velo2cam_calibration.cpp

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/*
  velo2cam_calibration - Automatic calibration algorithm for extrinsic
  parameters of a stereo camera and a velodyne Copyright (C) 2017-2021 Jorge
  Beltran, Carlos Guindel
 
  This file is part of velo2cam_calibration.
 
  velo2cam_calibration 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 of the License, or
  (at your option) any later version.
 
  velo2cam_calibration 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 velo2cam_calibration.  If not, see <http://www.gnu.org/licenses/>.
*/
 
/*
  velo2cam_calibration: Perform the registration step
*/
 
#define PCL_NO_PRECOMPILE
 
#include <pcl/registration/transformation_estimation_svd.h>
#include <pcl_conversions/pcl_conversions.h>
#include <pcl_ros/transforms.h>
#include <ros/package.h>
#include <ros/ros.h>
#include <std_msgs/Empty.h>
#include <std_msgs/Int32.h>
#include <tf/tf.h>
#include <tf/transform_broadcaster.h>
#include <tf/transform_listener.h>
#include <tinyxml.h>
#include <velo2cam_calibration/ClusterCentroids.h>
#include <velo2cam_utils.h>
 
using namespace std;
using namespace sensor_msgs;
 
ros::Publisher clusters_sensor2_pub, clusters_sensor1_pub;
ros::Publisher colour_sensor2_pub, colour_sensor1_pub;
ros::Publisher sensor_switch_pub;
ros::Publisher iterations_pub;
int nFrames;
bool sensor1Received, sensor2Received;
 
pcl::PointCloud<pcl::PointXYZ>::Ptr sensor1_cloud, sensor2_cloud;
pcl::PointCloud<pcl::PointXYZI>::Ptr isensor1_cloud, isensor2_cloud;
std::vector<pcl::PointXYZ> sensor1_vector(4), sensor2_vector(4);
 
tf::StampedTransform tf_sensor1_sensor2;
 
bool is_sensor1_cam, is_sensor2_cam;
bool skip_warmup, single_pose_mode;
string sensor1_frame_id = "";
string sensor1_rotated_frame_id = "";
string sensor2_frame_id = "";
string sensor2_rotated_frame_id = "";
 
typedef Eigen::Matrix<double, 12, 12> Matrix12d;
typedef Eigen::Matrix<double, 12, 1> Vector12d;
 
tf::Transform transf;
 
std::vector<std::vector<std::tuple<int, int, pcl::PointCloud<pcl::PointXYZ>,
                                   std::vector<pcl::PointXYZ>>>>
    sensor1_buffer;
std::vector<std::vector<std::tuple<int, int, pcl::PointCloud<pcl::PointXYZ>,
                                   std::vector<pcl::PointXYZ>>>>
    sensor2_buffer;
 
int S1_WARMUP_COUNT = 0, S2_WARMUP_COUNT = 0;
bool S1_WARMUP_DONE = false, S2_WARMUP_DONE = false;
int TARGET_POSITIONS_COUNT = 0;
int TARGET_ITERATIONS = 30;
 
bool sync_iterations;
bool save_to_file_;
bool publish_tf_;
bool calibration_ended;
bool results_every_pose;
 
long int sensor1_count, sensor2_count;
 
std::ofstream savefile;
 
void sensor1_callback(
    const velo2cam_calibration::ClusterCentroids::ConstPtr sensor1_centroids);
void sensor2_callback(
    velo2cam_calibration::ClusterCentroids::ConstPtr sensor2_centroids);
 
ros::NodeHandle *nh_;
 
ros::Subscriber sensor1_sub, sensor2_sub;
 
void calibrateExtrinsics(int seek_iter = -1) {
  std::vector<pcl::PointXYZ> local_sensor1_vector, local_sensor2_vector;
  pcl::PointCloud<pcl::PointXYZ>::Ptr local_sensor1_cloud(
      new pcl::PointCloud<pcl::PointXYZ>),
      local_sensor2_cloud(new pcl::PointCloud<pcl::PointXYZ>);
  pcl::PointCloud<pcl::PointXYZ> local_l_cloud, local_c_cloud;
 
  int used_sensor2, used_sensor1;
 
