• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.37 no.6
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• pp.545-554
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• 2019

This research aims to provide a building area extraction approach over the areas where data acquisition is impossible through field surveying, aerial photography and lidar scanning. Hence, high-resolution satellite images, which have high accessibility over the earth, are utilized for the automated building extraction in this study. 3D point clouds or DSM (Digital Surface Models), derived from the stereo image matching process, provides low quality of building area extraction due to their high level of noises and holes. In this regards, this research proposes a hybrid building area extraction approach which utilizes 3D point clouds (from image matching), and color and linear information (from imagery). First of all, ground and non-ground points are separated from 3D point clouds; then, the initial building hypothesis is extracted from the non-ground points. Secondly, color based building hypothesis is produced by considering the overlapping between the initial building hypothesis and the color segmentation result. Afterwards, line detection and space partitioning results are utilized to acquire the final building areas. The proposed approach shows 98.44% of correctness, 95.05% of completeness, and 1.05m of positional accuracy. Moreover, we see the possibility that the irregular shapes of building areas can be extracted through the proposed approach.

• Journal of the Korean Institute of Landscape Architecture
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• v.19 no.1
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• pp.45-59
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• 1991

본 연구에서는 객관적 환경지표와 그에 대한 인간의 주관적 반응간 의 인과적 관련도의 중요성이 강조된다. 좀 더 구체적으로, 거주자의 주관 적 반응인 주거만족과 객관적 환경지표의 하나인 주거환경유형들(건물유형 과 건물배치유형)과의 인과적 관련도가 본 연구에서 중점적으로 토의된다. 한국의 6개 대단위 공동주택단지가 본 연구의 대상지로 선정되었고, 표본 추출시 건물유형과 건물배치유형을 고려한 다단계 표집방법(multistage sampling)이 사용되었다. 설문면답방법(modified structured survey)에 의해 646명의 처리 가능한 응답이 수거되었다. 인과모형 검증의 첫 단계로서 다 수의 설문문항을 원래 관심있는 소수의 변수로 정선, 추출하기 위한 방법 으로 요인분석이 사용되었다. 요인분석으로부터 정선, 추출된 변수를 이용 해서 본 연구의 가설모형이 정립되고, 그 모형을 검증하기 위한 방법으로 경로분석이 사용되었다. 분석결과를 요약해 볼 때, 건물유형과 건물배치유 형 모두가 거주자의 지각, 인식, 태도 등의 적절한 매개변수들을 통해 거주 자의 주거만족에 유의한 영향을 미치는 것으로 나타났다. 건물유형은 일반 적으로 저층주거에서 고충주거로 바뀌면서, 거주자의 주거만족에 부정적인 영향을 미치고 있음이 확인되었고, 고층주거가 거주자에게 주는 시각적 단 조로움, 과밀감, 그리고 주차장을 포함한 옥외공간 이용상의 불편들과 또 그들로 인한 낮은 안전성 및 경관에 대한 불만족 등이 그 이유로서 밝혀졌 다. 건물배치유형의 경우, U자형의 배치유형이 선형배치유형에 비해 과밀 감 해소, 시각적 명료성 향상, 그리고 옥외공간 이용상의 편리 등 및 또 그 에 따른 경관에 대한 만족의 향상 때문에 거주자의 주거만족을 높이는 데 유리한 것으로 나타났다. 주거와 관련된 설계 및 계획분야를 위한 여러 다 양한 제안들이 본 연구에서 제시되고, 추후 관련 연구들을 위한 가능성들 도 토의되었다. 그 유용성 때문에, 아직 많은 이론적, 방법론적, 그리고 분 석상의 문제에도 불구하고, 객관적 환경지표들과 이용자들의 만족을 포함 한 다양한 주관적 변수들과의 관계를 경험적으로 밝히려는 시도가 계속되 어야 할 것으로 사료된다.

• Spatial Information Research
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• v.7 no.1
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• pp.89-101
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• 1999

This paper represents methods to calculate heights of buildings by estimating their shadow lengths in a single and panchromatic image of the KVR-1000 camera system Shadows are identified Com brightness intensity of each pixel, and their lengths are measured. Two methods are implemented to estimate heights from shadows. One method is to use a ratio of shadow s lengths with respect to heights of reference buildings measured on site. The other method uses sun elevation angles calculated from various camera s parameters at the exposure time. The estimated heights of 20 buildings are compared with heights measured on site, and the RMS errors for each method are 1.70m and 1.75m, respectively. When a resampling method to enhance identification of shadows is used and their lengths are accordingly re-calculated, the estimated errors for each method are significantly reduced to 1.17m and 1.16m, respectively. Meanwhile, effects of land slope on shadows can be hardly obtained unless detailed DTM(digital terrain model) are available, and they introduce additional errors up to 25m.

