수치지형도를 활용한 가시권 분석의 적정 분석방법에 관한 연구

여창환 ( Chang Hwan Yeo ),장영진 ( Young Jin Jang ) 한국지리정보학회 2011 한국지리정보학회지 Vol.14 No.1

본 연구의 목적은 GIS 분석기법을 활용한 가시권 분석이 활발해 지고 있으나 분석결과의 정확도에 대한 논의는 이루어지고 있지 않은 점에 착안하여 가시권 분석방법에 대한 심층적 논의를 통해 분석결과의 신뢰도를 높이는데 있다. 수치지형도를 활용한 가시권 분석은 분석 대상지의 특성, 수치지형도의 축척, 분석의 공간 해상도, 지형자료의 형태에 따라 상이하게 도출되어 분석결과의 오차를 발생시킬 수 있다. 이러한 측면에서 본 연구에서는 분석의 공간 해상도가 낮아지면 가시권 분석결과의 면적은 넓어지고 유효 한계해상도보다 해상도가 낮아지면 분석결과의 면적은 불안정한 변화추이를 보일 것이라는 가정 하에 공간 해상도별 가시면적의 변화추이와 공간 일치도 분석을 실시하였다. 연구결과를 요약하면 분석 대상지와 수치지형도의 축척, 공간 해상도, 입력된 지형자료의 형태에 따라 분석결과가 상이하게 도출되어 분석결과의 정확도에 영향을 미치는 것으로 나타났다. 즉, 가시영역이 산지 지형인 경우에서 안정적 분석결과가 도출되었다. 또 입력되는 지형자료의 경우는 제한된 조건에서 TIN보다 레스터 자료에서 안정적인 분석결과가 도출되었다. 마지막으로 해상도별 가시면적의 변화추이와 공간 일치도 분석결과에 비춰보면 축척별 수치지형도에 따른 유효한 최소의 공간 해상도가 존재하는데, 1/1,000의 경우는 8m, 1/5,000은 20m, 1/25,000은 35m를 넘지 않은 범위에서 분석하는 것이 바람직하다. 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).

연구논문 : 산지습지의 수문지형분석 방법론의 개발

장은세 ( Eun Se Jang ),이은형 ( Eun Hyung Lee ),김상현 ( Sang Hyun Kim ) 한국환경과학회 2015 한국환경과학회지 Vol.24 No.11

In this study, a digital terrain analysis had been performed for a mountainous watershed having wetlands. In order to consider the impact for wetland in the flow determination algorithm, the Laplace equation is implemented into the upslope accounting algorithm of wetness computation scheme. The computational algorithm of wetland to spatial contribution of downslope area and wetness was also developed to evaluate spatially distributed runoff due to the presence of wetland. Developed schemes were applied to Wangpichun watershed located Chuncuk mountain at Ulzingun, South Korea. Both spatial distribution of wetness and its histogram indicate that the developed scheme provides feasible consideration of wetland impact in spatial hydrologic analysis. The impact of wetland to downslope propagation pattern is also useful to evaluate spatially distributed runoff distribution.

Influence of Grid Cell Size and Flow Routing Algorithm on Soil-Landform Modeling

S. J. Park(박수진),G. R. Ruecker,W. A. Agyare,A. Akramhanov,D. Kim(김대현),P. L. G. Vlek 대한지리학회 2009 대한지리학회지 Vol.44 No.2

수치고도모형으로부터 산출된 지형변수는 지표면 프로세스와 관련된 공간모델의 개발에 있어 중요한 요소이다. 이 논문에서는 사면유역지수(upslope contributing area)가 토양성질의 공간적 분포를 예측하는 능력이, 사용한 알고리듬과 격자크기에 따라 어떻게 변하는지를 연구하였다. 상이한 환경조건을 지니는 여덟 군데의 연구지역에서 토양-경관 자료를 획득하여 이중 4개의 토양성질을 분석에 포함시켰다. 다섯 가지의 알고리듬을 통해 사면유역지수를 산출하여 이 지수들이 수치고도모형의 해상도에 얼마나 민감한지를 분석하였다. 다방향유수흐름 알고리듬(multiple flow algorithm)을 통해 계산된 지형변수가 대부분의 토양변수와 높은 상관관계를 보임과 동시에 격자크기의 변화에 낮은 민감도를 보였다. 지형변수와 토양변수 사이의 높은 상관관계는 15-50 m의 해상도에서 유사한 예측능력을 보였다. 격자크기를 증가시켰을때 발생하는 미세지형정보의 손실을 감안한다면, 15-30 m 정도의 공간적 스케일이 토양경관 모델링에 적합할 것으로 판단된다. Terrain parameters calculated from digital elevation models (DEM) have become increasingly important in current spatially distributed models of earth surface processes. This paper investigated how the ability of upslope area for predicting the spatial distribution of soil properties varies depending on the selection of spatial resolutions of DEM and algorithms. Four soil attributes from eight soil-terrain data sets collected from different environments were used. Five different methods of calculating upslope area were first compared for their dependency on different grid sizes of DEM. Multiple flow algorithms produced the highest correlation coefficients for most soil attributes and the lowest variations amongst different DEM resolutions and soil attributes. The high correlation coefficient remained unchanged at resolutions from 15 m to 50 m. Considering decreasing topographical details with increasing grid size, we suggest that the size of 15-30 m may be most suitable for soil-landscape analysis purposes in our study areas.

