本章内容:

 

1. surf特征点检测

2. cv::KeyPoint 属性分析

3.surf属性分析

 

1. surf特征点检测

输出结果

2. cv::KeyPoint 属性分析

输出结果:

3.surf属性分析

输出结果

 

源码

#include <ostream>
#include <opencv.hpp>
#include<opencv2/opencv.hpp>
#include "opencv2/xfeatures2d.hpp"

int main(int argc, char *argv[])
{
    /*
     本章内容:
        1. 初步认识 cv::xfeatures2d::SURF api接口
        2. cv::KeyPoint的属性
        3. cv::xfeatures2d::SURF 属性分析
    */
    cv::String fileName = "/home/wang/dev/Image/heihei.jpeg";
    cv::Mat src = cv::imread(fileName);

    if(src.data == NULL){
        printf("图像读入失败\n");
        return -1;
    }
    /*
     * API接口:    CV_WRAP static Ptr<SURF> create(double hessianThreshold=100,
                  int nOctaves = 4, int nOctaveLayers = 3,
                  bool extended = false, bool upright = false);

    */
    cv::imshow("src",src);
    cv::Ptr<cv::xfeatures2d::SURF> surf= cv::xfeatures2d::SURF::create();
    /* surf特征点检测
     * api接口:
     *     CV_WRAP virtual void detect( InputArray image,
                                 CV_OUT std::vector<KeyPoint>& keypoints,
                                 InputArray mask=noArray() );
            参数分析:
            @param image Image.
            @param keypoints The detected keypoints.
    */
    std::vector<cv::KeyPoint> KeyPs;
    surf->detect(src,KeyPs);
    cv::Mat dst;
    /* 绘图接口
     * CV_EXPORTS_W void drawKeypoints( InputArray image, const std::vector<KeyPoint>& keypoints, InputOutputArray outImage,
                               const Scalar& color=Scalar::all(-1), DrawMatchesFlags flags=DrawMatchesFlags::DEFAULT );
    */
    cv::drawKeypoints(src,KeyPs,dst);
    cv::imshow("dst",dst);

    /* cv::KeyPoint的属性:
            CV_PROP_RW Point2f pt; // 位置(x,y)
            CV_PROP_RW float size;  // 关键点的领域大小
            CV_PROP_RW float angle;  // 旋转角度
            CV_PROP_RW float response;  //
            CV_PROP_RW int octave;  // 金字塔的octave
            CV_PROP_RW int class_id;  // 关键点聚类时的id
    */
    // 打印输出结果
    std::cout << "KeyPs.size():= " << KeyPs.size() << std::endl;
    std::cout << "KeyPs[0].pt:= " << KeyPs[0].pt << std::endl;
    std::cout << "KeyPs[0].size:= " << KeyPs[0].size << std::endl;
    std::cout << "KeyPs[0].angle:= " << KeyPs[0].angle << std::endl;
    std::cout << "KeyPs[0].octave:= " << KeyPs[0].octave << std::endl;
    std::cout << "KeyPs[0].class_id:= " << KeyPs[0].class_id << std::endl;

    /*3.surf属性分析
       属性介绍:
            hessianThreshold  特征点检测阈值
            nOctaves  图像金字塔层的Octave数目
            nOctaveLayers 每组Octave中金字塔的层数
            Extended 0表示64维特征，1表示128维特征
            upright 是否计算旋转角度
      属性设置与获取API接口:
            CV_WRAP virtual void setHessianThreshold(double hessianThreshold) = 0;
            CV_WRAP virtual double getHessianThreshold() const = 0;

            CV_WRAP virtual void setNOctaves(int nOctaves) = 0;
            CV_WRAP virtual int getNOctaves() const = 0;

            CV_WRAP virtual void setNOctaveLayers(int nOctaveLayers) = 0;
            CV_WRAP virtual int getNOctaveLayers() const = 0;

            CV_WRAP virtual void setExtended(bool extended) = 0;
            CV_WRAP virtual bool getExtended() const = 0;

            CV_WRAP virtual void setUpright(bool upright) = 0;
            CV_WRAP virtual bool getUpright() const = 0;
    */
    std::cout << "默认 hessianThreshold= " << surf->getHessianThreshold() << std::endl;
    surf->setHessianThreshold(50);
    std::cout << "设置后 hessianThreshold= " << surf->getHessianThreshold() << std::endl;
    std::cout << "默认 nOctaves= " << surf->getNOctaves() << std::endl;
    surf->setNOctaves(5);
    std::cout << "设置后 nOctaves= " << surf->getNOctaves() << std::endl;
    std::cout << "默认 nOctaveLayers= " << surf->getNOctaveLayers() << std::endl;
    surf->setNOctaveLayers(5);
    std::cout << "设置后 nOctaveLayers= " << surf->getNOctaveLayers() << std::endl;
    std::cout << "默认 extended= " << surf->getExtended() << std::endl;
    surf->setExtended(1);
    std::cout << "设置后 extended= " << surf->getExtended() << std::endl;
    std::cout << "默认 upright= " << surf->getUpright() << std::endl;
    surf->setUpright(1);
    std::cout << "设置后 upright= " << surf->getUpright() << std::endl;

 

    cv::waitKey(0);
    return 1;
}