Patent ID: 6204852
Filing Date: 2001-03-20
Classification: G06F,G06T

Abstract:
A method of tracking, in a real world scene, three-dimensional position coordinates and orientation angles of an object having an end portion, a tip and an axis, said method being implemented in a computer system having a first video acquisition device and a second video acquisition device for monitoring, from different positions, an identification zone defined in the real world scene, said method comprising the steps of:(a) acquiring a first image of the object from the first video acquisition device and simultaneously acquiring a second image of the object from the second video acquisition device when the object is present in the identification zone;(b) determining a first set of pixel coordinates corresponding to the tip of the object and a first orientation angle for the end portion of the object from said first image and determining a second set of pixel coordinates corresponding to the tip of the object and a second orientation angle for the end portion of the object from said second image;(c) determining a first virtual line in the real world scene in accordance with said first set of pixel coordinates and a first perspective projection matrix defined in accordance with a monitoring orientation of the first video acquisition device, and determining a second virtual line in the real world scene in accordance with said second set of pixel coordinates and a second perspective projection matrix defined in accordance with a monitoring orientation of the second video acquisition device;(d) determining the three-dimensional position coordinates of the object end portion by identifying coordinates of a virtual intersection of said first and second virtual(e) determining a first parameter vector representative of a first linear projection of the object axis from said first image in accordance with said first set of pixel coordinates and said first orientation angle, and determining a second parameter vector representative of a second linear projection of the object axis from said second image in accordance with said second set of pixel coordinates and said second orientation angle;(f) determining parameters of a first virtual plane using said first parameter vector and said first perspective projection matrix, and defining a second virtual plane using said second parameter vector and said second perspective projection matrix; and(g) determining the three-dimensional orientation angles of the object by identifying orientation parameters of a third line defined by an intersection of said first and said second virtual planes.