• Journal of The Geomorphological Association of Korea
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• v.17 no.1
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• pp.73-84
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• 2010

This paper is to analyze effectiveness and efficiency of topographic features in visibility analysis. For this research aim, this paper compares the analysis results of topographic features and relationships between topographic features and their visibility analysis on surfaces. This paper employs peak, pass, pit, ridge and valley features from the topographic features for which five areas including mountain and plain areas in Britain are selected and their DEM data are generated. The summaries of the analysis results are as follows: Firstly, it is clear that relationship between high elevation points and their visibility is not highly correlated. This means that highly elevated points are not necessarily better visible areas and they are not suitable for searching for large visible areas. Secondly, the positions that can see large visible areas are highly correlated with their elevation and are distributed within a certain range which has small deviation of their correlation between visibility and elevation. This means that to search for large visible areas, it is necessary to employ the positions located at relatively high elevation area. Thirdly, for all of the five areas, the visibility results of the topographic features are compared with maximal visibility resulted from a while surface areas, and it is identified that topographic features show similar visibility performances of that maximal visibility. From the results stated above, it can be inferred that topographic features and its topographic characteristics are enable to be a research motivation to the visibility analysis topics. Furthermore, the results of this paper can be contributed to explore suitable variables and factors for solving multiple viewshed problems.

• The Journal of the Korea Contents Association
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• v.12 no.12
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• pp.787-796
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• 2012

This study, as a purpose of viewshed anaiysis is selected for the view route, View of the target yunseondo wonlim (scenic sites No.34) located in the terrain ridge. Using GIS Viewshed analysis carried out and the results reflect the view route was selected. The basic research for this study, the scenic sites such as the natural and cultural resources for the efficient and optimized to create the route view. Viewshed Analysis results could be summarized as follows: Along a scenic sites located inside the main ridge Viewshed analysis was carried out. This overlapping the cumulative results are Leading to Nakseojae(樂書齎) Seyeonjeong(洗然亭) from space in the visible frequency higher natural villages of the district. Selected the view route and were on the road and in the topographic map nesting along Visible high-frequency region. Based on the results of the nested Viewshed major selected six points Viewshed analysis was carried out. Resource for the surrounding landscape. Results determine whether the visibility of the surrounding landscape was identified as the viewable area appears good. Finally Viewshed Analysis results for six points in the final review.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.36 no.1
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• pp.97-108
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• 2018

The purpose of this study is to propose the construction of a visibility analysis model, which is the basis of the analysis for landscape management on the heritage sites such as historic villages and scenic sites. Results of the visibility analysis using DEM and the visibility analysis of DSM based on 3D mapping data are compared as follows: Precision level of the extracted data was confirmed to be less than 6.5cm, based on RTK survey results produced by constructing orthoimage data and DSM from the digital data of 2cm-class GSD(Ground Sample Distance) obtained by using a small UAV(Unmanned Aerial Vehicle). As a result of comparing the visibility analysis data of Digital Surface Model (DSM) using a small UAV with Digital Elevation Model(DEM) applying the height of the building to the Digital Topographic Map, it was confirmed that more realistic visibility analysis can be accomplished by applying DSM, as the structures such as fences, trees, and houses are reflected in the topographic data. The visibility analysis model using the 3D mapping technique can efficiently obtain the constantly changing topographic information when needed, by immediately constructing the data by utilizing a small UAV. It seems to be possible to propose a reasonable analysis result for preservation management such as landscape evaluation of cultural property.

• Proceedings of the Korea Contents Association Conference
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• 2012.05a
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• pp.137-138
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• 2012

현재 GIS의 수치화된 지형정보(DEM, TIN)를 기반으로 하는 가시권분석 방법은 현재 택지개발, 산불예방, 도시계획, 경관계획 등의 여러 분야에서 광범위하고 보편적으로 사용되고 있는바, 본 연구에서는 명승지 내부의 경로를 따라 예비조망점을 설정하고 GIS가시권 분석 후 현장검토를 함으로써 GIS가시권분석을 이용한 조망점 선정의 유용성 여부를 분석하였다. 분석결과 명승지내의 옛길에 대한 가시권분석결과와 현지검토 결과가 대부분 일치하는 것으로 나타나 명승지내의 경관자원발굴과 현상변경을 제한하는 타당성 있는 근거를 제시할 수 있을 것으로 예상된다.

• Journal of the Korean Association of Geographic Information Studies
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• v.9 no.3
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• pp.156-170
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• 2006

Determining the best visibility positions on terrain surface has been one of the frequently used analytical issues in GIS visibility analysis and the search for a solution has been carried out effectively using spatial search techniques. However, the spatial search process provides operational and methodological challenges for finding computational algorithms suitable for solving the best visibility site problem. For this problem, current GIS visibility analysis has not been successful due to limited algorithmic structure and operational performance. To meet these challenges, this paper suggests four algorithms explored robust search techniques: an extensive iterative search technique; a conventional solution based on the Tornqvist algorithm; genetic algorithm; and simulated annealing technique. The solution performance of these algorithms is compared on a set of visibility location problems and the experiment results demonstrate the useful feasibility. Finally, this paper presents the potential applicability of the new spatial search techniques for GIS visibility analysis by which the new search algorithms are of particular useful for tackling extensive visibility optimization problems as the next GIS analysis tool.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 2010.06a
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• pp.173-174
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• 2010

