Patent ID: 7355626
Filing Date: 2008-04-08
Classification: G08B

Abstract:
1. A surveillance system arranged to detect events in a scene comprising a predetermined volume in space, the surveillance system comprising: at least two arrays of passive infrared detector elements, optical collection means associated with each array and arranged to view the volume from different positions so that radiation from the volume is focused onto the respective arrays, and means for processing signals from the elements of the arrays to determine information regarding the location within which an event occurs on the basis of signals from each element of a set of elements, the set comprising at least one element from each of at least two arrays, each location consisting of a volume of intersection between the fields of view of a respective set of elements comprising an element from each of at least two arrays, wherein the processing means stores information defining three-dimensional surfaces or volumes within the scene, the surfaces or volumes being described by adjacent individual intersection volumes within the scene and the information determined by the processing means includes information regarding the location within which the event occurs relative to said defined surfaces or volumes within the scene.