Merge pull request oreillymedia#27 from oreillymedia/gary

pulling in example_18-01 start

CMakeLists.txt

@@ -61,6 +61,7 @@ add_executable( example_15-05 example_15-05.cpp )
 add_executable( example_15-BackgroundSubtractor example_15-BackgroundSubtractor.cpp )
 add_executable( example_16-01 example_16-01.cpp )
 add_executable( example_17-01 example_17-01.cpp )
+add_executable( example_18-01 example_18-01.cpp )
 #...
 
 target_link_libraries( example_02-01 ${OpenCV_LIBS} )
@@ -114,4 +115,5 @@ target_link_libraries( example_15-05 ${OpenCV_LIBS} )
 target_link_libraries( example_15-BackgroundSubtractor ${OpenCV_LIBS} )
 target_link_libraries( example_16-01 ${OpenCV_LIBS} )
 target_link_libraries( example_17-01 ${OpenCV_LIBS} )
+target_link_libraries( example_18-01 ${OpenCV_LIBS} )
 #...

example_18-01.cpp

@@ -0,0 +1,158 @@
+// Example 18-1. Reading a chessboard’s width and height, reading and collecting
+// the
+// requested number of views, and calibrating the camera
+#include <opencv2/opencv.hpp>
+#include <iostream>
+using namespace std;
+void help(char **argv) { // todo rewrite this
+  cout << "\n\n"
+       << "Example 18-1:\nReading a chessboard’s width and height,\n"
+       << "              reading and collecting the requested number of views,\n" 
+       << "              and calibrating the camera\n\n" 
+       << "Call:\n" << argv[0] << " <board_width> <board_height> <number_of_boards> <if_video,_delay_between_framee_capture> <image_scaling_factor>\n\n"
+       << " * First it reads in checker boards and calibrates itself\n" 
+       << " * Then it saves and reloads the calibration matricies\n"
+       << " * Then it creates an undistortion map and finaly\n"
+       << " * It displays an undistorted image\n"
+       << endl;
+}
+
+int main(int argc, char *argv[]) {
+  int n_boards = 0; 		// Will be set by input list
+  float image_sf = 0.5f;  	//Image scaling factor
+  float delay = 1.f;
+  int board_w = 0;
+  int board_h = 0;
+
+  if (argc < 4 || argc > 6) {
+    cout << "\nERROR: Wrong number of input parameters\n";
+    help(argv);
+    return -1;
+  }
+
+  board_w = atoi(argv[1]);
+  board_h = atoi(argv[2]);
+  n_boards = atoi(argv[3]);
+  if (argc > 4)
+    delay = atof(argv[4]);
+  if (argc > 5)
+    image_sf = atof(argv[5]);
+  int board_n = board_w * board_h;
+  cv::Size board_sz = cv::Size(board_w, board_h);
+  cv::VideoCapture capture(0);
+  if (!capture.isOpened()) {
+    cout << "\nCouldn't open the camera\n";
+    help(argv);
+    return -1;
+  }
+
+  // ALLOCATE STORAGE
+  //
+  vector<vector<cv::Point2f> > image_points;
+  vector<vector<cv::Point3f> > object_points;
+
+  // Capture corner views: loop until we've got n_boards successful
+  // captures (all corners on the board are found).
+  //
+  double last_captured_timestamp = 0;
+  cv::Size image_size;
+  while (image_points.size() < (size_t)n_boards) {
+    cv::Mat image0, image;
+    capture >> image0;
+    image_size = image0.size();
+    cv::resize(image0, image, cv::Size(), image_sf, image_sf, cv::INTER_LINEAR);
+
+    // Find the board
+    //
+    vector<cv::Point2f> corners;
+    bool found = cv::findChessboardCorners(image, board_sz, corners);
+
+    // Draw it
+    //
+    drawChessboardCorners(image, board_sz, corners, found);
+
+    // If we got a good board, add it to our data
+    //
+    double timestamp = (double)clock() / CLOCKS_PER_SEC;
+    if (found && timestamp - last_captured_timestamp > 1) {
+      last_captured_timestamp = timestamp;
+      image ^= cv::Scalar::all(255);
+      cv::Mat mcorners(corners);
+
+      // do not copy the data
+      mcorners *= (1. / image_sf);
+
+      // scale the corner coordinates
+      image_points.push_back(corners);
+      object_points.push_back(vector<cv::Point3f>());
+      vector<cv::Point3f> &opts = object_points.back();
+
+      opts.resize(board_n);
+      for (int j = 0; j < board_n; j++) {
+        opts[j] = cv::Point3f((float)(j / board_w), (float)(j % board_w), 0.f);
+      }
+      cout << "Collected our " << (int)image_points.size() << " of " << n_boards
+           << " needed chessboard images\n" << endl;
+    }
+    cv::imshow("Calibration", image);
+
+    // show in color if we did collect the image
+    if ((cv::waitKey(30) & 255) == 27)
+      return -1;
+  }
+
+  // END COLLECTION WHILE LOOP.
+  cv::destroyWindow("Calibration");
+  cout << "\n\n*** CALIBRATING THE CAMERA...\n" << endl;
+
+  // CALIBRATE THE CAMERA!
+  //
+  cv::Mat intrinsic_matrix, distortion_coeffs;
+  double err = cv::calibrateCamera(
+      object_points, image_points, image_size, intrinsic_matrix,
+      distortion_coeffs, cv::noArray(), cv::noArray(),
+      cv::CALIB_ZERO_TANGENT_DIST | cv::CALIB_FIX_PRINCIPAL_POINT);
+
+  // SAVE THE INTRINSICS AND DISTORTIONS
+  cout << " *** DONE!\n\nReprojection error is " << err
+       << "\nStoring Intrinsics.xml and Distortions.xml files\n\n";
+  cv::FileStorage fs("intrinsics.xml", cv::FileStorage::WRITE);
+  fs << "image_width" << image_size.width << "image_height" << image_size.height
+     << "camera_matrix" << intrinsic_matrix << "distortion_coefficients"
+     << distortion_coeffs;
+  fs.release();
+
+  // EXAMPLE OF LOADING THESE MATRICES BACK IN:
+  fs.open("intrinsics.xml", cv::FileStorage::READ);
+  cout << "\nimage width: " << (int)fs["image_width"];
+  cout << "\nimage height: " << (int)fs["image_height"];
+  cv::Mat intrinsic_matrix_loaded, distortion_coeffs_loaded;
+  fs["camera_matrix"] >> intrinsic_matrix_loaded;
+  fs["distortion_coefficients"] >> distortion_coeffs_loaded;
+  cout << "\nintrinsic matrix:" << intrinsic_matrix_loaded;
+  cout << "\ndistortion coefficients: " << distortion_coeffs_loaded << endl;
+
+  // Build the undistort map which we will use for all
+  // subsequent frames.
+  //
+  cv::Mat map1, map2;
+  cv::initUndistortRectifyMap(intrinsic_matrix_loaded, distortion_coeffs_loaded,
+                              cv::Mat(), intrinsic_matrix_loaded, image_size,
+                              CV_16SC2, map1, map2);
+
+  // Just run the camera to the screen, now showing the raw and
+  // the undistorted image.
+  //
+  for (;;) {
+    cv::Mat image, image0;
+    capture >> image0;
+    if (image0.empty())
+      break;
+    cv::remap(image0, image, map1, map2, cv::INTER_LINEAR, cv::BORDER_CONSTANT,
+              cv::Scalar());
+    cv::imshow("Undistorted", image);
+    if ((cv::waitKey(30) & 255) == 27)
+      break;
+  }
+  return 0;
+}