Writing Point Cloud data to PCD files — Point Cloud Library 0.0 documentation (original) (raw)

In this tutorial we will learn how to write point cloud data to a PCD file.

The code

First, create a file called, let’s say, pcd_write.cpp in your favorite editor, and place the following code inside it:

1#include 2#include <pcl/io/pcd_io.h> 3#include <pcl/point_types.h> 4 5int 6 main () 7{ 8 pcl::PointCloudpcl::PointXYZ cloud; 9 10 // Fill in the cloud data 11 cloud.width = 5; 12 cloud.height = 1; 13 cloud.is_dense = false; 14 cloud.resize (cloud.width * cloud.height); 15 16 for (auto& point: cloud) 17 { 18 point.x = 1024 * rand () / (RAND_MAX + 1.0f); 19 point.y = 1024 * rand () / (RAND_MAX + 1.0f); 20 point.z = 1024 * rand () / (RAND_MAX + 1.0f); 21 } 22 23 pcl::io::savePCDFileASCII ("test_pcd.pcd", cloud); 24 std::cerr << "Saved " << cloud.size () << " data points to test_pcd.pcd." << std::endl; 25 26 for (const auto& point: cloud) 27 std::cerr << " " << point.x << " " << point.y << " " << point.z << std::endl; 28 29 return (0); 30}

The explanation

Now, let’s break down the code piece by piece.

#include <pcl/io/pcd_io.h> #include <pcl/point_types.h>

The first file is the header that contains the definitions for PCD I/O operations, and second one contains definitions for several point type structures, including pcl::PointXYZ that we will use.

pcl::PointCloudpcl::PointXYZ cloud;

describes the templated PointCloud structure that we will create. The type of each point is set to pcl::PointXYZ, which is a structure that has x,y, and z fields.

The lines:

// Fill in the cloud data cloud.width = 5; cloud.height = 1; cloud.is_dense = false; cloud.resize (cloud.width * cloud.height);

for (auto& point: cloud) { point.x = 1024 * rand () / (RAND_MAX + 1.0f); point.y = 1024 * rand () / (RAND_MAX + 1.0f); point.z = 1024 * rand () / (RAND_MAX + 1.0f); }

fill in the PointCloud structure with random point values, and set the appropriate parameters (width, height, is_dense).

Then:

pcl::io::savePCDFileASCII ("test_pcd.pcd", cloud);

saves the PointCloud data to disk into a file called test_pcd.pcd

Finally:

std::cerr << "Saved " << cloud.size () << " data points to test_pcd.pcd." << std::endl;

for (const auto& point: cloud) std::cerr << " " << point.x << " " << point.y << " " << point.z << std::endl;

is used to show the data that was generated.

Compiling and running the program

Add the following lines to your CMakeLists.txt file:

1cmake_minimum_required(VERSION 3.5 FATAL_ERROR) 2 3project(pcd_write) 4 5find_package(PCL 1.2 REQUIRED) 6 7add_executable (pcd_write pcd_write.cpp) 8target_link_libraries (pcd_write ${PCL_LIBRARIES})

After you have made the executable, you can run it. Simply do:

You will see something similar to:

Saved 5 data points to test_pcd.pcd. 0.352222 -0.151883 -0.106395 -0.397406 -0.473106 0.292602 -0.731898 0.667105 0.441304 -0.734766 0.854581 -0.0361733 -0.4607 -0.277468 -0.916762

You can check the content of the file test_pcd.pcd, using:

$ cat test_pcd.pcd

.PCD v.5 - Point Cloud Data file format

FIELDS x y z SIZE 4 4 4 TYPE F F F WIDTH 5 HEIGHT 1 POINTS 5 DATA ascii 0.35222 -0.15188 -0.1064 -0.39741 -0.47311 0.2926 -0.7319 0.6671 0.4413 -0.73477 0.85458 -0.036173 -0.4607 -0.27747 -0.91676