C++ 从 pcl::PointCloud 创建 pcl::PointCloud::Ptr
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/10644429/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
Create a pcl::PointCloud::Ptr from a pcl::PointCloud
提问by Fantastic Mr Fox
I would like to know if this is possible. I have a function:
我想知道这是否可能。我有一个功能：
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:
它返回一个点云。我想知道是否可以采用这个点云，并制作一个指向它的副本的指针。pcl 像这样指向云：
pcl::PointCloud<pcl::PointXYZRGB>::Ptr cloudPTR(new pcl::PointCloud<pcl::PointXYZRGB>)
I have tried doing this:
我试过这样做：
pcl::PointCloud<pcl::PointXYZRGB>::Ptr cloudPTR(createPointCloud(nodeList))
This results in a pretty obvious error ie. createPointCloud doesnt return a pointer to a cloud.
这会导致一个非常明显的错误，即。createPointCloud 不返回指向云的指针。
I have also tried this:
我也试过这个：
pcl::PointCloud<pcl::PointXYZRGB>::Ptr cloudPTR = &createPointCloud(nodeList)
and this:
和这个：
pcl::PointCloud<pcl::PointXYZRGB>::Ptr cloudPTR(&createPointCloud(nodeList))
And this results in the compile error: "taking address of temporary"
这导致编译错误：“获取临时地址”
Is the only option to have the function return a pointer type or is there a way to do what i am asking?
是让函数返回指针类型的唯一选择还是有办法做到我所要求的？
EDIT:
编辑：
Both of the below answers are correct, I have awarded Jonathon the correct tick as he got in first this time.
以下两个答案都是正确的，我已经给了乔纳森正确的勾号，因为他这次是第一个进来的。
采纳答案by patatahooligan
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:
我知道这是旧的，可能不再用于 OP，但其他用户可能会偶然发现它。我建议这样做：
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.
Jonathon 的答案很危险的原因是 Pointcloud::Ptr 是 boost::shared_ptr 的 typedef，这意味着指向的对象的所有权。然而，在他的回答中，该对象实际上是一个局部变量，这意味着它可能会超出范围，而仍然有对它的引用，并且 shared_ptr 最终会对其调用 delete，这是未定义的行为。
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.
另一方面，使用 make_shared() 深度复制云。该程序将正常运行，但如果您不需要额外的副本，则远非最佳。
回答by ergosys
Yes, use the makeShared()method.
是的，使用makeShared()方法。