• The Journal of the Korea Contents Association
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• v.14 no.5
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• pp.425-435
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• 2014

The research for extracting man-made features such as building and road from the aerial photograph or satellite imagery has been performed actively. As lately the resolution of digital aerial photographs was improved, unwanted features(noise) would be often detected. An edge detection algorithm is developed to make up for such a noise problem, make boundaries of wanted objects clear and extract only needed features. The algorithm developed in this research performs separating RGB channels, differencing between channels, transforming in to binary images, excluding noises and restoring shapes, and edge extraction in order. The images to be used for edge detection are prepared through bundle adjustment, DTM extraction, orthorectification and mosaicking. The roof edges of small building on preprocessed digital aerial orthophotos were extracted using the algorithm developed in this study. The validity of the algorithms was proved by comparing edge results of small building extracted in this study with those of conventional methods.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.38 no.3
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• pp.237-246
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• 2020

Recently, as high resolution satellites data have been serviced, frequent DSM (Digital Surface Model) generation over urban areas has been possible. In addition, it is possible to detect changes using a high-resolution DSM at building level such that various methods of building change detection using DSM have been studied. In order to detect building changes using DSM, we need to generate a DSM using a stereo satellite image. The change detection method using D-DSM (Differential DSM) uses the elevation difference between two DSMs of different dates. The D-DSM method has difficulty in applying a precise vertical threshold, because between the two DSMs may have elevation errors. In this study, we focus on the urban structure change detection using D-nDSM (Differential nDSM) based on nDSM (Normalized DSM) that expresses only the height of the structures or buildings without terrain elevation. In addition, we attempted to reduce noise using a morphological filtering. Also, in order to improve the roadside buildings extraction precision, we exploited the urban road network extraction from nDSM. Experiments were conducted for high-resolution stereo satellite images of two periods. The experimental results were compared for D-DSM, D-nDSM, and D-nDSM with road extraction methods. The D-DSM method showed the accuracy of about 30% to 55% depending on the vertical threshold and the D-nDSM approaches achieved 59% and 77.9% without and with the morphological filtering, respectively. Finally, the D-nDSM with the road extraction method showed 87.2% of change detection accuracy.

• Proceedings of the KIEE Conference
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• 2008.10b
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• pp.139-140
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• 2008

지상라이다는 고정도의 3차원 영상을 제공하고 레이저 빔을 현장이나 대상물에 발사하여 짧은 시간에 수백만점의 3차원좌표를 기록할 수 있는 최신 측량장비로서 다양한 응용분야에서 두각을 나타내고 있다. 본 연구에서는 지상라이다를 이용한 건축물의 3자윈 자동 윤곽선 추출을 다룬다. 지상라이다는 건축물의 3차원 윤곽선을 신속하게 추출할 수 있지만 지상기반 시스템이므로 여러 가지 장애물 때문에 건국물의 하단부에서는 추출이 쉽지 않다. 기존 항공라이다를 이용한 알고리즘에서는 사진의 색상차나 모폴로지 특성에 의존하여 범위를 제한하고, 이를 기반으로 윤곽선을 추출하였다. 하지만 지상라이다의 경우 항공라이다에 비해 분해능이 월등히 높다. 또한, 지상라이다는 지상에서 측정하기 때문에 항공라이다에서 어려운 건축물의 측면이나 정면도 윤곽선 추출이 가능하기 때문에 본 논문에서는 사진을 이용하지 않고 전처리를 하지 않은 데이터를 직접 이용하여 건물의 정면 윤곽선을 추출하는 것을 제안한다. 건물의 크기와 데이터 수 즉, 라이다로 측정한 포인트 수를 고려한 효율적인 Decimation방법을 제안하고 또한, Decimation된 데이터이서 지역적으로 제일 큰 값과 작은 값을 찾아낸다. 그 중 많이 벗어난 점을 편차를 이용하여 제거한다. 이렇게 찾아낸 건축물의 외곽점들을 이어 만든 윤곽선을 최종적으로 보간하여 좀 더 현실과 가까운 윤곽선 추출 방법을 제안한다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.37 no.1
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• pp.203-215
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• 2017