  // Get final frame names for TF broadcaster
  string sensor1_final_transformation_frame = sensor1_frame_id;
  if (is_sensor1_cam) {
    sensor1_final_transformation_frame = sensor1_rotated_frame_id;
  }
  string sensor2_final_transformation_frame = sensor2_frame_id;
  if (is_sensor2_cam) {
    sensor2_final_transformation_frame = sensor2_rotated_frame_id;
  }
 
  int total_sensor1, total_sensor2;
 
  if (seek_iter > 0) {  // Add clouds (per sensor) from every position using
                        // last 'seek_iter' detection
    if (DEBUG) ROS_INFO("Seeking %d iterations", seek_iter);
 
    for (int i = 0; i < TARGET_POSITIONS_COUNT + 1; ++i) {
      if (DEBUG)
        ROS_INFO("Target position: %d, Last sensor2: %d, last sensor1: %d",
                 i + 1, std::get<0>(sensor2_buffer[i].back()),
                 std::get<0>(sensor1_buffer[i].back()));
      // Sensor 1
      auto it1 = std::find_if(
          sensor1_buffer[i].begin(), sensor1_buffer[i].end(),
          [&seek_iter](
              const std::tuple<int, int, pcl::PointCloud<pcl::PointXYZ>,
                               std::vector<pcl::PointXYZ>> &e) {
            return std::get<0>(e) == seek_iter;
          });
      if (it1 == sensor1_buffer[i].end()) {
        ROS_WARN("Could not sync sensor1");
        return;
      }
 
      local_sensor1_vector.insert(
          local_sensor1_vector.end(), std::get<3>(*it1).begin(),
          std::get<3>(*it1).end());  // Add sorted centers (for equations)
      *local_sensor1_cloud +=
          std::get<2>(*it1);  // Add centers cloud (for registration)
      used_sensor1 = std::get<1>(*it1);
      total_sensor1 = std::get<0>(*it1);
 
      // Sensor 2
      auto it2 = std::find_if(
          sensor2_buffer[i].begin(), sensor2_buffer[i].end(),
          [&seek_iter](
              const std::tuple<int, int, pcl::PointCloud<pcl::PointXYZ>,
                               std::vector<pcl::PointXYZ>> &e) {
            return std::get<0>(e) == seek_iter;
          });
      if (it2 == sensor2_buffer[i].end()) {
        ROS_WARN("Could not sync sensor2");
        return;
      }
 
      local_sensor2_vector.insert(
          local_sensor2_vector.end(), std::get<3>(*it2).begin(),
          std::get<3>(*it2).end());  // Add sorted centers (for equations)
      *local_sensor2_cloud +=
          std::get<2>(*it2);  // Add centers cloud (for registration)
      used_sensor2 = std::get<1>(*it2);
      total_sensor2 = std::get<0>(*it2);
    }
    ROS_INFO("Synchronizing cluster centroids");
  } else {  // Add clouds (per sensor) from every position using last available
            // detection
    for (int i = 0; i < TARGET_POSITIONS_COUNT + 1; ++i) {
      // Sensor 1
      local_sensor1_vector.insert(
          local_sensor1_vector.end(),
          std::get<3>(sensor1_buffer[i].back()).begin(),
          std::get<3>(sensor1_buffer[i].back())
              .end());  // Add sorted centers (for equations)
      *local_sensor1_cloud += std::get<2>(
          sensor1_buffer[i].back());  // Add centers cloud (for registration)
      used_sensor1 = std::get<1>(sensor2_buffer[i].back());
 
      // Sensor 2
      local_sensor2_vector.insert(
          local_sensor2_vector.end(),
          std::get<3>(sensor2_buffer[i].back()).begin(),
          std::get<3>(sensor2_buffer[i].back())
              .end());  // Add sorted centers (for equations)
      *local_sensor2_cloud += std::get<2>(
          sensor2_buffer[i].back());  // Add centers cloud (for registration)
    }
  }
 
  if (DEBUG) {
    sensor_msgs::PointCloud2 ros_cloud;
    pcl::toROSMsg(*local_sensor2_cloud, ros_cloud);
    ros_cloud.header.frame_id = sensor2_rotated_frame_id;
    clusters_sensor2_pub.publish(ros_cloud);
 
    pcl::toROSMsg(*local_sensor1_cloud, ros_cloud);
    ros_cloud.header.frame_id = sensor1_frame_id;
    clusters_sensor1_pub.publish(ros_cloud);
  }
 
