public void GetTriangleList()
{
using var subdiv = new Subdiv2D(new Rect(0, 0, 500, 500));
var points = new[] { new Point2f(300, 100), new Point2f(200, 300), new Point2f(400, 300) };
subdiv.Insert(points[0]);
subdiv.Insert(points[1]);
subdiv.Insert(points[2]);
var triangles = subdiv.GetTriangleList();
Assert.Single(triangles);
var triangleVertices = new[]
{
triangles[0].Item0, triangles[0].Item1, triangles[0].Item2, triangles[0].Item3, triangles[0].Item4, triangles[0].Item5,
};
foreach (var point in points)
{
Assert.Contains(point.X, triangleVertices);
Assert.Contains(point.Y, triangleVertices);
}
}
/// <summary>
/// Perform Delaunay triangulation on a given set of landmark points.
/// </summary>
/// <param name="points">The landmark points to use for triangulation.</param>
/// <returns>A list of Triangle structures that each refer to a single triangle of landmark points.</returns>
public static IEnumerable <Triangle> GetDelaunayTriangles(IEnumerable <Point> points)
{
var result = new List <Triangle>();
// calculate the bounding box around the points
var rect = Cv2.BoundingRect(points);
rect.Inflate(10, 10);
// the Subdiv2D class handles Delaunay triangulation
// first we add all points, and then start triangulation
Vec6f[] triangles;
using (var subdiv = new Subdiv2D(rect))
{
foreach (var p in points)
{
var cv_p = new OpenCvSharp.Point2f(p.X, p.Y);
subdiv.Insert(cv_p);
}
triangles = subdiv.GetTriangleList();
}
// return result as an enumeration of triangle structs
return(from t in triangles
let p1 = new Point(t[0], t[1])
let p2 = new Point(t[2], t[3])
let p3 = new Point(t[4], t[5])
where rect.Contains(p1) && rect.Contains(p2) && rect.Contains(p3)
select new Triangle(p1, p2, p3));
}
public void Run()
{
const int Size = 600;
// Creates random point list
var rand = new Random();
var points = Enumerable.Range(0, 100).Select(_ =>
new Point2f(rand.Next(0, Size), rand.Next(0, Size))).ToArray();
Mat img = Mat.Zeros(Size, Size, MatType.CV_8UC3);
foreach (var p in points)
{
img.Circle(p, 4, Scalar.Red, -1);
}
// Initializes Subdiv2D
var subdiv = new Subdiv2D();
subdiv.InitDelaunay(new Rect(0, 0, Size, Size));
subdiv.Insert(points);
// Draws voronoi diagram
Point2f[][] facetList;
Point2f[] facetCenters;
subdiv.GetVoronoiFacetList(null, out facetList, out facetCenters);
var vonoroi = img.Clone();
foreach (var list in facetList)
{
var before = list.Last();
foreach (var p in list)
{
vonoroi.Line(before, p, new Scalar(64, 255, 128), 1);
before = p;
}
}
// Draws delaunay diagram
Vec4f[] edgeList = subdiv.GetEdgeList();
var delaunay = img.Clone();
foreach (var edge in edgeList)
{
var p1 = new Point(edge.Item0, edge.Item1);
var p2 = new Point(edge.Item2, edge.Item3);
delaunay.Line(p1, p2, new Scalar(64, 255, 128), 1);
}
Cv2.ImShow("voronoi", vonoroi);
Cv2.ImShow("delaunay", delaunay);
Cv2.WaitKey();
Cv2.DestroyAllWindows();
}
public void GetVoronoiFacetList()
{
using var subdiv = new Subdiv2D(new Rect(0, 0, 500, 500));
var points = new[] { new Point2f(300, 100), new Point2f(200, 300), new Point2f(400, 300) };
subdiv.Insert(points);
subdiv.GetVoronoiFacetList(null, out var facetList, out var facetCenters);
Assert.Equal(3, facetList.Length);
Assert.Equal(3, facetCenters.Length);
Assert.Equal(4, facetList[0].Length);
}
public void Run()
{
const int Size = 600;
// Creates random point list
var rand = new Random();
var points = Enumerable.Range(0, 100).Select(_ =>
