Open Source Computer Vision Library https://opencv.org/
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Motion Analysis
===============
.. highlight:: cpp
CalcOpticalFlowBM
-----------------
Calculates the optical flow for two images by using the block matching method.
.. ocv:cfunction:: void cvCalcOpticalFlowBM( const CvArr* prev, const CvArr* curr, CvSize block_size, CvSize shift_size, CvSize max_range, int use_previous, CvArr* velx, CvArr* vely )
:param prev: First image, 8-bit, single-channel
:param curr: Second image, 8-bit, single-channel
:param block_size: Size of basic blocks that are compared
:param shift_size: Block coordinate increments
:param max_range: Size of the scanned neighborhood in pixels around the block
:param use_previous: Flag that specifies whether to use the input velocity as initial approximations or not.
:param velx: Horizontal component of the optical flow of
.. math::
\left \lfloor \frac{\texttt{prev->width} - \texttt{block\_size.width}}{\texttt{shift\_size.width}} \right \rfloor \times \left \lfloor \frac{\texttt{prev->height} - \texttt{block\_size.height}}{\texttt{shift\_size.height}} \right \rfloor
size, 32-bit floating-point, single-channel
:param vely: Vertical component of the optical flow of the same size ``velx`` , 32-bit floating-point, single-channel
The function calculates the optical flow for overlapped blocks ``block_size.width x block_size.height`` pixels each, thus the velocity fields are smaller than the original images. For every block in ``prev``
the functions tries to find a similar block in ``curr`` in some neighborhood of the original block or shifted by ``(velx(x0,y0), vely(x0,y0))`` block as has been calculated by previous function call (if ``use_previous=1``)
CalcOpticalFlowHS
-----------------
Calculates the optical flow for two images using Horn-Schunck algorithm.
.. ocv:cfunction:: void cvCalcOpticalFlowHS(const CvArr* prev, const CvArr* curr, int use_previous, CvArr* velx, CvArr* vely, double lambda, CvTermCriteria criteria)
:param prev: First image, 8-bit, single-channel
:param curr: Second image, 8-bit, single-channel
:param use_previous: Flag that specifies whether to use the input velocity as initial approximations or not.
:param velx: Horizontal component of the optical flow of the same size as input images, 32-bit floating-point, single-channel
:param vely: Vertical component of the optical flow of the same size as input images, 32-bit floating-point, single-channel
:param lambda: Smoothness weight. The larger it is, the smoother optical flow map you get.
:param criteria: Criteria of termination of velocity computing
The function computes the flow for every pixel of the first input image using the Horn and Schunck algorithm [Horn81]_. The function is obsolete. To track sparse features, use :ocv:func:`calcOpticalFlowPyrLK`. To track all the pixels, use :ocv:func:`calcOpticalFlowFarneback`.
CalcOpticalFlowLK
-----------------
Calculates the optical flow for two images using Lucas-Kanade algorithm.
.. ocv:cfunction:: void cvCalcOpticalFlowLK( const CvArr* prev, const CvArr* curr, CvSize win_size, CvArr* velx, CvArr* vely )
:param prev: First image, 8-bit, single-channel
:param curr: Second image, 8-bit, single-channel
:param win_size: Size of the averaging window used for grouping pixels
:param velx: Horizontal component of the optical flow of the same size as input images, 32-bit floating-point, single-channel
:param vely: Vertical component of the optical flow of the same size as input images, 32-bit floating-point, single-channel
The function computes the flow for every pixel of the first input image using the Lucas and Kanade algorithm [Lucas81]_. The function is obsolete. To track sparse features, use :ocv:func:`calcOpticalFlowPyrLK`. To track all the pixels, use :ocv:func:`calcOpticalFlowFarneback`.