OpenCV 3.0.0 SurfFeatureDetector and SurfDescriptorExtractor Errors

Question

I am attempting to implement the OpenCV 3.0.0 SURF Feature Description and Detection but after running the sample code on the OpenCV site, I receive a load of errors all related to SURF. Any idea of what could be going wrong? Thanks!

#include <stdio.h>
#include <iostream>
#include "opencv2/core.hpp"
#include "opencv2/features2d.hpp"
#include "opencv2/highgui.hpp"
#include "opencv2/calib3d.hpp"
#include "opencv2/xfeatures2d.hpp"
#include <opencv2/nonfree/nonfree.hpp>

using namespace cv;
using namespace cv::xfeatures2d;

void readme();

/** @function main */
int main(int argc, char** argv)
{
    if (argc != 3)
    {
        readme(); return -1;
    }

    Mat img_object = imread(argv[1], IMREAD_GRAYSCALE);
    Mat img_scene = imread(argv[2], IMREAD_GRAYSCALE);

    if (!img_object.data || !img_scene.data)
    {
        std::cout << " --(!) Error reading images " << std::endl; return -1;
    }

    //-- Step 1: Detect the keypoints using SURF Detector
    int minHessian = 400;

    Ptr<SURF> detector = SURF.create(minHessian);

    std::vector<KeyPoint> keypoints_object, keypoints_scene;

    detector.detect(img_object, keypoints_object);
    detector.detect(img_scene, keypoints_scene);

    //-- Step 2: Calculate descriptors (feature vectors)
    SurfDescriptorExtractor extractor;

    Mat descriptors_object, descriptors_scene;

    extractor.compute(img_object, keypoints_object, descriptors_object);
    extractor.compute(img_scene, keypoints_scene, descriptors_scene);

    //-- Step 3: Matching descriptor vectors using FLANN matcher
    FlannBasedMatcher matcher;
    std::vector< DMatch > matches;
    matcher.match(descriptors_object, descriptors_scene, matches);

    double max_dist = 0; double min_dist = 100;

    //-- Quick calculation of max and min distances between keypoints
    for (int i = 0; i < descriptors_object.rows; i++)
    {
        double dist = matches[i].distance;
        if (dist < min_dist) min_dist = dist;
        if (dist > max_dist) max_dist = dist;
    }

    printf("-- Max dist : %f \n", max_dist);
    printf("-- Min dist : %f \n", min_dist);

    //-- Draw only "good" matches (i.e. whose distance is less than 3*min_dist )
    std::vector< DMatch > good_matches;

    for (int i = 0; i < descriptors_object.rows; i++)
    {
        if (matches[i].distance < 3 * min_dist)
        {
            good_matches.push_back(matches[i]);
        }
    }

    Mat img_matches;
    drawMatches(img_object, keypoints_object, img_scene, keypoints_scene,
        good_matches, img_matches, Scalar::all(-1), Scalar::all(-1),
        std::vector<char>(), DrawMatchesFlags::NOT_DRAW_SINGLE_POINTS);

    //-- Localize the object
    std::vector<Point2f> obj;
    std::vector<Point2f> scene;

    for (int i = 0; i < good_matches.size(); i++)
    {
        //-- Get the keypoints from the good matches
        obj.push_back(keypoints_object[good_matches[i].queryIdx].pt);
        scene.push_back(keypoints_scene[good_matches[i].trainIdx].pt);
    }

    Mat H = findHomography(obj, scene, RANSAC);

    //-- Get the corners from the image_1 ( the object to be "detected" )
    std::vector<Point2f> obj_corners(4);
    obj_corners[0] = cvPoint(0, 0); obj_corners[1] = cvPoint(img_object.cols, 0);
    obj_corners[2] = cvPoint(img_object.cols, img_object.rows); obj_corners[3] = cvPoint(0, img_object.rows);
    std::vector<Point2f> scene_corners(4);

    perspectiveTransform(obj_corners, scene_corners, H);

    //-- Draw lines between the corners (the mapped object in the scene - image_2 )
    line(img_matches, scene_corners[0] + Point2f(img_object.cols, 0), scene_corners[1] + Point2f(img_object.cols, 0), Scalar(0, 255, 0), 4);
    line(img_matches, scene_corners[1] + Point2f(img_object.cols, 0), scene_corners[2] + Point2f(img_object.cols, 0), Scalar(0, 255, 0), 4);
    line(img_matches, scene_corners[2] + Point2f(img_object.cols, 0), scene_corners[3] + Point2f(img_object.cols, 0), Scalar(0, 255, 0), 4);
    line(img_matches, scene_corners[3] + Point2f(img_object.cols, 0), scene_corners[0] + Point2f(img_object.cols, 0), Scalar(0, 255, 0), 4);

    //-- Show detected matches
    imshow("Good Matches & Object detection", img_matches);

    waitKey(0);
    return 0;
}

/** @function readme */
void readme()
{
    std::cout << " Usage: ./SURF_descriptor <img1> <img2>" << std::endl;
}

Errors:

