• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.10 no.2
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• pp.49-55
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• 1992

Sampling techniques is very important in digital elevation model. There are scanning and digitizing method of sampling techniques. This study is limited in digitizing method. Continous sampling method use contour lines as same entity and grid method is a direct reading of sample elevation in each grid. Triangulated irregular method is needed to identity topographical lines to sample elevation data. As a results, authors know that continous sampling method has economic in input system and triangulated irregular method has a small memory size.

• Journal of Korean Society for Geospatial Information Science
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• v.14 no.4 s.38
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• pp.61-70
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• 2006

This paper presents photogrammetric processing to generate digital elevation models using SPOT-5 HRG stereo images and deals with the accuracy potential of HRG (High Resolution Geometry) supermode imagery for DEM generation. After bundle adjustment was preformed for sensor modelling, digital surface models were generated through the procedures of Epipolar image resampling and image matching. The DEM extracted from HRG imagery was compared along several test sections with the the refernce DEM which was obtained from the digital topographic maps of a scale of 1 to 5000. The ratio of the zone with DEM errors less than 5m to the whole zone was 53.8%, and about 2.5m RMSE was showed when assuming that the zones larger than 5m were affected by clouds, water bodies and buildings and excluding those zones from accuracy evaluation. In addition, the three-dimensional bird's eye view model and 3D building model were producted based on the DSM which was extracted from SPOT-5 HRG data.

• Water for future
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• v.32 no.3
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• pp.30-35
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• 1999

• Journal of the Korean Association of Geographic Information Studies
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• v.15 no.3
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• pp.36-51
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• 2012

The demand for a climatological dataset with a regular spaced grid is increasing in diverse fields such as ecological and hydrological modeling as well as regional climate impact studies. PRISM(Precipitation-Elevation Regressions on Independent Slopes Model) is a useful method to estimate high-altitude precipitation. However, it is not well discussed over the optimization of PRISM parameters and DEM(Digital Elevation Model) resolution in South Korea. This study developed the PRISM and then optimized parameters of the model and DEM resolution for producing a gridded annual average precipitation data of South Korea with 1km spatial resolution during the period 2000-2005. SCE-UA (Shuffled Complex Evolution-University of Arizona) method employed for the optimization. In addition, sensitivity analysis investigates the change in the model output with respect to the parameter and the DEM spatial resolution variations. The study result shows that maximum radius within which station search will be conducted is 67km. Minimum radius within which all stations are included is 31km. Minimum number of stations required for cell precipitation and elevation regression calculation is four. Optimizing DEM resolution is $1{\times}1km$. This study also shows that the PRISM output very sensitive to DEM spatial resolution variations. This study contributes to improving the accuracy of PRISM technique as it applies to South Korea.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.26 no.2
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• pp.111-116
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• 2008

The study installed non metric camera which was a 10 Mega Pixel camera in RC Helicopter. And the study controlled images hotographed in air on land, considering their overlap. The study could express DEM by abstracting TIN from the acquired images through image registration. Also, the study compared and examined accuracy between reference point and check point observed by Total Station which was a conventional type of survey. As the results, the study could get errors of $-0.194{\sim}0.224\;m$ on X axis, $-0.088{\sim}0.180\;m$ on Y axis and $-0.286{\sim}0.285\;m$ on Z axis. Expressing an error's RMSE in the checkpoint, the study could get of 0.021388 m on X axis, 0.015285 m on Y axis and 0.041872 m on Z axis. It is judged that the above photographing and analyzing technique are better than the existing Total Station to acquire more terrain elevation data.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.494-494
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• 2023

수치모형을 활용하여 하천 흐름을 해석하기 위해서는 하도의 형태를 나타내는 지형자료가 요구되며, 주흐름 방향에 직각 방향으로의 횡단면도는 다량의 자료가 필요하다. 측량을 통한 횡단면도의 확보는 시간과 비용이 많이 소요될 뿐 아니라 날씨와 같은 외부적 요인에 따라 측량 결과물의 정확도가 달라질 수 있다. 또한 하천의 유속이 매우 빠를 때에는 정확도 높은 횡단 측량자료를 얻기는 불가능하며 접근이 어려운 지역이나 중소규모의 하천 측량자료는 구축되어 있지 않은 실정이다. 이에 따라 위성영상과 수치표고모델(Digital Elevation Model, DEM)에 기반하여 하천구역과 하도의 특성을 정의하는 방법이 대안으로 제시되고 있다. 본 연구에서는 하천지형 측량자료가 존재하는 섬진강댐부터 오수천 합류전까지를 대상으로 가상하도 생성기법을 적용하고, 1차원 하천흐름해석을 수행하여 가상하도 구축방안의 유효성을 검토하고자 하였다. 위성영상 자료를 활용하여 하천구역을 정의하였으며 DEM에서 추출된 표고에 기반하여 제방고와 횡단면도를 구축하였다. 구축된 횡단면도와 실단면 비교시, DEM 표고 및 하천구역 정의 지점의 정확도에 따라 제방고가 달라지는 것으로 나타났으며, 홍수터에 대한 고려가 포함되지 않아 실단면과 다소 차이가 있는 것으로 확인된다. 구축한 지형자료를 1차원 하천흐름해석 모형인 K-River에 적용하였으며, 상류단 경계조건으로는 섬진강댐 방류량을 하류단 경계조건으로는 등류조건을 적용하였다. 구축영역 내 존재하는 지류의 유입량은 측방유입으로 고려하였다. 수치모의 결과로부터 구축된 횡단면의 최심고와 실단면의 최심고가 유사한 지점에서는 수위재현성이 양호한 것으로 확인되었다.