산불감시활동에 의한 탐지확률을 높이고, 감시자원의 효율적인 이용을 위해서는 산불 감시 우선지역에 대한 분석이 요구된다. 따라서 산불감시 우선지역을 추출하기 위해 가시권 분석과 산불발생확률 분석을 실시하였으며, 중첩을 통해 가중치를 부여하였다. 가시권 분석은 탐지확률과 관련된 감시자원의 높이, 산불연기높이, 지형의 roughness에 따른 유효가시거리 인자를 다르게 하여 실시하였다. 산불발생확률은 로지스틱 회귀분석모형과 연료, 기상, 지형인자 및 토지피복, 접근성 인자 DB를 이용하여 분석하였다. 개발된 산불감시 우선지역 분석체계는 산불감시자원의 효율성 제고를 위한 기초자료로 활용될 수 있을 것으로 예상되었다.

• Journal of the Korean Association of Geographic Information Studies
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• v.14 no.1
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• pp.40-48
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• 2011

The purpose of this study is to contribute enhancing the accuracy of viewshed analysis through the explanation for an analysis method of viewshed analysis using GIS. According to previous studies, the visible area using digital terrain in viewshed analysis depends on a visible interest area, scale of terrain, spatial resolution and surface data. In this study, we used trend analysis and RMSE analysis in order to find the effect of a visible interest area, scale of terrain, etc in viewshed analysis. Results of this study are as follows. First, the result of viewshed analysis depends on a visible interest area, scale of terrain, spatial resolution, surface data such as previous studies. Second, the results in forest area are reliable than those of flat area in terms of a visible interest area. Third, the results based on raster grid data are stable than those of TIN(triangulated irregular network) in terms of input surface data. Fourth, according to the result of trend and RMSE analysis, the spatial resolution for analysis is differently applied to different scales digital terrain map in viewshed analysis. In detail, it is desirable that the spatial resolution is set less than 10m(in the case of 1/1,000 digital terrain map), 20m(in the case of 1/5,000 map), 30m(1/25,000 map).

• Journal of the Korean Association of Geographic Information Studies
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• v.13 no.2
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• pp.11-20
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• 2010

In this study, the effects of stand height growth on GIS-based viewshed analysis were investigated. DSM was created by combining stand height layers on DEM using map algebra functions. In developing the tree height layers, the digital forest-type maps, forest site maps and stand yield tables of Korea Forest Research Institute were used. The time horizon for viewshed analysis were 40 years. Two viewpoints in crossings of downtown for viewshed analyses were chosen using a projective mapping technique. The effects of tree height growth over time on visibility were measured in terms of the depth of blind areas and the area of visible regions. The results of viewshed analyses show that 17% of visible regions is reduced when we use DSM instead of DEM. As the tree height grows, the visibility gets worse and worse and the depth of blind area increases.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2004.11a
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• pp.429-433
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• 2004

기존 가시권 분석에 있어서는 주거지 개발, 도로, 송전선 설치 등에 따른 시각적 영향을 분석하는 연구가 많이 이뤄졌다. 이들은 개발에 따른 시각적 영향을 분석하고 부정적 영향을 최소화시킴을 목표로 하고 있다. 경관이 안공요소의 침입을 수용할 수 있는 정도를 고려하여 각 경관의 수용능력에 따른 개발을 유도함으로써 시각적 환경의 질을 높이고자 하는 것이다. 또한 도심지의 개발로 인하여 중요 문화ㆍ관광자원의 훼손으로 오랫동안 잘 보존되어야할 관광자원에 대한 시각적 영향을 분석하고자 하였다. 본 논문에서는 많은 문화ㆍ관광자원을 보유하고 있는 경주시 지역에 대하여 가시권역을 시각화하고 분석하여 보았다. 우선 경주시 지역에 대한 1:25,000 수치지형도 9장을 중첩하여 Arcview 프로그램을 이용하여 등고선만을 추출하였으며, 추출된 등고선도를 가지고 DEM을 생성한 후 Arc/GIS의 Workstation Arc/Info를 이용하여 가시권역을 나타내어 보았다. 이렇게 나타난 가시권역과 문화ㆍ관광지역과의 중첩을 통하여 가시지역의 범위를 분석하여 본 결과 관측점에서의 가시범위가 약 70%정도로 나타났다.

• Journal of the Korean Association of Geographic Information Studies
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• v.8 no.3
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• pp.84-95
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• 2005

This paper presents solution heuristics to solving optimal multiple-viewpoint location problems that are based on topographic features. The visibility problem is to maximise the viewshed area for a set of viewpoints on digital elevation models (DEM). For this analysis, five areas are selected, and fundamental topographic features (peak, pass, and pit) are extracted from the DEMs of the study areas. To solve the visibility problem, at first, solution approaches based on the characteristics of the topographic features are explored, and then, a benchmark test is undertaken that solution performances of the solution methods, such as computing times, and visible area sizes, are compared with the performances of traditional spatial heuristics. The feasibility of the solution methods, then, are discussed with the benchmark test results. From the analysis, this paper can conclude that fundamental topographic features based solution methods suggest a new sight of visibility analysis approach which did not discuss in traditional algorithmic approaches. Finally, further research avenues are suggested such as exploring more sophisticated selection process of topographic features related to visibility analysis, exploiting systematic methods to extract topographic features, and robust spatial analytical techniques and optimization techniques that enable to use the topographic features effectively.