func calcDeltaEnergy(flow *C.IplImage, config *Configuration) float64 {
var i C.int
var dx, dy, mx, my float64
totalPixels := flow.width * flow.height
// Determine mean movement vector.
for i = 0; i < totalPixels; i++ {
value := C.cvGet2D(unsafe.Pointer(flow), i/flow.width, i%flow.width)
mx += float64(value.val[0])
my += float64(value.val[1])
}
mx = math.Abs(mx / float64(totalPixels))
my = math.Abs(my / float64(totalPixels))
// Accumulate the change in flow across all the pixels.
for i = 0; i < totalPixels; i++ {
// Remove the mean movement vector to compenstate for the sculpture that might be swaying in the wind.
value := C.cvGet2D(unsafe.Pointer(flow), i/flow.width, i%flow.width)
dx += math.Max((math.Abs(float64(value.val[0])) - mx), 0.0)
dy += math.Max((math.Abs(float64(value.val[1])) - my), 0.0)
}
// average out the magnitude of dx and dy across the whole image.
dx = dx / float64(totalPixels)
dy = dy / float64(totalPixels)
// The magnitude of accumulated flow forms our change in energy for the frame.
deltaE := math.Sqrt((dx * dx) + (dy * dy))
fmt.Printf("INFO: f:%f m:[%f,%f]\n", deltaE, mx, my)
// Clamp the energy to start at 0 for 'still' frames with little/no motion.
deltaE = math.Max(0.0, (deltaE - config.MovementThreshold))
// Scale the flow to be less than 0.1 for 'active' frames with lots of motion.
deltaE = deltaE / config.OpticalFlowScale
return deltaE
}
func (img *Image) ScalarAt(pos ...int) Scalar {
n := len(pos)
var s C.CvScalar
if n == 1 {
s = C.cvGet1D(img.ptr, C.int(pos[0]))
} else if n == 2 {
s = C.cvGet2D(img.ptr, C.int(pos[0]), C.int(pos[1]))
} else if n == 3 {
s = C.cvGet3D(img.ptr, C.int(pos[0]), C.int(pos[1]), C.int(pos[2]))
}
return Scalar{float64(s.val[0]), float64(s.val[1]), float64(s.val[2]), float64(s.val[3])}
}
/* Get2D return a specific element from a 2-dimensional matrix. */
func (m *Mat) Get2D(x, y int) Scalar {
ret := C.cvGet2D(unsafe.Pointer(m), C.int(x), C.int(y))
return Scalar(ret)
}
/* Get2D return a specific element from a 2-dimensional matrix. */
func (img *IplImage) Get2D(x, y int) Scalar {
ret := C.cvGet2D(unsafe.Pointer(img), C.int(y), C.int(x))
return Scalar(ret)
}