Improving target localization accuracy of wireless visual sensor networks

This paper discusses the target localization problem of wireless visual sensor networks. Specifically, each node with a low-resolution camera extracts multiple feature points to represent the target at the sensor node level. A statistical method of merging the position information of different sensor nodes to select the most correlated feature point pair at the base station is presented. This method releases the influence of the accuracy of target extraction on the accuracy of target localization in universal coordinate system. Simulations show that, compared with other relative approach, our proposed method can generate more desirable target localization's accuracy, and it has a better trade-off between camera node usage and localization accuracy

Power Management in Sensing Subsystem of Wireless Multimedia Sensor Networks

A wireless sensor network consists of sensor nodes deployed over a geographical area for monitoring physical phenomena like temperature, humidity, vibrations, seismic events, and so on. Typically, a sensor node is a tiny device that includes three basic components: a sensing subsystem for data acquisition from the physical surrounding environment, a processing subsystem for local data processing and storage, and a wireless communication subsystem for data transmission. In addition, a power source supplies the energy needed by the device to perform the programmed task. This power source often consists of a battery with a limited energy budget. In addition, it is usually impossible or inconvenient to recharge the battery, because nodes are deployed in a hostile or unpractical environment. On the other hand, the sensor network should have a lifetime long enough to fulfill the application requirements. Accordingly, energy conservation in nodes and maximization of network lifetime are commonly recognized as a key challenge in the design and implementation of WSNs. Experimental measurements have shown that generally data transmission is very expensive in terms of energy consumption, while data processing consumes significantly less (Raghunathan et al., 2002). The energy cost of transmitting a single bit of information is approximately the same as that needed for processing a thousand operations in a typical sensor node (Pottie & Kaiser, 2000). The energy consumption of the sensing subsystem depends on the specific sensor type. In some cases of scalar sensors, it is negligible with respect to the energy consumed by the processing and, above all, the communication subsystems. In other cases, the energy expenditure for data sensing may be comparable to, or even greater (in the case of multimedia sensing) than the energy needed for data transmission. In general, energy-saving techniques focus on two subsystems: the communication subsystem (i.e., energy management is taken into account in the operations of each single node, as well as in the design of networking protocols), and the sensing subsystem (i.e., techniques are used to reduce the amount or frequency of energy-expensive samples).Postprint (published version

CITRIC: A low-bandwidth wireless camera network platform

In this paper, we propose and demonstrate a novel wireless camera network system, called CITRIC. The core component of this system is a new hardware platform that integrates a camera, a frequency-scalable (up to 624 MHz) CPU, 16 MB FLASH, and 64 MB RAM onto a single device. The device then connects with a standard sensor network mote to form a camera mote. The design enables in-network processing of images to reduce communication requirements, which has traditionally been high in existing camera networks with centralized processing. We also propose a back-end client/server architecture to provide a user interface to the system and support further centralized processing for higher-level applications. Our camera mote enables a wider variety of distributed pattern recognition applications than traditional platforms because it provides more computing power and tighter integration of physical components while still consuming relatively little power. Furthermore, the mote easily integrates with existing low-bandwidth sensor networks because it can communicate over the IEEE 802.15.4 protocol with other sensor network platforms. We demonstrate our system on three applications: image compression, target tracking, and camera localization

Distributed Calibration of Wireless Multimedia Sensor Networks

Wireless Multimedia Sensor Networks (WMSNs) are gaining popularity among researchers over the past few years. Knowledge of the geographic locations of the sensor nodes is very important in such sensor networks. Location calibration is a method that uses the connectivity information, the estimated distance information among the sensor nodes, as well as the vision images to find the location of the sensor nodes in WMSNs. We generate local maps for nodes in immediate vicinity and merge them together to get a global map. Local maps are prone to be incorrect mainly due to distribution symmetry in a grid based network and uncertainties in the classical multidimensional scaling. Performance measures to calculate and study the same have been developed and described in detail. In this research we propose a new algorithm which corrects the error to improve the location calibration in WMSN. The major contribution of our thesis lies in developing the theoretical framework for distributed camera calibration based on vision data, local inter-node distances and local topology. Moreover our work does not need any moving targets to perform distributed camera calibration. We further develop innovative algorithms for local map generation and map merging. We evaluated the proposed approach through computer simulations. This location calibration algorithm can thus be used to develop self-organized wireless multimedia sensor networks. We demonstrate the effectiveness of our proposed approach through computer simulation. We demonstrate the proposed approach for different base node and successfully build the global map. The percentage of accuracy obtained demonstrate that the 80% of the nodes can have a good local map, however the global map obtained can accurately localize all the nodes in the network. This brings a completion to the scope of this thesis, the framework developed further provides an opportunity to extend this algorithm to real time wireless multimedia sensor networks.School of Electrical & Computer Engineerin

Website Technology Trends for Augmented Reality Development

Augmented reality (AR) is a technology that is gaining increasing attention from academics and industry. AR is relied upon to be an innovative technology to enrich ways of interacting with the physical and cyberspace around users that can enhance user experience in various fields. Platforms for AR applications are usually hardware based and mobile based, for mobile applications AR is usually based. AR-based hardware requires quite expensive support, this is seen from the rendering space requirements and this makes it inflexible while AR-based applications on mobile smartphones require large storage space and do not make it convenient for cross-platform use. Currently many researchers are trying to create and develop website-based AR, as a solution to the spread of AR to be flexible and save storage space, website technology development trends are used as a method for improving the performance of website-based AR. Other support comes from open-source software and more developer platforms and program courses for Web AR that are made public. This paper reviews the state-of-the-art, various methods, technologies and challenges of existing AR, this can be a trigger for more research interest and efforts to provide AR experienc