Showing papers by "Avinash C. Kak published in 2007"

API-Based and Information-Theoretic Metrics for Measuring the Quality of Software Modularization

Abstract: We present in this paper a new set of metrics that measure the quality of modularization of a non-object-oriented software system. We have proposed a set of design principles to capture the notion of modularity and defined metrics centered around these principles. These metrics characterize the software from a variety of perspectives: structural, architectural, and notions such as the similarity of purpose and commonality of goals. (By structural, we are referring to intermodule coupling-based notions, and by architectural, we mean the horizontal layering of modules in large software systems.) We employ the notion of API (application programming interface) as the basis for our structural metrics. The rest of the metrics we present are in support of those that are based on API. Some of the important support metrics include those that characterize each module on the basis of the similarity of purpose of the services offered by the module. These metrics are based on information-theoretic principles. We tested our metrics on some popular open-source systems and some large legacy-code business applications. To validate the metrics, we compared the results obtained on human-modularized versions of the software (as created by the developers of the software) with those obtained on randomized versions of the code. For randomized versions, the assignment of the individual functions to modules was randomized

A Light-Weight Event-Driven Protocol for Sensor Clustering in Wireless Camera Networks

Abstract: We propose a light-weight event-driven protocol for wireless camera networks to allow for formation and propagation of clusters of cameras for the purpose of collaborative processing during object tracking. Cluster formation is triggered by the detection of objects with specific features. Our protocol allows for simultaneous formation and propagation of multiple clusters. Cameras being directional devices, more than one cluster may track a single object since groups of cameras outside each others communication range may see the same object. Entry into a cluster and cluster membership maintenance require a sensor node to confirm the presence of features of the object being tracked. Each cluster elects its own leader among the cameras that observe the same target. When a cluster leader loses track of an object, it assigns the leadership role to another cluster member. To avoid high communication overhead among cluster members, single-hop clusters are formed, i.e., every member of a cluster is within the communication range of the cluster head. We have implemented a simple version of this protocol on a test-bed and provide an experimental evaluation.

A New Approach for Active Stereo Camera Calibration

Abstract: By active stereo we mean a stereo vision system that allows for independent panning and tilting for each of the two cameras. One advantage of active stereo in relation to regular stereo is the former's wider effective field of view; if an object is too close to the camera baseline, the depth to the object can still be estimated accurately by panning the cameras appropriately. Another advantage of active stereo is that it can yield a larger number of depth measurements simultaneously for each position of the platform on which the camera system is mounted. Panning and tilting over a large angular range, while being the main reason for the advantages of active stereo, also make it more challenging to calibrate such systems. For a calibration procedure to be effective for active stereo, the estimated parameters must be valid over the entire range of the pan and tilt angles. This paper presents a new approach to the calibration of such vision systems. Our method is based on the rationale that an active stereo calibration procedure must explicitly estimate the locations and the orientations of the pan and tilt rotating axes for the cameras through a closed-form solution. When these estimates for the axes are combined with the homogeneous transform relationships that link the various coordinate frames, we end with a calibration that is valid over a large variation in the pan and tilt angles.

A QoS Evaluation Testbed for Mac Protocols for Wireless Camera Networks

Abstract: Existing QoS metrics can only be used for wireless sensor networks when the capability of sensor nodes is limited to making simple measurements such as temperature, pressure, etc. These metrics do not capture the communication patterns encountered when sensing is more elaborate, as in wireless camera networks where the need for distributed computation of image data may result in highly bursty communications among the nodes in a cluster. Whether or not a wireless camera network can successfully engage in, say, an object tracking task depends on whether the MAC protocol allows for these communication patterns to succeed with high reliability. Our testbed characterizes a MAC protocol on the basis of the following three criteria: time-bounded parameter-estimation accuracy (TIBPEA), latency, and energy efficiency. (An example of TIBPEA would be the precision with which an object can be located in space in a time-bounded manner by a cluster of nodes in the presence of bursty communications entailed by collaborative computing.) Our testbed simulator models bursty communications by enhanced data broadcast rates as needed by a vision task. Our paper includes characterization of a well-known MAC protocol.