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Detecting and tracking dynamic clusters of spatial events
We present a work in progress on developing a tool supporting real-time detection of significant clusters of spatial events and observing their evolution. The tool consists of an incremental stream clustering algorithm and coordinated map and timeline displays showing current situation and cluster evolution
Learning Behavioural Context
The original publication is available at www.springerlink.co
A taxonomy framework for unsupervised outlier detection techniques for multi-type data sets
The term "outlier" can generally be defined as an observation that is significantly different from
the other values in a data set. The outliers may be instances of error or indicate events. The
task of outlier detection aims at identifying such outliers in order to improve the analysis of
data and further discover interesting and useful knowledge about unusual events within numerous
applications domains. In this paper, we report on contemporary unsupervised outlier detection
techniques for multiple types of data sets and provide a comprehensive taxonomy framework and
two decision trees to select the most suitable technique based on data set. Furthermore, we
highlight the advantages, disadvantages and performance issues of each class of outlier detection
techniques under this taxonomy framework
Independent Motion Detection with Event-driven Cameras
Unlike standard cameras that send intensity images at a constant frame rate,
event-driven cameras asynchronously report pixel-level brightness changes,
offering low latency and high temporal resolution (both in the order of
micro-seconds). As such, they have great potential for fast and low power
vision algorithms for robots. Visual tracking, for example, is easily achieved
even for very fast stimuli, as only moving objects cause brightness changes.
However, cameras mounted on a moving robot are typically non-stationary and the
same tracking problem becomes confounded by background clutter events due to
the robot ego-motion. In this paper, we propose a method for segmenting the
motion of an independently moving object for event-driven cameras. Our method
detects and tracks corners in the event stream and learns the statistics of
their motion as a function of the robot's joint velocities when no
independently moving objects are present. During robot operation, independently
moving objects are identified by discrepancies between the predicted corner
velocities from ego-motion and the measured corner velocities. We validate the
algorithm on data collected from the neuromorphic iCub robot. We achieve a
precision of ~ 90 % and show that the method is robust to changes in speed of
both the head and the target.Comment: 7 pages, 6 figure
Investigating the Kinematics of Coronal Mass Ejections with the Automated CORIMP Catalog
Studying coronal mass ejections (CMEs) in coronagraph data can be challenging
due to their diffuse structure and transient nature, compounded by the
variations in their dynamics, morphology, and frequency of occurrence. The
large amounts of data available from missions like the Solar and Heliospheric
Observatory (SOHO) make manual cataloging of CMEs tedious and prone to human
error, and so a robust method of detection and analysis is required and often
preferred. A new coronal image processing catalog called CORIMP has been
developed in an effort to achieve this, through the implementation of a dynamic
background separation technique and multiscale edge detection. These algorithms
together isolate and characterise CME structure in the field-of-view of the
Large Angle Spectrometric Coronagraph (LASCO) onboard SOHO. CORIMP also applies
a Savitzky-Golay filter, along with quadratic and linear fits, to the
height-time measurements for better revealing the true CME speed and
acceleration profiles across the plane-of-sky. Here we present a sample of new
results from the CORIMP CME catalog, and directly compare them with the other
automated catalogs of Computer Aided CME Tracking (CACTus) and Solar Eruptive
Events Detection System (SEEDS), as well as the manual CME catalog at the
Coordinated Data Analysis Workshop (CDAW) Data Center and a previously
published study of the sample events. We further investigate a form of
unsupervised machine learning by using a k-means clustering algorithm to
distinguish detections of multiple CMEs that occur close together in space and
time. While challenges still exist, this investigation and comparison of
results demonstrates the reliability and robustness of the CORIMP catalog,
proving its effectiveness at detecting and tracking CMEs throughout the LASCO
dataset.Comment: 23 pages, 11 figures, 1 tabl
FPGA-based Anomalous trajectory detection using SOFM
A system for automatically classifying the trajectory of a moving object in a scene as usual or suspicious is presented. The system uses an unsupervised neural network (Self Organising Feature Map) fully implemented on a reconfigurable hardware architecture (Field Programmable Gate Array) to cluster trajectories acquired over a period, in order to detect novel ones. First order motion information, including first order moving average smoothing, is generated from the 2D image coordinates (trajectories). The classification is dynamic and achieved in real-time. The dynamic classifier is achieved using a SOFM and a probabilistic model. Experimental results show less than 15\% classification error, showing the robustness of our approach over others in literature and the speed-up over the use of conventional microprocessor as compared to the use of an off-the-shelf FPGA prototyping board
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