  // SVD code
  pcl::PointCloud<pcl::PointXYZ>::Ptr sorted_centers1(
      new pcl::PointCloud<pcl::PointXYZ>());
  pcl::PointCloud<pcl::PointXYZ>::Ptr sorted_centers2(
      new pcl::PointCloud<pcl::PointXYZ>());
 
  for (int i = 0; i < local_sensor1_vector.size(); ++i) {
    sorted_centers1->push_back(local_sensor1_vector[i]);
    sorted_centers2->push_back(local_sensor2_vector[i]);
  }
 
  Eigen::Matrix4f final_transformation;
  const pcl::registration::TransformationEstimationSVD<pcl::PointXYZ,
                                                       pcl::PointXYZ>
      trans_est_svd(true);
  trans_est_svd.estimateRigidTransformation(*sorted_centers1, *sorted_centers2,
                                            final_transformation);
 
  tf::Matrix3x3 tf3d;
  tf3d.setValue(final_transformation(0, 0), final_transformation(0, 1),
                final_transformation(0, 2), final_transformation(1, 0),
                final_transformation(1, 1), final_transformation(1, 2),
                final_transformation(2, 0), final_transformation(2, 1),
                final_transformation(2, 2));
 
  tf::Quaternion tfqt;
  tf3d.getRotation(tfqt);
 
  tf::Vector3 origin;
  origin.setValue(final_transformation(0, 3), final_transformation(1, 3),
                  final_transformation(2, 3));
 
  transf.setOrigin(origin);
  transf.setRotation(tfqt);
 
  static tf::TransformBroadcaster br;
  tf_sensor1_sensor2 = tf::StampedTransform(transf.inverse(), ros::Time::now(),
                                            sensor1_final_transformation_frame,
                                            sensor2_final_transformation_frame);
  if (publish_tf_) br.sendTransform(tf_sensor1_sensor2);
 
  tf::Transform inverse = tf_sensor1_sensor2.inverse();
  double roll, pitch, yaw;
  double xt = inverse.getOrigin().getX(), yt = inverse.getOrigin().getY(),
         zt = inverse.getOrigin().getZ();
  inverse.getBasis().getRPY(roll, pitch, yaw);
 
  if (save_to_file_) {
    savefile << seek_iter << ", " << xt << ", " << yt << ", " << zt << ", "
             << roll << ", " << pitch << ", " << yaw << ", " << used_sensor1
             << ", " << used_sensor2 << ", " << total_sensor1 << ", "
             << total_sensor2 << endl;
  }
 
  cout << setprecision(4) << std::fixed;
  cout << "Calibration finished succesfully." << endl;
  cout << "Extrinsic parameters:" << endl;
  cout << "x = " << xt << "\ty = " << yt << "\tz = " << zt << endl;
  cout << "roll = " << roll << "\tpitch = " << pitch << "\tyaw = " << yaw << endl;
 
  sensor1Received = false;
  sensor2Received = false;
}
 
void sensor1_callback(
    const velo2cam_calibration::ClusterCentroids::ConstPtr sensor1_centroids) {
  sensor1_frame_id = sensor1_centroids->header.frame_id;
  if (!S1_WARMUP_DONE) {
    S1_WARMUP_COUNT++;
    cout << "Clusters from " << sensor1_frame_id << ": " << S1_WARMUP_COUNT
         << "/10" << '\r' << flush;
    if (S1_WARMUP_COUNT >= 10)  // TODO: Change to param?
    {
      cout << endl;
      sensor1_sub.shutdown();
      sensor2_sub.shutdown();
 
      cout << "Clusters from " << sensor1_frame_id
           << " received. Is the warmup done? [Y/n]" << endl;
      string answer;
      getline(cin, answer);
      if (answer == "y" || answer == "Y" || answer == "") {
        S1_WARMUP_DONE = !S1_WARMUP_DONE;
 
        if (!S2_WARMUP_DONE) {
          cout << "Filters for sensor 1 are adjusted now. Please, proceed with "
                  "the other sensor."
               << endl;
        } else {  // Both sensors adjusted
          cout << "Warmup phase completed. Starting calibration phase." << endl;
          std_msgs::Empty myMsg;
          sensor_switch_pub.publish(myMsg);  //
        }
      } else {  // Reset counter to allow further warmup
        S1_WARMUP_COUNT = 0;
      }
 
      sensor1_sub = nh_->subscribe<velo2cam_calibration::ClusterCentroids>(
          "cloud1", 100, sensor1_callback);
      sensor2_sub = nh_->subscribe<velo2cam_calibration::ClusterCentroids>(
          "cloud2", 100, sensor2_callback);
    }
    return;
  }
 
