Modeling and calibration of automated zoom lenses
Modeling and calibration of automated zoom lenses
Zoom tracking and its applications
Machine Vision and Applications
A framework for virtual videography
Proceedings of the 2nd international symposium on Smart graphics
Tracking While Zooming Using Affine Transfer and Multifocal Tensors
International Journal of Computer Vision
Information Theoretic Focal Length Selection for Real-Time Active 3-D Object Tracking
ICCV '03 Proceedings of the Ninth IEEE International Conference on Computer Vision - Volume 2
Reactive Control of Zoom while Fixating Using Perspective and Affine Cameras
IEEE Transactions on Pattern Analysis and Machine Intelligence
Resolution vs. tracking error: zoom as a gain controller
CVPR'03 Proceedings of the 2003 IEEE computer society conference on Computer vision and pattern recognition
Automatica (Journal of IFAC)
Dynamic view planning by effective particles for three-dimensional tracking
IEEE Transactions on Systems, Man, and Cybernetics, Part B: Cybernetics - Special issue on human computing
Note: Low-resolution color-based visual tracking with state-space model identification
Computer Vision and Image Understanding
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The tuning of a constant velocity Kalman filter, used for tracking by a camera fitted with a variable focal-length lens, is shown to be preserved under a scale change in process noise if accompanied by an inverse scaling in the focal length, provided the image measurement error is of fixed size in image coordinates. Based on this observation, a practical method of zoom control has been built by setting an upper limit on the probability that the innovation (and hence fixation error) exceeds the image half-width. The innovation covariance matrix used to determine the innovation limit is derived over two timescales, which enables a rapid zooming out response and slower zooming in. Experimental simulations are presented, before results are given from a video-rate implementation using a camera with two motorized orientation axes and fitted with a computer-controlled zoom lens. The delays in the feedback loops, comprising image capture delay, platform response lag and zoom lens response lag, are carefully calibrated by fitting to their frequency responses. It is found that the cumulative uncertainty in delay gives rise to an image error which is part constant and part proportional to focal length, resulting in a beneficial adaptation of the filter.