如何使用浮点数组中的数据初始化cv :: Mat [英] How can I initialize a cv::Mat with data from a float array

问题描述

我需要创建一个cv::Mat变量，该变量用来自float *数组的数据初始化. 这应该是基本的，但是我很难弄清楚.

我有代码:

float *matrixAB = <120 floating point array created elsewhere>;
cv::Mat cv_matrixAB = cv::Mat(12, 10, CV_32F, &matrixAB);

但cv_matrixAB从不包含float值，更重要的是与matrixAB中包含的数据不匹配.

如果我将行更改为:

cv::Mat cv_matrixAB = cv::Mat(12, 10, CV_32F, matrixAB);

则cv_matrixAB.data均为0.我也尝试过使用CV_64F作为类型，但是我看到了相同的行为.

谁能帮助我确定我要去哪里?根据cv::Mat构造函数文档，我应该能够以float *数组的形式提供数据.

更新:此处的更多信息: 甚至以下代码也不起作用. printf显示63，这当然不是dummy_query_data中的值.

float dummy_query_data[10] = { 1, 2, 3, 4,
                               5, 6, 7, 8 };
cv::Mat dummy_query = cv::Mat(2, 4, CV_32F, dummy_query_data);
printf("%f\n", (float)dummy_query.data[3]);

解决方案

您还好.但是，您应该使用at<float>()而不是 .data (这会给你uchar *).或者直接使用cout << mat;打印其所有元素.它将为您带来预期的结果.

float dummy_query_data[10] = { 1, 2, 3, 4, 5, 6, 7, 8 };
cv::Mat dummy_query = cv::Mat(2, 4, CV_32F, dummy_query_data);

cout << dummy_query.at<float>(0,2) << endl;
cout << dummy_query << endl;

它将输出:

3
[1, 2, 3, 4;
  5, 6, 7, 8]

I need to create a cv::Mat variable that is initialized with my data from a float * array. This should be basic, but I'm having trouble figuring it out.

I have the code:

float *matrixAB = <120 floating point array created elsewhere>;
cv::Mat cv_matrixAB = cv::Mat(12, 10, CV_32F, &matrixAB);

but cv_matrixAB never contains float values, and more importantly doesn't match the data contained in matrixAB.

If I change the line to:

cv::Mat cv_matrixAB = cv::Mat(12, 10, CV_32F, matrixAB);

then the cv_matrixAB.data are all 0. I have also tried using CV_64F as the type, but I see the same behaivor.

Can anyone help me identify where I am going wrong? According to the cv::Mat constructor documentation, I should be able to provide my data in the form of a float * array.

Update: a little more info here: Even the following code does not work. The printf displays 63, which of course is not a value in dummy_query_data.

float dummy_query_data[10] = { 1, 2, 3, 4,
                               5, 6, 7, 8 };
cv::Mat dummy_query = cv::Mat(2, 4, CV_32F, dummy_query_data);
printf("%f\n", (float)dummy_query.data[3]);

解决方案

You're doing fine. But you should access the mat element by using at<float>() instead of .data (which will give you uchar *). Or simply use cout << mat; to print all its elements. It will give you the expected result.

float dummy_query_data[10] = { 1, 2, 3, 4, 5, 6, 7, 8 };
cv::Mat dummy_query = cv::Mat(2, 4, CV_32F, dummy_query_data);

cout << dummy_query.at<float>(0,2) << endl;
cout << dummy_query << endl;

It will output:

3
[1, 2, 3, 4;
  5, 6, 7, 8]

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