Question

我刚刚开始使用C ++ OpenCV学习SVM，并参考了SVM文档here。我想尝试从链接中获取示例源代码以首先熟悉它，但我无法运行示例源代码。它返回错误：

错误1错误C2065：'CvSVMParams'：未声明的标识符

我正在使用Visual Studio 2012和OpenCV 3.0.0。设置过程应该是正确的，因为除此之外所有其他代码都运行良好。

Answer 1

很多事情发生了变化from OpenCV 2.4 to OpenCV 3.0。其中，机器学习模块，不向后兼容。

这是OpenCV tutorial code for the SVM，OpenCV 3.0的更新：

#include <opencv2/core.hpp>
#include <opencv2/imgproc.hpp>
#include "opencv2/imgcodecs.hpp"
#include <opencv2/highgui.hpp>
#include <opencv2/ml.hpp>

using namespace cv;
using namespace cv::ml;

int main(int, char**)
{
    // Data for visual representation
    int width = 512, height = 512;
    Mat image = Mat::zeros(height, width, CV_8UC3);

    // Set up training data
    int labels[4] = { 1, -1, -1, -1 };
    Mat labelsMat(4, 1, CV_32SC1, labels);

    float trainingData[4][2] = { { 501, 10 }, { 255, 10 }, { 501, 255 }, { 10, 501 } };
    Mat trainingDataMat(4, 2, CV_32FC1, trainingData);

    // Set up SVM's parameters
    Ptr<SVM> svm = SVM::create();
    svm->setType(SVM::C_SVC);
    svm->setKernel(SVM::LINEAR);
    svm->setTermCriteria(TermCriteria(TermCriteria::MAX_ITER, 100, 1e-6));

    // Train the SVM with given parameters
    Ptr<TrainData> td = TrainData::create(trainingDataMat, ROW_SAMPLE, labelsMat);
    svm->train(td);

    // Or train the SVM with optimal parameters
    //svm->trainAuto(td);

    Vec3b green(0, 255, 0), blue(255, 0, 0);
    // Show the decision regions given by the SVM
    for (int i = 0; i < image.rows; ++i)
        for (int j = 0; j < image.cols; ++j)
        {
            Mat sampleMat = (Mat_<float>(1, 2) << j, i);
            float response = svm->predict(sampleMat);

            if (response == 1)
                image.at<Vec3b>(i, j) = green;
            else if (response == -1)
                image.at<Vec3b>(i, j) = blue;
        }

    // Show the training data
    int thickness = -1;
    int lineType = 8;
    circle(image, Point(501, 10), 5, Scalar(0, 0, 0), thickness, lineType);
    circle(image, Point(255, 10), 5, Scalar(255, 255, 255), thickness, lineType);
    circle(image, Point(501, 255), 5, Scalar(255, 255, 255), thickness, lineType);
    circle(image, Point(10, 501), 5, Scalar(255, 255, 255), thickness, lineType);

    // Show support vectors
    thickness = 2;
    lineType = 8;
    Mat sv = svm->getSupportVectors();

    for (int i = 0; i < sv.rows; ++i)
    {
        const float* v = sv.ptr<float>(i);
        circle(image, Point((int)v[0], (int)v[1]), 6, Scalar(128, 128, 128), thickness, lineType);
    }

    imwrite("result.png", image);        // save the image

    imshow("SVM Simple Example", image); // show it to the user
    waitKey(0);

}

输出应如下所示：

Answer 2

我发现上面的代码有效但我需要进行一些小修改才能将标签转换为整数。修改以粗体显示：

// Set up training data **Original**:

int labels[4] = { 1, -1, -1, -1 };

Mat labelsMat(4, 1, **CV_32SC1**, labels);

// Set up training data **Modified**:

int labels[4] = { 1, -1, -1, -1 };

Mat labelsMat(4, 1, **CV_32S**, labels);

OpenCV无法设置SVM参数

2 个答案: