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Pose Estimation: Where is my error in reasoning?

Hi,

I am trying to do pose estimation. But I am clearly doing something wrong. Let's say I have an pattern consisting of 4 Markers (A,B,C,D). Each of these markers has an image coordinate and a pattern coordinate. The origin of the pattern is the center of the polygon.

Pattern upright

The image coordinates (x/y) are the following. (In a 1280x960 image)

Origin(616/814)

A(561/664)

B(702/838)

C(637/982)

D(520/755)

Pattern coordinates (x/y/z)

Origin(0/0/0)

A(-12/32/0)

B(18/-5/0)

C(12/-36/0)

D(21/13/0)

Now it rotates by 90 degrees, but my coordinate system does not rotate with the pattern. I am wondering what is wrong? Is it because the Z coordinate is always 0?

Pattern horizontal

(x/y)

Origin(632/784)

A(718/812)

B(567/938)

C(441/909)

D(632/784)

Pattern coordinates (x/y/z)

Origin(0/0/0)

A(32/12/0)

B(-4/18/0)

C(-35/11/0)

D(11/19/0)

I am using solvePnP like this

 cv::solvePnP(patternPoints, imgPoints, cameraMatrix, distCoeffs, rvec, tvec);

Drawing the axis

//Method Call
pattern.drawAxis(image, camMatrix, distCoeffs, rvec, tvec,10);

//Implementation (taken from aruco.cpp)

void drawAxis(InputOutputArray _image, InputArray _cameraMatrix, InputArray _distCoeffs,
              InputArray _rvec, InputArray _tvec, float length) {

    CV_Assert(_image.getMat().total() != 0 &&
              (_image.getMat().channels() == 1 || _image.getMat().channels() == 3));
    CV_Assert(length > 0);

    // project axis points
    vector< Point3f > axisPoints;
    axisPoints.push_back(Point3f(0, 0, 0));
    axisPoints.push_back(Point3f(length, 0, 0));
    axisPoints.push_back(Point3f(0, length, 0));
    axisPoints.push_back(Point3f(0, 0, length));
    vector< Point2f > imagePoints;
    projectPoints(axisPoints, _rvec, _tvec, _cameraMatrix, _distCoeffs, imagePoints);

    // draw axis lines
    line(_image, imagePoints[0], imagePoints[1], Scalar(0, 0, 255), 3);
    line(_image, imagePoints[0], imagePoints[2], Scalar(0, 255, 0), 3);
    line(_image, imagePoints[0], imagePoints[3], Scalar(255, 0, 0), 3);
}