void PointCloudHandler(const sensor_msgs::PointCloud2ConstPtr& input)
{
     ROS_INFO("received pc");
     tr = tf::Transform(btMatrix3x3(1,0,0,
                               0,1,0,  
                                0,0,1),  
                                btVector3(0,0,-5));
 
     pcl::PointCloud<pcl::PointXYZRGB>::Ptr cloud_in = pcl::PointCloud<pcl::PointXYZRGB>::Ptr(new pcl::PointCloud<pcl::PointXYZRGB>);                                    
     pcl::PointCloud<pcl::PointXYZRGB>::Ptr cloud_out = pcl::PointCloud<pcl::PointXYZRGB>::Ptr(new pcl::PointCloud<pcl::PointXYZRGB>);
  
     pcl::fromROSMsg(*input, *cloud_in); 
 
     pcl_ros::transformPointCloud(*cloud_in, *cloud_out, tr.inverse());
 
     sensor_msgs::PointCloud2 pc_out_msg;
     pcl::toROSMsg(*cloud_out, pc_out_msg);
 
 
     pub_point_cloud.publish (pc_out_msg);
 }