conversion of sensor_msgs::PointCloud2ConstPtr

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Just a small addition to this answer. That's because the first (PointCloud2ConstPtr) is a pointer (Ptr), hence the *

Thanks guys! Is this copying the pointcloud, which allocates new memory? If yes, is there another way to do it?

This might be a really 'new' comment. ConstPtr types are typedef(s) for boost::shared_ptr (shared pointer) to manage the life-cycle of pointer-memories. There won't be any new memory allocated but reuse of an already allocated memory.