  if (!S2_WARMUP_DONE) {
    return;
  }
 
  if (DEBUG) ROS_INFO("sensor1 (%s) pattern ready!", sensor1_frame_id.c_str());
 
  if (sensor1_buffer.size() == TARGET_POSITIONS_COUNT) {
    sensor1_buffer.resize(TARGET_POSITIONS_COUNT + 1);
  }
 
  if (is_sensor1_cam) {
    std::ostringstream sstream;
    sstream << "rotated_" << sensor1_frame_id;
    sensor1_rotated_frame_id = sstream.str();
 
    pcl::PointCloud<pcl::PointXYZ>::Ptr xy_sensor1_cloud(
        new pcl::PointCloud<pcl::PointXYZ>());
 
    fromROSMsg(sensor1_centroids->cloud, *xy_sensor1_cloud);
 
    tf::TransformListener listener;
    tf::StampedTransform transform;
    try {
      listener.waitForTransform(sensor1_rotated_frame_id, sensor1_frame_id,
                                ros::Time(0), ros::Duration(20.0));
      listener.lookupTransform(sensor1_rotated_frame_id, sensor1_frame_id,
                               ros::Time(0), transform);
    } catch (tf::TransformException &ex) {
      ROS_WARN("TF exception:\n%s", ex.what());
      return;
    }
 
    tf::Transform inverse = transform.inverse();
    double roll, pitch, yaw;
    inverse.getBasis().getRPY(roll, pitch, yaw);
 
    pcl_ros::transformPointCloud(*xy_sensor1_cloud, *sensor1_cloud, transform);
  } else {
    fromROSMsg(sensor1_centroids->cloud, *sensor1_cloud);
  }
 
  sensor1Received = true;
 
  sortPatternCenters(sensor1_cloud, sensor1_vector);
  if (DEBUG) {
    colourCenters(sensor1_vector, isensor1_cloud);
 
    sensor_msgs::PointCloud2 colour_cloud;
    pcl::toROSMsg(*isensor1_cloud, colour_cloud);
    colour_cloud.header.frame_id =
        is_sensor1_cam ? sensor1_rotated_frame_id : sensor1_frame_id;
    colour_sensor1_pub.publish(colour_cloud);
  }
 
  sensor1_buffer[TARGET_POSITIONS_COUNT].push_back(
      std::tuple<int, int, pcl::PointCloud<pcl::PointXYZ>,
                 std::vector<pcl::PointXYZ>>(
          sensor1_centroids->total_iterations,
          sensor1_centroids->cluster_iterations, *sensor1_cloud,
          sensor1_vector));
  sensor1_count = sensor1_centroids->total_iterations;
 
  if (DEBUG) ROS_INFO("[V2C] sensor1");
 
  for (vector<pcl::PointXYZ>::iterator it = sensor1_vector.begin();
       it < sensor1_vector.end(); ++it) {
    if (DEBUG)
      cout << "l" << it - sensor1_vector.begin() << "="
           << "[" << (*it).x << " " << (*it).y << " " << (*it).z << "]" << endl;
  }
 
  // sync_iterations is designed to extract a calibration result every single
  // frame, so we cannot wait until TARGET_ITERATIONS
  if (sync_iterations) {
    if (sensor2_count >= sensor1_count) {
      calibrateExtrinsics(sensor1_count);
    } else {
      if (tf_sensor1_sensor2.frame_id_ != "" &&
          tf_sensor1_sensor2.child_frame_id_ != "") {
        static tf::TransformBroadcaster br;
        tf_sensor1_sensor2.stamp_ = ros::Time::now();
        if (publish_tf_) br.sendTransform(tf_sensor1_sensor2);
      }
    }
    return;
  }
 
  // Normal operation (sync_iterations=false)
  if (sensor1Received && sensor2Received) {
    cout << min(sensor1_count, sensor2_count) << "/30 iterations" << '\r' << flush;
 
    std_msgs::Int32 it;
    it.data = min(sensor1_count, sensor2_count);
    iterations_pub.publish(it);
 
    if (sensor1_count >= TARGET_ITERATIONS &&
        sensor2_count >= TARGET_ITERATIONS) {
      cout << endl;
      sensor1_sub.shutdown();
      sensor2_sub.shutdown();
 
