opencv_contour.cpp

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/*
 * Copyright (C) Roland Meertens and Peng Lu
 *
 * This file is part of paparazzi
 *
 * paparazzi is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2, or (at your option)
 * any later version.
 *
 * paparazzi is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with paparazzi; see the file COPYING.  If not, see
 * <http://www.gnu.org/licenses/>.
 */
#include "opencv_contour.h"
#include <opencv2/core/core.hpp>
#include <opencv2/imgproc/imgproc.hpp>
#include "opencv_image_functions.h"
 
using namespace cv;
using namespace std;
 
struct contour_estimation cont_est;
struct contour_threshold cont_thres;
 
RNG rng(12345);
 
// YUV in opencv convert to YUV on Bebop
void yuv_opencv_to_yuv422(Mat image, char *img, int width, int height)
{
//Turn the opencv RGB colored image back in a YUV colored image for the drone
  for (int row = 0; row < height; row++) {
    for (int col = 0; col < width; col++) {
      // Extract pixel color from image
      cv::Vec3b &c = image.at<cv::Vec3b>(row, col);
 
      // Set image buffer values
      int i = row * width + col;
      img[2 * i + 1] = c[0]; // y;
      img[2 * i] = col % 2 ? c[1] : c[2]; // u or v
    }
  }
}
 
void uyvy_opencv_to_yuv_opencv(Mat image, Mat image_in, int width, int height)
{
//Turn the opencv RGB colored image back in a YUV colored image for the drone
  for (int row = 0; row < height; row++) {
    for (int col = 0; col < width; col++) {
      // Extract pixel color from image
      cv::Vec3b c = image_in.at<cv::Vec3b>(row, col);
      cv::Vec3b c_m1 = image_in.at<cv::Vec3b>(row, col);
      cv::Vec3b c_p1 = image_in.at<cv::Vec3b>(row, col);
      if (col > 0) {
        c_m1 = image_in.at<cv::Vec3b>(row, col - 1);
      }
      if (col < width) {
        c_p1 = image_in.at<cv::Vec3b>(row, col + 1);
      }
      image.at<cv::Vec3b>(row, col)[0] = c[1] ;
      image.at<cv::Vec3b>(row, col)[1] = col % 2 ? c[0] : c_m1[0];
      image.at<cv::Vec3b>(row, col)[2] = col % 2 ? c_p1[0] : c[0];
 
    }
  }
}
 
void find_contour(char *img, int width, int height)
{
  // Create a new image, using the original bebop image.
  Mat M(width, height, CV_8UC2, img); // original
  Mat image, edge_image, thresh_image;
 
  // convert UYVY in paparazzi to YUV in opencv
  cvtColor(M, M, CV_YUV2RGB_Y422);
  cvtColor(M, M, CV_RGB2YUV);
 
  // Threshold all values within the indicted YUV values.
  inRange(M, Scalar(cont_thres.lower_y, cont_thres.lower_u, cont_thres.lower_v), Scalar(cont_thres.upper_y,
          cont_thres.upper_u, cont_thres.upper_v), thresh_image);
 
  vector<vector<Point> > contours;
  vector<Vec4i> hierarchy;
  edge_image = thresh_image;
  int edgeThresh = 35;
  Canny(edge_image, edge_image, edgeThresh, edgeThresh * 3);
  findContours(edge_image, contours, hierarchy, CV_RETR_EXTERNAL, CV_CHAIN_APPROX_SIMPLE, Point(0, 0));
 
  // Get the moments
  vector<Moments> mu(contours.size());
  for (unsigned int i = 0; i < contours.size(); i++) {
    mu[i] = moments(contours[i], false);
  }
 
  //  Get the mass centers:
  vector<Point2f> mc(contours.size());
  for (unsigned int i = 0; i < contours.size(); i++) {
    mc[i] = Point2f(mu[i].m10 / mu[i].m00 , mu[i].m01 / mu[i].m00);
  }
 
  Mat drawing = Mat::zeros(edge_image.size(), CV_8UC3);
  for (unsigned int i = 0; i < contours.size(); i++) {
    Scalar color = Scalar(rng.uniform(0, 255), rng.uniform(0, 255), rng.uniform(0, 255));
    drawContours(drawing, contours, i, color, 2, 8, hierarchy, 0, Point());
    circle(drawing, mc[i], 4, color, -1, 8, 0);
  }
 
  // Find Largest Contour
  int largest_contour_index = 0;
  int largest_area = 0;
  Rect bounding_rect;
 
  // iterate through each contour.
  for (unsigned int i = 0; i < contours.size(); i++) {
    //  Find the area of contour
    double a = contourArea(contours[i], false);
    if (a > largest_area) {
      largest_area = a;
      // Store the index of largest contour
      largest_contour_index = i;
      // Find the bounding rectangle for biggest contour
      bounding_rect = boundingRect(contours[i]);
    }
  }
  Scalar color(255, 255, 255);
  // Draw the contour and rectangle
  drawContours(M, contours, largest_contour_index, color, CV_FILLED, 8, hierarchy);
 
  rectangle(M, bounding_rect,  Scalar(0, 255, 0), 2, 8, 0);
 
  // some figure can cause there are no largest circles, in this case, do not draw circle
  circle(M, mc[largest_contour_index], 4, Scalar(0, 255, 0), -1, 8, 0);
  Point2f rect_center(bounding_rect.x + bounding_rect.width / 2 , bounding_rect.y + bounding_rect.height / 2);
  circle(image, rect_center, 4, Scalar(0, 0, 255), -1, 8, 0);
 
  // Convert back to YUV422, and put it in place of the original image
  grayscale_opencv_to_yuv422(M, img, width, height);
  float contour_distance_est;
  //estimate the distance in X, Y and Z direction
  float area = bounding_rect.width * bounding_rect.height;
  if (area > 28000.) {
    contour_distance_est = 0.1;
  }
  if ((area > 16000.) && (area < 28000.)) {
    contour_distance_est = 0.5;
  }
  if ((area > 11000.) && (area < 16000.)) {
    contour_distance_est = 1;
  }
  if ((area > 3000.) && (area < 11000.)) {
    contour_distance_est = 1.5;
  }
  if (area < 3000.) {
    contour_distance_est = 2.0;
  }
  cont_est.contour_d_x = contour_distance_est;
  float Im_center_w = width / 2.;
  float Im_center_h = height / 2.;
  float real_size = 1.; // real size of the object
  cont_est.contour_d_y = -(rect_center.x - Im_center_w) * real_size / float(bounding_rect.width); // right hand
  cont_est.contour_d_z = -(rect_center.y - Im_center_h) * real_size / float(bounding_rect.height); // point downwards
}