• The KIPS Transactions:PartB
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• v.14B no.3 s.113
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• pp.171-182
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• 2007

We propose a simple method for tracking a nonparameterized subject contour in a single video stream with a moving camera and changing background. Then we present a method to eliminate the tracked contour object by replacing with the background scene we get from other frame. First we track the object using LOD (Level-of-Detail) canny edge maps, then we generate background of each image frame and replace the tracked object in a scene by a background image from other frame that is not occluded by the tracked object. Our tracking method is based on level-of-detail (LOD) modified Canny edge maps and graph-based routing operations on the LOD maps. We get more edge pixels along LOD hierarchy. Our accurate tracking is based on reducing effects from irrelevant edges by selecting the stronger edge pixels, thereby relying on the current frame edge pixel as much as possible. The first frame background scene is determined by camera motion, camera movement between two image frames, and other background scenes are computed from the previous background scenes. The computed background scenes are used to eliminate the tracked object from the scene. In order to remove the tracked object, we generate approximated background for the first frame. Background images for subsequent frames are based on the first frame background or previous frame images. This approach is based on computing camera motion. Our experimental results show that our method works nice for moderate camera movement with small object shape changes.

• Korean Journal of Computational Design and Engineering
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• v.10 no.6
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• pp.444-454
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• 2005

Recently, the requirements of multi-resolution models of a solid model, which represent an object at multiple levels of feature detail, are increasing for engineering tasks such as analysis, network-based collaborative design, and virtual prototyping and manufacturing. The research on this area has focused on several topics: topological frameworks for representing multi-resolution solid models, criteria for the level of detail (LOD), and generation of valid models after rearrangement of features. As a solution to the feature rearrangement problem, the new concept of the effective zone of a feature is introduced in the former part of the paper. In this paper, we propose a feature-based non-manifold modeling system to provide multi-resolution models of a feature-based solid or non-manifold model on the basis of the effective feature zones. To facilitate the implementation, we introduce the class of the multi-resolution feature whose attributes contain all necessary information to build a multi-resolution solid model and extract LOD models from it. In addition, two methods are introduced to accelerate the extraction of LOD models from the multi-resolution modeling database: the one is using an NMT model, known as a merged set, to represent multi-resolution models, and the other is storing differences between adjacent LOD models to accelerate the transition to the other LOD. We also suggest the volume of the feature, regardless of feature type, as a criterion for the LOD. This criterion can be used in a wide range of applications, since there is no distinction between additive and subtractive features unlike the previous method.

• 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 Digital Contents Society
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• v.9 no.3
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• pp.509-516
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• 2008

We propose the Hybrid Rendering model to support multi-resolution for computer graphics. LOD method for computer graphics system considering performance of device environment and end-user preference usually adopts mesh resolution, mipmap in texture rendering, or oct-tree data structure in ray tracing. The hybrid rendering model, as a local shading model combining Gouraud shading model and a flat shading model, applies a proper shading method to each of polygons consisting of an object. This method can be an effective alternative to reduce real-time rendering time so that it can be utilized in real time adaptive service of computer graphic contents among various device environments under ubiquitous environments.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.828-831
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• 2005

In feature-based multi-resolution modeling, the features are rearranged according to a criterion for the levels of detail (LOD) of multi-resolution models. In this paper, two different LOD criteria are investigated and discussed. The one is the volumes of subtractive features, together with the precedence of additive features over subtractive features. The other is the volumes of features, regardless of whether the feature types are subtractive or additive. In addition, the algorithms to define and extract the LOD models based on the criteria are also described. The criterion of the volumes of features can be used for a wide range of applications in CAD and CAE in virtue of its generality.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.32 no.2
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• pp.143-151
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• 2014

As the interest in indoor space increases, the demands for various services based on indoor space is increasing. With the demands, to construct spatial information for indoor space is also required, but there is not defined the LOD(Level of Detail) for indoor spatial data. Therefore, in this paper we classified data for indoor space data construction, and then we defined the accuracy and detail about the level of detail to provide suitable application services according to the type and representation method of each data. Most previous researches are focus on the geometrical representation, but in this paper we define a indoor LOD model based on type and representation method of data. In addition, we present applicable services with proposed LOD model and suggest a guideline for construction and application of indoor space.

