• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2005.11a
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• pp.81-104
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• 2005

Accurate 3D models in urban areas are essential for a variety of applications, such as virtual visualization, CIS, and mobile communications. LiDAR(Light Detection and Ranging) is a relatively new technology for directly obtaining 3D points. Because Manual 3D data reconstruction from LiDAR data is very costly and time consuming, many researchs is focused on the automatic extraction of the useful data. In this paper, we classified ground and non-ground points data from LiDAR data by using filtering, and we reconstructed the DTM(Digital Terrain Model) using ground points data, buildings using nonground points data. After the reconstruction, we assessed the accuracy of the DTM and buildings. As a result of, DTM from LiDAR data were 0.16m and 0.59m in high raised apartments areas and low house areas respectively, and buildings were matched with the accuracy of a l/5,000 digital map.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.29 no.6
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• pp.687-695
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• 2011

Many internet portals provide maps with spatial information services. Recently, various images including aerial, satellite, street view, and photo-realistic 3D city models are provided as well as maps. This study suggested a method for geometric correction of the panoramic aerial images in the internet portal and 3D building modeling using information which is available in the internet. The key of this study is to obtain all necessary data easily from internet without restrictions. Practically, the ground control coordinates could be available from geo-referenced internet maps, and stereo pairs of the aerial images and close-range photographs for photo-realistic object modeling are provided by the internet service. However, the ground control points are not suitable for accurate mapping. RMSE of the plotting was about 9 meters and reduced upto 4 meters after coordinate transformation. The proposed methods would be applicable to various applications of photo-realistic object modeling which do not require high accuracy.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.5
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• pp.607-617
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• 2014

This paper proposed the M&S(Modeling & Simulation) method of channel characterization of satellite communication in the operating area of satellite OTM(On-The-Move) terminal. In M&S, received signal profile was acquired by HTZ warfare software which uses 3 dimensional map including building, road information and geographical features, and then was analyzed statistically. And a received signal profile and its statistics from M&S data were compared with those from measured data. The research showed that the simulated received signal profile matched the measured one about 74.8 percent and simulated statistics matched well as roadside trees were excluded.

• Journal of the Korean GEO-environmental Society
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• v.22 no.2
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• pp.35-39
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• 2021

Photogrammetry using drone can produce high-resolution ortho image and acquire high-accuracy 3D information, which is useful. Therefore, this study attempted to determine the possibility of using drone-photogrammetry in park construction by producing a topographic map using drone-photogrammetry and analyzing the problems and accuracy generated during production. For this purpose, we created ortho image and DSM (digital surface model) using drone images and created topographic status map by vectorizing them. Accuracy was compared based on topographic status map by GPS (global positioning system) and TS (total station). The resulting of analyzing mean of the residuals at check points showed that 0.044 m in plane and 0.066 m in elevation, satisfying the tolerance range of 1/1,000 numerical maps, and result of compared lake size showed a difference of about 4.4%. On the other hand, it was difficult to obtain accurate height values for terrain in which existed vegetation when producing the topographic map, and in the case of underground buried objects, it is not possible to confirm it in the image, so direct spatial information acquisition was necessary. Therefore, it is judged that the topographic status map using drone photogrammetry can be efficiently constructed if direct spatial data acquisition is achieved for some terrain.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.12
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• pp.1095-1100
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• 2007

Visibility of the satellite navigation is related to a environmental condition of a receiver. Obstacles like buildings and trees in urban areas can block signals and have effects on accuracy and reliability of positioning. This paper presents a method of creating 3D analysis model of urban canyon of Seoul using three-Dimensional digital map. Analysis techniques of visible satellites with Ray-Polygon Collision Detection and validation of algorithm through field tests are discussed. We have compared and analyzed the visibility of GPS and Galileo with respect to separate and simultaneous tracking in view of DOP (Dilution of Precision) using the 3D GIS digital map.

• Journal of the Korea Institute of Military Science and Technology
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• v.9 no.1 s.24
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• pp.72-79
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• 2006

This study was focused on analyzing mathematical model for optimal allocation of surveillance equipment which is operated on the natural geographical condition, such as DMZ fence area. Optimal allocation algorithm was studied for the equipment to develop the whole surveillance and watch model for the two area as testing. Also 3D visualization program was developed to display and analyze the detecting effect. The results show that our suggested model will be available for enhancing security condition on the watching area.

• Journal of Korean Society for Geospatial Information Science
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• v.19 no.1
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• pp.97-103
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• 2011

LiDAR system has become a popular tool for generating 3D surface data such as Digital Surface Model. Extraction of valuable information, such as digital building models, from LiDAR data has been an attractive research subject. This research addresses to extract planar patches from LiDAR data. Planar patches are important primitives consisting of man-made objects such as buildings. In order to determine the best fitted planes, this research proposed a method to reduce/eliminate the impact of the outliers and the intersection areas of two planes. After finishing plane fitting, planar patches are segmented by pseudo color values which are calculated by determined three plane parameters for each LiDAR point. In addition, a segmentation procedure is conducted using the pseudo color values to find planar patches. This paper evaluates the feasibility of the proposed method using both airborne and terrestrial LiDAR data.