• Proceedings of the KSRS Conference
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• 2006.03a
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• pp.19-23
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• 2006

본 연구는 컬러항공사진을 이용하여 컬러영상, 그레이영상 그리고 각 밴드별(RGB) 수치고도모형(DEM)을 생성하여 정확도를 평가하기 위한 것이다. 항공 영상지도의 경우 불과 4-5년 전까지만 해도 흑백항공사진 필름을 이용해 왔으나 최근 들어 판독을 더욱 용이하게 하기 위하여 컬러항공사진을 많이 이용하고 있다. 품질이 높은 정사영상제작을 위해서는 정확한 수치고도모형이 필요하다. 수치고도모형을 생성하기 위한 대표적인 방법으로 수치지도를 이용하는 방법과 영상정합기법을 이용하여 수치고도모형을 생성할 수 있다. 영상정합기법에 의한 수치고도모형 생성 방법은 흑백항공사진에서와는 달리 컬러항공사진은 항공사진 전용 스캐너에서 3개의 밴드(RGB)로 스캔된 영상을 사용한다. 본 연구에서는 수치고도모형의 정확도를 분석하기 위하여 모두 5가지 영상(컬러영상, 그레이영상, Red 영상, Green 영상, Blue 영상)을 획득하였으며 각 밴드별 수치고도모형을 생성하여 수치지도에서 추출된 표고점 자료와의 평균제곱근오차(RMSE) 값을 비교하였다. 본 연구에서는 Red 영상을 이용하는 경우 가장 정확한 수치고도모형을 얻을 수 있었음을 실험을 통해 검증하였다.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.10 no.2
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• pp.25-30
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• 1992

Most algorithms in computer vision and digital photogrammetry assume that digital stereo pairs are registered in epipolar geometry. But, an aerial stereo pair is not likely to be in epiplar geometry since the attitude of the camera at the instant of exposure is different at every exposure station. In this paper, stereo digital imagery is obtained from aerial stereo pair by scanner. Then procesure to resample the digital imagery to epipolar geometry using exterior orientation elements after absolute orientation is described. As a result, a stereo imagery in epipolar geometry is produced from stereo digital imagery. Epipolar imagery in this paper is applied to the image matching method by digital image correlation technique. Then, a digital elevation model is produced from the result of image matching. The digital elevation model in this paper is compared to the other digital elevation model produced by analytical plotter. As a result, an economical method to generate digital elevation model is presented.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.23 no.3
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• pp.251-260
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• 2005

The Development of CCD has contributed to great advancement in mapping technology with giving benefits to research community of photogrammetry. The purpose of this paper is to find the best selection of interpolation method for creating a terrain model form close range digital photogrammetry. T-test as a kind of statistical analysis was conducted to analyze the similarity of hydraulic model with close range digital photogrammetry and trigonometric leveling. Also, many interpolation methods such as inverse distance, kriging, nearest neighbor and TIN about the hydraulic model interpolation were conducted to compare the results for computer to display actual terrain an optimum interpolation of the digital elevation model form close range digital photogrammetry. The results revealed that kriging and TIN interpolation were efficient methods to judge the hazard interpolation law by analyzing geometric similarity of hydraulic model against hydraulic model application.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.24 no.5
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• pp.389-397
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• 2006

The purpose of the present paper is to offer an analysis of LiDAR data processing and three dimensional terrain for Geographic Information System (CIS) applications. Generally, LiDAR survey is the method which obtains quantitative and qualitative information of the terrain using airborne laser scanning (ALS). We will get a most topographic data at a Triangular Irregular Network (TIN), Digital Surface Model (DSM) and Digital Elevation Model (DEM) using LiDAR data. We examined many factors such as visibility, hillshade, aspect and slope using DEM and DSM. The analyzing results obtained from each item are thought to be regarded as leading factors in the terrain analysis. It is to be hoped that LiDAR survey will contribute a new approach to the terrain analysis.