void infoCallback(const sensor_msgs::CameraInfoConstPtr& info_msg)
 {
   if (calibrated)
     return;
   cam_model_.fromCameraInfo(info_msg);
   pattern_detector_.setCameraMatrices(cam_model_.intrinsicMatrix(), cam_model_.distortionCoeffs());
   
   calibrated = true;
   image_sub_ = nh_.subscribe("/camera/rgb/image_mono", 1, &CalibrateKinectCheckerboard::imageCallback, this);
   
   ROS_INFO("[calibrate] Got image info!");
 }