatial model and the higher the shooting angle, the higher precision. Also, there was no significant relationship with precision. In terms of baseline-height ratio, the precision tended to be improved as the baseline-height ratio increased.

• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.346-346
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• 2020

홍수기 효과적인 하천관리를 위해서는 광역 모니터링을 위한 기술 확보가 매우 중요하며, 최근 드론을 활용한 하천 모니터링에 관한 관심이 점차 증가되고 있다. 하천관리에 필요한 드론 탑재용 센서는 기본적으로 RGB 광학센서를 비롯하여 근적외선(Nir) 및 열적외선 센서가 함께 운용되는 것이 효과적이다. 그러나 현재 판매되는 드론 카메라를 살펴보면 근적외선과 열적외선 센서가 별도로 분리되어 있고 광학센서에 비해 상대적으로 매우 고가로 판매되고 있는 실정이다. 따라서 하천 모니터링을 위해서는 광학(RGB), 근적외선 그리고 열적외선 센서가 통합된 저가의 탑재체 개발이 시급하고 이를 활용한 하천 모니터링 프로세스를 정립할 필요가 있다. 본 연구에서는 일반 드론에 쉽게 탑재 가능한 하천 모니터링용 탑재체를 개발하였으며, 이를 기반으로 하천 홍수 및 부유사 모니터링에 활용하였다. 광학센서는 하천의 주요 형상을 확인하는데 이용하였으며, 근적외선 센서는 홍수 및 부유사 탐지에 활용하였다. 특히 본 연구에서는 비교적 넓은 하천 구역에 대한 공간정보를 구축하기 위해 75% 이상의 중복도를 가지고 촬영하도록 세팅하였으며 영상접합 SW를 활용하여 정사영상을 생성하였다. 구축한 근적외선 정사영상으로부터 영상분석 프로그램을 활용하여 홍수 및 부유사 영역을 추출하였으며 이를 통해 홍수기 하천 모니터링 및 치수 업무 의사결정을 위한 정보를 제공할 수 있었다. 저가용 드론 센서는 상용 SW와의 연계가 어렵기 때문에 자동비행 프로그램처럼 해당 위치별 영상 촬영이 어려운 한계가 있었으며, 본 연구에서는 센서의 제원특성을 활용하여 자동비행 SW에서도 일정 이상의 중복도를 확보할 수 있는 비행고도별 촬영시간 등을 종합적으로 설계하였다. 이를 통해 해당 지역에 대한 하천 모니터링용 정사영상을 구축할 수 있었으며 기존의 고가용 드론 센서와 유사한 효과를 가져올 수 있었다.

• Journal of Korean Society for Geospatial Information Science
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• v.24 no.3
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• pp.3-9
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• 2016

UAV(unmanned aerial vehicle) can quickly produce orthoimage with high-spatial resolution and DSM(digital surface model) at low cost. However, vertical and horizontal positioning accuracy of orthoimage and DSM, which are obtained by UAV, are influenced by image processing techniques, quality of aerial photo, the number and position of GCPs(ground control points) and overlap in flight plan. In this study, effects of overlap and the number of GCPs are analyzed in orthoimage and DSM. Positioning accuracy are estimated based on RMSE(root mean square error) by using dataset of nine pairs. In the experiments, Overlaps and the number of GCPs have influence on horizontal and vertical accuracy of orthoimage and DSM.