Accord.Math.Geometry.CoplanarPosit.GetError C# (CSharp) Method

        private float GetError( Point[] imagePoints, Matrix3x3 rotation, Vector3 translation )
        {
            Vector3 v1 = rotation * modelPoints[0] + translation;
            v1.X = v1.X * focalLength / v1.Z;
            v1.Y = v1.Y * focalLength / v1.Z;

            Vector3 v2 = rotation * modelPoints[1] + translation;
            v2.X = v2.X * focalLength / v2.Z;
            v2.Y = v2.Y * focalLength / v2.Z;

            Vector3 v3 = rotation * modelPoints[2] + translation;
            v3.X = v3.X * focalLength / v3.Z;
            v3.Y = v3.Y * focalLength / v3.Z;

            Vector3 v4 = rotation * modelPoints[3] + translation;
            v4.X = v4.X * focalLength / v4.Z;
            v4.Y = v4.Y * focalLength / v4.Z;

            Point[] modeledPoints = new Point[4]
            {
                new Point( v1.X, v1.Y ),
                new Point( v2.X, v2.Y ),
                new Point( v3.X, v3.Y ),
                new Point( v4.X, v4.Y ),
            };

            float ia1 = GeometryTools.GetAngleBetweenVectors( imagePoints[0], imagePoints[1], imagePoints[3] );
            float ia2 = GeometryTools.GetAngleBetweenVectors( imagePoints[1], imagePoints[2], imagePoints[0] );
            float ia3 = GeometryTools.GetAngleBetweenVectors( imagePoints[2], imagePoints[3], imagePoints[1] );
            float ia4 = GeometryTools.GetAngleBetweenVectors( imagePoints[3], imagePoints[0], imagePoints[2] );

            float ma1 = GeometryTools.GetAngleBetweenVectors( modeledPoints[0], modeledPoints[1], modeledPoints[3] );
            float ma2 = GeometryTools.GetAngleBetweenVectors( modeledPoints[1], modeledPoints[2], modeledPoints[0] );
            float ma3 = GeometryTools.GetAngleBetweenVectors( modeledPoints[2], modeledPoints[3], modeledPoints[1] );
            float ma4 = GeometryTools.GetAngleBetweenVectors( modeledPoints[3], modeledPoints[0], modeledPoints[2] );

            return (
                System.Math.Abs( ia1 - ma1 ) +
                System.Math.Abs( ia2 - ma2 ) +
                System.Math.Abs( ia3 - ma3 ) +
                System.Math.Abs( ia4 - ma4 )
                ) / 4;
        }