• The Transactions of the Korea Information Processing Society
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• v.7 no.3
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• pp.766-775
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• 2000

Representing 3-D objects with LOD requires a set of appropriate meshes according to the detail requirements. We have developed a system for improved geometry model data transmission and management by having only the wavelet coefficienets of the model corresponding to the detail levels, instead of generation all the meshes through wavelet transformation, when generating multiresolution meshes.

• The Journal of the Korea Contents Association
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• v.7 no.9
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• pp.26-33
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• 2007

NPR is the area of research which does the image creation of the impression where the hazard person who creates made a human intimate image by the hand in objective. NPR in Cartoon-Rendering when the human being recognizes a thing, it is a technique which expresses a thing to use an appearance and the line which are a means of basic and intuitional expression. Also Cartoon the person probably is, the hazard which helps, raises the efficiency of namely meaning delivery and a simplification technique with the means for it uses. Is like this cartoon basic rules where the simplification and omission are life, from modeling, the low of LOD technique which it is using specially actively from game and one pulse communication is having a common point. The research which it sees Cartoon effects of GPU bases which use DirectX Shader programs LOD it leads and it applies the method for about under presenting it expresses Cartoon effects in exterior.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2009.04a
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• pp.356-359
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• 2009

본 연구에서는 교량의 정보를 효율적으로 관리하고 활용할 수 있는 3차원 형상기반 표준정보모델을, 현실 세계와 유사한 3차원 가상공간에 표현함으로써 실제 공간에 대해 보다 정확한 분석을 수행 할 수 있도록 교량정보모델과 3차원 지리정보체계를 연계하는 방안을 제시하였다. 교량의 표준정보모델은 기존에 개발된 STEP 기반의 교량정보모델을 활용하였으며, 3차원 지리정보체계는 지리정보상에 3차원 도시객체를 표현하기 위한 표준데이터모델인 CityGML를 활용하였다. 교량정보모델을 GIS와 연계하기 위한 핵심 요소인 교량구조물의 형상표현 LOD(Level of Detail)는 CityGML의 가이드라인을 준용하여 교량구조물에 적합하도록 새롭게 구성하였다. 즉, 빌딩구조물 위주로 정의되어진 기존의 CityGML의 한계점을 극복하기 위해, 총 5단계의 교량구조물의 LOD를 작성하여 각 단계별로 지리정보 상에 교량 형상을 표현할 수 있도록 LOD를 정의하였다. 또한, 두 모델을 소프트웨어적으로 연계하기 위하여 기존의 STEP 기반 교량정보모델을 활용하여, GIS의 정보로 변환하기 위한 소프트웨어 아키텍처를 구성하였다.

• Proceedings of the Korea Society for Simulation Conference
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• 2002.11a
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• pp.163-170
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• 2002

Terrain surfaces have to be modeled in very detail and wheel-surface contacting geometry must be well defined in order to obtain proper ground-reaction and friction forces for realistic simulation of off-road vehicles. Delaunay triangulation is one of the most widely used methods in modeling 3-dimensional terrain surfaces, and T-search is a relevant algorithm for searching resulting triangular polygons. The T-search method searches polygons in successive order and may not allow real-time computation of off-road vehicle dynamics if the terrain is modeled with many polygons, depending on the computer performance used in the simulation. In order to accelerate the searching speed of T-search, a terrain database of triangular polygons is modeled in multi-levels by adopting the LOD (Level of Detail) method used in realtime computer graphics. Simulation results show that the new LOD search is effective in shortening the required computing time. The LOD search can be even further accelerated by introducing an NN (Neural Network) algorithm, in the cases where a appropriate range of moving paths can be predicted by cultual information of the simulated terrain, such as lakes, houses, etc.. Numerical tests show that LOD-NN search almost double the speed of the original T-search.