Problem with NormalEstimation for finding Normals in PCL

Question

I am trying to use Normal Estimation for finding normals at points in clouds so that I can pass it to the FPFH keypoint detector. Here is my code:-

#include <pcl/io/pcd_io.h>
#include <pcl/features/normal_3d.h>
#include <pcl/features/fpfh.h>

int
main(int argc, char** argv)
{
    // Object for storing the point cloud.
    pcl::PointCloud<pcl::PointXYZ>::Ptr cloud(new pcl::PointCloud<pcl::PointXYZ>);
    // Object for storing the normals.
    pcl::PointCloud<pcl::Normal>::Ptr normals(new pcl::PointCloud<pcl::Normal>);
    // Object for storing the FPFH descriptors for each point.
    pcl::PointCloud<pcl::FPFHSignature33>::Ptr descriptors(new pcl::PointCloud<pcl::FPFHSignature33>());

    // Read a PCD file from disk.
    if (pcl::io::loadPCDFile<pcl::PointXYZ> ("/home/ashwin/pcl/test/table_scene_mug_stereo_textured.pcd", *cloud) == -1) 
        {
          PCL_ERROR ("Couldn't read file p1.pcd \n");
          return (-1);
        }
    std::cout << "Loaded " << cloud->width <<"x"<< cloud->height <<"="<< cloud->width*cloud->height << std::endl;

    // Estimate the normals.
    pcl::NormalEstimation<pcl::PointXYZ, pcl::Normal> normalEstimation;
    normalEstimation.setInputCloud(cloud);
    normalEstimation.setRadiusSearch(15);

    pcl::search::KdTree<pcl::PointXYZ>::Ptr kdtree(new pcl::search::KdTree<pcl::PointXYZ>);
    normalEstimation.setSearchMethod(kdtree);
    normalEstimation.compute(*normals);

    std::cout<< "Normal size: " << normals->size() << std::endl;

}

I am getting the following output:-

Loaded 640x480=307200 [pcl::KdTreeFLANN::setInputCloud] Cannot create a KDTree with an empty input cloud! Normal size: 0

As you can see input cloud has 307200 points. I am unable to understand why am I getting the 'empty input cloud' error?

Here is my CMakerLists.txt:-

cmake_minimum_required(VERSION 2.8 FATAL_ERROR)

project(registration_api)

find_package(PCL 1.8 REQUIRED)

include_directories(${PCL_INCLUDE_DIRS})
link_directories(${PCL_LIBRARY_DIRS})
add_definitions(${PCL_DEFINITIONS})

add_executable (fpfh_descriptor_trial fpfh_descriptor_trial.cpp)
target_link_libraries (fpfh_descriptor_trial ${PCL_LIBRARIES})

can you share your point cloud data? Try to use ```normalEstimation.setKSearch(number of Neighbour) instead of setRadiusSearch — Joy Mazumder
When I run your code, after changing setRadiusSearch(15) to setKSearch(15), the code run without any problem. I don't think that line caused the problem though. It's just that radius search with a radius of 15 took too long and I killed it. — Jing Zhao
By the way, the data OP used is present in PCL release. And you can get that from here. — Jing Zhao
@JingZhao I tried using setKSearch(15) but still, I am getting exact same result. I have updated the post with my CmakeLists.txt if that helps. — Ashwin
@JoyMazumder here is the link for .pcd file I used github.com/PointCloudLibrary/pcl/tree/master/test — Ashwin

Ashwin Ashwin · Accepted Answer · 2020-05-19T00:26:03

I couldn't find the reason for this issue but I got the code running by transferring it to a different folder. I am still wondering how it solved my issue, but it did.

Problem with NormalEstimation for finding Normals in PCL

1 Answers