new Point2f(rand.Next(0, Size), rand.Next(0, Size))).ToArray();
Mat img = Mat.Zeros(Size, Size, MatType.CV_8UC3);
foreach (var p in points)
{
img.Circle(p, 4, CvColor.Red, -1);
}
// Initializes Subdiv2D
var subdiv = new Subdiv2D();
subdiv.InitDelaunay(new Rect(0, 0, Size, Size));
subdiv.Insert(points);
// Draws voronoi diagram
Point2f[][] facetList;
Point2f[] facetCenters;
subdiv.GetVoronoiFacetList(null, out facetList, out facetCenters);
var vonoroi = img.Clone();
foreach (var list in facetList)
{
var before = list.Last();
foreach (var p in list)
{
vonoroi.Line(before, p, new CvColor(64, 255, 128), 1);
before = p;
}
}
// Draws delaunay diagram
Vec4f[] edgeList = subdiv.GetEdgeList();
var delaunay = img.Clone();
foreach (var edge in edgeList)
{
var p1 = new Point(edge.Item0, edge.Item1);
var p2 = new Point(edge.Item2, edge.Item3);
delaunay.Line(p1, p2, new CvColor(64, 255, 128), 1);
}
Cv2.ImShow("voronoi", vonoroi);
Cv2.ImShow("delaunay", delaunay);
Cv2.WaitKey();
Cv2.DestroyAllWindows();
}
private static IEnumerable <int[]> GetDelaunayTriangulationIndexes(Rect rect, List <Point2f> points)
{
rect = Cv2.BoundingRect(points).Union(rect);
using (var subdivision = new Subdiv2D(rect))
{
subdivision.Insert(points);
var triangulation = subdivision.GetTriangleList();
foreach (var cell in triangulation)
{
var p1 = new Point2f(cell.Item0, cell.Item1);
var p2 = new Point2f(cell.Item2, cell.Item3);
var p3 = new Point2f(cell.Item4, cell.Item5);
if (rect.Contains(p1) && rect.Contains(p2) && rect.Contains(p3))
{
var indexA = points.IndexOf(p1);
var indexB = points.IndexOf(p2);
var indexC = points.IndexOf(p3);
var indexes = new[] { indexA, indexB, indexC };
yield return(indexes);
}
}
}
}
private void CreateDelaunay(ref Mat img, ref Subdiv2D subdiv, ref VectorOfPointF points,
bool drawAnimated, ref VectorOfVectorOfInt triangleIndexes)
{
PointF[] pointsArr = points.ToArray();
foreach (PointF p in pointsArr)
{
subdiv.Insert(p);
if (drawAnimated)
{
Mat imgCopy = img.Clone();
DrawDelaunay(ref imgCopy, ref subdiv, new MCvScalar(255, 255, 255));
CvInvoke.Imshow("Delaunay Triangulation", imgCopy);
}
}
// Unfortunately we don't get the triangles by there original point indexes.
// We only get them with their vertex coordinates.
// So we have to map them again to get the triangles with their point indexes.
Size size = img.Size;
Rectangle rect = new Rectangle(0, 0, size.Width, size.Height);
VectorOfInt ind = new VectorOfInt();
int[] indArr = new int[3];
Triangle2DF[] triangleList = subdiv.GetDelaunayTriangles();
for (int i = 0; i < triangleList.Length; i++)
{
Triangle2DF t = triangleList[i];
PointF ptzero = new PointF {
X = t.V0.X, Y = t.V0.Y
};
PointF[] PZero = new PointF[] { ptzero };
PointF ptone = new PointF {
X = t.V1.X, Y = t.V1.Y
};
PointF[] POne = new PointF[] { ptone };
PointF pttwo = new PointF {
X = t.V2.X, Y = t.V2.Y
};
PointF[] PTwo = new PointF[] { pttwo };
VectorOfPointF pt = new VectorOfPointF();
pt.Push(PZero);
pt.Push(POne);
pt.Push(PTwo);
if (rect.Contains(new Point((int)pt[0].X, (int)pt[0].Y)) &&
rect.Contains(new Point((int)pt[1].X, (int)pt[1].Y)) &&
rect.Contains(new Point((int)pt[2].X, (int)pt[2].Y)))
{
for (int j = 0; j < 3; j++)
{
for (int k = 0; k < points.Size; k++)
{
if (Math.Abs(pt[j].X - points[k].X) < 1.0 &&
Math.Abs(pt[j].Y - points[k].Y) < 1)
{
indArr[j] = k;
}
}
}
}
ind = new VectorOfInt(indArr);
triangleIndexes.Push(ind);
}
}