      string answer;
      if (single_pose_mode) {
        answer = "n";
      } else {
        cout << "Target iterations reached. Do you need another target "
                "location? [y/N]"
             << endl;
        getline(cin, answer);
      }
      if (answer == "n" || answer == "N" || answer == "") {
        calibrateExtrinsics(-1);
        calibration_ended = true;
      } else {  // Move the target and start over
        if (results_every_pose) calibrateExtrinsics(-1);
        TARGET_POSITIONS_COUNT++;
        cout << "Please, move the target to its new position and adjust the "
                "filters for each sensor before the calibration starts."
             << endl;
        // Start over if other position of the target is required
        std_msgs::Empty myMsg;
        sensor_switch_pub.publish(myMsg);  // Set sensor nodes to warmup phase
        S1_WARMUP_DONE = false;
        S1_WARMUP_COUNT = 0;
        S2_WARMUP_DONE = false;
        S2_WARMUP_COUNT = 0;
        sensor1Received = false;
        sensor2Received = false;
        sensor1_count = 0;
        sensor2_count = 0;
      }
      sensor1_sub = nh_->subscribe<velo2cam_calibration::ClusterCentroids>(
          "cloud1", 100, sensor1_callback);
      sensor2_sub = nh_->subscribe<velo2cam_calibration::ClusterCentroids>(
          "cloud2", 100, sensor2_callback);
      return;
    }
  } else {
    if (tf_sensor1_sensor2.frame_id_ != "" &&
        tf_sensor1_sensor2.child_frame_id_ != "") {
      static tf::TransformBroadcaster br;
      tf_sensor1_sensor2.stamp_ = ros::Time::now();
      if (publish_tf_) br.sendTransform(tf_sensor1_sensor2);
    }
  }
}
 
void sensor2_callback(
    velo2cam_calibration::ClusterCentroids::ConstPtr sensor2_centroids) {
  sensor2_frame_id = sensor2_centroids->header.frame_id;
  if (!S2_WARMUP_DONE && S1_WARMUP_DONE) {
    S2_WARMUP_COUNT++;
    cout << "Clusters from " << sensor2_frame_id << ": " << S2_WARMUP_COUNT
         << "/10" << '\r' << flush;
    if (S2_WARMUP_COUNT >= 10)  // TODO: Change to param?
    {
      cout << endl;
      sensor1_sub.shutdown();
      sensor2_sub.shutdown();
 
      cout << "Clusters from " << sensor2_frame_id
           << " received. Is the warmup done? (you can also reset this "
              "position) [Y/n/r]"
           << endl;
      string answer;
      getline(cin, answer);
      if (answer == "y" || answer == "Y" || answer == "") {
        S2_WARMUP_DONE = !S2_WARMUP_DONE;
 
        if (!S1_WARMUP_DONE) {
          cout << "Filters for sensor 2 are adjusted now. Please, proceed with "
                  "the other sensor."
               << endl;
        } else {  // Both sensors adjusted
          cout << "Warmup phase completed. Starting calibration phase." << endl;
          std_msgs::Empty myMsg;
          sensor_switch_pub.publish(myMsg);  //
        }
      } else if (answer == "r" ||
                 answer == "R") {  // Reset this position and
                                   // go back to Sensor 1 warmup
        S1_WARMUP_DONE = false;
        S1_WARMUP_COUNT = 0;
        S2_WARMUP_DONE = false;
        S2_WARMUP_COUNT = 0;
        sensor1Received = false;
        sensor2Received = false;
        sensor1_count = 0;
        sensor2_count = 0;
        cout << "Please, adjust the filters for each sensor before the "
                "calibration starts."
             << endl;
      } else {  // Reset counter to allow further warmup
        S2_WARMUP_COUNT = 0;
      }
      sensor1_sub = nh_->subscribe<velo2cam_calibration::ClusterCentroids>(
          "cloud1", 100, sensor1_callback);
      sensor2_sub = nh_->subscribe<velo2cam_calibration::ClusterCentroids>(
          "cloud2", 100, sensor2_callback);
    }
    return;
  } else if (!S2_WARMUP_DONE) {
    return;
  }
  if (DEBUG) ROS_INFO("sensor2 (%s) pattern ready!", sensor2_frame_id.c_str());
 
  if (sensor2_buffer.size() == TARGET_POSITIONS_COUNT) {
    sensor2_buffer.resize(TARGET_POSITIONS_COUNT + 1);
  }
 
  if (is_sensor2_cam) {
    std::ostringstream sstream;
    sstream << "rotated_" << sensor2_frame_id;
    sensor2_rotated_frame_id = sstream.str();
 
