-Fix a bug in EllipseLeastSquareFitting, such that a positive value of the angle of the ellipse indicates counter-clock-wise rotation. Now it is consistent with the ellipse drawing function.

-Added  GeneratePointCloud function

git-svn-id: https://emgucv.svn.sourceforge.net/svnroot/emgucv/trunk@556 d7f09016-e345-0410-b530-edf29a71df78

Emgu.CV.Test/AutoTestVarious.cs

@@ -1092,7 +1092,6 @@ namespace Emgu.CV.Test
          }
       }
 
-
       [Test]
       public void TestEllipseFitting()
       {
@@ -1100,22 +1099,18 @@ namespace Emgu.CV.Test
          int sampleCount = 100;
 
          Image<Bgr, byte> img = new Image<Bgr, byte>(400, 400, new Bgr(Color.White));
-         PointF[] pts = new PointF[sampleCount];
-         for (int i = 0; i < pts.Length; i++)
-         {
-            int x = r.Next(200) + 50;
-            int y = r.Next(300) + 50;
-            pts[i] = new PointF(x, y);
 
-            img.Draw(new CircleF(pts[i], 2), new Bgr(Color.Green), 1);
-
-         }
+         Ellipse modelEllipse = new Ellipse(new PointF(200, 200), new SizeF(150, 60), 30);
+         PointF[] pts = PointCollection.GeneratePointCloud(modelEllipse, sampleCount);
+         foreach (PointF p in pts)
+            img.Draw(new CircleF(p, 2), new Bgr(Color.Green), 1);
 
          Stopwatch watch = Stopwatch.StartNew();
-         Ellipse e = PointCollection.EllipseLeastSquareFitting(pts);
+         Ellipse fittedEllipse = PointCollection.EllipseLeastSquareFitting(pts);
          watch.Stop();
 
-         img.Draw(e, new Bgr(Color.Red), 2);
+         //img.Draw(modelEllipse, new Bgr(Color.Orange), 2);
+         img.Draw(fittedEllipse, new Bgr(Color.Red), 2);
          //ImageViewer.Show(img, String.Format("Time used: {0}milliseconds", watch.ElapsedMilliseconds));
       }
 

Emgu.CV/PointAndLine/PointCollection.cs

@@ -116,6 +116,15 @@ namespace Emgu.CV
             seq,
             block);
          Ellipse e = new Ellipse(CvInvoke.cvFitEllipse2(seq));
+
+         //The angle returned by cvFitEllipse2 has the wrong sign.
+         //Returned angle is clock wise rotation, what we need for the definition of MCvBox is the counter clockwise rotation.
+         //For this, we needs to change the sign of the angle
+         MCvBox2D b = e.MCvBox2D;
+         b.angle = -b.angle;
+         if (b.angle < 0) b.angle += 360;
+         e.MCvBox2D = b;
+         
          handle.Free();
          Marshal.FreeHGlobal(seq);
          Marshal.FreeHGlobal(block);
@@ -278,5 +287,28 @@ namespace Emgu.CV
          handle.Free();
          return points3D;
       }
+
+      /// <summary>
+      /// Generate a random point cloud around the ellipse. 
+      /// </summary>
+      /// <param name="e">The region where the point cloud will be generated. The axes of e corresponds to std of the random point cloud.</param>
+      /// <param name="numberOfPoints">The number of points to be generated</param>
+      /// <returns>A random point cloud around the ellipse</returns>
+      public static PointF[] GeneratePointCloud(Ellipse e, int numberOfPoints)
+      {
+         PointF[] cloud = new PointF[numberOfPoints];
+         GCHandle handle = GCHandle.Alloc(cloud, GCHandleType.Pinned);
+         using (Matrix<float> points = new Matrix<float>(numberOfPoints, 2, handle.AddrOfPinnedObject()))
+         using (Matrix<float> xValues = points.GetCol(0))
+         using (Matrix<float> yValues = points.GetCol(1))
+         using (RotationMatrix2D<float> rotation = new RotationMatrix2D<float>(e.MCvBox2D.center, e.MCvBox2D.angle, 1.0))
+         {
+            xValues.SetRandNormal(new MCvScalar(e.MCvBox2D.center.X), new MCvScalar(e.MCvBox2D.size.Width / 2.0f));
+            yValues.SetRandNormal(new MCvScalar(e.MCvBox2D.center.Y), new MCvScalar(e.MCvBox2D.size.Height / 2.0f));
+            rotation.RotatePoints(points);
+         }
+         handle.Free();
+         return cloud;
+      }
    }
 }