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double free or corruption (out) error with PCL

asked 2022-09-28 16:19:06 -0500

dvy gravatar image

updated 2022-09-29 23:56:06 -0500

ravijoshi gravatar image

System used: ROS2 foxy on Ubuntu 20.04 with PCL 1.10 installed on amd64 architecture.

I have created a C++ subscriber for ROS2 topic velodyne_points of the message type sensor_msgs::msg::PointCloud2. Since, this is ROS2 message and PCL can't handle it. So, I first convert it to something (pcl::PCLPointCloud2 cloud;) which PCL can understand using pcl_conversions::toPCL(*msg, cloud); where msg is the pointer to ROS message and cloud contains the converted PCL data. Then, I want to apply PCL's voxelGrid functionality. Since voxelGrid.setInputCloud(cloudPtr); takes the argument as a pointer(the const boost shared pointer to a PointCloud message), I create one which points to PCL "cloud" using pcl::PCLPointCloud2::Ptr cloudPtr (&cloud);, process it further and save the result in a memory location pointed by cloud_filtered. But as soon as program reaches the end of this subscriber callback function, it gives an error double free or corruption (out) on the terminal and execution stops (No error in compilation, only in execution).

I tried to understand this error but I am not trying to free some pointer explicitly which is already free. This issue happens because of the line pcl::PCLPointCloud2::Ptr cloudPtr (&cloud); because when I tried commenting this line and the voxelization steps, execution worked well. But I need to do voxelization and some more steps after it is done (ground plane segmentation, clustering etc.).

I am trying to build ROS2 package and run the executable using this command : clear && colcon build --packages-select custom_nav_stack_pkg --symlink-install && source install/local_setup.bash && ros2 run custom_nav_stack_pkg cpp_executable which looks fine to me.

Here is the code.

#include <memory>
#include <iostream>

#include "rclcpp/rclcpp.hpp"
#include "std_msgs/msg/string.hpp"
#include "sensor_msgs/msg/point_cloud2.hpp"
#include <pcl/point_cloud.h>
#include <pcl/point_types.h>
#include <pcl/PCLPointCloud2.h>
#include <pcl/conversions.h>
#include <pcl_conversions/pcl_conversions.h>
#include <pcl/visualization/cloud_viewer.h>
#include <boost/foreach.hpp>
#include <pcl/filters/voxel_grid.h>

class MinimalSubscriber : public rclcpp::Node
    MinimalSubscriber()    //Constructor which has the same name as that of class followed by a parentheses. A constructor in C++ is a special method that is automatically called when an object of a class is created. 
    : Node("minimal_subscriber")
      subscription_ = this->create_subscription<sensor_msgs::msg::PointCloud2>
      ("velodyne_points", 10, std::bind(&MinimalSubscriber::topic_callback, this, std::placeholders::_1));

    void topic_callback(const sensor_msgs::msg::PointCloud2::SharedPtr msg) const
      RCLCPP_INFO(this->get_logger(), "I received the message , height is: '%d'", msg->height); //
      pcl::PCLPointCloud2 cloud;
      pcl_conversions::toPCL(*msg, cloud);

      RCLCPP_INFO(this->get_logger(), "I received the PCL message , height is: '%d'", cloud.height);

      std::cerr << "PointCloud before filtering: " << cloud.width * cloud.height 
             << " data points (" << pcl::getFieldsList (cloud) << ")." << std::endl;

      // Declaring pointer for the PCL "cloud" 
      pcl::PCLPointCloud2::Ptr cloudPtr (&cloud);

      // define a new container for the data
      pcl::PCLPointCloud2::Ptr cloud_filtered (new pcl::PCLPointCloud2 ());

      // define a voxelgrid
      pcl::VoxelGrid<pcl::PCLPointCloud2> voxelGrid;
      // set input to cloud
      // set the leaf size (x, y, z)
      voxelGrid.setLeafSize(0.1, 0.1, 0.1);
      // apply the ...
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answered 2022-09-29 06:01:39 -0500

ravijoshi gravatar image

There are a few changes needed to fix the error. The following should work:

void topic_callback(const sensor_msgs::msg::PointCloud2::SharedPtr msg_ptr) const
  pcl::PCLPointCloud2::Ptr cloud_in_ptr(new pcl::PCLPointCloud2);
  pcl_conversions::toPCL(*msg_ptr, *cloud_in_ptr);

  RCLCPP_INFO_STREAM(get_logger(), "[Input PointCloud] width " << cloud_in_ptr->width << " height " << cloud_in_ptr->height);

  pcl::PCLPointCloud2::Ptr cloud_out_ptr(new pcl::PCLPointCloud2);
  pcl::voxelGrid<pcl::PCLPointCloud2> voxel_grid;
  voxel_grid.setLeafSize(0.1, 0.1, 0.1);

  RCLCPP_INFO_STREAM(get_logger(), "[Output PointCloud] width " << cloud_out_ptr->width << " height " << cloud_out_ptr->height);
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@rajivjoshi : Thanks a lot! It worked like a charm. By the way, can you please also explain the reason for the failure and the fix?

dvy gravatar image dvy  ( 2022-09-29 12:34:30 -0500 )edit

I am glad it worked. Notice that you are calling the class directly. Pay attention to the () after PCLPointCloud2 . The pcl::PCLPointCloud2::Ptr is a smart pointer, so you just need to provide the class name only, i.e., without (). Next, the voxelGrid filter requires smart pointer as input, so I created it at the beginning and used it inside pcl_conversions::toPCL. Notice the dereferencing of pointer here.

ravijoshi gravatar image ravijoshi  ( 2022-09-29 23:54:48 -0500 )edit

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Asked: 2022-09-28 16:19:06 -0500

Seen: 504 times

Last updated: Sep 29 '22