• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2002.04a
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• pp.129-139
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• 2002

DEM을 구축하는 여러 방법 중 항공레이저측량을 이용하여 DEM을 구축하면 정확도 및 품질이 우수하고, 현시성 있는 DEM을 얻을 수 있다. 이에, 본 연구에서는 기존의 DEM구축방법과 신기술에 의한 DEM 구축방법을 품질 및 경제적 면에서 비교ㆍ평가하여 우리나라 국가 DEM의 구축방안을 제안하는데 그 목적이 있으며, 이를 위하여 DEM의 소요정확도 파악, 지형(또는 사용목적)별 적정한 격자간격 도출, DEM 구축방법별 경제성을 분석하고 추진일정을 제안하였다.

• Journal of Korean Society for Geospatial Information Science
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• v.6 no.2 s.12
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• pp.21-34
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• 1998

SAR is an active imaging sensor emitting its own energy source and can be operated in all weather conditions. Thus SAR provides data which can not be obtained by an optical sensor. In this study, the potentials and problems of the techniques for DEM extraction from the SAR imagery were evaluated through theoretical researches and practical experiments. And then the accuracy was tested by RMS error between the digitized map contour and the results from this experiment. Here, two types of DEM extraction method were evaluated. One was an analytical photogrammetric technique, and the other was a SAR interferometric processing. From the experiment, we found that the photogrammetric technique is currently the most suitable method considering topographic conditions of Korea. In the SAR interferometry technique, we also conclude that the problems caused by decorrelations due to the temporal reasons and due to the scattering effects from vegetation should be solved.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.494-494
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• 2023

수치모형을 활용하여 하천 흐름을 해석하기 위해서는 하도의 형태를 나타내는 지형자료가 요구되며, 주흐름 방향에 직각 방향으로의 횡단면도는 다량의 자료가 필요하다. 측량을 통한 횡단면도의 확보는 시간과 비용이 많이 소요될 뿐 아니라 날씨와 같은 외부적 요인에 따라 측량 결과물의 정확도가 달라질 수 있다. 또한 하천의 유속이 매우 빠를 때에는 정확도 높은 횡단 측량자료를 얻기는 불가능하며 접근이 어려운 지역이나 중소규모의 하천 측량자료는 구축되어 있지 않은 실정이다. 이에 따라 위성영상과 수치표고모델(Digital Elevation Model, DEM)에 기반하여 하천구역과 하도의 특성을 정의하는 방법이 대안으로 제시되고 있다. 본 연구에서는 하천지형 측량자료가 존재하는 섬진강댐부터 오수천 합류전까지를 대상으로 가상하도 생성기법을 적용하고, 1차원 하천흐름해석을 수행하여 가상하도 구축방안의 유효성을 검토하고자 하였다. 위성영상 자료를 활용하여 하천구역을 정의하였으며 DEM에서 추출된 표고에 기반하여 제방고와 횡단면도를 구축하였다. 구축된 횡단면도와 실단면 비교시, DEM 표고 및 하천구역 정의 지점의 정확도에 따라 제방고가 달라지는 것으로 나타났으며, 홍수터에 대한 고려가 포함되지 않아 실단면과 다소 차이가 있는 것으로 확인된다. 구축한 지형자료를 1차원 하천흐름해석 모형인 K-River에 적용하였으며, 상류단 경계조건으로는 섬진강댐 방류량을 하류단 경계조건으로는 등류조건을 적용하였다. 구축영역 내 존재하는 지류의 유입량은 측방유입으로 고려하였다. 수치모의 결과로부터 구축된 횡단면의 최심고와 실단면의 최심고가 유사한 지점에서는 수위재현성이 양호한 것으로 확인되었다.

• Journal of the Korean Association of Geographic Information Studies
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• v.15 no.3
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• pp.36-51
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• 2012

The demand for a climatological dataset with a regular spaced grid is increasing in diverse fields such as ecological and hydrological modeling as well as regional climate impact studies. PRISM(Precipitation-Elevation Regressions on Independent Slopes Model) is a useful method to estimate high-altitude precipitation. However, it is not well discussed over the optimization of PRISM parameters and DEM(Digital Elevation Model) resolution in South Korea. This study developed the PRISM and then optimized parameters of the model and DEM resolution for producing a gridded annual average precipitation data of South Korea with 1km spatial resolution during the period 2000-2005. SCE-UA (Shuffled Complex Evolution-University of Arizona) method employed for the optimization. In addition, sensitivity analysis investigates the change in the model output with respect to the parameter and the DEM spatial resolution variations. The study result shows that maximum radius within which station search will be conducted is 67km. Minimum radius within which all stations are included is 31km. Minimum number of stations required for cell precipitation and elevation regression calculation is four. Optimizing DEM resolution is $1{\times}1km$. This study also shows that the PRISM output very sensitive to DEM spatial resolution variations. This study contributes to improving the accuracy of PRISM technique as it applies to South Korea.