Recently, interest in Pedestrian Navigation Service (PNS) is being increased due to the diffusion of smart phone and the improvement of location determination technology and it is efficient to use landmarks in route guidance for pedestrians due to the characteristics of pedestrians' movement and success rate of path finding. Accordingly, researches on extracting landmarks have been progressed. However, preceding researches have a limit that they only considered the difference between buildings and did not consider visual attention of maps in display of PNS. This study improves this problem by defining building attributes as local variable and global variable. Local variables reflect the saliency of buildings by representing the difference between buildings and global variables reflects the visual attention by representing the inherent characteristics of buildings. Also, this study considers the connectivity of network and solves the overlapping problem of landmark candidate groups by network voronoi diagram. To extract landmarks, we defined building attribute data based on preceding researches. Next, we selected a choice point for pedestrians in pedestrian network data, and determined landmark candidate groups at each choice point. Building attribute data were calculated in the extracted landmark candidate groups and finally landmarks were extracted by principal component analysis. We applied the proposed method to a part of Gwanak-gu, Seoul and this study evaluated the extracted landmarks by making a comparison with labels and landmarks used by portal sites such as the NAVER and the DAUM. In conclusion, 132 landmarks (60.3%) among 219 landmarks of the NAVER and the DAUM were extracted by the proposed method and we confirmed that 228 landmarks which there are not labels or landmarks in the NAVER and the DAUM were helpful to determine a change of direction in path finding of local level.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.8
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• pp.3785-3793
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• 2011

The purpose of this study is to devise the overall problems (such as, rights and obligations between users, owners, managers regarding commercial rental buildings, benefit/benefit in return, and the relevant regulations and systems) of the building maintenance system through field surveys, expert interviews, and literature reviews. In this rapidly changing society, there are a huge amount of needs for various reforms which can meet the diversity in each area, so it is greatly important to choose priority for the best improvement for efficient and economic expenses due to limited time, human resources and budgets. In this regard, the study extracted the evaluation elements from the devised problems with the viewpoint of BSC, calculated the weights through application of AHP to the extracted evaluation elements, evaluated the difference between before/after application of weights, and set the status, which makes it possible to realize the effective solutions and the reasonable expenses for all parties. By doing so, it is expected that the building maintenance system which maximizes the value and guarantees the user's convenience with smart functions of the building, will be realized in the near future.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.5
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• pp.3213-3219
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• 2014

Currently, increase of greenhouse gas has had a signigicant impact on climate change in urbanization. As a result, the government has been looking for ways to take advantage of the trees that generate oxygen and reduce carbon dioxide for the prevention of climate change. It is essential to extract individual tree for calculating the amount of carbon dioxide reduction of trees. Aerial LIDAR data have three-dimensional information of building as well as trees as form of point clouds. In this study, automated model was developed to extract individual tree using aerial LIDAR data. For this purpose, we established a methodology for extracting trees and then proceeded the process of developing it as an automated model based on model builder of ArcGIS Software. In order to evaluate the applicability of the developed model, the model was compared with commercial software in study area located in Yongin City. Through the experimental result, the proposed model was extract trees 9.91% higher than commercial software. From this results, it was found that the model effectively extracted trees.

• Korean Journal of Remote Sensing
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• v.33 no.6_2
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• pp.1151-1157
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• 2017

Street Trees is an important object for urban environment improvement. Especially the height of the trees needs to be precisely measured as a factor that greatly influences the removal of air pollutants in the Urban Street Canyons. In this study, we extracted the height of the tree based on the stereo image using the precisely adjusted UAV Images of the target area. The adjustment of UAV image was applied photogrammetric SfM (Structure from motion) based on the collinear condition. We measured the height of the trees on the Street Canyon using stereoscopic vision on stereo plotting system. We also acquired the height of the building adjacent to the street trees and the average height of the road surface was calculated for accurate measurement of the height of each object. Through the visual analysis with the plotting operation system, it was possible to measure height of the tree and to calculate the relative height difference value with building quickly. This means that the height of buildings and trees can be calculated without making a 3D point cloud of UAV and it has the advantage of being able to utilize non-experts. In the future, further studies for semiautomatic/automation of this technique should be performed. The development and research of these technologies is expected to help to understand the current status of environmental policies and roadside trees in urban areas.