Right use of initUndistortRectifyMap and remap from OpenCV - c++

Question

I want to undistort a camera image. The undistort function of OpenCV is too slow, so I want to split it like mentioned in the documentation into the 2 calls of initUndistortRectifyMap (as init step) and remap (in the render loop).
At first, I tried a test program with the principal approach:
//create source matrix
cv::Mat srcImg(res.first, res.second, cvFormat, const_cast<char*>(pImg));
//fill matrices
cv::Mat cam(3, 3, cv::DataType<float>::type);
cam.at<float>(0, 0) = 528.53618582196384f;
cam.at<float>(0, 1) = 0.0f;
cam.at<float>(0, 2) = 314.01736116032430f;
cam.at<float>(1, 0) = 0.0f;
cam.at<float>(1, 1) = 532.01912214324500f;
cam.at<float>(1, 2) = 231.43930864205211f;
cam.at<float>(2, 0) = 0.0f;
cam.at<float>(2, 1) = 0.0f;
cam.at<float>(2, 2) = 1.0f;
cv::Mat dist(5, 1, cv::DataType<float>::type);
dist.at<float>(0, 0) = -0.11839989180635836f;
dist.at<float>(1, 0) = 0.25425420873955445f;
dist.at<float>(2, 0) = 0.0013269901775205413f;
dist.at<float>(3, 0) = 0.0015787467748277866f;
dist.at<float>(4, 0) = -0.11567938093172066f;
cv::Mat map1, map2;
cv::initUndistortRectifyMap(cam, dist, cv::Mat(), cam, cv::Size(res.second, res.first), CV_32FC1, map1, map2);
cv::remap(srcImg, *m_undistImg, map1, map2, cv::INTER_CUBIC);
The format of my camera image is BGRA. The code compiles and starts, but the resulting image is wrong:
Any ideas, what's wrong with my code?

Answer 1

It works, yes. To be honest, I don't remember exactly what the problem was. I interchanged width and height or somethink like that.
This is my running code:
//create source matrix
cv::Mat srcImg(resolution.second, resolution.first, cvFormat, const_cast<unsigned char*>(pSrcImg));
//look if an update of the maps is necessary
if ((resolution.first != m_width) || (m_height != resolution.second))
{
m_width = resolution.first;
m_height = resolution.second;
cv::initUndistortRectifyMap(*m_camData, *m_distData, cv::Mat(), *m_camData, cv::Size(resolution.first, resolution.second), CV_32FC1, *m_undistMap1, *m_undistMap2);
}
//create undistorted image
cv::remap(srcImg, *m_undistortedImg, *m_undistMap1, *m_undistMap2, cv::INTER_LINEAR);
return reinterpret_cast<unsigned char*>(m_undistortedImg->data);