• Proceedings of the Korea Water Resources Association Conference
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• 2006.05a
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• pp.204-208
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• 2006

This study is to develop a distributed urban flood runoff model that simulates the road runoff and to test the applicability of the model by applying to Pyeongtaek city of $12.2km^2$. To generate the runoff along the runoff, agree burned DEM (Digital Elevation Model) with road networks was suggested and the proper spatial resolution of DEM was identified finer than 15 m. To test the model applicability, 32 points on the road networks were selected and the hydrographs of each point were generated. The test showed reasonable results that increase the road runoff from the high elevation roads to the low elevation roads and the road runoff considering rainwater drainage from the road also showed reasonable results.

• Korean Journal of Remote Sensing
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• v.13 no.1
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• pp.57-73
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• 1997

This paper is related to the correction of radiometric distortions induced by topographic relief. RADARSAT SAR image data were obtained over the mountainous area near southern part of Seoul. Initially, the SAR data was geometrically corrected and registered to plane rectangular coordinates so that each pixel of the SAR image has known topographic parameters. The topographic parameters (slope and aspect) at each pixel position were calculated from the digital elevation model (DEM) data having a comparable spatial resolution with the SAR data. Local incidence angle between the incoming microwave and the surface normal to terrain slope was selected as a primary geometric factor to analyze and to correct the radiometric distortions. Using digital maps of forest stands, several fields of rather homogeneous forest stands were delineated over the SAR image. Once the effects of local incidence angle on the radar backscatter were defined, the radiometric correction was performed by an empirical fuction that was derived from the relationship between the geometric parameters and mean radar backscatter. The correction effects were examined by ground truth data.

• Journal of the Korean Association of Geographic Information Studies
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• v.21 no.2
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• pp.34-43
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• 2018

DEM(Digital Elevation Model) being fundamental data in geospatial domain is produced from different data and using various methods. As they are derived their precision varies and altering derivative in application. In this work, we compare two widely used DEMs namely(Advanced Land Observing Satellite World 3D 30m and Shuttle Radar Topography Mission Global 30m) around coastal islands in Gyeongsangnam-do, South Korea. First statistics of each DEM were calculated and later overlapped in Landsat image for visual comparison of areas below and above zero-meter elevation. As a result, it was found that DEMs were highly correlated with each other and had similar statistics. Besides having few high differences in hilly land area, they were able to represent the coastal lines. It has also been noted that they have many negative values and should carefully select study area covering full watershed in coastal regions to avoid negative elevation even after filling the sinks.

• Korean Journal of Remote Sensing
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• v.34 no.3
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• pp.545-552
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• 2018

Grounding line is used as evidence of the mass balance showing the vulnerability of Antarctic glaciers and ice shelves. In this research, we utilized a high resolution digital elevation model of glacier surface derived by recently launched satellites to estimate the position of grounding line of Campbell Glacier in East Antarctica. TanDEM-X and TerraSAR-X data in single-pass interferometry mode were acquired on June 21, 2013 and September 10, 2016 and CryoSat-2 radar altimeter data were acquired within 15 days from the acquisition date of TanDEM-X. The datasets were combined to generate a high resolution digital elevation model which was used to estimate the grounding line position. During the 3 years of observation, there weren't any significant changes in grounding line position. Since the average density of ice used in estimating grounding line is not accurately known, the variations of the grounding line was analyzed with respect to the density of ice. There was a spatial difference from the grounding line estimated by DDInSAR whereas the estimated grounding line using the characteristics of the surface of the optical satellite images agreed well when the ice column density was about $880kg/m^3$. Although the reliability of the results depends on the vertical accuracy of the bathymetry in this study, the hydrostatic ice thickness has greater influence on the grounding line estimation.

