OpenCV ProjectPoints keeps plotting all image points at top left of screen - c++

Question

I am trying to project 3D (x,y,z) axes via the openCV projectPoints function onto a chessboard after calibration, but every time I run my code, the axes all point to a specific projected image point on the screen.
example output image
The cameraMatrix and distCoeffs are read in from data that was wrote to a file during calibration. They are:
CameraMatrix[1372.852997982289, 0, 554.2708806543288;
0, 1372.852997982289, 906.4327368600385;
0, 0, 1]
distCoeff[0.02839203221556521;
0.442572399014994;
-0.01755006951285373;
-0.0008989327508155589;
-1.836490953232962]
The rotation and translation values are being computed in real-time via SolvePnP every time a bool is turned on via keypress. An example of a their output values are:
R =
[-0.9065211432378315;
0.3787201875924527;
-0.2788943269946833]
T =
[-0.4433059282649063;
-0.6745750872705997;
1.13753594660495]
While SolvePnP is being computed, I press another keypress to draw the 3D axes from the origin as written in the code below. And the rotation and translation values are passed into the projectPoint function. However, the axesProjectedPoints image points output for each axis is always very similar and in the range of:
[100.932, 127.418]
[55.154, 157.192]
[70.3054, 162.585]
Note the axesProjectedPoints is initialized out of the loop as a vector<Point2f> axesProjectedPoints
The reprojection error is fairly good, and under 1 pixel.
The projectPoints code:
if (found) {
// read calibration data -- function that reads calibration data saved to a file
readCameraConfig(cameraMatrix, distCoeffs);
// draw corners
drawChessboardCorners(convertedImage, patternsize, corners, found);
// draw 3D axes using projectPoints
// used 0.04 because the chessboard square is 0.01778 m
std::vector<Point3f> axis;
axis.push_back(cv::Point3f(0.04, 0, 0));
axis.push_back(cv::Point3f(0, 0.04, 0));
axis.push_back(cv::Point3f(0, 0, 0.04));
// the rotation_values and translation values are outputs from the openCV solvePnp function that is being computed separately in real-time every time i press a keypress
projectPoints(axis, rotation_values, translation_values, cameraMatrix, distCoeffs, axesProjectedPoints);
cout << "image points" << endl;
for (auto &n : axesProjectedPoints) {
cout << n << endl;
}
cv::line(convertedImage, corners[0], axesProjectedPoints[0], {255,0,0}, 5);
cv::line(convertedImage, corners[0], axesProjectedPoints[1], {0,255,0}, 5);
cv::line(convertedImage, corners[0], axesProjectedPoints[2], {0,0,255}, 5);
}
the solvePnP part of code:
/* calculate board's pose (rotation and translation) */
bool flag = false;
if (flag) {
printf("Calculating board's pose (rotation and translation) ...\n");
// read calibration data
readCameraConfig(cameraMatrix, distCoeffs);
// create undistorted corners or image points
undistortPoints(corners, imagePoints, cameraMatrix, distCoeffs);
//cout << "POINTS" << endl;
std::vector<Point3d> objp;
for(auto &i : points) {
objp.push_back(i);
//cout << i << endl;
}
//cout << "CORNERS" << endl;
std::vector<Point2d> imagep;
for(auto &j : imagePoints) {
imagep.push_back(j);
//cout << j << endl;
}
cout << "point size" << endl;
cout << objp.size() << endl;
// calculate pose
solvePnP(objp, imagep, cameraMatrix, distCoeffs, rotation_values, translation_values, true, SOLVEPNP_ITERATIVE);
// print rotation and translation values
cout << "R = " << endl << " " << rotation_values << endl << endl;
cout << "T = " << endl << " " << translation_values << endl << endl;
}
}