• Journal of the Korean Association of Geographic Information Studies
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• v.11 no.3
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• pp.151-165
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• 2008

Ground slope and aspect are important parameters for physical deterministic water balance models like BROOK90 or hydrological models which attempt to calculate evapotranspiration, snowmelt, and net radiation. This study constructs a Digital Elevation Model(DEM) and examines how DEM resolution can change the average ground slope and aspect of a river basin and attempts to evaluate the effects on simulation results of BROOK90, a physical deterministic water balance model. The study area is Byungcheon river basin in Korea. DEM has been constructed using a 1:25,000 digital map with the methods of TIN and Topo To Raster. The total of 20 DEMs with 10m~100m resolution have been constructed, with a 10m interval. It was found that the higher the DEM resolution, the steeper the average ground slope value of the Byungcheon river basin. In turn, the direct solar radiation of a hilly area in the model increased the evapotranspiration and reduced the stream runoff in the Byungcheon river basin. On the other hand, a lower DEM resolution tends to move the average aspect from southeast to south in the Byungcheon river basin. Accordingly, it was found that stream runoff was reduced and evapotranspiration increased.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.23 no.2
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• pp.147-156
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• 2005

SAR interferometry (InSAR) is a technique to generate 3-Dimentional spatial information using complex data pairs observed by antennas at different locations. In case of the Two-pass differential SAR inteferometry (DInSAR), the topographic phase signature can be separated from the contribution of surface deformation in the interferometric phase. In this study, InSAR and DInSAR were implemented with ERS- l/2 tandem pair to produce DEM. The accuracy of the Resulting DEMs was analyzed.

• Journal of the Korean earth science society
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• v.40 no.2
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• pp.119-134
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• 2019

In order to analyze the observational environment of solar radiation stations operated by the Korea Meteorological Administration (KMA), we used the digital elevation model (DEM) and the solar radiation model to calculate a topographical shading, sky view factor (SVF) and solar radiation by surrounding terrain. The sky line and SVF were calculated using high resolution DEM around 25 km of the solar stations. We analyzed the topographic effect by analyzing overlapped solar map with sky line. Particularly, Incheon station has low SVF whereas Cheongsong and Chupungryong station have high SVF. In order to validation the contribution of topographic effect, the solar radiation calculated using GWNU solar radiation model according to the sky line and SVF under the same meteorological conditions. As a result, direct, diffuse and global solar radiation were decreased by 12.0, 5.6, and 4.7% compared to plane surface on Cheongsong station. The 6 stations were decreased amount of mean daily solar radiation to the annual solar radiation. Among 42 stations, eight stations were analyzed as the urgent transfer stations or moving equipment quickly and more than half of stations (24) were required to review the observational environment. Since the DEM data do not include artifacts and vegetation around the station, the stations need a detail survey of observational environment.

• Journal of Korean Society for Geospatial Information Science
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• v.23 no.4
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• pp.3-10
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• 2015

The various studies and applications for UAVS(Unmaned Aerial Vehicle System) have been recently increased as a new technology to create 3D spatial information rapidly and accurately. UAV(Unmanned Aerial Vehicle) is economical when comparing with conventional technique, such as satellite and aerial survey, and can quickly obtain high resolution data under 5cm. This paper examined the utilizing possibility to creating 3D spatial information and analysis the compatibility the UAV data obtained by non-metric digital camera with conventional numerical photogrammetric system. The DEM and normal orthophoto is created by exclusive S/W and DPW(Digital Photogrammetry Workstation) then analysis the accuracy of created data. As a result, the accuracy of the created DEM and normal orthophoto, which is obtained by UAV then processed by DPW, is not satisfied;so it is estimated that the compatibility the UAV data with conventional numerical photogrammetric system is low.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.25 no.1
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• pp.55-62
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• 2007

Recent advances in airborne LiDAR technology allow rapid and inexpensive measurements of topography over large areas. The generation of DTM/DEM is essential to numerous applications such as the fields of civil engineering, environment, city planning and flood modeling. The demand for LiDAR data is increasing due to the reduced cost for DTM generation and the increased reliability, precision and completeness. In order to generate DTM, measurements from non-ground features such as building and vegetation have to be classified and removed. In this paper, a segmented morphology filter was developed to detect non-ground LiDAR measurements. First, segments LiDAR point clouds based on the elevation. Secondly classifies those protruding segments into non-ground points. Those non-ground points such as building and vegetation are removed, while ground points are preserved for DTM generation. For experiments, data sets used in Comparison of Filters (ISPRS, 2003) depicting urban and rural areas were selected. The experimental results show that the proposed filter can remove most of the non-ground points effectively with less commission and omission errors.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2004.04a
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• pp.263-266
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• 2004

We make DEM of the area that elevation value varies rapidly by the aid. This study evaluates the accuracy and workability between the existing DEM making mathod by processing break line and the DEM absorption method by using the program like ARC TIN or AML. The object data of DEM generation is 1/5,000 digital map publicated by NGII and this study uses 100pieces of map as the criteria. We correct the error by Geoconv and generate DEM by using ARC TIN, ARC VIEW. Accuracy Evaluation accomplished by drawing 100 points from 1/5000 digital map.