• Journal of the Korean Association of Geographic Information Studies
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• v.13 no.3
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• pp.42-52
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• 2010

The purpose of this study is to produce digital elevation model (DEM) in the Jebu tidal flat, one of the west coast of the Korean Peninsula, by means of photogrammetric techniques from aerial digital stereo-images. Produced DEM would be become the fundamental data for change detection of the sediment and erosion. To do so, epipolar line is established by relative orientation. Area-based matching is then carried out based on this line and matching size according to surface property of tidal flat after a classified image is produced from reflectance and texture of the surface. As the results, DEM generated by the proposed method showed subtle changes in height more precisely than DEM using the fixed matching size and DEM by the commercial S/W in the region, such as tidal flats having few level differences.

• Journal of the Korean Association of Geographic Information Studies
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• v.5 no.3
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• pp.19-32
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• 2002

Topographic information is indispensable in the applications that require elevational data. These applications are exemplified by watershed partition, extraction of drainage networks, viewshed analysis, derivation of geomorphologic features, quantification of landslide-terrain, and identification of topographic settings susceptible to landsliding. Therefore, we study the accuracy of data on topographic parameters derived from digital elevation models(DEMs). This research wished to analyze the effect that data source and grid size get in topography parameter using gridded DEM. An analysis of topography parameter extract and compared drainage basin, watershed slope, stream network using DEM is constructed by digital map and DTED DEM. Especially, when extract stream network from gridded DEM, received much effects according to threshold value of flowaccumulation regardless of DEM grid size. Therefore, this study applied equal threshold value of flowaccumulation for two data sources, and compare and analyzed stream network.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.32 no.1
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• pp.19-27
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• 2014

Kompsat-3 is an optical high-resolution earth observation satellite launched in May 2012. In addition to its 0.7m spatial resolution, Kompsat-3 is capable of in-track stereo acquisition enabling quality Digital Elevation Model(DEM) generation. Typical DEM generation procedure requires accurate control points well-distributed over the entire image region. But we often face difficult situations especially when the area of interests is oversea or inaccessible area. One solution to this is to use existing geospatial data even though they only cover a part of the image. This paper aimed to assess accuracy of DEM from Kompsat-3 with different scenarios including no control point, Rational Polynomial Coefficients(RPC) relative adjustment, and RPC adjustment with control points. Experiments were carried out for Kompsat-3 stereo data in USA. We used Digital Orthophoto Quadrangle(DOQ) and Shuttle Radar Topography Mission(SRTM) as control points sources. The generated DEMs are compared to a LiDAR DEM for accuracy assessment. The test results showed that the relative RPC adjustment significantly improved DEM accuracy without any control point. And comparable DEM could be derived from single control point from DOQ and SRTM, showing 7 meters of mean elevation error.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.29 no.2
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• pp.165-173
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• 2011

Generally, A acquisition of the target is affected by the detector performance and whether it is covered with features or not. This paper represented the comparative analysis of the detection probability for DEM and DSM, when we used by the infrared surveillance device. In the first place, we c1assified as the visible area and invisible area for DEM and DSM, and obtained the acquisition probability values using the ACQUIRE mode. We have known that The Detection Probability of the DSM is very lower than the DEM and is rising when elevates the height value of the detection point.

• Proceedings of the KSRS Conference
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• 2004.10a
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• pp.522-525
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• 2004

Interferometry SAR (InSAR) is a technique to generate topographic map from complex data pairs observed by antennas at different locations. However, to obtain topographic information using InSAR is difficult task because it requires series of complicated process including phase unwrapping and precise recovery of the SAR geometry. Especially, accuracy of the DEM (Digital Elevation Model) produced by repeat pass single SAR pair could be influenced by atmospheric effect. Recently, a new InSAR technique to improve accuracy of DEM has been introduced that utilizes low resolution DEM with a number of SAR image pairs. The coarse DEM plays an important role in reducing phase unwrapping error caused by layover and satellite orbit error. In this study, we implemented DInSAR (Differential InSAR) method which combines low resolution DEMs and ERS tandem pair images. GTOPO30 DEM with 1km resolution, SRTM-3 DEM with 100m resolution, and DEM with 10m resolution derived from 1:25,000 digital vector map were used to investigate feasibility of DInSAR. The accuracy of the DEMs generated both by InSAR and DInSAR was evaluated.

