Create a pcl::PointCloud::Ptr from a pcl::PointCloud

Question

I would like to know if this is possible. I have a function:

 pcl::PointCloud<pcl::PointXYZRGB> createPointCloud(std::Vector<Nodes> input)

which returns a point cloud. I would like to know if it is possible to take this point cloud, and make a pointer to a copy of it. pcl makes pointers to clouds like this:

pcl::PointCloud<pcl::PointXYZRGB>::Ptr cloudPTR(new pcl::PointCloud<pcl::PointXYZRGB>)

I have tried doing this:

pcl::PointCloud<pcl::PointXYZRGB>::Ptr cloudPTR(createPointCloud(nodeList))

This results in a pretty obvious error ie. createPointCloud doesnt return a pointer to a cloud.

I have also tried this:

pcl::PointCloud<pcl::PointXYZRGB>::Ptr cloudPTR = &createPointCloud(nodeList)

and this:

pcl::PointCloud<pcl::PointXYZRGB>::Ptr cloudPTR(&createPointCloud(nodeList))

And this results in the compile error: "taking address of temporary"

Is the only option to have the function return a pointer type or is there a way to do what i am asking?

EDIT:

Both of the below answers are correct, I have awarded Jonathon the correct tick as he got in first this time.

Underground

Answer 1

I know this is old and probably of no more use to OP, but other users might stumble upon it. I would suggest doing it as follows:

pcl::PointCloud<pcl::PointXYZRGB>::Ptr cloudPTR(new pcl::PointCloud<pcl::PointXYZRGB>);
*cloudPTR = createPointCloud(nodeList);

The reason Jonathon's answer is dangerous is that Pointcloud::Ptr is a typedef for a boost::shared_ptr which implies ownership of the object pointed to. In his answer, however, the object is actually a local variable meaning that it might go out of scope while there are still references to it and that shared_ptr will eventually call delete on it, which is undefined behavior.

Using make_shared() on the other hand deep copies the cloud. The program will work correctly, but if you didn't need the extra copy, it is far from optimal.

Postnatal

Which pcl header file needs to be included for this one? – Monometallism

Answer 2

Yes, use the makeShared() method.

Lengthways

he's not using std::shared_ptr. he's using a library specific RAII ptr class. std::make_shared() will not work with it. – Chromous

@johnathon Where did I mention std:: anything? Follow the link. – Lengthways

This might work as well, I have used @jonathon's answer though. – Underground

Ptr pcl::PointCloud< PointT >::makeShared is not make_shared(), ergo the reference to the std lib. – Chromous

@Ben, if you look at the code, it's just a convenience wrapper for Ptr (new PointCloud<PointT> (*this)) – Lengthways

I have tried using this method and it works a treat, @jonathon, you should remove your down vote. Both methods work. – Underground

@Lengthways appologuise for the down vote, it's been removed. Sorry, make_shared() which is what you had is straight out of the std lib, easy to get confused if your accustom to using it in code as much as i am though. – Chromous

@johnathon, OK, we can be friends now. ;-) – Lengthways

Very understandable @jonathon, thanks for both your input, they are both equally correct answers, who am i supposed to give the tick to? – Underground