Browsing by Author "Chou, Hong-Long"

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A Performance Controllable Octree Construction Method
(2008)
Chen, Zen
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Chou, Hong-Long
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Chen, Wen-Chao
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資訊工程學系
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Department of Computer Science
The conventional octree construction method is implemented iteratively at consecutive subdivision levels. The resultant octree models at different subdivision levels contain quite different octant compositions, so the system performance, in terms of model accuracy, memory space and construction time, changes widely with the subdivision level number. Since the big system performance gap is not desirable for the practical application, new construction methods must have a finer control over the system performance. In the paper a new construction method is proposed using new types of octree octants. Interesting properties and computer simulations of the new method are presented. The performance comparison between the conventional method and the new method is made under the comparable XOR projection error condition. It is shown that under this condition the memory space and construction time required by the conventional method can be reduced significantly by the new method.
A quality controllable multi-view object reconstruction method for 3D imaging systems
(2010-07-01)
Chen, Wen-Chao
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Chou, Hong-Long
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Chen, Zen
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資訊工程學系
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Department of Computer Science
This paper addresses a novel multi-view visual hull mesh reconstruction for 3D imaging with a system quality control capability. There are numerous 3D imaging methods including multi-view stereo algorithms and various visual hull/octree reconstruction methods known as modeling from silhouettes. The octree based reconstruction methods are conceptually simple to implement, while encountering a conflict between model accuracy and memory size. Since the tree depth is discrete, the system performance measures (in terms of accuracy, memory size, and computation time) are generally varying rapidly with the pre-specified tree depth. This jumping system performance is not suitable for practical applications; a desirable 3D reconstruction method must have a finer control over the system performance. The proposed method aims at the visual quality control along with better management of memory size and computation time. Furthermore, dynamic object modeling is made possible by the new method. Also, progressive transmission of the reconstructed model from coarse to fine is provided. The reconstruction accuracy of the 3D model acquired is measured by the exclusive OR (XOR) projection error between the pairs of binary images: the reconstructed silhouettes and the true silhouettes in the multiple views. Interesting properties of the new method and experimental comparisons with other existing methods are reported. The performance comparisons are made under either a comparable silhouette inconsistency or a similar triangle number of the mesh model. It is shown that under either condition the new method requires less memory size and less computation time. (C) 2010 Published by Elsevier Inc.
New efficient octree construction from multiple object silhouettes with construction quality control
(2006)
Chen, Zen
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Chou, Hong-Long
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資訊工程學系
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Department of Computer Science
In this paper, we propose an octree construction method with a new subdivision strategy which is governed by the degree of overlapping between each generated octant and the object. The specification of a maximum level of subdivision required in the conventional method is not needed. We introduce "grey-grey" and "grey-black" nodes based on a construction quality measure. The construction quality is measured by the maximum 2D projection error of the projected octant image with respective to the object silhouette in all views. Only those octants which are "grey-grey" nodes will be subdivided. Furthermore, we present a fast computation of the 2D projection and a new intersection test to reduce the computer processing time. Computer simulations are conducted to show that the new method outperforms the conventional method in terms of memory space and computation time subject to the same level of construction quality.