code show as below:

#include <iostream>
#include <pcl/io/pcd_io.h>
#include <pcl/point_types.h>
#include <pcl/ModelCoefficients.h>
#include <pcl/filters/project_inliers.h>
#include<stdio.h>

int
main(int argc, char** argv)
{
	pcl::PointCloud<pcl::PointXYZ>::Ptr cloud(new pcl::PointCloud<pcl::PointXYZ>);
	pcl::PointCloud<pcl::PointXYZ>::Ptr cloud_projected(new pcl::PointCloud<pcl::PointXYZ>);

	// Fill in the cloud data
	cloud->width = 5;
	cloud->height = 1;
	cloud->points.resize(cloud->width * cloud->height);

	for (size_t i = 0; i < cloud->points.size(); ++i)
	{
		cloud->points[i].x = 1024 * rand() / (RAND_MAX + 1.0f);
		cloud->points[i].y = 1024 * rand() / (RAND_MAX + 1.0f);
		cloud->points[i].z = 1024 * rand() / (RAND_MAX + 1.0f);
	}

	std::cerr << "Cloud before projection: " << std::endl;
	for (size_t i = 0; i < cloud->points.size(); ++i)
		std::cerr << "    " << cloud->points[i].x << " "
		<< cloud->points[i].y << " "
		<< cloud->points[i].z << std::endl;

	// Create a set of planar coefficients with X=Y=0,Z=1
	pcl::ModelCoefficients::Ptr coefficients(new pcl::ModelCoefficients());
	coefficients->values.resize(4);
	coefficients->values[0] = 1;
	coefficients->values[1] = 0;
	coefficients->values[2] = 0;
	coefficients->values[3] = 0;

	// Create the filtering object
	pcl::ProjectInliers<pcl::PointXYZ> proj;
	proj.setModelType(pcl::SACMODEL_PLANE);
	proj.setInputCloud(cloud);
	proj.setModelCoefficients(coefficients);
	proj.filter(*cloud_projected);

	std::cerr << "Cloud after projection: " << std::endl;
	for (size_t i = 0; i < cloud_projected->points.size(); ++i)
		std::cerr << "    " << cloud_projected->points[i].x << " "
		<< cloud_projected->points[i].y << " "
		<< cloud_projected->points[i].z << std::endl;
	getchar();
	return (0);
}

Make a slight modification to solve the crash problem when running the program.

The method to solve the program crash: add #include<stdio.h> to the header file and add getchar() before return;

Program running effect:

Project source download link: link: https://pan.baidu.com/s/1U7lmM_zGujZJ8_pWm1OpdA
Extraction code: y9dq

Among them, the PCL version is 1.9.1.

Reference blog post: 1,pcl point projected to a plane