• Spatial Information Research
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• v.14 no.3 s.38
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• pp.321-334
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• 2006

3D spatial data are of increasing interest in landscape analysis, urban planning and map services based on Web, because of its reality. But the amount of 3D spatial data are very large in comparison with 2D spatial data. Therefore it is necessary to have a efficient methods to transfer and visualize 3D spatial data. The concept of Level of Detail in Computer Graphics is effective. This paper briefly presents two LOD data models of data transmission based on the spatial data model of international standards. First, it is separated LOD model that gives a LOD level to object. Second is Selective LOD model that gives a LOD level to object's element. We compared the efficiency of 3D data transmission based on two LOD model.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.28 no.1
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• pp.117-124
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• 2010

Lots of changes in Weolmido have occurred in the historical and cultural aspects owing w the geographical features. This study aims at restoring Weolmido to the past shape three-dimensionally and analyzing its changes. For achieving this goal, I made use of paper maps made in 1918, 1928, and 1969, a digital map produced in 2008, and aerial photos photographed in 1954. And I attempted to grasp the architectural shape and the topographical limn by using photos in those times and put them to practical use for restitution. Image restitution was carried out under the method of mapping and photogrammetry. As the result of restitution, I could restore each shape of Weolmido for those past times to the original condition three-dimensionally and catch its changes according to the difference of times.

• Journal of the Korea Computer Graphics Society
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• v.13 no.4
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• pp.21-27
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• 2007

The 3D Delaunay triangulation is the most widely used method for the mesh creation via the triangulation of a 3D point cloud. However, the method involves a heavy computational cost and, hence, in many interactive applications, it is not appropriate for surface triangulation. In this paper, we propose an efficient triangulation method to create a surface mesh from a 3D point cloud. We divide a set of object points into multiple subsets and apply the 2D Delaunay triangulation to each subset. A given 3D point cloud is cut into slices with respect to the OBB(Oriented Bounding Box) of the point set. The 2D Delaunay triangulation is applied to each subset producing a partial triangulation. The sum of the partial triangulations constitutes the global mesh. As a postprocessing process, we eliminate false edges introduced in the split steps of the triangulation and improve the results. The proposed method can be effectively applied to various image-based modeling applications.

• Journal of KIISE:Databases
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• v.30 no.2
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• pp.157-167
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• 2003

Spatial relations among objects we one of the most frequently used searching criteria for a query based on the contents of 3-D images. However, the existing researches have mainly focused only the absolute directional relations based on a fixed viewpoint in 2-D images. So, this paper presents a representation method of viewpoint based directional relations that enables spatial relations among objects to be retrieved based on a viewpoint of an observer. The retrieval technique based on our method is a]so described. In this paper, the notion of 3D string is defined to express the spatial relations in a 3-D space. A retrieval method based on relative directional relations among objects from a viewpoint of an observer is also presented. The proposed method simplifies the retrieval of viewpoint-based directional relations because 2D+1D scheme reduces the dimension.

• Journal of Korea Society of Industrial Information Systems
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• v.13 no.1
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• pp.11-21
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• 2008

Recently, it has shown an increased interest in 3D stereoscopic contents due to the development of the digital image media. Therefore, many techniques in 3D stereoscopic image generation have being researched and developed. However, it is difficult to generate high immersion and natural 3D stereoscopic contents, because the lack of 3D geometric information imposes restrictions in 2D image. In addition, control of the camera interval and rendering of the both eyes must be repetitively accomplished for the stereo effect being high. Therefore, we propose integrated editing system for 3D stereoscopic contents production using a variety of images. Then we generate 3D model from projective geometric information in single 2D image using image-based modeling method. And we offer real-time interactive 3D stereoscopic preview function for determining high immersion 3D stereo view. And then we generate intuitively 3D stereoscopic contents of high-quality through a stereoscopic LCD monitor and a polarizing filter glasses.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.25 no.2
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• pp.165-175
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• 2007

Nowadays, architecture in urban areas is dominated by the goal of spanning wide spaces and creating openings large enough to distribute daylight to building interiors. Daylight availability of building in city strongly depends not only on the building's height but also on spaces between buildings. Recently numbers of disputes over the daylight availability are increasing in high density developed areas because residents' demand for pleasant residential environment is getting stronger. Therefore in this study we constructed the three-dimensional information of buildings using LiDAR data connected with digital map and then suggested conclusions by applying it to daylight availability analysis. This study presents an approach to judge accurately the violation of a right to enjoy sunshine by using altitude and azimuths of the sun, simulating three-dimensional urban space precisely, and classifying the total duration of sunshine and the continuous duration of sunshine each householder. We expect that local government performs precisely the confirmation and permission business about urban planning and design by advising this approach.

