• Proceedings of the Korean Information Science Society Conference
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• 1999.10b
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• pp.595-597
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• 1999

기존의 LOD 제어방법들은 랜더링속도를 성공적으로 증가시켜왔으나 오버헤드가 크다는 단점을 갖고 있다. 이러한 오버헤드는 각 vertex마다 view-frustum clipping, back-face culling, 스크린 공간 기하학적 오차계산과 같은 view-dependent refinement criteria를 측정하고, 메쉬의 LOD를 바꾸기 위해서 edge collapse/vertex split를 수행하기 때문이다. 제안하는 방법은 메쉬를 여러 개의 region들로 나누고 vertex가 아닌 region에 대해 view-dependent refinement criteria를 측정하므로 오버헤드가 훨씬 작다. 또한 각 region 들의 LOD가 바뀔 때 미리 만들어 둔 LOD 버전들중에서 하나를 선택하기만 하면 되므로, edge collapse/vertex split을 수행하는 오버헤드는 없다. 실험적으로 제안하는 LOD 제어방법은 기존의 방법들보다 작은 메모리를 사용하고 LOD 제어 오버헤드도 적으며, LOD 제어를 하지 않은 경우보다 2배-5배의 랜더링 속도향상을 얻었다.

• Journal of the Korea Society for Simulation
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• v.10 no.3
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• pp.95-103
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• 2001

Rendering of 3D terrain data in real-time is difficult because of its large scale. So, it is necessary to use level-of-detail(LOD) that uses fewer data, but makes almost similar image to the original. We present an algorithm for real-time LOD generation and rendering of 3D terrain data. The algorithm applies wavelet transform to the terrain data, and then generates quadtree based view-dependent LOD using wavelet coefficients that are the output of wavelet transform. It also uses frame-to-frame coherence and view culling for high frame rates.

• Korean Journal of Computational Design and Engineering
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• v.19 no.1
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• pp.61-67
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• 2014

This paper proposes a procedure enabling the extraction of view-dependent triangular approximations from a height map. In general, procedures to approximate a height map use tree hierarchies. These methods, however, have a limitation in terms of accuracy, because they depend on tree hierarchy than terrain features. To overcome the difficult, we apply the simplification method for triangular meshes to a height map. The proposed procedure maintains full decimation procedure to support multiresolution. The maintenance of decimation procedure results in creation of the groups (trees), each of which consists of vertices that can be merged into one vertex (root node). As the groups have tolerance which is determined by some tests, they support the generation of view-dependent arbitrary triangular meshes.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.30 no.4
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• pp.335-342
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• 2012

3D point cloud is widely used in Architecture, Civil Engineering, Medical, Computer Graphics, and many other fields. Due to the improvement of 3D laser scanner, a massive 3D point cloud whose gigantic file size is bigger than computer's memory requires efficient preprocessing and visualization. We suggest a data structure to solve the problem; a 3D point cloud is gradually subdivided by arbitrary-sized cube grids structure and corresponding point cloud subsets generated by the center of each grid cell are achieved while preprocessing. A massive 3D point cloud file is tested through two algorithms: QSplat and ours. Our algorithm, grid-based, showed slower speed in preprocessing but performed faster rendering speed comparing to QSplat. Also our algorithm is further designed to editing or segmentation using the original coordinates of 3D point cloud.