• Journal of Korean Society for Geospatial Information Science
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• v.2 no.2 s.4
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• pp.99-108
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• 1994

In this thesis, we propose the 3D terrain modelling method for the better understanding of the geographic information. The process of 3D terrain medelling consists of three steps. The first step is to obtain real-world data from satellite images and stored in the form of DEM(Digital Elevation Model). The second one is to extract the meaningful data from DEM data based on LOD(Level Of Detail). And the third is to construct the 3D surface by TIN(Triangulated Irregular Network) with the extracted meaingful data. The proposed dynamic TIN reconstruction algorithm locally reconstruct the existed TIN model with the additional a new point. In this way, we can construct the TIN with the reduced time and can simulated 3D terrain model in real time.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.8
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• pp.838-848
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• 2014

We present a simulation study of an algorithm for the range and angle of arrival(AOA) estimation with an interferometric synthetic aperture radar(InSAR) altimeter using a real digital elevation model(DEM). We also illustrate a step-by-step procedure of generating raw InSAR data, as well as their range and azimuth compressed data, which is to be used for the subsequent altitude and angle estimation. The AOA is estimated using a deterministic maximum likelihood estimator(DMLE) applied to the first arrived point for each pulse in the compressed data obtained with three antennas. The range bin size and the pulse repetition interval(PRI) are much smaller than the cell size of the DEM used in this study. To make the DEM compatible to the radar parameters, we first generate a higher resolution DEM by linearly interpolating the given DEM. After a brief description of the principle of the InSAR altimeter, the algorithms for altitude and angle estimation are presented, and their performance is assessed through simulation.

• Korean Journal of Remote Sensing
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• v.25 no.4
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• pp.375-381
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• 2009

In this paper, synthetic aperture radar (SAR) clutter images are simulated based on the extensive analyses for radar backscatter characteristics of various earth surfaces, and the simulated images are compared with measured SAR images. At first, the surface parameters including soil moisture content and surface roughness parameters and other parameters for vegetation canopies are measured for various surfaces. The backscattering coefficients for the surfaces are computed using theoretical and empirical models for surface scattering and the radiative transfer for vegetation-canopy scattering. Then, the digital elevation map (DEM) and land cover map (LCM) are used for the SAR image generation. The SAR impulse response (correlation function) is also employed to simulated reliable SAR images. Finally, the appropriate speckle and texture parameters for various earth surfaces are used for generating the SAR clutter images.

• Proceedings of the KSRS Conference
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• 2007.10a
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• pp.25-28
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• 2007

Precise digital elevation model (DEM) is an important issue in coastal area where DEMs in a time series are especially required. Although LIDAR system is useful in coastal regions, it is not yet popular in Korea mainly because of its high surveying cost and national security reasons. Recently, precise coastal DEM have been made using radar interferometry, waterline method. One of these methods, Spaceborne imaging radar interferometry has been widely used to measure the topography and deformation of the Earth. We acquired ALOS PALSAR FBD mode (Fine Beam Dual) data for evaluating the quality of interferograms and their coherency. The purpose of this study is construction of DEM using the ALOS PALSAR data using radar interferometry and analysis of surface characteristics by coherence and magnitude map over the Ganghwado and Siwha tidal flats and near coastal lands.

• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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• pp.667-672
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• 2007

Land-use in Cheongju region is changing rapidly because of the increased interactions of human activities with the environment as population increases. We used multi-temporal Landsat images (1991 and 2000) and DEM data in a post-classification analysis with GIS to map land-use distribution and to analyse factors influencing the land-use changes for Cheongju City. Land-use statistics revealed that substantial land-use changes have taken place and that the built-up areas have expanded by about $17.57km^2(11.47%)$ over the study period (1991-2000). Agricultural lands and forests have decreased substantially while urban and barren lands have been on the increase. Rapid economic developments together with the increasing population were noted to be the major factors influencing rapid land use changes. Urban expansion has replaced urban and barren lands, thereby affecting habitat quality and leading to serious environmental degradation.

