无法用ArUco 3.1.0检测OpenCV标记

Question

我试图编写一个简单的C++例程，首先将ArUco标记的预定义字典(例如4x4_100)写到文件夹中，然后使用OpenCV 3.1和VisualStudio2017在从文件夹中选择的特定图像中检测ArUco标记。我已经编译了所有使用ArUco标记所需的OpenCV--控制库。我的例程构建没有任何错误，但即使在提供了所有正确的参数(如图像、字典等)之后，我也很难检测到标记。内置的“aruco：：检测标记”函数。你能帮我理解一下我的方法有什么问题吗？下面是一个最小的工作示例，测试映像附在40.jpg“之后

#include "opencv2\core.hpp"
#include "opencv2\imgproc.hpp"
#include "opencv2\imgcodecs.hpp"
#include "opencv2\aruco.hpp"
#include "opencv2\highgui.hpp"
#include <sstream>
#include <fstream>
#include <iostream>

using namespace cv;
using namespace std;

// Function to write ArUco markers
void createArucoMarkers()
{

// Define variable to store the output markers
    Mat outputMarker;
// Choose a predefined Dictionary of markers
    Ptr< aruco::Dictionary> markerDictionary = aruco::getPredefinedDictionary(aruco::PREDEFINED_DICTIONARY_NAME::DICT_4X4_50);
// Write each of the markers to a '.jpg' image file
    for (int i = 0; i < 50; i++)
    {
        aruco::drawMarker(markerDictionary, i, 500, outputMarker, 1);
        ostringstream convert;
        string imageName = "4x4Marker_";
        convert << imageName << i << ".jpg";
        imwrite(convert.str(), outputMarker);

    }
}


// Main body of the routine
int main(int argv, char** argc)
{
    createArucoMarkers();

// Read a specific image
    Mat frame = imread("4x4Marker_40.jpg", CV_LOAD_IMAGE_UNCHANGED);
// Define variables to store the output of marker detection
    vector<int> markerIds;
    vector<vector<Point2f>> markerCorners, rejectedCandidates;
// Define a Dictionary type variable for marker detection  
    Ptr<aruco::Dictionary> markerDictionary = aruco::getPredefinedDictionary(aruco::PREDEFINED_DICTIONARY_NAME::DICT_4X4_50);

// Detect markers
    aruco::detectMarkers(frame, markerDictionary, markerCorners, markerIds);

// Display the image
    namedWindow("Webcam", CV_WINDOW_AUTOSIZE);
    imshow("Webcam", frame);
// Draw detected markers on the displayed image
    aruco::drawDetectedMarkers(frame, markerCorners, markerIds);
    cout << "\nmarker ID is:\t"<<markerIds.size();
    waitKey();

}

Answer 1

在您的代码中有一些问题：

1. 在调用imshow之前，您将使用drawDetectedMarkers显示图像，因此您将永远看不到检测到的标记。
2. 您显示的是markerIds向量的大小，而不是其中包含的值。
3. (这是主要的问题)您的标记周围没有空白，因此不可能检测到。

一个建议是:在#include语句中使用正斜杠，而不是反斜杠。正斜杠在任何地方都能工作，反斜杠只在Windows上工作。

这在我的机器上有效。请注意，我将图像作为彩色图像加载，以便更容易地查看drawDetectedMarkers的结果。

#include <opencv2/core.hpp>
#include <opencv2/imgproc.hpp>
#include <opencv2/imgcodecs.hpp>
#include <opencv2/aruco.hpp>
#include <opencv2/highgui.hpp>
#include <sstream>
#include <fstream>
#include <iostream>

using namespace cv;
using namespace std;

// Function to write ArUco markers
void createArucoMarkers()
{

    // Create image to hold the marker plus surrounding white space
    Mat outputImage(700, 700, CV_8UC1);
    // Fill the image with white
    outputImage = Scalar(255);
    // Define an ROI to write the marker into
    Rect markerRect(100, 100, 500, 500);
    Mat outputMarker(outputImage, markerRect);

    // Choose a predefined Dictionary of markers
    Ptr< aruco::Dictionary> markerDictionary = aruco::getPredefinedDictionary(aruco::PREDEFINED_DICTIONARY_NAME::DICT_4X4_50);
    // Write each of the markers to a '.jpg' image file
    for (int i = 0; i < 50; i++)
    {
        //Draw the marker into the ROI
        aruco::drawMarker(markerDictionary, i, 500, outputMarker, 1);
        ostringstream convert;
        string imageName = "4x4Marker_";
        convert << imageName << i << ".jpg";
        // Note we are writing outputImage, not outputMarker
        imwrite(convert.str(), outputImage);

    }
}


// Main body of the routine
int main(int argv, char** argc)
{
    createArucoMarkers();

    // Read a specific image
    Mat frame = imread("4x4Marker_40.jpg", CV_LOAD_IMAGE_COLOR);
    // Define variables to store the output of marker detection
    vector<int> markerIds;
    vector<vector<Point2f>> markerCorners, rejectedCandidates;
    // Define a Dictionary type variable for marker detection
    Ptr<aruco::Dictionary> markerDictionary = aruco::getPredefinedDictionary(aruco::PREDEFINED_DICTIONARY_NAME::DICT_4X4_50);

    // Detect markers
    aruco::detectMarkers(frame, markerDictionary, markerCorners, markerIds);

    // Display the image
    namedWindow("Webcam", CV_WINDOW_AUTOSIZE);
    // Draw detected markers on the displayed image
    aruco::drawDetectedMarkers(frame, markerCorners, markerIds);
    // Show the image with the detected marker
    imshow("Webcam", frame);

    // If a marker was identified, show its ID
    if (markerIds.size() > 0) {
        cout << "\nmarker ID is:\t" << markerIds[0] << endl;
    }
    waitKey(0);

}