From 9c3de4bcabdec862972e93acfb949b231876a24e Mon Sep 17 00:00:00 2001
From: Razvan Mihalyi <r.mihalyi@jacobs-university.de>
Date: Tue, 18 Sep 2012 10:31:37 +0200
Subject: [PATCH] Add C++ implementation of chessboard detection and set up
 interactive user mode

---
 calibrate.cc | 73 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 73 insertions(+)
 create mode 100644 calibrate.cc

diff --git a/calibrate.cc b/calibrate.cc
new file mode 100644
index 0000000..2a36461
--- /dev/null
+++ b/calibrate.cc
@@ -0,0 +1,73 @@
+#include <opencv2/highgui/highgui.hpp>
+#include <opencv2/core/core.hpp>
+#include <opencv2/opencv.hpp>
+#include <opencv2/imgproc/imgproc.hpp>
+#include <opencv2/video/video.hpp>
+
+#include <fstream>
+#include <iostream>
+
+using namespace std;
+using namespace cv;
+
+enum {INTERACTIVE_MODE, PRESPECIFIED_MODE};
+
+#define KEY_ESCAPE 1048603
+#define KEY_SPACE 1048608
+#define KEY_CLOSE_WINDOW -1
+
+int main(int argc, char** argv)
+{
+	int user_mode;
+	if (argc > 2) 
+		cerr << "Usage: ./calibrate [number of frames]\n";
+	else 
+	if (argc == 1) 
+	{
+		user_mode = INTERACTIVE_MODE;
+		cout << "Camera calibration using interactive behavior. Press SPACE to grab frame.\n";
+	} 
+	else 
+	{
+		user_mode = PRESPECIFIED_MODE;
+		cout << "Camera calibration using " << argv[1] << " frames.\n";
+	}
+
+	VideoCapture cap(-1); // open the default camera
+	if(!cap.isOpened())  // check if opening camera stream succeeded
+	{
+		cerr << "Camera could not be found. Exiting.\n";
+		return -1;
+	}
+
+	namedWindow("Camera Image", CV_WINDOW_KEEPRATIO);
+	for(int count = 0; ; ++count)
+	{
+		cout << "Frame: " << count << "\n";		
+	  Mat frame;
+	  cap >> frame; // get a new frame from camera
+	  imshow("Camera Image", frame);
+		int key_pressed = waitKey(0);
+		if (key_pressed == KEY_CLOSE_WINDOW || key_pressed == KEY_ESCAPE) break;
+		else 
+		if (user_mode == INTERACTIVE_MODE) 
+		{		
+			if (key_pressed == KEY_SPACE) 
+			{
+				Size pattern_size(4, 6); //interior number of corners
+				vector<Point2f> corners; //this will be filled by the detected corners
+				bool pattern_found = findChessboardCorners( frame, pattern_size, corners, CALIB_CB_ADAPTIVE_THRESH + CALIB_CB_NORMALIZE_IMAGE + CALIB_CB_FAST_CHECK);
+			
+				if(pattern_found) // to tweak params: http://bit.ly/QyoU3k
+					cornerSubPix(frame, corners, Size(11, 11), Size(-1, -1), TermCriteria(CV_TERMCRIT_EPS + CV_TERMCRIT_ITER, 30, 0.1));
+
+				drawChessboardCorners(frame, pattern_size, Mat(corners), pattern_found);
+				imshow("Calibrated", frame);
+				waitKey(30);
+			}		
+		}
+	}
+
+	// the camera will be deinitialized automatically in VideoCapture destructor
+	return 0;
+}