수치고도모델을 이용한 오대산 국립공원지역의 지형분석

김철민 ( Cheol Min Kim ),이준우 ( Joon Woo Lee ),권태호 ( Tae Ho Kwon ) 한국환경생태학회 1996 한국환경생태학회지 Vol.9 No.1

Hybrid approach to detect water bodies and their flow paths

Kim, JongChun,Paik, Kyungrock 한국방재학회 2015 한국방재학회 학술발표대회논문집 Vol.14 No.-

Detection of water bodies and their flow paths is elemental process of terrain analysis in any application related with surface water. Several algorithms have been proposed for automatic extraction of surface flow paths from Digital Elevation Models (DEMs) (e.g., O’Callaghan and Mark, 1984; Tarboton, 1997; Paik, 2008). While these algorithms have been widely applied, DEMs-based approaches have fundamental limitation in detecting water bodies. To resolve this issue, we propose a hybrid approach that utilizes DEMs and satellite imagery together. These dataset supplement each other’s weakness, providing extra information for better detection of water bodies and flow paths. The proposed approach is tested for the Geum River, showing successfully extraction of flow boundaries and more resonable flow paths within water bodies.

A Soil Moisture Upscaling Technique Based on Topographic Attributes

Sanghyun Kim,Yongseok Kwak,Su-Jin Kim 한국기상학회 2009 Asia-Pacific Journal of Atmospheric Sciences Vol.45 No.2

This paper proposes an upscaling technique using a long­term measurement of soil moisture at a hillslope scale. A monitoring scheme for soil moisture was designed and operated over a year. The analysis period was divided into four periods in keeping with the seasonal variation of soil moisture and considering the characteristics of terrain features. Based on rigorous regression analysis, significant relationships were established between the seasonalmean soilmoisture values at point scale and topographic attributes. The cumulative distribution function(CDF)matching technique was employed to upscale the soil moisture from the fine resolution obtained from local measurements to coarser resolution at the watershed scale. The spatial distribution of soil depth can be predicted through the application of the multi­resolution valley bottom flatness algorithm. The scaling issues of different resolutions in the terrain analysis could be partially resolved during the CDF matching procedure. However, the uncertainty associated with the complex terrain of the watershed remained in the parameters for the valley bottom evaluation. The spatial distribution of soil water could be predicted in the watershed scale by combing the CDF matching technique with a soil depth prediction scheme.

지형분석을 이용한 산지토양 탄소의 분포 예측과 불확실성

정관용 ( Gwanyong Jeong ) 한국지형학회 2016 한국지형학회지 Vol.23 No.3

Soil carbon(C) is an essential property for characterizing soil quality. Understanding spatial patterns of soil C is particularly limited for mountain areas. This study aims to predict the spatial pattern of soil C using terrain analysis in a steep mountainous area. Specifically, model performances and prediction uncertainties were investigated based on the number of resampling repetitions. Further, important predictors for soil C were also identified. Finally, the spatial distribution of uncertainty was analyzed. A total of 91 soil samples were collected via conditioned latin hypercube sampling and a digital soil C map was developed using support vector regression which is one of the powerful machine learning methods. Results showed that there were no distinct differences of model performances depending on the number of repetitions except for 10-fold cross validation. For soil C, elevation and surface curvature were selected as important predictors by recursive feature elimination. Soil C showed higher values in higher elevation and concave slopes. The spatial pattern of soil C might possibly reflect lateral movement of water and materials along the surface configuration of the study area. The higher values of uncertainty in higher elevation and concave slopes might be related to geomorphological characteristics of the research area and the sampling design. This study is believed to provide a better understanding of the relationship between geomorphology and soil C in the mountainous ecosystem.

Time series modeling of the spatial distribution of soil moisture in a mountainous hillslope headwater

김상현 한국지질과학협의회 2011 Geosciences Journal Vol.15 No.4

The spatial distribution of soil moisture depth profiles on a hillslope at the headwater of a mountainous forest watershed in Korea was obtained from time series measurements performed using a refined soil moisture monitoring system. Digital terrain analysis based on intensive field surveying was applied to configure the spatial distribution of soil moisture along the steep regolith. The upslope contributing area and topographic wetness index were employed to determine the optimal locations of sensors for time domain reflectometry (TDR) monitoring along two transects. In the early autumn of 2007, 37 time series were recorded over three weeks and used as data for modeling, accounting for the known reliability of the data and the preliminary evaluation of measured soil moisture histories in the context of time series modeling assumptions. A systematic modeling procedure involving pretreatment, investigation of stochastic structure, modeling practice with heuristic repetition, and diagnostic checking was applied to selected soil moisture time series. The two transects showed differences in the distribution of the explanatory models. Transect A, covering a region of relatively fine soil texture, showed a systematic model distribution in the context of soil depth, whereas transect B across coarser soil occasionally produced inconsistent depth profile modeling results. The predictability of the models tends to reduce substantially at the outlet of the hillslope region, possibly due to active subsurface runoff generation near the channel.

