• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2004.11a
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• pp.173-178
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• 2004

This paper presents photogrammetric processing to generate digital elevation models and deals with the accuracy potential of SPOT-5 HRG supermode imagery for DEM generation. The DEMs obtained from digital topographic maps of 1/5000 scale were used as the refernce DEM data. DEMs extracted from HRG dats were compared with digital topograpic map DEMs on severed test sections. And digital surface model(DSM), refering to above the ground like buildings, was produced about the test built-up area.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2004.11a
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• pp.519-522
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• 2004

The purpose of this research is to design a road using digital photogrammatry method to generate DEM(digital elevation model) and digital ortho image based on GSIS which was applied to the road simulation. The example study area was the suburbs of Jeju city. To this study, 1/5,000 digital map and GSIS technique were used for optimum road design of the island based on Arc View software. Using this software we can Set an overlay map by combination of hill shade map, slope map, aspect map, and building buffer map. Based on this overlap map, we designed the best road line and along this line we performed three dimensional road simulation using Microstation CAD and Inroads road design programs. From the results, we found that the DEM and digital ortho image acquired from stereoairphoto using digital photogrammatry was satisfied for choosing the best roadline and the developed three dimensional road simulation technique using GSIS technique was very useful to estimate the reasonable road design before the real road construction works.

• Journal of Environmental Science International
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• v.25 no.8
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• pp.1165-1176
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• 2016

The accuracy of digital elevation models (DEMs) is crucial for properly estimating flood inundation area. DEM pixel size is especially important when generating flood inundation maps of small streams with a channel width of less than 50 m. In Korea, DEMs with large spatial resolutions of 30 m have been widely applied to generate flood inundation maps, even for small streams. Additionally, when making river master plans, field observations of stream cross-sections, as well as reference points in the middle of the river, have not previously been used to enhance the DEM. In this study, it was graphically demonstrated that high-resolution DEMs can increase the accuracy of flood inundation mapping, especially for small streams. Also, a methodology was proposed to modify the existing low-resolution DEMs by adding additional survey reference points, including river cross-sections, and interpolating them into a high spatial resolution DEM using the inverse distance weighting method. For verification purposes, the modified DEM was applied to Han stream on Jeju Island. The modified DEM showed much better accuracy when describing morphological features near the stream. Moreover, the flood inundation maps were formulated with the original 30 m pixel DEM and the modified 0.1 m pixel DEM using HEC-RAS modeling of the actual flood event of Typhoon Nari, and then compared with the flood history map of Nari. The results clearly indicated that the modified DEM generated a similar inundation area, but a very poor estimate of inundation area was derived from the original low-resolution DEM.

• Korean Journal of Geomatics
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• v.3 no.2
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• pp.107-114
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• 2004

The National Geographic Information Institute (NGII) in korea, through the National Geographic Information System (NGIS) Program, has prepared to generate and disseminate digital elevation data for Korea. This is a pilot research to propose a policy for production, maintenance, and supply of Korea Digital Elevation Data(KDED). Customer demands for accuracy and resolution of DEM was surveyed through a questionnaire. In order to investigate the quality, the technical efficiency and the production cost, a tentative DEM in a small test site was generated based on digital topographic maps (original paper map scale 1:5,000), analytical plotter, and LIDAR. The Accuracy standard for KDED was derived based on source data generation methods. As a result of this research, a uniformly spaced grid model was recommended for KDED. Its preferable grid space is 5m in urban areas and its vicinity, and 10m in field and mountainous area. LIDAR has been valuated as a proper KDED generation method fulfilling customers' demands for the accuracy.

• Journal of Korean Society for Geospatial Information Science
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• v.15 no.4
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• pp.3-9
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• 2007

Recently, the efforts of systematic understanding and utilization of geographic phenomenon for human life as a important factor among activity of mankind are increasing. It is necessary to express topography connected with space. Especially, the technology of geographic analysis using DEM can supply the information rapidly and accurately about elevation and terrain slope of the subject area under the necessity of high 3D quality geographic information. In this study, creating more precise DEM derived from LiDAR data, quantitative analysis on the subject area about elevation and terrain slope is done under comparison with Digital Topographic map Scale 1:1000. LiDAR data is more detailed than Digital Topographic map to express the elevation of the subject area ($39.89{\sim}77.48m$), and terrain slope by analysis using DEM derived from LiDAR data come out minutely about 90%. It can be concluded that the LiDAR data is very applicable and accurate for 3D topographic terrain slope analysis.

• Journal of Industrial Technology
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• v.25 no.B
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• pp.47-54
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• 2005

The goal of this study is to generate a landslide potential map using GIS(Geographic Information System) based method. A simple and efficient algorithm is proposed to generate a landslide potentialities map from DEM(Digital Elevation Model) and existing maps. The categories of controlling factors for landslides, aspect of slope, soil, vegetation are defined. The weight value for landslide potentialities is calculated from AHP(Analytic Hierarchy Process) method. Slope and Slope-direction is extracted from DEM, and soil information is extracted from digital soil map. Also, vegetation information is extracted from digital vegetation map. Finally, as overlaying, landslide potentialities map is made out, and it is compared with landslide place.

• Korean Journal of Remote Sensing
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• v.17 no.2
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• pp.121-129
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• 2001

A DEM(digital elevation model) is generated from a SPOT panchromatic stereo-pair using automated algorithms over a 8 km$\times$10 km region around Mokpo city. The aims are to continue the accuracy assessment over diverse conditions and to examine the applicability of a SPOT DEM for coastal disaster monitoring. The accuracy is assessed with respect to three reference data sets: 10 global positioning system records, 19 leveling data, and 1:50,000 topography map. The planimetric error is 10.6m r.m.s. and the elevation erroer ranges from 12.4m to 14.4m r.m.s.. The DEM accuracy of the flat Mokpo region is consistent with that over a mountainous area, which supports the robustness of the algorithms. It was found that coordinate transformation errors are significant at a few meters when using the data from leveling and topographic maps. The error budget is greater than the requirements for coastal disaster monitoring. Exploiting that a sub-scene is used, the affine transformation improves the accuracy by 50% during the camera modeling.

• 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.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.20 no.2
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• pp.127-136
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• 2002

DEM(Digital Elevation Model) is used widely in image processing, water resources, construction, GIS, landscape architecture, telecommunication, military operations and other related areas. And it is used especially in producing ortho-photo based on specific DEM and developing 3D GIS database vividly. As LiDAR(Light and Detection And Ranging) system emerged recently, DEM could be developed in urban area more efficiently and more economically, compared to the conventional DEM Production. Traditional method using check points for elevation has tome limitations in structure's height accuracy by LiDAR, because it uses only terrain height. Accordingly after the downtown of Chungju city was selected as a test field in this paper and DEM and digital ortho images was produced by way of LiDar survey, the accuracy was evaluated through analytical plotting map. The result shows that in case of buildings in LiDAR DEM, the accuracy is 0.30 m in X, 0.62 m in Y and RMS is 1.17 m. The difference distribution between DEM and plotting map in range of $\pm$10 cm was 36.2% and $\pm$10 cm $\pm$20 cm was 43.53%. The accuracy of LiDAR in this study meets 1/5,000 which is the regulation for map of NGI(National Geography Institute) and LiDAR can be possibly used in many other applied area.

• 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.