• Korean Journal of Remote Sensing
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• v.20 no.3
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• pp.163-173
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• 2004

The objective of this study is to develop a method to generate micro-relief digital elevation model (DEM) data of the tidal mudflats using multi-temporal Landsat Thematic Mapper (TM) data. Field spectroscopy measurements showed that reflectance of the exposed mudflat, shallow turbid water, and normal coastal water varied by TM band wavelength. Two sets of DEM data of the inter-tidal mudflat area were generated by interpolating several waterlines extracted from multi-temporal TM data acquired at different sea levels. The waterline appearing in the near-infrared band was different from the one in the middle-infrared band. It was found that the waterline in TM band 4 image was the boundary between the shallow turbid water and normal coastal water and used as a second contour line having 50cm water depth in the study area. DEM data generated by using both TM bands 4 and 5 rendered more detailed topographic relief as compared to the one made by using TM band 5 alone.

• 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.

• Proceedings of the KSRS Conference
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• 2002.10a
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• pp.292-296
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• 2002

This study has been accomplished as a experimental study for field application of 3D Perspective Image Map creation using Digital Topographical Map and based on the Ortho-Projection Image which is generated from Satellite Overlay Images and the precise Relative Coordinates of longitude, latitude and altitude which is corrected by GCP(Ground Control Point). AS to Contour Lines Map which is created by Coordinate conversion of 1:5,000 Topographical Map, we firstly made Satellite Image Map to substitute for Digital Topographical Map through overlapping the original images on top of each Ortho-Projection Image created and checking the accuracy. In addition to 3D Image Map creation for 3D Terrain analysis of a target district, Slope Gradient Analysis, Aspect Analysis and Terrain Elevation Model generation, multidirectional 3D Image generation by DEM can be carried out through this study. This study is to develop a mapping technology with which we can generate 3D Satellite Images of a target district through the composition of Digital Maps and Facility Blueprint and arbitrarily create 3D Perspective Images of the target district from any view point.

• Journal of Korea Water Resources Association
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• v.53 no.7
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• pp.545-555
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• 2020

A feasibility modeling for potential hydroelectric dam site selection was suggested using 1 sec ASTGTM (ASTER Global Digital Elevation Model) and Terra/Aqua MODIS (Moderate Resolution Imaging Spectroradiometer) derived land use (MCD12Q1) data. The modeling includes DEM pre-processing of peak, sink, and flat, river network generation, watershed delineation and segmentation, terrain analysis of stream cross section and reservoir storage, and estimation of submerged area for compensation. The modeling algorithms were developed using Python and as an open source GIS. When a user-defined stream point is selected, the model evaluates potential hydroelectric head, reservoir surface area and storage capacity curve, watershed time of concentration from DEM, and compensation area from land use data. The model was tested for 4 locations of already constructed Buhang, BohyunMountain, Sungdeok, and Yeongju dams. The modeling results obtained maximum possible heads of 37.0, 67.0, 73.0, 42.0 m, surface areas of 1.81, 2.4, 2.8, 8.8 ㎢, storages of 35.9, 68.0, 91.3, 168.3×10⁶ ㎥ respectively. BohyunMountain and Sungdeok show validity but in case of Buhang and Yeongju dams have maximum head errors. These errors came from the stream generation error due to ASTGTM. So, wrong dam watershed boundary limit the head. This study showed a possibility to estimate potential hydroelectric dam sites before field investigation especially for overseas project.

• Journal of Korea Water Resources Association
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• v.30 no.5
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• pp.539-548
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• 1997

A physically based model for rainfall runoff simulation in agricultural watershed equipped with tile drains is presented. This model is developed from the TOPMODEL which is based on the detailed topographic information provided by Digital Elevation Model (DEM). Nine possible flow generation scenarios in the tile drained basin are suggested and used in the development of the model. The model can identify the portions of the hydrograph resulting from tile flow, subsurface flow and surface flow. The performance of the model is assessed through a calibration and validation process. The results of the analysis show that the model describes the physical system well and provides a better insight into the hillslope hydrology of agricultural watersheds with tile drainage.