subscriber_filter_republisher.cpp

 // Include the ROS library
 //#include <ros/ros.h>

 // Include pcl
 #include <pcl_conversions/pcl_conversions.h>
 #include <pcl/point_cloud.h>
 #include <pcl/point_types.h>
 #include <pcl/filters/voxel_grid.h>

 // Include PointCloud2 message
 #include <sensor_msgs/PointCloud2.h>

 // Topics (still to be modified correctly)
 static const std::string IMAGE_TOPIC = "/camera/depth/points";
 static const std::string PUBLISH_TOPIC = "/pcl/points";

 // ROS Publisher
 ros::Publisher pub;

 void cloud_cb(const sensor_msgs::PointCloud2ConstPtr& cloud_msg)
 {
     // Container for original & filtered data
     pcl::PCLPointCloud2* cloud = new pcl::PCLPointCloud2;
     pcl::PCLPointCloud2ConstPtr cloudPtr(cloud);
     pcl::PCLPointCloud2 cloud_filtered;

     // Convert to PCL data type
     pcl_conversions::toPCL(*cloud_msg, *cloud);

     // Perform the actual filtering
     pcl::VoxelGrid<pcl::PCLPointCloud2> sor;
     sor.setInputCloud (cloudPtr);
     sor.setLeafSize (0.1, 0.1, 0.1);
     sor.filter (cloud_filtered);

     // Convert to ROS data type
     sensor_msgs::PointCloud2 output;
     pcl_conversions::moveFromPCL(cloud_filtered, output);

     // Publish the data
     pub.publish (output);
 }

 int main (int argc, char** argv)
 {
     // Initialize the ROS Node ""
     ros::init (argc, argv, "subscriber_filter_republisher");
     ros::NodeHandle nh;

     // Print "Hello" message with node name to the terminal and ROS log file
     ROS_INFO_STREAM("Hello from ROS Node: " << ros::this_node::getName());

     // Create a ROS Subscriber to IMAGE_TOPIC with a queue_size of 1 and a callback function to cloud_cb
     ros::Subscriber sub = nh.subscribe(IMAGE_TOPIC, 1, cloud_cb);

     // Create a ROS publisher to PUBLISH_TOPIC with a queue_size of 1
     pub = nh.advertise<sensor_msgs::PointCloud2>(PUBLISH_TOPIC, 1);

     // Spin
     ros::spin();

     // Success
     return 0;
 }