1>c:\users\belayachiry\documents\visual studio 2013\projects\imagewatch\imagewatch\source.cpp(34): warning C4832: token '.' is illegal after UDT 'cv::xfeatures2d::SURF'
1>          c:\users\belayachiry\documents\opencv\opencv\build\include\opencv2\nonfree\nonfree.hpp(111) : see declaration of 'cv::xfeatures2d::SURF'
1>c:\users\belayachiry\documents\visual studio 2013\projects\imagewatch\imagewatch\source.cpp(34): error C2275: 'cv::xfeatures2d::SURF' : illegal use of this type as an expression
1>          c:\users\belayachiry\documents\opencv\opencv\build\include\opencv2\nonfree\nonfree.hpp(111) : see declaration of 'cv::xfeatures2d::SURF'
1>c:\users\belayachiry\documents\visual studio 2013\projects\imagewatch\imagewatch\source.cpp(34): error C2228: left of '.create' must have class/struct/union
1>c:\users\belayachiry\documents\visual studio 2013\projects\imagewatch\imagewatch\source.cpp(38): error C2039: 'detect' : is not a member of 'cv::Ptr<cv::xfeatures2d::SURF>'
1>c:\users\belayachiry\documents\visual studio 2013\projects\imagewatch\imagewatch\source.cpp(39): error C2039: 'detect' : is not a member of 'cv::Ptr<cv::xfeatures2d::SURF>'
1>c:\users\belayachiry\documents\visual studio 2013\projects\imagewatch\imagewatch\source.cpp(42): error C2259: 'cv::xfeatures2d::SURF' : cannot instantiate abstract class
1>          due to following members:
1>          'void cv::xfeatures2d::SURF::setHessianThreshold(double)' : is abstract
1>          c:\users\belayachiry\documents\opencv\opencv\build\include\opencv2\nonfree\nonfree.hpp(127) : see declaration of 'cv::xfeatures2d::SURF::setHessianThreshold'
1>          'double cv::xfeatures2d::SURF::getHessianThreshold(void) const' : is abstract
1>          c:\users\belayachiry\documents\opencv\opencv\build\include\opencv2\nonfree\nonfree.hpp(128) : see declaration of 'cv::xfeatures2d::SURF::getHessianThreshold'
1>          'void cv::xfeatures2d::SURF::setNOctaves(int)' : is abstract
1>          c:\users\belayachiry\documents\opencv\opencv\build\include\opencv2\nonfree\nonfree.hpp(130) : see declaration of 'cv::xfeatures2d::SURF::setNOctaves'
1>          'int cv::xfeatures2d::SURF::getNOctaves(void) const' : is abstract
1>          c:\users\belayachiry\documents\opencv\opencv\build\include\opencv2\nonfree\nonfree.hpp(131) : see declaration of 'cv::xfeatures2d::SURF::getNOctaves'
1>          'void cv::xfeatures2d::SURF::setNOctaveLayers(int)' : is abstract
1>          c:\users\belayachiry\documents\opencv\opencv\build\include\opencv2\nonfree\nonfree.hpp(133) : see declaration of 'cv::xfeatures2d::SURF::setNOctaveLayers'
1>          'int cv::xfeatures2d::SURF::getNOctaveLayers(void) const' : is abstract
1>          c:\users\belayachiry\documents\opencv\opencv\build\include\opencv2\nonfree\nonfree.hpp(134) : see declaration of 'cv::xfeatures2d::SURF::getNOctaveLayers'
1>          'void cv::xfeatures2d::SURF::setExtended(bool)' : is abstract
1>          c:\users\belayachiry\documents\opencv\opencv\build\include\opencv2\nonfree\nonfree.hpp(136) : see declaration of 'cv::xfeatures2d::SURF::setExtended'
1>          'bool cv::xfeatures2d::SURF::getExtended(void) const' : is abstract
1>          c:\users\belayachiry\documents\opencv\opencv\build\include\opencv2\nonfree\nonfree.hpp(137) : see declaration of 'cv::xfeatures2d::SURF::getExtended'
1>          'void cv::xfeatures2d::SURF::setUpright(bool)' : is abstract
1>          c:\users\belayachiry\documents\opencv\opencv\build\include\opencv2\nonfree\nonfree.hpp(139) : see declaration of 'cv::xfeatures2d::SURF::setUpright'
1>          'bool cv::xfeatures2d::SURF::getUpright(void) const' : is abstract
1>          c:\users\belayachiry\documents\opencv\opencv\build\include\opencv2\nonfree\nonfree.hpp(140) : see declaration of 'cv::xfeatures2d::SURF::getUpright'
1>c:\users\belayachiry\documents\visual studio 2013\projects\imagewatch\imagewatch\source.cpp(87): warning C4018: '<' : signed/unsigned mismatch
1>c:\users\belayachiry\documents\visual studio 2013\projects\imagewatch\imagewatch\source.cpp(105): warning C4244: 'argument' : conversion from 'int' to 'float', possible loss of data
1>c:\users\belayachiry\documents\visual studio 2013\projects\imagewatch\imagewatch\source.cpp(105): error C3861: 'line': identifier not found
1>c:\users\belayachiry\documents\visual studio 2013\projects\imagewatch\imagewatch\source.cpp(106): warning C4244: 'argument' : conversion from 'int' to 'float', possible loss of data
1>c:\users\belayachiry\documents\visual studio 2013\projects\imagewatch\imagewatch\source.cpp(106): error C3861: 'line': identifier not found
1>c:\users\belayachiry\documents\visual studio 2013\projects\imagewatch\imagewatch\source.cpp(107): warning C4244: 'argument' : conversion from 'int' to 'float', possible loss of data
1>c:\users\belayachiry\documents\visual studio 2013\projects\imagewatch\imagewatch\source.cpp(107): error C3861: 'line': identifier not found
1>c:\users\belayachiry\documents\visual studio 2013\projects\imagewatch\imagewatch\source.cpp(108): warning C4244: 'argument' : conversion from 'int' to 'float', possible loss of data
1>c:\users\belayachiry\documents\visual studio 2013\projects\imagewatch\imagewatch\source.cpp(108): error C3861: 'line': identifier not found

Answer 1

Occurred some modifications in the OpenCV 3.0 with these tools.

Where is

• detector.detect(img_object, keypoints_object); should be detector->detect(img_object, keypoints_object);
• SurfDescriptorExtractor extractor; should be Ptr<SURF> extractor = SURF::create();

Take a look at this website

The others erros should desapear now, I guess.