ABNORMAL OBJECT TRACK DETERMINATION USING A GAUSSIAN PROCESSES BASED VARIATIONAL BAYES EXPECTATION MAXIMISATION

Methods and apparatus for determining whether a provided object track (24) is abnormal, an object track (24) being a set of values of a physical property of an object (2) measured over a period of time, the method comprising: providing a model comprising one or more functions (26), each function (26) being representative of an object track (24) that is defined to be normal; assigning the provided object track (24) to a function (26); and comparing the provided object track (24) to the assigned function (26) to determine whether that object track (24) is abnormal. Providing the model comprises: for each of a plurality of objects (2), determining an object track (24), wherein the determined object tracks (24) are defined as normal object tracks (24); and using the determined tracks (24), performing a Gaussian Processes based Variational Bayes Expectation Maximisation process to learn the one or more functions (26).