수치고도모델을 이용한 옥녀봉의 형국 유형별 풍수적 특성 연구

서춘석,천인호 국토연구원 2015 국토연구 Vol.85 No.-

In this study, the characteristic analysis of geomancy and terrain for forty mountains named of Oknyeobong using digital elevation model is conducted to examine the geomantic meaning in a modern point of view. According to the pandect of place names, shape type of Oknyeobong is categorized as Sanbal, Danjang, Danjwa, Tangeum, Jikgeum, and Geumban. As terrain analysis results, types of Sanbal, Danjang and Danjwa showed high elevation and large scale which are related to the shape of dressing up whereas types of Tangeum, Jikgeum, and Geumban showed low elevation and small scale which are related to the shape of everyday life. After analyze the shapes based on the four animal theory, the principle points are located in the middle of Oknyeobongs and mountains facing to them have smaller scale than the principle peaks which means that the existing geomancy theory has numerically significant. Mountains in position of right and left side of principle point which are called as blue dragon and white tiger points in the four animal theory showed shape of protecting the principle point from winds with slightly higher elevation than the principle point. Oknyeobong’s peaks showed slightly steep and bilaterally symmetric shape. As results of average elevation angle, Oknyeobong showed visually stable shape. 본 논문에서는 전국에 산재하고 있는 40개의 옥녀봉을 대상으로 하여 GIS 지형분석 기법을 적용함으로써 풍수적, 지형적 특성을 분석하고 이를 통해 옥녀봉의 형국 구분이 가지는 풍수적 의미를 현대적 관점에서 파악하고자 하였다. 지명총람 등의 자료에 의하면 옥녀봉의 형국은 크게 옥녀산발형, 옥녀단장형, 옥녀단좌형, 옥녀탄금형, 옥녀직금형, 옥녀금반형 등으로 구분되고 있다. 지형분석 결과를 살펴보면 옥녀가 자신을 가꾸는 모습인 옥녀산발형, 옥녀단장형, 옥녀단좌형의 옥녀봉은 고도가 상대적으로 높고 규모 또한 큰 데 반해, 일상생활과 밀접한 관련이 있는 옥녀탄금형, 옥녀직금형, 옥녀금반형의 옥녀봉은 고도가 낮고 규모도 작았다. 사신사 이론에 근거하여 형국을 분석해본 결과, 옥녀봉의 중간 높이에 주로 혈이 위치하고 안산이 주산에 비해 규모가 작아 주산을 압도할 수 없다는 풍수이론이 수치상으로 유의함을 나타내었다. 또한 혈에 비해 청룡과 백호가 약간 높은 고도에서 바람을 잘 막아주는 형태를 나타내었다. 또한 옥녀봉의 봉우리는 약간 가파른 형태로 좌우가 대칭인 안정적인 산 형태를 보이고 있다.

무인항공시스템을 이용한 도시공간 지형모델 생성 및 정확도 평가

도명식,임언택,채정환,김성훈 한국ITS학회 2018 한국ITS학회논문지 Vol.17 No.5

본 연구에서는 대학 캠퍼스를 대상으로 드론을 활용한 정사영상 및 지형모델의 생성 방안 을 제시하고 정확도 평가를 실시하였다. 나아가 기존 대부분의 정확도 평가를 위한 연구에서 GPS 자료를 활용한 사례가 대부분 이였으나 본 연구에서는 삼각수준측량을 통해 얻은 기준 값을 활용한 정확도 평가 및 검증을 실시하였다. 정확도 분석 결과 모든 시나리오에서 항공사진측량 작업규정에서 정한 허용범위 내의 성과 를 얻어 드론을 활용한 항공사진측량 및 응용분야에 활용가능성을 확인하였으며, 정교한 DTM 을 작성하기 위해서는 정밀 분류과정을 통해 빌딩, 수목, 인공 객체 등의 간섭을 없애고 정확한 표면의 높이의 등고선(Contour) 작성이 가능한 방안을 제시하였다. 본 연구의 성과는 드론을 활용한 지형모델 생성 및 정확도 평가에서 향후 관련 분야의 기초적 자료로 활용될 것으로 기대된다. The author tried to propose the orthographic and DTM (digital terrain model) creation and evaluate the accuracy for an university campus using UAV (unmanned aerial vehicle) system. Most previous studies used GPS-based data, but in this paper, the observations of triangulation level measurements was used for comparison of accuracy. Accuracy analysis results showed that the operational requirements for aerial photographic standards are satisfied in all scenaries. The author confirmed availability in aviation photo measurements and applications using UAV (Drone). In order to create a sophisticated DTM and contour, we need to eliminate interference from building, trees, and artificial objects. The results of this study are expected to be used as the basis for future studies in the creation of DTM and the accuracy assessments using Drone.