/// <summary>
/// Finds the convexity defects in a contour given a convex hull.
/// </summary>
///
/// <param name="contour">The contour.</param>
/// <param name="convexHull">The convex hull of the contour.</param>
/// <returns>A list of <see cref="ConvexityDefect"/>s containing each of the
/// defects found considering the convex hull of the contour.</returns>
///
public List <ConvexityDefect> FindDefects(List <IntPoint> contour, List <IntPoint> convexHull)
{
if (contour.Count < 4)
{
throw new ArgumentException("Point sequence size should have at least 4 points.");
}
if (convexHull.Count < 3)
{
throw new ArgumentException("Convex hull must have at least 3 points.");
}
// Find all convex hull points in the contour
int[] indexes = new int[convexHull.Count];
for (int i = 0, j = 0; i < contour.Count; i++)
{
if (convexHull.Contains(contour[i]))
{
indexes[j++] = i;
}
}
List <ConvexityDefect> defects = new List <ConvexityDefect>();
// For each two consecutive points in the convex hull
for (int i = 0; i < indexes.Length - 1; i++)
{
ConvexityDefect current = extractDefect(contour, indexes[i], indexes[i + 1]);
if (current.Depth > MinimumDepth)
{
defects.Add(current);
}
}
// Consider area between the last point and the first point
{
ConvexityDefect current = extractDefect(contour, indexes[indexes.Length - 1], indexes[0]);
if (current.Depth > MinimumDepth)
{
defects.Add(current);
}
}
return(defects);
}
