Create Mat from Vector<point2f> Assertion failed error

Question

I was trying to write Point2f imagePoints to a Mat image in openCV. I was following the link below.

Create Mat from vector<point2f>

But I am getting 'Assertion failed' error. Please help.

Code:

std::vector<cv::Point3d> objectPoints;
std::vector<cv::Point2d> imagePoints;

cv::Mat intrisicMat(3, 3, cv::DataType<double>::type);
intrisicMat.at<double>(0, 0) = param.focalLength.first;
intrisicMat.at<double>(0, 1) = 0;
intrisicMat.at<double>(0, 2) = param.principalPoint.first;

intrisicMat.at<double>(1, 0) = 0;
intrisicMat.at<double>(1, 1) = param.focalLength.second;
intrisicMat.at<double>(1, 2) = param.principalPoint.second;

intrisicMat.at<double>(2, 0) = 0;
intrisicMat.at<double>(2, 1) = 0;
intrisicMat.at<double>(2, 2) = 1;

cv::Mat rVec(3, 1, cv::DataType<double>::type); // Rotation vector
rVec.at<double>(0) = 0;
rVec.at<double>(1) = 0;
rVec.at<double>(2) = 0;

cv::Mat tVec(3, 1, cv::DataType<double>::type); // Translation vector
tVec.at<double>(0) = 0;
tVec.at<double>(1) = 0;
tVec.at<double>(2) = 0;

cv::Mat distCoeffs(5, 1, cv::DataType<double>::type);   // Distortion vector
distCoeffs.at<double>(0) = param.distortionRadial.at(0);
distCoeffs.at<double>(1) = param.distortionRadial.at(1);
distCoeffs.at<double>(2) = param.distortionTangential.first;
distCoeffs.at<double>(3) = param.distortionTangential.second;
distCoeffs.at<double>(4) = param.distortionRadial.at(2);


projectPoints(objectPoints, rVec, tVec, intrisicMat, distCoeffs, imagePoints);
Mat depthImage = Mat(imagePoints);
imwrite("E:/softwares/1.8.0.71/bin/depthImage.jpg", depthImage);
cout << "depthImage.channels()=" << depthImage.channels() << endl;

Error:

OpenCV Error: Assertion failed (image.channels() == 1 || image.channels() == 3 || image.channels() == 4) in cv::imwrite_, file E:\softwares\opencv-3.1.0\opencv-3.1.0\modules\imgcodecs\src\loadsave.cpp, line 455

My image has 2 channels. So ImWrite() is throwing assertion failed error. How can I create a Mat image using the Image points if not like this?

Answer 1

With what you have written in the comments, it seems that you're trying to imwrite your Mat to a file. The problem is, a Mat from Vector<Point2f> will give a 2 channels matrix, which is not compatible with any image format (grayscale, RGB or RGBA).

Moreover, please edit your main post to show the code (using markdown) so it is easier to read and then help you.