connected_components.cpp

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#include <bwi_mapper/connected_components.h>
#include <bwi_mapper/map_utils.h>

#include <opencv2/opencv_modules.hpp>
#ifdef HAVE_OPENCV_IMGPROC
// this is OpenCV 3 and we need extra includes
#include <opencv2/imgproc/imgproc.hpp>
#endif

namespace bwi_mapper {

  ConnectedComponents::ConnectedComponents (const cv::Mat& image,
      std::vector<int32_t>& component_map) {

    cv::Mat src = image.clone();
    cv::Mat dst = cv::Mat::zeros(src.rows, src.cols, CV_32S);
    std::vector<std::vector<cv::Point> > contours;
    std::vector<cv::Vec4i> hierarchy;

    cv::findContours(src, contours, hierarchy, 
        CV_RETR_CCOMP, CV_CHAIN_APPROX_SIMPLE);

    number_components_ = 0;
    for(int idx = 0; idx >= 0; idx = hierarchy[idx][0]) {
      cv::Scalar color(number_components_ + 1);
      cv::drawContours(dst, contours, idx, color, CV_FILLED, 8, hierarchy);
      number_components_++;
    }

    component_map.clear();
    component_map.resize(dst.rows * dst.cols);

    size_t map_idx = 0;
    for (int j = 0; j < dst.rows; ++j) {
      const int32_t* dst_row = dst.ptr<int32_t>(j);
      for (int i = 0; i < dst.cols; ++i) {
        component_map[map_idx] = dst_row[i] - 1;
        ++map_idx;
      }
    }

  }

  size_t ConnectedComponents::getNumberComponents() {
    return number_components_;
  }

} /* bwi_mapper */