Calculates a gradient orientation of a motion history image

[mask,orientation] = cv.calcMotionGradient(mhi, delta1, delta2)
[...] = cv.calcMotionGradient(..., 'OptionName', optionValue, ...)

Input

• mhi Motion history single-channel floating-point image.
• delta1 Minimal (or maximal) allowed difference between mhi values within a pixel neighorhood.
• delta2 Maximal (or minimal) allowed difference between mhi values within a pixel neighorhood. That is, the function finds the minimum (m(x,y)) and maximum (M(x,y)) mhi values over 3x3 neighborhood of each pixel and marks the motion orientation at (x,y) as valid only if: min(delta1,delta2) <= M(x,y) - m(x,y) <= max(delta1,delta2)

Output

• mask Output mask image that has the type uint8 and the same size a mhi. Its non-zero elements mark pixels where the motion gradient data is correct.
• orientation Output motion gradient orientation image that has the same type and the same size as mhi. Each pixel of the image is a motion orientation, from 0 to 360 degrees.

Options

• ApertureSize Aperture size of the cv.Sobel operator.

The function calculates a gradient orientation at each pixel (x,y) as:

 orientation(x,y) = arctan((dmhi / dy) / (dmhi / dx))

In fact, fastAtan2() and phase() are used so that the computed angle is measured in degrees and covers the full range 0..360. Also, the mask is filled to indicate pixels where the computed angle is valid.