• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.11 no.4
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• pp.145-151
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• 2006

The water line moving on the intertidal flat during a flood indicates depth contours between low and high water lines. The water lines extracted from the consecutive images are rectified to get the ground coordinates of each depth contour and integrated to provide three dimensional information of Intertidal flat topography. The tidal flat outside Saemankeum-1 sea dike shows the most obvious changes of tidal flat topography after the construction of sea dikes. This tidal flat topography was observed using digital camera images, and the calculated depths were very similar to in-situ measurement data. Topography changes obtained from two different period data were also examined.

• Journal of Korean Society for Geospatial Information Science
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• v.18 no.1
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• pp.135-143
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• 2010

The national base map has its value sand roles as the basic spatial information of the nation. The current national base map that is a 1/5,000 digital map, however, has failed to perform its roles as basic spatial information due to the limitations with its quality and accuracy and requires measures to complement them. Thus this study set out to suggest ways to advance the current 1/5,000 national base map, selected topography and natural features of a digital map that could be made with GSD 0.25m digital aerial photographs, and set up the optimal ways to make a digital map by conducting an experiment of making an optimal digital map with such photographs. It also analyzed the map made with GSD 0.25m digital aerial photographs for accuracy and usability. In order to establish a set of criteria of making a digital map with GSD 0.25m digital aerial photographs, the investigator carried out analyses and picked topography and natural features items, which include 9 large categories, 31 medium categories, and 509 small categories. Then an experiment of making a digital map was conducted according to the digital map making method. As a result, solid drawing was selected as the optimal way to making a digital map, and the optimal process was established. Using the research achievements, a model digital map was made with GSD 0.25mm digital aerial photographs. The map recorded about two times horizontal and vertical location accuracy than the old 1/5,000 digital map and was capable of detailed descriptions of topography and natural features. A new national base map made with GSD 0.25m digital aerial photographs will provide reliable spatial data, thus increasing the level of satisfaction among people and the level of advancement of national base maps.

• The Journal of the Korea Contents Association
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• v.8 no.3
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• pp.270-278
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• 2008

This study : An analysis of position accuracy of topography according to using LiDAR data, aerial photo and digital map for a study area was conducted. The study area was selected in Hadan area, Sahagu, Busan aerial LiDAR data and aerial photo in the scales of 1:20,000, which are high tech surveying ways were used. The final digital orthoimage according to orientation process for each image and image resampling was producted. Using it, a checkpoint was chosen, information about the checkpoints selected was extracted, a coordinate of Horizontal Position through the screen digitizing was also extracted. Both the coordinates of LiDAR data and aerial photo using digital map in the scales of 1:20,000 announced to the public from NGII(National Geographic Information Institute) were gradually compared and analyzed. Based on the digital map, as a result of being both compared and analyzed, it has shown to us that horizontal position of aerial photo is more accurate than that of aerial LiDAR surveying (RMSE-building x:24cm, y:26cm).

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.2
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• pp.419-424
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• 2009

This paper show about the possibility of practical application after building VR(virtual reality) data based on Airborne LiDAR data which determines complicated topography quickly for the 3D-GIS construction. In this paper, we collected Airborne LiDAR data, digital map, serial photo and a basic design. The results are expected some effective determination by 3D-GIS construction based on LiDAR data. Hereafter, because the research will be able to be given quickly topography information on ubiquitous environment the field of construction and GIS will be able to be helped.

