# Revision history [back]

### SolvePNP. Compensate for head rotation

Hi all! I need to orientate detected face points to parallel with camera view.

I use the following code:

public void CalculateEulerAngles(int faceIndex)
{
var objectPoints = new List<Point3f>
{
...
};

var marks = Faces[faceIndex].Marks;
var imagePoints = new List<Point2f>
{
...
};

var focalLength = Image.Cols;
var center = new Point2f(Image.Cols / 2f, Image.Rows / 2f);
var cameraMatrix = new double[,] {{focalLength, 0, center.X}, {0, focalLength, center.Y}, {0, 0, 1}};

double[] rvec, tvec;
Cv2.SolvePnP(objectPoints, imagePoints, cameraMatrix, null, out rvec, out tvec);

double[,] rvecRodrigues;
Cv2.Rodrigues(rvec, out rvecRodrigues);

double[] eulerAngles;
double[,] camMatrix;
GetEulerAngles(rvecRodrigues, out eulerAngles, out camMatrix);

//

Point2f[] points;
double[,] jacobian;
Cv2.ProjectPoints(objectPoints, rvec, tvec, cameraMatrix, null, out points, out jacobian);

for (int i = 0; i < points.Length; i++)
Cv2.Circle(Image, (int)points[i].X, (int)points[i].Y, 5, Scalar.Aqua);

//
}

void GetEulerAngles(double[,] rvec, out double[] euler, out double[,] camMatrix)
{
double[] transVect, eulerAngles;
double[,] cameraMatrix,rotMatrix,rotMatrixX,rotMatrixY,rotMatrixZ;
double[,] projMatrix =
{
{rvec[0, 0], rvec[0, 1], rvec[0, 2], 0},
{rvec[1, 0], rvec[1, 1], rvec[1, 2], 0},
{rvec[2, 0], rvec[2, 1], rvec[2, 2], 0}
};

Cv2.DecomposeProjectionMatrix(projMatrix, out cameraMatrix, out rotMatrix, out transVect,
out rotMatrixX, out rotMatrixY, out rotMatrixZ, out eulerAngles);

euler = eulerAngles;
camMatrix = cameraMatrix;
}


But, I don't know how I can rotate points use calculated Euler angles to orientate parallel with camera view, so points always "flatted" to camera. Thanks guys