OpenCV - C++ Code runs in Eclipse but not in terminal?

Question

I am trying to make the follwing Code by Mohammad Reza Mostajabi ( http://alum.sharif.ir/~mostajabi/Tutorial.html ) run under Ubuntu 12.04 with OpenCV 2.4.6.1. I made some minor changes with the libraries included and added "cv::initModule_nonfree()" right after starting the main file.

#include "cv.h" 
#include "highgui.h"
#include "ml.h"
#include <stdio.h>
#include <iostream>
#include <opencv2/features2d/features2d.hpp>
#include <opencv2/imgproc/imgproc.hpp>
#include <opencv2/highgui/highgui.hpp>
#include <opencv2/nonfree/nonfree.hpp>
#include <vector>

using namespace cv; 
using namespace std;

using std::cout;
using std::cerr;
using std::endl;
using std::vector;






char ch[30];

//--------Using SURF as feature extractor and FlannBased for assigning a new point to the nearest one in the dictionary
Ptr<DescriptorMatcher> matcher = DescriptorMatcher::create("FlannBased");
Ptr<DescriptorExtractor> extractor = new SurfDescriptorExtractor();
SurfFeatureDetector detector(500);
//---dictionary size=number of cluster's centroids
int dictionarySize = 1500;
TermCriteria tc(CV_TERMCRIT_ITER, 10, 0.001);
int retries = 1;
int flags = KMEANS_PP_CENTERS;
BOWKMeansTrainer bowTrainer(dictionarySize, tc, retries, flags);
BOWImgDescriptorExtractor bowDE(extractor, matcher);



void collectclasscentroids() {
    IplImage *img;
    int i,j;
    for(j=1;j<=4;j++)
    for(i=1;i<=60;i++){
        sprintf( ch,"%s%d%s%d%s","train/",j," (",i,").jpg");
                    const char* imageName = ch;
                    img = cvLoadImage(imageName,0);
                    vector<KeyPoint> keypoint;
                    detector.detect(img, keypoint);
                    Mat features;
                    extractor->compute(img, keypoint, features);
                    bowTrainer.add(features);
    }
return;
}



int main(int argc, char* argv[])
{
    cv::initModule_nonfree();
    int i,j;
    IplImage *img2;
    cout<<"Vector quantization..."<<endl;
    collectclasscentroids();
    vector<Mat> descriptors = bowTrainer.getDescriptors();
    int count=0;
    for(vector<Mat>::iterator iter=descriptors.begin();iter!=descriptors.end();iter++)
    {
        count+=iter->rows;
    }
    cout<<"Clustering "<<count<<" features"<<endl;
    //choosing cluster's centroids as dictionary's words
    Mat dictionary = bowTrainer.cluster();
    bowDE.setVocabulary(dictionary);
    cout<<"extracting histograms in the form of BOW for each image "<<endl;
    Mat labels(0, 1, CV_32FC1);
    Mat trainingData(0, dictionarySize, CV_32FC1);
    int k=0;
    vector<KeyPoint> keypoint1;
    Mat bowDescriptor1;
    //extracting histogram in the form of bow for each image 
for(j=1;j<=4;j++)
    for(i=1;i<=60;i++){


                    sprintf( ch,"%s%d%s%d%s","train/",j," (",i,").jpg");
                    const char* imageName = ch;
                    img2 = cvLoadImage(imageName,0);

                    detector.detect(img2, keypoint1);


                        bowDE.compute(img2, keypoint1, bowDescriptor1);

                        trainingData.push_back(bowDescriptor1);

                        labels.push_back((float) j);
    }



    //Setting up SVM parameters
    CvSVMParams params;
    params.kernel_type=CvSVM::RBF;
    params.svm_type=CvSVM::C_SVC;
    params.gamma=0.50625000000000009;
    params.C=312.50000000000000;
    params.term_crit=cvTermCriteria(CV_TERMCRIT_ITER,100,0.000001);
    CvSVM svm;



    printf("%s\n","Training SVM classifier");

    bool res=svm.train(trainingData,labels,cv::Mat(),cv::Mat(),params);

    cout<<"Processing evaluation data..."<<endl;


    Mat groundTruth(0, 1, CV_32FC1);
    Mat evalData(0, dictionarySize, CV_32FC1);
     k=0;
    vector<KeyPoint> keypoint2;
    Mat bowDescriptor2;


    Mat results(0, 1, CV_32FC1);;
    for(j=1;j<=4;j++)
    for(i=1;i<=60;i++){


                    sprintf( ch,"%s%d%s%d%s","eval/",j," (",i,").jpg");
                    const char* imageName = ch;
                    img2 = cvLoadImage(imageName,0);

                    detector.detect(img2, keypoint2);
                        bowDE.compute(img2, keypoint2, bowDescriptor2);

                        evalData.push_back(bowDescriptor2);
                        groundTruth.push_back((float) j);
                        float response = svm.predict(bowDescriptor2);
                        results.push_back(response);
    }



    //calculate the number of unmatched classes 
    double errorRate = (double) countNonZero(groundTruth- results) / evalData.rows;
    printf("%s%f","Error rate is ",errorRate);
    return 0;

}

After doing this I can compile the Code without problems. I can also run it within Eclipse, but once I try to make it work in terminal I get the following error message:

" OpenCV Error: Assertion failed (!_descriptors.empty()) in add, file /home/mark/Downloads/FP/opencv-2.4.6.1/modules/features2d/src/bagofwords.cpp, line 57 terminate called after throwing an instance of 'cv::Exception' what(): /home/mark/Downloads/FP/opencv-2.4.6.1/modules/features2d/src/bagofwords.cpp:57: error: (-215) !_descriptors.empty() in function add "

I've been trying to solve the problem for a few days now, but I just cannot get rid of this error. I also tried to do it with CodeBlocks, which gives me the same error. I would appreciate some help very much!

Thanks!

Answer 1

It's possible that your program fails to load input images (when launched from the terminal window) because it can't find them. Make sure that your input images are copied to the directory from which you run the application. Eclipse may have a different home directory and hence it sees the image when the program is started in Eclipse.