• Korean Journal of Remote Sensing
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• v.30 no.5
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• pp.617-625
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• 2014

The Rational Function Model has been used as a replacement sensor model in most commercial photogrammetric systems due to its capability of maintaining the accuracy of the physical sensor models. Although satellite images with rational polynomial coefficients have been used to determine three-dimensional position, it has limitations in the accuracy for large scale topographic mapping. In this study, high resolution stereo satellite images, QuickBird-2, were used to investigate how much the three-dimensional position accuracy was affected by the No. of ground control points, polynomial order, and distribution of GCPs. As the results, we can confirm that these experiments satisfy the accuracy requirements for horizontal and height position of 1:25,000 map scale.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.235-235
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• 2021

아시아 몬순기후의 영향에 의해 우리나라는 2020년 7월부터 9월까지 약 90일간의 장마로 인해 크고 작은 수재해가 발생하였다. 특히, 안성, 충주, 음성 그리고 곡성 등에서 인명피해가 발생하였으며, 그 외 13개소에서 많은 재산 피해가 발생하였다. 2020년 산사태/토석류 재해로 인한 전국적인 피해액은 약 3,900억으로 보고되고 있으며, 매년 집중호우에 의해 피해 양상이 변하고, 도시지역에서의 발생이 빈번하게 늘고 있다. 집중호우에 의한 산사태/토석류 전이 피해를 저감시키기 위해서는 발생 물질이 어디까지 이동할 수 있는지에 대한 위험범위확산에 대한 연구가 중요하며, 이런 연구를 기반으로 인명피해를 줄이기 위한 연구가 필요하다. 이를 위해 본 연구에서는 천수방정식, 유변학특성 식 그리고 연행침식 식을 조합하여 개발된 적응형 격자기반 2차원 토석류 모델을 이용하여 안성, 음성 그리고 단성지역에서 발생했었던 산사태/토석류 전이 피해 양상을 해석하였다. 산사태 발생 후 2~3일 이내에 지표 지질 및 지형 조사를 실시하였으며, UAV 및 항공사진을 이용하여 산사태 및 토석류의 형태를 맵핑하였다. 지질 및 지형조사 시 간이 Vein tester를 이용하여 야외에서 토양 물성관련 자료를 취득하였으며, 토석류의 이동 흔적(나무 등에의 토석류 타격 흔적)을 이용하여 조사지점에서의 최대 토석류 흐름 깊이를 추정하였다. 정확한 토석류의 유속에 대한 자료 부족으로 2011년 우면산에서 발생한 약 26m/s의 속도를 이용하여 토석류의 흐름 특성을 계산하였다. 이와 더불어 연행침식의 계산을 위해 발생지점 부터 토석류가 퇴적된 하류부까지 기반암의 노출 및 퇴적 정보를 통해 최대 침식 깊이를 추정하여 입력자료로 활용하였다. 토석류 맵핑자료와 비교 결과 정확도가 90%이상으로 나타났으며, 토석류 발생 후 안성 200초, 음성 180초 그리고 단성 180초 이내로 토석류가 하류까지 이동할 수 있는 것으로 계산되었다. 본 연구와 같이 산사태/토석류 발생 메커니즘 해석에 대한 지속적인 연구를 통해 산지 재해에 의한 인명 피해를 줄일 수 있는 토석류확산범위 해석에 대한 연구가 지속적으로 필요할 것으로 판단된다.

• Fire Science and Engineering
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• v.22 no.2
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• pp.63-69
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• 2008

The characteristics of the spread of a forest fire are generally related to the attributes of combustibles, geographical features, and meteorological conditions, such as wind conditions. The most common methodology used to create a prediction model for the spread of forest fires, based on the numerical analysis of the development stages of a forest fire, is an analysis of heat energy transmission by the stage of heat transmission. When a forest fire breaks out, the analysis of the transmission velocity of heat energy is quantifiable by the spread velocity of flame movement through a physical and chemical analysis at every stage of the fire development from flame production and heat transmission to its termination. In this study, the formula used for the 1-D surface forest fire behavior prediction model, derived from a numerical analysis of the surface flame spread rate of solid combustibles, is introduced. The formula for the 1-D surface forest fire behavior prediction model is the estimated equation of the flame spread velocity, depending on the condition of wind velocity on the ground. Experimental and theoretical equations on flame duration, flame height, flame temperature, ignition temperature of surface fuels, etc., has been applied to the device of this formula. As a result of a comparison between the ROS(rate of spread) from this formula and ROSs from various equations of other models or experimental values, a trend suggesting an increasing curved line of the exponent function under 3m/s or less wind velocity condition was identified. As a result of a comparison between experimental values and numerically analyzed values for fallen pine tree leaves, the flame spread velocity reveals a prediction of an approximately 10% upward tendency under wind velocity conditions of 1 to 2m/s, and of an approximately 20% downward tendency under those of 3m/s.