getTriangleList（）OpenCV C ++给出了奇怪的结果

Question

OpenCV for C ++中的getTriangleList（）如何工作？特别是，我们得到许多额外的点作为三角形点，这些点从哪里突然出现？点数（-1800，-1800）等 矢量vi只包含（1,1）。

This is the image of point 1 1 being sent in and the triangle has many points.

cout << "Enter first images' tie points:\t";
for (int i = 0; i < n; ++i)
{
    int a, b;
    cin >> a >> b;
    Point2f p(a, b);
    vi.push_back(p);
}

生成三角形的逻辑如下：

Size size = I.size();
Rect R(0, 0, size.width, size.height);
Subdiv2D a(R);
//a.initDelaunay(R);

for( vector<Point2f>::iterator it = vi.begin(); it != vi.end(); it++)
{
    a.insert(*it);
}

vector<Vec6f> triangle;
a.getTriangleList(triangle);

Answer 1

我不知道为什么，但是getTriangleList（）还会返回图像外部的三角形。它可能与Voronoi图的制作方式有关，但我不了解这些三角形如何为我们提供帮助。因此，您需要删除这些三角形。我做了对我有用的功能。约有20％的三角形，但完全或部分脱离了图像。

std::vector<Vec6f> FaceMorpher::pointsToTriangles(std::vector<Point2f> points)
{
  Rect rect(0, 0, _widthImage, _heightmage); //choose the space we want to work in, in this case all the image
  Subdiv2D subdiv(rect); //object representing the points is a Voronoi diagram so it can easily triangulise the points
  for (auto& point : points)
    subdiv.insert(point); //subdiv updates the Voronoi diagram each time a point is inserted

  std::vector<Vec6f> triangles;
  subdiv.getTriangleList(triangles); //generate the triangles by splitting polygons formed by Voronoi diagram into triangles

  //Remove triangles that are not  completly inside the image
  std::vector<Vec6f> trianglesInsideImg;
  for (size_t i = 0; i < triangles.size(); i++)
  {
    Vec6f t = triangles[i];
    auto p1 = Point(cvRound(t[0]), cvRound(t[1]));
    auto p2 = Point(cvRound(t[2]), cvRound(t[3]));
    auto p3 = Point(cvRound(t[4]), cvRound(t[5]));

    if (rect.contains(p1) && rect.contains(p2) && rect.contains(p3))
    {
      Vec6f triangle;
      triangle[0] = p1.x;
      triangle[1] = p1.y;
      triangle[2] = p2.x;
      triangle[3] = p2.y;
      triangle[4] = p3.x;
      triangle[5] = p3.y;
      trianglesInsideImg.push_back(triangle);
    }
  }

  return trianglesInsideImg; 
}