I'm trying to determine the distance between two object by using two cameras (OCV 2.3.1, MSVC++, Win7) but can't calculate the object's objectPoints. I think this is because the image points aren't being rectified before their disparity is calculated.
I. WHAT I DO FIRST Step 1. Calibrate each camera by itself
int numSquares = numCornersHor * numCornersVer;
Size board_sz = Size(numCornersHor, numCornersVer);
Mat cameraMatrix = Mat(3, 3, CV_32FC1);
Mat distCoeffs;
vector<Mat> rvecs, tvecs;
cameraMatrix.ptr<float>(0)[0] = 1;
cameraMatrix.ptr<float>(1)[1] = 1;
calibrateCamera(object_points, image_points, image.size(),
cameraMatrix, distCoeffs, rvecs, tvecs);
Step 2. Calibrate the cameras to together.
int numCornersHor = 4;
int numCornersVer = 3;
const float squareSize = 1.75;
Size imageSize = Size(numCornersHor, numCornersVer);
int numSquares = numCornersHor * numCornersVer;
for(int i = 0; i < pairs; i++ )
{
for( int j = 0; j < imageSize.height; j++ )
{
for( int k = 0; k < imageSize.width; k++ )
{
objectPoints[i].push_back(Point3f(jsquareSize, ksquareSize, 0));
}
}
}
Mat R, T, E, F;
rms = stereoCalibrate(
objectPoints,
imagePoints[0], imagePoints[1],
cameraMatrix[0], distCoeffs[0],
cameraMatrix[1], distCoeffs[1],
imageSize,
R, T, E, F,
TermCriteria(CV_TERMCRIT_ITER+CV_TERMCRIT_EPS, 100, 1e-5),
CV_CALIB_FIX_ASPECT_RATIO +
CV_CALIB_ZERO_TANGENT_DIST +
CV_CALIB_SAME_FOCAL_LENGTH +
CV_CALIB_RATIONAL_MODEL +
CV_CALIB_FIX_K3 + CV_CALIB_FIX_K4 + CV_CALIB_FIX_K5
);
Step 3. Create the rectification data
stereoRectify(
cameraMatrix[0], cameraMatrix[1],
distCoeffs[0], distCoeffs[1],
imageSize,
R, T,
RC1, RC2, //RC1: Rotation matrix Camera 1
PC1, PC2,
Q,
CALIB_ZERO_DISPARITY,
1,
imageSize);
II. WHAT I BELIEVE Goal: I'm trying undistort and rectify the image points of one object in the image from camera 1 and the image from camera 2 (I do this process twice: once while the clay pigeon's on the launcher and once one frame before the clay pigeon disintegrates)
Method: I believe that I don't need to use initUndistortRectifyMap then Remap but can instead just use undistortPoints. I think undistortPoints undistorts the points of interest and rectifies them.
III. WHAT I DO SECOND You can ignore this if my beliefs aren't correct.
undistortPoints(launcherC1, launcherC1Undistorted, cameraMatrixC1, distCoeffsC1, R1, P1);
undistortPoints(launcherC2, launcherC2Undistorted, cameraMatrixC2, distCoeffsC2, R2, P2);
undistortPoints(clayPigeonC1, clayPigeonC1Undistorted, cameraMatrix1, distCoeffs1, R1, P1);
undistortPoints(clayPigeonC2, clayPigeonC2Undistorted, cameraMatrix2, distCoeffs2, R2, P2);
The input and output arrays for undistortPoints (launcherC1, launcherC1Undistorted, ... clayPigeonC2, clayPigeonC2Undistorted) are vectors of Point2f objects.
IV. DISCREPANCY BETWEEN BELIEF AND REALITY After all undistortPoints functions are run,
- launcherC1Undisorted.y does not equal launcherC2Undistorted.y
- clayPigeonC1Undistorted.y does not equal clayPigeonC2Undistorted.y.
They are up to 30% different.
V. QUESTIONS Q1: In addition to undistorting them does undistortPoints also rectify points? Q1.1_yes. Are the values of y supposed to be equal after rectification? Q1.1.1_yes Can you tell from the code I've included what I'm doing wrong so that they don't? Q1_no If undistortPoints doesn't rectify the points then how do I rectify them?
Thank you for any assistance. Charles++
Originally posted by Cherry 3.14 on ROS Answers with karma: 41 on 2012-05-04
Post score: 1