• Proceedings of the Korea Water Resources Association Conference
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• 2004.05b
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• pp.1267-1270
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• 2004

DEM(Digital Elevation Model)을 활용한 기술이 수자원분야에서 필수적인 GIS 활용기술인 이유는 DEM을 이용할 경우 유역의 수문학적 지형특성인자를 객관적인 방법으로 추출할 수 있고 이를 활용하여 분포형 수문모형을 개발, 적용할 수 있기 때문이다. 국내에서도 GIS를 이용하여 수문모형의 입력인자를 추출한 다든가 분포형 수문모형에 대한 연구를 수행할 경우 DEM을 활용한 연구를 수행하고 있다. 이러한 것은 GIS S/W인 Arc/Info, ArcView, WMS 등에서 DEM을 활용하여 수문학적인 유역분석 기능을 제공해 주기 때문에 가능하다. 즉, DEM을 이용하여 하천망을 추출하고, 유역을 분한하고 이를 이용하여 유역 Boundary 내에서의 지형특성인자를 추출하는 기능을 말한다 본 연구는 수자원분야에서 GIS를 활용할 때 필요한 필수기능인 DEM의 활용기술을 순수 국내기술로 개발하였다. DEM활용에 대한 최신 알고리즘을 검토하여 국내 기술로 개발된 GIS Engine인 GEOMaina v.3.0을 이용하여 수문학적인 DEM 활용 Module을 개발하였으며 HyGIS(Hydrologic Geography Information System)라 명하였다. 본 연구에서는 개발된 HyGIS를 이용하여 수문학적 지형특성인자를 추출하고 기존에 사용되어오던 GIS S/W와 비교 검토하여 HyGIS의 환용 가능성에 대하여 검토하고자 한다.

• Magazine of the Korean Society of Agricultural Engineers
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• v.44 no.7
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• pp.25-35
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• 2002

In this study, the effect of DEM (Digital Elevation Model) resolution (15m, 30m, 50m, 70m, 100m, 200m, 300m) on the hydrological simulation was examined using the BASINS (Better Assessment Science Integrating point and Nonpoint Source) for the Heukcheon watershed (303.3 ㎢) data from 1998 to 1999. Generally, as the cell size of DEM increased, topographical changes were observed as the original range of elevation decreased. The processing time of watershed delineation and river network needed more time and effort on smaller cell size of DEM. The larger DEM demonstrated had some errors in the junction of river network which might affect on the simulation of water quantity and quality. The area weighted average watershed slope became milder but the length weighted average channel slope became steeper as the DEM size increased. DEM resolution affected substantially on the topographical parameter but less on the hydrological simulation. Considering processing time and accuracy on hydrological simulation, DEM grid size of 100m is recommended for this range of watershed size.

• Spatial Information Research
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• v.17 no.3
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• pp.381-387
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• 2009

This study investigates the use of geomorphic analysis results obtained from high-resolution LiDAR-derived DEM. The results of analysis, slope angle and eigenvalue ratio (ER) were derived from the DEM for 3 landslide and 1 non-landslide occurrence area. Results of this study highlighted the importance of geomorphic analysis in characterizing landslide feature as well as the various contents in their future occurrence and activity. The relationship between the results of geomorphic analysis and landslides are well expressed in this paper.

• Korean Journal of Remote Sensing
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• v.16 no.1
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• pp.99-108
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• 2000

The purpose of this paper is to combine digital elevation models (DEM) using SPOT satellite stereo images. After DEM extraction, a grid of longitude and latitude is generated using the results of DEM extraction. Heights at each grid location are determined from the obtained DEMs by using triangular image warping interpolation that uses the heights of the three nearest neighbors. The final heights at each grid location can then be determined by using the maximum likelihood as a fusion strategy. The input images used in this paper are two pairs of SPOT stereo images and experiments show that heights of DEM are successfully fused

• 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.