crop_foremost.cpp

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//#include <ros/ros.h>
#include <nodelet/nodelet.h>
#include <image_transport/image_transport.h>
#include <boost/thread.hpp>
#include <cv_bridge/cv_bridge.h>
#include <opencv2/imgproc/imgproc.hpp>

namespace depth_image_proc {

namespace enc = sensor_msgs::image_encodings;

class CropForemostNodelet : public nodelet::Nodelet
{
  // Subscriptions
  boost::shared_ptr<image_transport::ImageTransport> it_;
  image_transport::Subscriber sub_raw_;

  // Publications
  boost::mutex connect_mutex_;
  image_transport::Publisher pub_depth_;

  virtual void onInit();

  void connectCb();

  void depthCb(const sensor_msgs::ImageConstPtr& raw_msg);

  double distance_;
};

void CropForemostNodelet::onInit()
{
  ros::NodeHandle& nh = getNodeHandle();
  ros::NodeHandle& private_nh = getPrivateNodeHandle();
  private_nh.getParam("distance", distance_);
  it_.reset(new image_transport::ImageTransport(nh));

  // Monitor whether anyone is subscribed to the output
  image_transport::SubscriberStatusCallback connect_cb = boost::bind(&CropForemostNodelet::connectCb, this);
  // Make sure we don't enter connectCb() between advertising and assigning to pub_depth_
  boost::lock_guard<boost::mutex> lock(connect_mutex_);
  pub_depth_ = it_->advertise("image", 1, connect_cb, connect_cb);
}

// Handles (un)subscribing when clients (un)subscribe
void CropForemostNodelet::connectCb()
{
  boost::lock_guard<boost::mutex> lock(connect_mutex_);
  if (pub_depth_.getNumSubscribers() == 0)
  {
    sub_raw_.shutdown();
  }
  else if (!sub_raw_)
  {
    image_transport::TransportHints hints("raw", ros::TransportHints(), getPrivateNodeHandle());
    sub_raw_ = it_->subscribe("image_raw", 1, &CropForemostNodelet::depthCb, this, hints);
  }
}

void CropForemostNodelet::depthCb(const sensor_msgs::ImageConstPtr& raw_msg)
{
  cv_bridge::CvImagePtr cv_ptr;
  try
  {
    cv_ptr = cv_bridge::toCvCopy(raw_msg);
  }
  catch (cv_bridge::Exception& e)
  {
    ROS_ERROR("cv_bridge exception: %s", e.what());
    return;
  }

  // Check the number of channels
  if(sensor_msgs::image_encodings::numChannels(raw_msg->encoding) != 1){
    NODELET_ERROR_THROTTLE(2, "Only grayscale image is acceptable, got [%s]", raw_msg->encoding.c_str());
    return;
  }

  // search the min value without invalid value "0"
  double minVal;
  cv::minMaxIdx(cv_ptr->image, &minVal, 0, 0, 0, cv_ptr->image != 0);

  int imtype = cv_bridge::getCvType(raw_msg->encoding);
  switch (imtype){
    case CV_8UC1:
    case CV_8SC1:
    case CV_32F:
      cv::threshold(cv_ptr->image, cv_ptr->image, minVal + distance_, 0, CV_THRESH_TOZERO_INV);
      break;
    case CV_16UC1:
    case CV_16SC1:
    case CV_32SC1:
    case CV_64F:
      // 8 bit or 32 bit floating array is required to use cv::threshold
      cv_ptr->image.convertTo(cv_ptr->image, CV_32F);
      cv::threshold(cv_ptr->image, cv_ptr->image, minVal + distance_, 1, CV_THRESH_TOZERO_INV);

      cv_ptr->image.convertTo(cv_ptr->image, imtype);
      break;
  }

  pub_depth_.publish(cv_ptr->toImageMsg());
}

} // namespace depth_image_proc

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