    pcl::PointCloud<pcl::PointXYZ>::Ptr xy_sensor2_cloud(
        new pcl::PointCloud<pcl::PointXYZ>());
 
    fromROSMsg(sensor2_centroids->cloud, *xy_sensor2_cloud);
 
    tf::TransformListener listener;
    tf::StampedTransform transform;
    try {
      listener.waitForTransform(sensor2_rotated_frame_id, sensor2_frame_id,
                                ros::Time(0), ros::Duration(20.0));
      listener.lookupTransform(sensor2_rotated_frame_id, sensor2_frame_id,
                               ros::Time(0), transform);
    } catch (tf::TransformException &ex) {
      ROS_WARN("TF exception:\n%s", ex.what());
      return;
    }
 
    tf::Transform inverse = transform.inverse();
    double roll, pitch, yaw;
    inverse.getBasis().getRPY(roll, pitch, yaw);
 
    pcl_ros::transformPointCloud(*xy_sensor2_cloud, *sensor2_cloud, transform);
  } else {
    fromROSMsg(sensor2_centroids->cloud, *sensor2_cloud);
  }
 
  sensor2Received = true;
 
  sortPatternCenters(sensor2_cloud, sensor2_vector);
 
  if (DEBUG) {
    colourCenters(sensor2_vector, isensor2_cloud);
 
    sensor_msgs::PointCloud2 colour_cloud;
    pcl::toROSMsg(*isensor2_cloud, colour_cloud);
    colour_cloud.header.frame_id =
        is_sensor2_cam ? sensor2_rotated_frame_id : sensor2_frame_id;
    colour_sensor2_pub.publish(colour_cloud);
  }
 
  sensor2_buffer[TARGET_POSITIONS_COUNT].push_back(
      std::tuple<int, int, pcl::PointCloud<pcl::PointXYZ>,
                 std::vector<pcl::PointXYZ>>(
          sensor2_centroids->total_iterations,
          sensor2_centroids->cluster_iterations, *sensor2_cloud,
          sensor2_vector));
  sensor2_count = sensor2_centroids->total_iterations;
 
  if (DEBUG) ROS_INFO("[V2C] sensor2");
 
  for (vector<pcl::PointXYZ>::iterator it = sensor2_vector.begin();
       it < sensor2_vector.end(); ++it) {
    if (DEBUG)
      cout << "c" << it - sensor2_vector.begin() << "="
           << "[" << (*it).x << " " << (*it).y << " " << (*it).z << "]" << endl;
  }
 
  // sync_iterations is designed to extract a calibration result every single
  // frame, so we cannot wait until TARGET_ITERATIONS
  if (sync_iterations) {
    if (sensor1_count >= sensor2_count) {
      calibrateExtrinsics(sensor2_count);
    } else {
      if (tf_sensor1_sensor2.frame_id_ != "" &&
          tf_sensor1_sensor2.child_frame_id_ != "") {
        static tf::TransformBroadcaster br;
        tf_sensor1_sensor2.stamp_ = ros::Time::now();
        if (publish_tf_) br.sendTransform(tf_sensor1_sensor2);
      }
    }
    return;
  }
 
  // Normal operation (sync_iterations=false)
  if (sensor1Received && sensor2Received) {
    cout << min(sensor1_count, sensor2_count) << "/30 iterations" << '\r' << flush;
 
    std_msgs::Int32 it;
    it.data = min(sensor1_count, sensor2_count);
    iterations_pub.publish(it);
 
    if (sensor1_count >= TARGET_ITERATIONS &&
        sensor2_count >= TARGET_ITERATIONS) {
      cout << endl;
      sensor1_sub.shutdown();
      sensor2_sub.shutdown();
 
      string answer;
      if (single_pose_mode) {
        answer = "n";
      } else {
        cout << "Target iterations reached. Do you need another target "
                "location? [y/N]"
             << endl;
        getline(cin, answer);
      }
      if (answer == "n" || answer == "N" || answer == "") {
        calibrateExtrinsics(-1);
        calibration_ended = true;
      } else {  // Move the target and start over
        if (results_every_pose) calibrateExtrinsics(-1);
        TARGET_POSITIONS_COUNT++;
        cout << "Please, move the target to its new position and adjust the "
                "filters for each sensor before the calibration starts."
             << endl;
        // Start over if other position of the target is required
        std_msgs::Empty myMsg;
        sensor_switch_pub.publish(myMsg);  // Set sensor nodes to warmup phase
        S1_WARMUP_DONE = false;
        S1_WARMUP_COUNT = 0;
        S2_WARMUP_DONE = false;
        S2_WARMUP_COUNT = 0;
        sensor1Received = false;
        sensor2Received = false;
        sensor1_count = 0;
        sensor2_count = 0;
      }
      sensor1_sub = nh_->subscribe<velo2cam_calibration::ClusterCentroids>(
          "cloud1", 100, sensor1_callback);
      sensor2_sub = nh_->subscribe<velo2cam_calibration::ClusterCentroids>(
          "cloud2", 100, sensor2_callback);
      return;
    }
  } else {
    if (tf_sensor1_sensor2.frame_id_ != "" &&
        tf_sensor1_sensor2.child_frame_id_ != "") {
      static tf::TransformBroadcaster br;
      tf_sensor1_sensor2.stamp_ = ros::Time::now();
      if (publish_tf_) br.sendTransform(tf_sensor1_sensor2);
    }
  }
}
 
int main(int argc, char **argv) {
  ros::init(argc, argv, "velo2cam_calibration");
  ros::NodeHandle nh;              // GLOBAL
  nh_ = new ros::NodeHandle("~");  // LOCAL
 
  string csv_name;
 
  nh_->param<bool>("sync_iterations", sync_iterations, false);
  nh_->param<bool>("save_to_file", save_to_file_, false);
  nh_->param<bool>("publish_tf", publish_tf_, true);
  nh_->param<bool>("is_sensor2_cam", is_sensor2_cam, false);
  nh_->param<bool>("is_sensor1_cam", is_sensor1_cam, false);
  nh_->param<bool>("skip_warmup", skip_warmup, false);
  nh_->param<bool>("single_pose_mode", single_pose_mode, false);
  nh_->param<bool>("results_every_pose", results_every_pose, false);
  nh_->param<string>("csv_name", csv_name,
                     "registration_" + currentDateTime() + ".csv");
 
  sensor1Received = false;
  sensor1_cloud =
      pcl::PointCloud<pcl::PointXYZ>::Ptr(new pcl::PointCloud<pcl::PointXYZ>);
  isensor1_cloud =
      pcl::PointCloud<pcl::PointXYZI>::Ptr(new pcl::PointCloud<pcl::PointXYZI>);
  sensor2Received = false;
  sensor2_cloud =
      pcl::PointCloud<pcl::PointXYZ>::Ptr(new pcl::PointCloud<pcl::PointXYZ>);
  isensor2_cloud =
      pcl::PointCloud<pcl::PointXYZI>::Ptr(new pcl::PointCloud<pcl::PointXYZI>);
 
  sensor1_sub = nh_->subscribe<velo2cam_calibration::ClusterCentroids>(
      "cloud1", 100, sensor1_callback);
  sensor2_sub = nh_->subscribe<velo2cam_calibration::ClusterCentroids>(
      "cloud2", 100, sensor2_callback);
 
  if (DEBUG) {
    clusters_sensor2_pub =
        nh_->advertise<sensor_msgs::PointCloud2>("clusters_sensor2", 1);
    clusters_sensor1_pub =
        nh_->advertise<sensor_msgs::PointCloud2>("clusters_sensor1", 1);
 
    colour_sensor2_pub =
        nh_->advertise<sensor_msgs::PointCloud2>("colour_sensor2", 1);
    colour_sensor1_pub =
        nh_->advertise<sensor_msgs::PointCloud2>("colour_sensor1", 1);
  }
 
  sensor_switch_pub = nh.advertise<std_msgs::Empty>("warmup_switch", 1);
  iterations_pub = nh_->advertise<std_msgs::Int32>("iterations", 1);
 
  calibration_ended = false;
 
  if (save_to_file_) {
    ostringstream os;
    os << getenv("HOME") << "/v2c_experiments/" << csv_name;
    if (save_to_file_) {
      if (DEBUG) ROS_INFO("Opening %s", os.str().c_str());
      savefile.open(os.str().c_str());
      savefile << "it, x, y, z, r, p, y, used_sen1, used_sen2, total_sen1, "
                  "total_sen2"
               << endl;
    }
  }
 
  if (skip_warmup) {
    S1_WARMUP_DONE = true;
    S2_WARMUP_DONE = true;
    ROS_WARN("Skipping warmup");
  } else {
    cout << "Please, adjust the filters for each sensor before the calibration "
            "starts."
         << endl;
  }
 
  ros::Rate loop_rate(30);
  while (ros::ok() && !calibration_ended) {
    ros::spinOnce();
  }
 
  sensor1_sub.shutdown();
  sensor2_sub.shutdown();
 
  if (save_to_file_) savefile.close();
 
  // Save calibration params to launch file for testing
 
  // Get time
  time_t rawtime;
  struct tm *timeinfo;
  char buffer[80];
 
  time(&rawtime);
  timeinfo = localtime(&rawtime);
 
  strftime(buffer, 80, "%Y-%m-%d-%H-%M-%S", timeinfo);
  std::string str(buffer);
 
  // Get tf data
  tf::Transform inverse = tf_sensor1_sensor2.inverse();
  double roll, pitch, yaw;
  double xt = inverse.getOrigin().getX(), yt = inverse.getOrigin().getY(),
         zt = inverse.getOrigin().getZ();
  inverse.getBasis().getRPY(roll, pitch, yaw);
 
  std::string path = ros::package::getPath("velo2cam_calibration");
  string backuppath = path + "/launch/calibrated_tf_" + str + ".launch";
  path = path + "/launch/calibrated_tf.launch";
 
  cout << endl
       << "Creating .launch file with calibrated TF in: " << endl
       << path.c_str() << endl;
  // Create .launch file with calibrated TF
  TiXmlDocument doc;
  TiXmlDeclaration *decl = new TiXmlDeclaration("1.0", "utf-8", "");
  doc.LinkEndChild(decl);
  TiXmlElement *root = new TiXmlElement("launch");
  doc.LinkEndChild(root);
 
  TiXmlElement *arg = new TiXmlElement("arg");
  arg->SetAttribute("name", "stdout");
  arg->SetAttribute("default", "screen");
  root->LinkEndChild(arg);
 
  string sensor2_final_transformation_frame = sensor2_frame_id;
  if (is_sensor2_cam) {
    sensor2_final_transformation_frame = sensor2_rotated_frame_id;
    std::ostringstream sensor2_rot_stream_pub;
    sensor2_rot_stream_pub << "0 0 0 -1.57079632679 0 -1.57079632679 "
                           << sensor2_rotated_frame_id << " "
                           << sensor2_frame_id << " 10";
    string sensor2_rotation = sensor2_rot_stream_pub.str();
 
    TiXmlElement *sensor2_rotation_node = new TiXmlElement("node");
    sensor2_rotation_node->SetAttribute("pkg", "tf");
    sensor2_rotation_node->SetAttribute("type", "static_transform_publisher");
    sensor2_rotation_node->SetAttribute("name", "sensor2_rot_tf");
    sensor2_rotation_node->SetAttribute("args", sensor2_rotation);
    root->LinkEndChild(sensor2_rotation_node);
  }
 
  string sensor1_final_transformation_frame = sensor1_frame_id;
  if (is_sensor1_cam) {
    sensor1_final_transformation_frame = sensor1_rotated_frame_id;
    std::ostringstream sensor1_rot_stream_pub;
    sensor1_rot_stream_pub << "0 0 0 -1.57079632679 0 -1.57079632679 "
                           << sensor1_rotated_frame_id << " "
                           << sensor1_frame_id << " 10";
    string sensor1_rotation = sensor1_rot_stream_pub.str();
 
    TiXmlElement *sensor1_rotation_node = new TiXmlElement("node");
    sensor1_rotation_node->SetAttribute("pkg", "tf");
    sensor1_rotation_node->SetAttribute("type", "static_transform_publisher");
    sensor1_rotation_node->SetAttribute("name", "sensor1_rot_tf");
    sensor1_rotation_node->SetAttribute("args", sensor1_rotation);
    root->LinkEndChild(sensor1_rotation_node);
  }
 
  std::ostringstream sstream;
  sstream << xt << " " << yt << " " << zt << " " << yaw << " " << pitch << " "
          << roll << " " << sensor2_final_transformation_frame << " "
          << sensor1_final_transformation_frame << " 100";
  string tf_args = sstream.str();
 
  TiXmlElement *node = new TiXmlElement("node");
  node->SetAttribute("pkg", "tf");
  node->SetAttribute("type", "static_transform_publisher");
  node->SetAttribute("name", "velo2cam_tf");
  node->SetAttribute("args", tf_args);
  root->LinkEndChild(node);
 
  // Save XML file and copy
  doc.SaveFile(path);
  doc.SaveFile(backuppath);
 
  if (DEBUG) cout << "Calibration process finished." << endl;
 
  return 0;
}