Video tracking

Video tracking

Video tracking is the process of locating a moving object (or several ones) in time using a camera. An algorithm analyses the video frames and outputs the location of moving targets within the video frame.

The main difficulty in video tracking is to associate target locations in consecutive video frames, especially when the objects are moving fast relative to the frame rate. Here, video tracking systems usually employ a motion model which describes how the image of the target might change for different possible motions of the object to track.

Examples of simple motion models are:
* to track planar objects, the motion model is a 2D transformation (affine transformation or homography) of an image of the object (e.g. the initial frame)
* when the target is a rigid 3D object, the motion model defines its aspect depending on its 3D position and orientation
* for video compression, key frames are divided into macroblocks. The motion model is a disruption of a key frame, where each macroblock is translated by a motion vector given by the motion parameters
* the image of deformable objects can be covered with a mesh, the motion of the object is defined by the position of the nodes of the mesh.

The role of the tracking algorithm is to analyse the video frames in order to estimate the motion parameters. These parameters characterize the location of the target.

Common algorithms

There are two major components of a visual tracking system; "Target Representation and Localization" and "Filtering and Data Association".

"Target Representation and Localization" is mostly a bottom-up process. Typically the computational complexity for these algorithms is low. The following are some common "Target Representation and Localization" algorithms:
* Blob tracking: Segmentation of object interior (for example blob detection, block-based correlation or optical flow)
* Kernel-based tracking (Mean-shift tracking): An iterative localization procedure based on the maximization of a similarity measure (Bhattacharyya coefficient).
* Contour tracking: Detection of object boundary (e.g. active contours or Condensation algorithm)
* Visual feature matching: Registration

"Filtering and Data Association" is mostly a top-down process, which involves incorporating prior information about the scene or object, dealing with object dynamics, and evaluation of different hypotheses. The computational complexity for these algorithms is usually much higher. The following are some common "Filtering and Data Association" algorithms:
* Kalman filter: An optimal recursive Bayesian filter for linear functions subjected to Gaussian noise.
* Particle filter: Useful for sampling the underlying state-space distribution of non-linear and non-Gaussian processes.

ee also

*Match moving
*Motion capture


* D. Comaniciu, V. Ramesh, and P. Meer, "Kernel-Based Object Tracking", "IEEE Trans. on Pattern Analysis and Machine Intelligence, Vol. 25, no. 5, May 2003.
* M. Arulampalam, S. Maskell, N. Gordon, and T. Clapp, "A Tutorial on Particle Filters for Online Nonlinear/Non-Gaussian Bayesian Tracking", "IEEE Trans. on Signal Processing, Vol. 50, no. 2, Feb. 2002.

Wikimedia Foundation. 2010.

Игры ⚽ Поможем сделать НИР

Look at other dictionaries:

  • Tracking — can refer to: Tracking (education), separating children into different classes according to their academic ability Tracking, in computer graphics, a vital part of match moving Tracking, in portfolio management, matching or comparing with a stock… …   Wikipedia

  • Video 2000 — Note: This article is about the format sometimes known as VCC or Video Compact Cassette . It should not be confused with Philips s earlier (and incompatible) videocassette format called VCR or Video Cassette Recording . Video 2000 (or V2000; also …   Wikipedia

  • Tracking — Le tracking est un système logiciel qui permet suivre un déplacement. Le tracking le plus connu est le tracking vidéo utilisé dans les films ou les jeux vidéo. Le terme tracking est également utilisé dans le monde de l internet : il s agit… …   Wikipédia en Français

  • Video Home System — Bandbreite: 1/2″ (1,27 cm) Farbe: Unterträger …   Deutsch Wikipedia

  • Video 2000 — Bandbreite: ½ Zoll (2 × ¼ Zoll) Farbe: herabgesetzte Farbe Ton: Längsspur (Stereo) Laufzeit …   Deutsch Wikipedia

  • Video detection and ranging — (VIDAR) is a technique to measure the speed or other information of a distant vehicle using advanced stereoscopic imaging techniques. VIDAR technology has application in remote sensing, traffic enforcement. Applications Military and law… …   Wikipedia

  • Video-Recorder — VHS Videorekorder VHS Videorekorder offen …   Deutsch Wikipedia

  • Video Cassette Recorder — VHS Videorekorder VHS Videorekorder offen …   Deutsch Wikipedia

  • Video Tape Rekorder — VHS Videorekorder VHS Videorekorder offen …   Deutsch Wikipedia

  • Tracking shot — During filming of The Alamo, a tracking shot was used during a battle scene In motion picture terminology, a tracking shot (also known as a dolly shot or trucking shot) is a segment in which the camera is mounted on a camera dolly, a wheeled… …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”