Question

我想声明，填充，访问OpenCV（C ++）中与 namespace cv 兼容的多维矩阵。我发现没有快速简单的例子。你能帮帮我吗？

Answer 1

以下是NAryMatIterator文档中的简短示例;它展示了如何在OpenCV中创建，填充和处理多维矩阵：

void computeNormalizedColorHist(const Mat& image, Mat& hist, int N, double minProb)
{
    const int histSize[] = {N, N, N};

    // make sure that the histogram has a proper size and type
    hist.create(3, histSize, CV_32F);

    // and clear it
    hist = Scalar(0);

    // the loop below assumes that the image
    // is a 8-bit 3-channel. check it.
    CV_Assert(image.type() == CV_8UC3);
    MatConstIterator_<Vec3b> it = image.begin<Vec3b>(),
                             it_end = image.end<Vec3b>();
    for( ; it != it_end; ++it )
    {
        const Vec3b& pix = *it;
        hist.at<float>(pix[0]*N/256, pix[1]*N/256, pix[2]*N/256) += 1.f;
    }

    minProb *= image.rows*image.cols;
    Mat plane;
    NAryMatIterator it(&hist, &plane, 1);
    double s = 0;
    // iterate through the matrix. on each iteration
    // it.planes[*] (of type Mat) will be set to the current plane.
    for(int p = 0; p < it.nplanes; p++, ++it)
    {
        threshold(it.planes[0], it.planes[0], minProb, 0, THRESH_TOZERO);
        s += sum(it.planes[0])[0];
    }

    s = 1./s;
    it = NAryMatIterator(&hist, &plane, 1);
    for(int p = 0; p < it.nplanes; p++, ++it)
        it.planes[0] *= s;
}

另外，请查看cv::compareHist功能，了解NAryMatIterator here的其他使用示例。

Answer 2

要创建一个大小为100x100x3的多维矩阵，使用浮点数，一个通道，并将所有元素初始化为10，您可以这样写：

int size[3] = { 100, 100, 3 };
cv::Mat M(3, size, CV_32FC1, cv::Scalar(10));

要循环并输出矩阵中的元素，您可以这样做：

for (int i = 0; i < 100; i++)
  for (int j = 0; j < 100; j++)
    for (int k = 0; k < 3; k++) 
      std::cout << M.at<cv::Vec3f>(i,j)[k] << ", ";

但是，请注意使用此处记录的多维矩阵的麻烦：How do i get the size of a multi-dimensional cv::Mat? (Mat, or MatND)

OpenCV中使用C ++的Matrix中的多维数据

2 个答案: