point_cloud_xyz.cpp

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#include <ros/ros.h>
#include <nodelet/nodelet.h>
#include <image_transport/image_transport.h>
#include <pcl_ros/point_cloud.h>
#include <pcl/point_types.h>
#include <sensor_msgs/image_encodings.h>
#include <image_geometry/pinhole_camera_model.h>
#include <boost/thread.hpp>
#include "depth_traits.h"

namespace depth_image_proc {

namespace enc = sensor_msgs::image_encodings;

class PointCloudXyzNodelet : public nodelet::Nodelet
{
  // Subscriptions
  boost::shared_ptr<image_transport::ImageTransport> it_;
  image_transport::CameraSubscriber sub_depth_;
  int queue_size_;

  // Publications
  boost::mutex connect_mutex_;
  typedef pcl::PointCloud<pcl::PointXYZ> PointCloud;
  ros::Publisher pub_point_cloud_;

  image_geometry::PinholeCameraModel model_;

  virtual void onInit();

  void connectCb();

  void depthCb(const sensor_msgs::ImageConstPtr& depth_msg,
               const sensor_msgs::CameraInfoConstPtr& info_msg);

  // Handles float or uint16 depths
  template<typename T>
  void convert(const sensor_msgs::ImageConstPtr& depth_msg, PointCloud::Ptr& cloud_msg);
};

void PointCloudXyzNodelet::onInit()
{
  ros::NodeHandle& nh         = getNodeHandle();
  ros::NodeHandle& private_nh = getPrivateNodeHandle();
  it_.reset(new image_transport::ImageTransport(nh));

  // Read parameters
  private_nh.param("queue_size", queue_size_, 5);

  // Monitor whether anyone is subscribed to the output
  ros::SubscriberStatusCallback connect_cb = boost::bind(&PointCloudXyzNodelet::connectCb, this);
  // Make sure we don't enter connectCb() between advertising and assigning to pub_point_cloud_
  boost::lock_guard<boost::mutex> lock(connect_mutex_);
  pub_point_cloud_ = nh.advertise<PointCloud>("points", 1, connect_cb, connect_cb);
}

// Handles (un)subscribing when clients (un)subscribe
void PointCloudXyzNodelet::connectCb()
{
  boost::lock_guard<boost::mutex> lock(connect_mutex_);
  if (pub_point_cloud_.getNumSubscribers() == 0)
  {
    sub_depth_.shutdown();
  }
  else if (!sub_depth_)
  {
    image_transport::TransportHints hints("raw", ros::TransportHints(), getPrivateNodeHandle());
    sub_depth_ = it_->subscribeCamera("image_rect", queue_size_, &PointCloudXyzNodelet::depthCb, this, hints);
  }
}

void PointCloudXyzNodelet::depthCb(const sensor_msgs::ImageConstPtr& depth_msg,
                                   const sensor_msgs::CameraInfoConstPtr& info_msg)
{
  PointCloud::Ptr cloud_msg(new PointCloud);
  cloud_msg->header = depth_msg->header;
  cloud_msg->height = depth_msg->height;
  cloud_msg->width  = depth_msg->width;
  cloud_msg->is_dense = false;
  cloud_msg->points.resize(cloud_msg->height * cloud_msg->width);

  // Update camera model
  model_.fromCameraInfo(info_msg);

  if (depth_msg->encoding == enc::TYPE_16UC1)
  {
    convert<uint16_t>(depth_msg, cloud_msg);
  }
  else if (depth_msg->encoding == enc::TYPE_32FC1)
  {
    convert<float>(depth_msg, cloud_msg);
  }
  else
  {
    NODELET_ERROR_THROTTLE(5, "Depth image has unsupported encoding [%s]", depth_msg->encoding.c_str());
    return;
  }

  pub_point_cloud_.publish (cloud_msg);
}

template<typename T>
void PointCloudXyzNodelet::convert(const sensor_msgs::ImageConstPtr& depth_msg, PointCloud::Ptr& cloud_msg)
{
  // Use correct principal point from calibration
  float center_x = model_.cx();
  float center_y = model_.cy();

  // Combine unit conversion (if necessary) with scaling by focal length for computing (X,Y)
  double unit_scaling = DepthTraits<T>::toMeters( T(1) );
  float constant_x = unit_scaling / model_.fx();
  float constant_y = unit_scaling / model_.fy();
  float bad_point = std::numeric_limits<float>::quiet_NaN();

  PointCloud::iterator pt_iter = cloud_msg->begin();
  const T* depth_row = reinterpret_cast<const T*>(&depth_msg->data[0]);
  int row_step = depth_msg->step / sizeof(T);
  for (int v = 0; v < (int)cloud_msg->height; ++v, depth_row += row_step)
  {
    for (int u = 0; u < (int)cloud_msg->width; ++u)
    {
      pcl::PointXYZ& pt = *pt_iter++;
      T depth = depth_row[u];

      // Missing points denoted by NaNs
      if (!DepthTraits<T>::valid(depth))
      {
        pt.x = pt.y = pt.z = bad_point;
        continue;
      }

      // Fill in XYZ
      pt.x = (u - center_x) * depth * constant_x;
      pt.y = (v - center_y) * depth * constant_y;
      pt.z = DepthTraits<T>::toMeters(depth);
    }
  }
}

} // namespace depth_image_proc

// Register as nodelet
#include <pluginlib/class_list_macros.h>
PLUGINLIB_EXPORT_CLASS(depth_image_proc::PointCloudXyzNodelet,nodelet::Nodelet);