PCL common operations

Copy point cloud

1. Add points to the new point cloud

   cloud->push_back(point);
   

2. Add by index

   template <typename PointT> 
   void copyPoints(const pcl::PointCloud<PointT> &cloud_in, const std::vector<int> &indices, pcl::PointCloud<PointT> &cloud_out)
   {
         
   	if (indices.size() == cloud_in.points.size())
   	{
         
   		cloud_out = cloud_in;
   		return;
   	}
   	cloud_out.points.resize(indices.size());
   	cloud_out.header = cloud_in.header;
   	cloud_out.width = static_cast<uint32_t>(indices.size());
   	cloud_out.height = 1;
   	cloud_out.is_dense = cloud_in.is_dense;
   	cloud_out.sensor_orientation_ = cloud_in.sensor_orientation_;
   	cloud_out.sensor_origin_ = cloud_in.sensor_origin_;
   	for (size_t i = 0; i < indices.size(); ++i)
   	{
         
   		cloud_out[i] = cloud_in[indices[i]];
   	}
   }