2943619
High resolution catadioptric omni-directional stereo sensor for robot vision
Autonomous robots need to acquire both omnidirectional view and stereo in real-time without sacrificing too much image resolution. The recent catadioptric omni-directional vision sensors provide simple affordable real-time omni-directional images but only at the cost of rather low image resolutions. This work describes a novel omni-directional stereo image sensor providing the highest resolution while still retaining the simplicity and real-time advantages that are unique to the family of catadioptric sensors. Only one simple reflective surface, a beam splitter and two regular (perspective) cameras are needed.
31903182
The Fourier slice theorem for range data reconstruction
Abstract This paper proposes a new approach to resolve the ambiguity problem in multistriping laser triangulation systems [1] . The application of this new method to circularly symmetrical objects can achieve time and space complexity of order one. No optical shutter is required in this new method. The new solution is based on the Fourier slice theorem, which forms the basis of X-ray CT (computed tomography) reconstruction. This paper demonstrates how this theorem can also be used to resolve multistripe laser ambiguity effectively.
51877153
ATPC: adaptive transmission power control for wireless sensor networks
Extensive empirical studies presented in this paper confirm that the quality of radio communication between low power sensor devices varies significantly with time and environment. This phenomenon indicates that the previous topology control solutions, which use static transmission power, transmission range, and link quality, might not be effective in the physical world. To address this issue, online transmission power control that adapts to external changes is necessary. This paper presents ATPC, a lightweight algorithm of Adaptive Transmission Power Control for wireless sensor networks. In ATPC, each node builds a model for each of its neighbors, describing the correlation between transmission power and link quality. With this model, we employ a feedback-based transmission power control algorithm to dynamically maintain individual link quality over time. The intellectual contribution of this work lies in a novel pairwise transmission power control, which is significantly different from existing node-level or network-level power control methods. Also different from most existing simulation work, the ATPC design is guided by extensive field experiments of link quality dynamics at various locations and over a long period of time. The results from the real-world experiments demonstrate that 1) with pairwise adjustment, ATPC achieves more energy savings with a finer tuning capability and 2) with online control, ATPC is robust even with environmental changes over time.
15193012
Unsupervised link discovery in multi-relational data via rarity analysis
A significant portion of knowledge discovery and data mining research focuses on finding patterns of interest in data. Once a pattern is found, it can be used to recognize satisfying instances. The new area of link discovery requires a complementary approach, since patterns of interest might not yet be known or might have too few examples to be learnable. We present an unsupervised link discovery method aimed at discovering unusual, interestingly linked entities in multi-relational datasets. Various notions of rarity are introduced to measure the "interestingness" of sets of paths and entities. These measurements have been implemented and applied to a real-world bibliographic dataset where they give very promising results.
12106413
Similarity queries in the DISIMA image DBMS
In the DISIMA system, an image is composed of salient objects that are regions of interest in the image. A salient object has some syntactic properties (shape, color, textures) on which some similarity searches are defined. In addition, a global multi-precision image similarity based on multi-scale color histograms allows similarity queries on images and sub-images.
1538276
Distributed spatio-temporal similarity search
In this paper we introduce the distributed spatio-temporal similarity search problem: given a query trajectory Q, we want to find the trajectories that follow a motion similar to Q, when each of the target trajectories is segmented across a number of distributed nodes. We propose two novel algorithms, UB-K and UBLB-K, which combine local computations of lower and upper bounds on the matching between the distributed subsequences and Q. Such an operation generates the desired result without pulling together all the distributed subsequences over the fundamentally expensive communication medium. Our solutions find applications in a wide array of domains, such as cellular networks, wild life monitoring and video surveillance. Our experimental evaluation using realistic data demonstrates that our framework is both efficient and robust to a variety of conditions.
8641285
A data compression technique for sensor networks with dynamic bandwidth allocation
In this paper, we have presented a new data compression technique, designed for historical information compression in sensor networks. Our method employs the LVQ learning process to construct the codebook and the codebook's updates are compressed to save bandwidth for sensor data transmission. In addition, we have addressed the dynamic bandwidth allocation problem in sensor networks. Our DBA algorithm can dynamically adjust the communication bandwidth of different sensors in order to balance data compression qualities at different sensors.