Emgu CV Library Documentation
cvCalcMotionGradient Method (mhi, mask, orientation, delta1, delta2, apertureSize)
NamespacesEmgu.CVCvInvokecvCalcMotionGradient(IntPtr, IntPtr, IntPtr, Double, Double, Int32)

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Calculates the derivatives Dx and Dy of mhi and then calculates gradient orientation as: orientation(x,y)=arctan(Dy(x,y)/Dx(x,y)) where both Dx(x,y)' and Dy(x,y)' signs are taken into account (as in cvCartToPolar function). After that mask is filled to indicate where the orientation is valid (see delta1 and delta2 description).
Declaration Syntax
C#Visual BasicVisual C++
public static void cvCalcMotionGradient(
	IntPtr mhi,
	IntPtr mask,
	IntPtr orientation,
	double delta1,
	double delta2,
	int apertureSize
)
Public Shared Sub cvCalcMotionGradient ( _
	mhi As IntPtr, _
	mask As IntPtr, _
	orientation As IntPtr, _
	delta1 As Double, _
	delta2 As Double, _
	apertureSize As Integer _
)
public:
static void cvCalcMotionGradient(
	IntPtr mhi, 
	IntPtr mask, 
	IntPtr orientation, 
	double delta1, 
	double delta2, 
	int apertureSize
)
Parameters
mhi (IntPtr)
Motion history image
mask (IntPtr)
Mask image; marks pixels where motion gradient data is correct. Output parameter.
orientation (IntPtr)
Motion gradient orientation image; contains angles from 0 to ~360.
delta1 (Double)
The function finds minimum (m(x,y)) and maximum (M(x,y)) mhi values over each pixel (x,y) neihborhood and assumes the gradient is valid only if min(delta1,delta2) <= M(x,y)-m(x,y) <= max(delta1,delta2).
delta2 (Double)
The function finds minimum (m(x,y)) and maximum (M(x,y)) mhi values over each pixel (x,y) neihborhood and assumes the gradient is valid only if min(delta1,delta2) <= M(x,y)-m(x,y) <= max(delta1,delta2).
apertureSize (Int32)
Aperture size of derivative operators used by the function: CV_SCHARR, 1, 3, 5 or 7 (see cvSobel).

Assembly: Emgu.CV (Module: Emgu.CV) Version: 1.5.0.0 (1.5.0.0)