Context-Based Arithmetic Coding
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Camera Motions Synonyms ▶ Image device movements
Definition Camera motions are defined as set of camera movements generated by users in both fixed and mobile situations. Estimating camera motion parameters from a video sequence constitutes one of the central themes in computer vision and multimedia. These parameters are widely used to efficiently store and manage large volumes of video data as references to particular video segments, and to track objects in digital video. Figure 1 depicts typical types of camera motions. Translations of the camera along the horizontal and vertical axes of the imaging plane are called track and boom, respectively. Translation in the direction of the optical
Track right
camera axis is called dolly. Pan refers to the turning around the vertical axis, whereas tilt refers to the turning around the horizontal axis. The camera rotation around the optical axis is called roll. In addition to the above motion types, many cameras can also change the focal length or zoom. Camera motion parameters estimation constitutes an extensively researched area due to its use in applications such as video compression, augmented reality, and video stabilization. Existing methods can estimate camera motions by operating in the compressed domain [1,2], which makes them attractive for today’s video and visual communication systems. Qualitative estimation of camera motion parameters can also be derived from the composition of optical flow models [3]. Figure 2 depicts schematically the optical flows generated by some basic camera motions.
Cross-References ▶ Video Codec, Exposure Values ▶ Video Stabilization
References 1.
R. Ewerth, M. Schwalb, P. Tessmann, and B. Freisleben, ‘‘Estimation of Arbitrary Camera Motion in MPEG Videos,’’ Proceedings of International Conference on Pattern Recognition, Vol. 1, 2004, pp. 512–515.
Boom up Dolly backward
Pan right
Tilt up
Pan left
Dolly forward
Track left Boom down
Camera Motions. Figure 1. Examples of typical camera motions.
Roll up
Tilt down
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C
Camera Shake Compensation
Tracking
Booming
Rolling
Zoom out
Camera Motions. Figure 2. Optical flows generated by the basic camera motions.
2.
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Y.P Tan, D.D. Saur, S.R. Kulkarni, and P.J. Ramadge, ‘‘Rapid Estimation of Camera Motion from Compressed Video with Application to Video Annotation,’’ IEEE Transactions on Circuits and Systems for Video Technology, Vol. 10, No. 1, February 2000, pp. 133–146. Y. Wang, J. Ostermann, Y.Q. Zhang, ‘‘Video Processing and Communications,’’ Prentice Hall, 2002.
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Browser
HTML HTML HTML
CSS
Cascading Style Sheets. Figure 1. Transforming an HTML document using CSS to create alternative HTML representations.
Camera Shake Compensation ▶ Video Stabilization
Cascading Style Sheets Definition Cascading Style Sheets (CSS) was introduced within the HTML 4.0 specification to separate content from formatting, and to provide precise document layout and format control. The Hypertext Markup Language allows authors to intersperse tags for controlling the display or formattin
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