• Proceedings of the KSRS Conference
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• 1999.11a
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• pp.343-348
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• 1999

Delineation of watersheds is one of the most basic steps for water resource management and National Park management. The purpose of this study is to investigate how to utilize Thematic Mappers scenes to compare watersheds created by running a model with those produced by digitizing topographic maps of Keum River basin. A methodology is designed and tested using Geographic Information Systems (GIS) and remote sensing to map areas with various thematic maps. A CAD data on watersheds from the Decision Support system for Water Quality is converted into GIS format. The digital elevation model with 100-meter resolution is used to create watershed by cumulative watershed method. TM scenes are also classified by new procedures including stacking method, NDVI, NDWI, and unsupervised classification methods. To evaluate the relative correctness Kyerongsan National Park was studied intensively whose area was divided into 6 watersheds in both cases. The boundaries of watershed from the model are less correct than those of the topographic maps. This result shows that automated watershed creating system needs higher-resolution digital elevation model than 100-meters.

• Spatial Information Research
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• v.13 no.1 s.32
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• pp.43-53
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• 2005

This paper presents tile modeling of non-point source pollutants runoff and its desirable water environmental management to closed waterbody. To obtain spatially distributed environmental information, fro have used contour data to extract stream channels automatically and to divide networks of watershed. A Quasi Digital Elevation Model (DEM) has been developed, validated, and adopted to estimate the runoff of total nitrogen pollutant from watershed. The GIS-linked model can be applied effectively to the non-point source pollutants from watersheds considering water conditions in receiving waters. It will be useful to manage water environment in receiving waters.

• Proceedings of the KSRS Conference
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• 2008.10a
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• pp.14-17
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• 2008

KOMPSAT-2 is the seventh high-resolution satellite in the world that provides both 1m panchromatic images and 4m multispectral images of the GSD. It is expected to be used across many different fields including digital mapping, territorial and environmental monitoring. However, due to the complexity and security concern involved with the use of the MSC, the use of KOMPSAT-2 images are limited in terms of geometric data, such as satellite orbits and detailed mapping information. This study aims to generate the DEM and orthoimage by using the stereo images of KOMPSAT-2 and to explore the applicability of geo-spatial information with KOMPSAT-2. In order to ensure generation of DEMs of optimal accuracy, the RPCs data and a suitable number of GCPs were used. The accuracy of DEM generated in this research compared with DEM generated from 1:5,000 digital map. The mean differences between horizontal position of the orthoimage and the digital map data are found to be ${\pm}$3.1m, which is in the range of ${\pm}$3.5m, within the permitted limit of a 1:5,000 digital map. The results suggest that DEM can be adequately used to produce digital maps under 1:5,000 scale.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.15 no.2
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• pp.1-8
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• 2007

In this research, algorithm and software for the medium frequency signal analysis of DGPS(Differential Global Positioning System) station were developed. Based on new MF(Medium Frequency) algorithm, the software of NDGPS(National DGPS) signal analysis was developed for coverage analysis. Predicted MF propagation data from this software was compared to the measurement data for the verification of a developed MF algorithm. GIS(Geographic Information System) techniques including digital map with elevation data were used because MF propagation is closely related to ground conductivity, mountains, building intensity.

• Journal of Platform Technology
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• v.11 no.4
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• pp.13-18
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• 2023

3D content rendering is one of the important factors that give a sense of realism when creating content, and this process takes a lot of time. In this paper, we proposed a method to improve rendering performance by reducing the vast amount of 3D data in the web environment, and conducted a performance test using DEM and 3D model elevation data. As a result of the experiment, the digital elevation model showed faster performance than the Blender-based 3D modeling, but when the screen was moved using OrbitControl, the fps dropped momentarily. In the case of Terrain, if the range is limited to a speed that maintains 24 to 60 fps using frustum culling and LOD techniques, it is considered that a higher quality map can be produced than GeoTIFF.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2003.10a
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• pp.403-409
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• 2003

LiDAR(Light Detection and Ranging) is considered to be a very accurate and useful tool for detection and reconstruction of ground objects. LiDAR data has information about both intensity and x,y,z position of the ground objects. LiDAR data can be collected from both first and last-return, which are called multi-return, with up to 5 different returns simultaneously. In this paper, an approach to reconstruct buildings in urban area using LiDAR multi-return data is presented. The reconstructed buildings are combined with DEM(Digital Elevation Model) produced from DSM(Digital Surface Model) in given area to implement 3D modeling. As a result, it is shown that buildings in urban area can be reconstructed and classified by the integration of the multi-return and intensity data of LiDAR.