• 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.20 no.1
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• pp.1-11
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• 2002

This study set up a purpose in the efficient utilization of security target objects. This purpose is the following: Firstly, this study analyzed problem about deleted areas for security described on aerial photography image. Secondly, this study made clustering and labeling to recognize censored areas of image. Finally, this study tried to maximize various utilizability of digital image data through postprocessing algorithm. Based on these courses, the results of this study appeared that brightness value of image increased depending on topography and quantities of topographic features. It was estimated that these was able to utilized by useful estimative data in judging information of topography and topographic features included in the total image. Besides, in the image recognition and postprocessing, the better result value was not elicited than in a mountainous region. Because it was included that a lots of topography and topographic features was similarly recognized with the process for deletion of the existing security target objects in urban and suburb region. This result appeared that the topography and quantities of topographic features absolutely affected the recognition and processing of image.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.1470-1472
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• 2003

Hyperion, as hyperspectral data, is carried on NASA’s EO-1 satellite, can be used in more subtle discrimination on forest cover, with 224 band in 360 ?2580 nm (10nm interval). In this study, Hyperion image is used to investigate the effects of topography on the classification of forest cover, and to assess whether the topographic correction improves the discrimination of species units for practical forest mapping. A publicly available Digital Elevation Model (DEM), at a scale of 1:25,000, is used to model the radiance variation on forest, considering MSR(Mean Spectral Ratio) on antithesis aspects. Hyperion, as hyperspectral data, is corrected on a pixel-by-pixel basis to normalize the scene to a uniform solar illumination and viewing geometry. As a result, the approach on topographic effect normalization in hyperspectral data can effectively reduce the variation in detected radiance due to changes in forest illumination, progress the classification of forest cover.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.23 no.2
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• pp.189-196
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• 2005

Recently as map making skills developed and as digital maps prevailed, peoples began to take interest in the realistic 3dimension topography rather than the flat 2 dimension one. The experiment is done by using the topographical information from the digital maps, To analyze the preciseness of this 3dimension topography, analysis of the coordinate-changed standard map image and the location errors of the plane and height from digital values of the map's topography by layers and features, were done. The visual results of locational values differed by every programs of coordinate transformation. Errors of locations also appeared from the methods of correcting the visual sources, when deciding the standard source's datum point. The plan's accuracy of the image data coordinate transformation is about ${\pm}4.1m$. In ground distance, therefore, it is included in the allowed error of the 1:25,000 scale changed map, satisfying the plan's accuracy. Also, by the use of reasonably spaced grid, it satisfied the visual topographical accuracy. Because the 3 dimension topographical map can be produced effectively and rapidly by using various scale's standard map image and the digital map, the further practical use of 3 dimension topographic map made by using the existing topographies and changed maps has high expectations.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2003.10a
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• pp.391-396
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• 2003

The digital map expresses natural topography and artificial things with 3D position coordinates in the computer such as the road, railway, building, river, mountain, paddy and dryland. Therefore, those should contribute to the information-oriented society by maintaining information and providing it to users quickly. However it is difficult to maintain the most recent topographic information all the time because of restricted budget and time. The purpose of this study is to investigate and analyze the updating area of the digital map using remotely sensed data, and to furnish the useful information reducing cost and time. To predict updating area of the digital map, we applied the urban changes analysis method to Landsat TM images from produced date of the digital map to up-to-date. Classification method for urban change analysis applied single band process algorithm. This study presents that updating area of the digital map is predicted by only the rate of 40% on total research area.

• Proceedings of the Korean Geotechical Society Conference
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• 2004.03b
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• pp.904-909
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• 2004

The study area adjoins with Yangsan fault in Sangbuk-myeon, Samsam-ri, Kyongsang-namdo and consist of the natural steep slope. After drawing data layer which have altitude by using digital topography data, it is converted to lattice DEM of $10m{\times}10m$ size. From this, gradient map of unit lattice, slant direction map and shadow relif map are made. Using flow apportioning algorithm, upper slope contributing area and wetness index by established lattice can be calculated. Area that have high wetness index shows lineament structure of northwest-southeast direction, and this agrees with shear fracture system. The result of electricity specific resistance survey in the study area shows that area of high wetness index has low electricity specific resistance anomaly. That is, wetness index conforms with distribution of fractured zone that accompanied chemical weathering of rock. Therefore, wetness index can be used as the method of detecting fractured zones and judging the stability of the area.