boost serialization of opencv types

Question

I have the following members of a class (v1 & v2) that I need to serialize to file using boost serialization and then read back in at a later stage.

The first one is a vector of a vector of an open cv type Point3f, and the other is a vector of a vector of type opencv Vec6f as can be seen below.

#include this in the class header 
#include <boost/serialization/vector.hpp>
#include <boost/archive/text_oarchive.hpp>
#include <boost/archive/text_iarchive.hpp>
#include <boost/archive/binary_oarchive.hpp>
#include <boost/archive/binary_iarchive.hpp>

//private member variables
std::vector< std::vector<cv::Point3f> > v1;
std::vector< std::vector<cv::Vec6f> > v2;


// Allow serialization to access non-public data members.
friend class boost::serialization::access;

template<class Archive>
  void serialize(Archive & ar, const unsigned int version)
  {
    ar & v1;
    ar & v2;
   
  }

I have this defined at the top of my header file so that it can understand how to serialize the point3f and Vec6f types. Is this correct way? I can save the data but when I go to read it all back in, it has the right number of array of vectors but each entry has values of 0. What am I doing wrong? I presume it's do do with the serialize functions themselves but not sure.

namespace boost {
namespace serialization {

template<class Archive>
void serialize(Archive &ar, cv::Point3_<float> pt3, const unsigned int)
{
    ar & pt3.x;
    ar & pt3.y;
    ar & pt3.z;
}

template<class Archive>
void serialize(Archive &ar, cv::Vec<float,6> vec6, const unsigned int)
{
    ar & vec6[0];
    ar & vec6[1];
    ar & vec6[2];
    ar & vec6[3];
    ar & vec6[4];
    ar & vec6[5];
}

}
}

I use this code to write

std::ofstream ofs1("v1test.bin"); 
boost::archive::binary_oarchive oa1(ofs1);
oa1 << v1;

and I use this code to read

std::ifstream ifs1("v1test.bin");
boost::archive::binary_iarchive ia1(ifs1);        
std::vector< std::vector<cv::Point3f> > test;
ia1 >> test; // this contains the right structure but all values are 0

Any help or points in the right direction would be appreciated

Answer 1

I figured it out - stupid mistake - forgot to add a reference to the variables when passing them in - should be this

namespace boost {
namespace serialization {

template<class Archive>
void serialize(Archive &ar, cv::Point3_<float> &pt3, const unsigned int)
{
    ar & pt3.x;
    ar & pt3.y;
    ar & pt3.z;
}

template<class Archive>
void serialize(Archive &ar, cv::Vec<float,6> &vec6, const unsigned int)
{
    ar & vec6[0];
    ar & vec6[1];
    ar & vec6[2];
    ar & vec6[3];
    ar & vec6[4];
    ar & vec6[5];
}

}
}