Re-Create Tf class using the Eigen3 linear algebra library

[jaybdub]

Extended the Eigen::Transform class, to include names between the reference frames. I called this class keytrack::NamedTransform.

For reference on Transform class see Eigen/src/Geometry/Transform.h. Look here for information on template inheritance, and here for information on constructor inheritance.

#ifndef KEYTRACK_TF_H
#define KEYTRACK_TF_H

#include <Eigen/Dense>

//using namespace Eigen;

namespace keytrack 
{

template<typename _Scalar, int _Dim, int _Mode, int _Options = Eigen::AutoAlign>
class NamedTransform: public Eigen::Transform<_Scalar, _Dim, _Mode, _Options>
{
  private:
    char* _a_name;
    char* _b_name;
  public:
    NamedTransform(const char a_name[], const char b_name[])
    {
      _a_name = (char*)a_name;
      _b_name = (char*)b_name;
    };
};

}
#endif

[jaybdub]

Switched to a new class that does not inherit Eigen::Transform, but rather contains it. The reason for doing this is that several of the return types for the methods inherited in NamedTransform, are of type Eigen::Transform. Thus, NamedTransform could not be directly assigned from functions that return Eigen::Transform, like Eigen::Transform::Identity().

The new classed is named TfLink as shown below.

#ifndef KEYTRACK_TF_H
#define KEYTRACK_TF_H

#include <Eigen/Dense>

//using namespace Eigen;

namespace keytrack 
{

class TfLink
{
  private:
    char* _a_name;
    char* _b_name;
    Eigen::Transform<float, 3, Eigen::Affine> _tf;
  public:
    TfLink(const char a_name[], const char b_name[])
    {
      _a_name = (char*)a_name;
      _b_name = (char*)b_name;
      _tf = Eigen::Transform<float, 3, Eigen::Affine>::Identity();
    };
    Eigen::Transform<float, 3, Eigen::Affine> tf()
    {
      return _tf;
    };
    char *a_name()
    {
      return _a_name;
    };
    char *b_name()
    {
      return _b_name;
    };
};

}
#endif

[jaybdub]

Now I'm thinking scrap the class type to remove unneeded complexity. A simple struct with two strings representing each reference frame that the tf describes, and a tf object.

//To compile:
//    g++ tf_eigen_test.cpp -I/home/john/eigen3

//#include "tf_eigen.h"
#include <Eigen/Dense>
#include <iostream>

using namespace Eigen;
using namespace std;

struct TfLink {
  char* a;
  char* b;
  Transform<float, 3, Affine> tf;
};
int main(){
  TfLink t;
  t.a = "camera";
  t.b = "robot";
  Vector3f axis;
  axis << 1,0,0;
  t.tf = AngleAxisf(2.0f,axis);
  cout << t.b << " as seen from " << t.a << endl;
  cout << t.tf.matrix() << endl;
  return 0;
}