public static List <Point[]> SelectMarkers(List <Point[]> candidateCorners, Bitmap undistoredImage)
{
return(candidateCorners.Where(corners =>
{
int minX = int.MaxValue;
int maxX = int.MinValue;
int minY = int.MaxValue;
int maxY = int.MinValue;
double perimeter = 0;
for (int i = 0; i < corners.Length; i++)
{
perimeter += Math.Sqrt(Math.Pow(corners[i].X - corners[(i + 1) % corners.Length].X, 2) +
Math.Pow(corners[i].Y - corners[(i + 1) % corners.Length].Y, 2));
minX = Math.Min(minX, corners[i].X);
maxX = Math.Max(maxX, corners[i].X);
minY = Math.Min(minY, corners[i].Y);
maxY = Math.Max(maxY, corners[i].Y);
}
var side = perimeter / 4;
var total_cnt = 0;
var border_cnt = 0;
double border_sum = 0;
for (int x = minX; x <= maxX; x++)
{
for (int y = minY; y <= maxY; y++)
{
if (CornerDetector.checkPointInPolygon(new Point(x, y), corners.ToList()))
{
total_cnt++;
var dist = Douglas_Peucker.CalcDistFromPointToPolygon(new Point(x, y), corners);
var pixel = undistoredImage.GetPixel(x, y);
var res = 0.21 * pixel.R + 0.72 * pixel.G + 0.07 * pixel.B;
if (dist < side * borderRate)
{
border_cnt++;
border_sum += res;
}
}
}
}
var average = border_sum / border_cnt;
return average <= blackThreshold;
}).ToList());
}
public static List <Point[]> FindCorners(MyImage source)
{
var dx = new int[] { 1, -1, 0, 0 };
var dy = new int[] { 0, 0, 1, -1 };
var minMarkerPerimeterRate = 0.05;
var minDimension = Math.Min(source.Height, source.Width);
var minPerimeter = minDimension * minMarkerPerimeterRate;
Console.WriteLine("MinPerimeter = " + minPerimeter);
var candidateCorners = new List <List <Point> >();
var visited = new bool[source.Height, source.Width];
for (int x = 1; x < source.Height - 1; x++)
{
for (int y = 1; y < source.Width - 1; y++)
{
if (!visited[x, y] && source.red[x, y] >= whiteThreshold)
{
var points = new List <Point>();
var queue = new Queue <Point>();
var startPixel = new Point(x, y);
queue.Enqueue(startPixel);
visited[x, y] = true;
while (queue.Count > 0)
{
var currentPixel = queue.Dequeue();
points.Add(currentPixel);
for (int direction = 0; direction < dx.Length; direction++)
{
var nextPoint = new Point(currentPixel.X + dx[direction], currentPixel.Y + dy[direction]);
if (!visited[nextPoint.X, nextPoint.Y] && source.red[nextPoint.X, nextPoint.Y] >= whiteThreshold)
{
queue.Enqueue(nextPoint);
visited[nextPoint.X, nextPoint.Y] = true;
}
}
}
points = SortPoints(points);
var corners = new List <Point>();
Douglas_Peucker.DouglasPeucker(points, 0, points.Count - 1, ref corners, true);
double perimeter = 0;
var minSide = double.MaxValue;
var maxSide = double.MinValue;
for (int i = 0; i < corners.Count; i++)
{
var side = Math.Sqrt(Math.Pow(corners[i].X - corners[(i + 1) % corners.Count].X, 2) +
Math.Pow(corners[i].Y - corners[(i + 1) % corners.Count].Y, 2));
perimeter += side;
minSide = Math.Min(minSide, side);
maxSide = Math.Max(maxSide, side);
}
if (corners.Count == 4 &&
minSide / maxSide > 0.6 &&
perimeter >= minPerimeter)
{
Console.WriteLine("corner 1: " + corners[0]);
Console.WriteLine(minSide + " " + maxSide + " " + minSide / maxSide + " " + perimeter);
candidateCorners.Add(corners);
}
}
;
}
}
;
return(candidateCorners.Select(c => c.Select(p => new Point(p.Y, p.X)).ToArray()).ToList());
}