Papers by Ryutarou Ohbuchi
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The recent popularity of digital media such as CD-ROM and the Internet has prompted exploration o... more The recent popularity of digital media such as CD-ROM and the Internet has prompted exploration of techniques for embedding data, either visibly or invisibly, into text, image, and audio objects. Applications of such data embedding include copyright identification, theft deterrence, and inventory. This paper discusses techniques for embedding data into 3D models. Given objects consisting of points, lines, (connected) polygons, or curved surfaces, the algorithms described in this paper produce polygonal models with data embedded into either their vertex coordinates, their vertex topology (connectivity), or both. A description of the background and requirements is followed by a discussion of where, and by what fundamental methods, data can be embedded into 3D polygonal models. The paper then presents several data-embedding algorithms, with examples, based on these fundamental methods.
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Computer Communications, 1998
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The development of an interactive system that will display 3-D structures from a series of 2-D im... more The development of an interactive system that will display 3-D structures from a series of 2-D images acquired incrementally by a conventional 2-D ultrasound echographic (2DE) scanner is discussed. The user-guided scanner head is mounted on a mechanical arm that tracks the position and orientation of an image frame. The design and implementation of the system, visualization algorithm, and results of an experiment with a doll phantom to test its feasibility are reported
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In this paper, we present approaches toward an interactive visualization of a real time input, ap... more In this paper, we present approaches toward an interactive visualization of a real time input, applied to 3-D visualizations of 2-D ultrasound echography data. The first, 3 degrees-of- freedom (DOF) incremental system visualizes a 3-D volume acquired as a stream of 2-D slices with location and orientation with 3 DOF. As each slice arrives, the system reconstructs a regular 3-D volume and renders it. Rendering is done by an incremental image-order ray- casting algorithm which stores and reuses the results of expensive resampling along the rays for speed. The second is our first experiment toward real-time 6 DOF acquisition and visualization. Two-dimensional slices with 6 DOF are reconstructed off-line, and visualized at an interactive rate using a parallel volume rendering code running on the graphics multicomputer Pixel-Planes 5.
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This paper describes an automatic annotation, or autotagging, algorithm that attaches textual tag... more This paper describes an automatic annotation, or autotagging, algorithm that attaches textual tags to 3D models based on their shape and semantic classes. The proposed method employs Manifold Ranking by Zhou et al, an algorithm that takes into account both local and global distributions of feature points, for tag relevance computation. Using Manifold Ranking, our method propagates multiple tags attached to a training subset of models in a database to the other tag-less models. After the relevance values for multiple tags are computed for tag-less points, the method selects, based on the distribution of feature points for each tag, the threshold at which the tag is selected or discarded for the points. Experimental evaluation of the method using a text-based 3D model retrieval setting showed that the proposed method is effective in autotagging 3D shape models.
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Distance measures, along with shape features, are the most critical components in a shape-based 3... more Distance measures, along with shape features, are the most critical components in a shape-based 3D model retrieval system. Given a shape feature, an optimal distance measure will vary per query, per user, or per database. No single, fixed distance measure would be satisfactory all the time. This paper focuses on a method to adapt distance measure to the database to be queried by using learning-based dimension reduction algorithms. We experimentally compare six such dimension reduction algorithms, both linear and non-linear, for their efficacy in the context of shape-based 3D model retrieval. We tested the efficacy of these methods by applying them to five global shape features. Among the dimension reduction methods we tested, non-linear manifold learning algorithms performed better than the other, e.g. linear algorithms such as principal component analysis. Performance of the best performing combination is roughly the same as the top finisher in the SHREC 2006 contest.
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Journal of Computer Applications in Technology, 2005
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Papers by Ryutarou Ohbuchi