passing SVM to gpu::HOG

gpu_hog.cpp

// might need to check
// http://stackoverflow.com/questions/15033363/obtaining-weights-in-cvsvm-the-svm-implementation-of-opencv/15070681#15070681
// for more info on how to get the svm from the CvSVM object to pass to HOG

#include <iostream>
#include <fstream>
#include <string>
#include <sstream>
#include <iomanip>
#include <stdexcept>
#include <opencv2/core/utility.hpp>
#include "opencv2/cuda.hpp"
#include "opencv2/highgui.hpp"
#include "opencv2/objdetect.hpp"
#include "opencv2/imgproc.hpp"

using namespace std;
using namespace cv;

int main()
{

  cv::cuda::printShortCudaDeviceInfo(cv::cuda::getDevice());
  
  Size win_size(args.win_width, args.win_width * 2); //(64, 128) or (48, 96)
  Size win_stride(args.win_stride_width, args.win_stride_height);
  
  vector<float> detector;
  
  string filepath = "path/to/svm/file";
  
  CvSVM svm;
  svm.load(filepath.c_str());
  
  cv::cuda::HOGDescriptor gpu_hog(win_size, Size(16, 16), Size(8, 8), Size(8, 8), 9,
                                 cv::cuda::HOGDescriptor::DEFAULT_WIN_SIGMA, 0.2, gamma_corr,
                                 cv::cuda::HOGDescriptor::DEFAULT_NLEVELS);
  gpu_hog.setSVMDetector(svm.get_support_vector(0));
  cuda::GpuMat gpu_img;
  
  while()
  {
    gpu_img.upload(img); // assuming an img came from somewhere
    gpu_hog.detectMultiScale(gpu_img, found, hit_threshold, win_stride, Size(0, 0), scale, gr_threshold);

    for (size_t i = 0; i < found.size(); i++)
    {
        Rect r = found[i];
        rectangle(img_to_show, r.tl(), r.br(), Scalar(0, 255, 0), 3);
    }

    putText(img_to_show, "Mode: GPU", Point(5, 25), FONT_HERSHEY_SIMPLEX, 1., Scalar(255, 100, 0), 2);
  } 
}