/// <summary>
/// Create a template
/// </summary>
private void TrainTemplate()
{
try
{
results.Clear();
using (Mat src = new Mat())
using (Mat output = new Mat())
using (Mat gx = new Mat())
using (Mat gy = new Mat())
using (Mat magnitude = new Mat())
using (Mat direction = new Mat())
{
/// convert to gray image
Cv2.CvtColor(template, src, ColorConversionCodes.RGB2GRAY);
/// using the canny algorithm to get edges
Cv2.Canny(src, output, TrainParame.Threshold1, TrainParame.Threshold2, TrainParame.ApertureSize, TrainParame.L2gradient);
Cv2.FindContours(output, out var contours, out var hierarchy, TrainParame.Mode, TrainParame.Method);
/// use the sobel filter on the template image which returns the gradients in the X (Gx) and Y (Gy) direction.
Cv2.Sobel(src, gx, MatType.CV_64F, 1, 0, 3);
Cv2.Sobel(src, gy, MatType.CV_64F, 0, 1, 3);
/// compute the magnitude and direction(radians)
Cv2.CartToPolar(gx, gy, magnitude, direction);
/// save edge info
var sum = new Point2d(0, 0);
for (int i = 0, m = contours.Length; i < m; i++)
{
for (int j = 0, n = contours[i].Length; j < n; j++)
{
var cur = contours[i][j];
var fdx = gx.At <double>(cur.Y, cur.X, 0); // dx
var fdy = gy.At <double>(cur.Y, cur.X, 0); // dy
var der = new Point2d(fdx, fdy); // (dx,dy)
var mag = magnitude.At <double>(cur.Y, cur.X, 0); // √(dx²+dy²)
var dir = direction.At <double>(cur.Y, cur.X, 0); // atan2(dy,dx)
results.Add(new PointInfo
{
Point = cur,
Derivative = der,
Direction = dir,
Magnitude = mag == 0 ? 0 : 1 / mag,
});
sum += cur;
}
}
/// update Center and Offset in PointInfo
var center = new Point2d(sum.X / results.Count, sum.Y / results.Count);
foreach (var item in results)
{
item.Update(center);
}
/// overlay display origin image, edge(green) and center point(red)
Cv2.DrawContours(template, new[] { results.Select(_ => _.Point) }, -1, Scalar.LightGreen, 2);
//Cv2.DrawContours(template, contours, -1, Scalar.LightGreen, 2);
Cv2.Circle(template, center.ToPoint(), 2, Scalar.Red, -1);
}
/// update UI
RaisePropertyChanged(nameof(Template));
}
catch (Exception ex)
{
Trace.TraceError(ex.Message);
Trace.TraceError(ex.StackTrace);
}
}