• Journal of the Korean Institute of Intelligent Systems
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• v.15 no.1
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• pp.42-47
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• 2005

In this papcr, we address the 3D reconstruction of the indoor circumstance using what the data is extracted by a pall of image from Stereo Camera. Generally sucaking, there arc three methods to extract 3-Dimensional data using IR sensor, Laser sensor and Stereo camera sensor. The best is stereo camera sensor which can show a high performance at a reasonable price. We used 'Window Correlation Matching Method' to extract 3-Dimensional data in stereo image. We proposed new Method to reduce error data, said 'Histogram Weighted Hough Transform'. Owing to this mettled, we reduced error data in each stereo image. So reconstruction is well done. 3-Dimensional Reconstruction is accomplished by using the DirectX that is well known as 3D-Game development tool. We show that the stereo camera can be not only used to extract 3-dimensional data but also applied to reconstruct the 3-Dimensional circumstance. And we try to reduce the error data using various method.

• 한국방재학회:학술대회논문집
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• 2009.02b
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• pp.74.1-74.1
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• 2009

• 한국공간정보시스템학회:학술대회논문집
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• 2007.06a
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• pp.313-317
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• 2007

도시 소음이 미치는 경제적, 사회적 영향이 커짐에 따라 최근 도시소음에 대한 관심이 높아지고 있다. 그러나 기존의 2차원 소음지도를 통해서는 점점 복잡해지고 대규모화 되어 가는 건물의 각 공간에 대한 소음분석 및 시각화에 한계가 있다. 따라서 본 연구에서는 소음데이터의 3차원 시각화 및 공간별 소음분석을 위해 토폴로지가 부여된 3차원 GIS 데이터 모델을 제시하였다. 건물의 각 공간을 볼륨과 벽체들로 구성하고 공간간의 토폴로지를 부여하기 위해 DB에서 관계를 정의해주고 DB의 볼륨테이블과 벽체테이블에 저장된 소음데이터를 이용하여 3차원 소음분석 및 시각화가 가능하도록 하였다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.8B
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• pp.1152-1160
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• 2001

본 논문에서는 수동주사로 얻은 2차원 연속 프레임으로 3차원 초음파 영상 재구성을 위한 연속 프레임의 프레임간 거리 추정 방법을 제안하였다. 수동주사로 얻은 연속 프레임은 프레임간 거리가 불균일하기 때문에 이를 그대로 3차원 영상으로 재구성하면 실제 인체 장기의 형태와 다른 영상을 얻게 된다. 제안한 알고리듬에서는 연속 프레임의 프레임간 거리를 추정하기 위하여 매 프레임의 블록별 측면거리 상관함수를 얻고, 측면거리 상관함수들이 프로브의 진행축과 초음파 센서의 배열축이 이루는 평면상에서 등방성을 가진다는 가정 하에 인접 프레임 내의 각 블록간의 프레임간 거리를 추정하였다. 인접 프레임간 추정거리는 프레임 내에서 블록단위로 추정된 프레임간 거리를 평균하여 얻었다. 실험 결과, 제안한 알고리듬의 프레임간 추정거리 곡선은 기준 진행거리 상관함수를 이용한 방법의 추정거리 곡선에 비해서 실제 프레임간 거리 곡선에 가까웠고, SNR 비교에서 제안한 방법이 기존의 방법에 비해 좋은 결과를 보였다. 그리고, 기존의 알고리듬에 비해 제안한 알고리듬으로 재구성한 3차원 영상이 원영상에 더 흡사한 것을 볼 수 있었다.