Beginner question with CostFunctiontoFunctor

[Minh Vo]

Hi,

I am trying out the CostFunctionToFunctor api code on ceres-solver.org. Essentially, it is just this:

template<typename T>void RotateAndTranslatePoint(const T* rotation, const T* translation, const T* point, T* result)
{
     return;
}
class IntrinsicProjection : public SizedCostFunction<2, 5, 3>
{
     public:
        IntrinsicProjection(const double* observations);
        virtual bool Evaluate(double const* const* parameters, double* residuals, double** jacobians) const
        {
             residuals[0] = 0.0;
             jacobians[0][0] = 0.0;
             return true;
        }      
};

struct CameraProjection
{
         CameraProjection(double* observation)
         {
             intrinsic_projection_.reset(new CostFunctionToFunctor<2, 5, 3>(new IntrinsicProjection(observation)));
         }
        

         template <typename T> bool operator()(const T* rotation, const T* translation, const T* intrinsics, const T* point, T* residual) const
         {
              T transformed_point[3];
              RotateAndTranslatePoint(rotation, translation, point, transformed_point);
              return (*intrinsic_projection_)(intrinsics, transformed_point, residual);
         }

    private:
        ceres::internal::scoped_ptr<CostFunctionToFunctor<2, 5, 3> > intrinsic_projection_;
};

and it is being called by:

double dummy[2];
CostFunction* cost_function = new AutoDiffCostFunction<CameraProjection, 2, 3, 3, 3, 5>(new CameraProjection(dummy));
problem.AddResidualBlock(cost_function, NULL, dummy, dummy, dummy, dummy);

However, I keep getting the error when compliing:unresolved external symbol "public: __cdecl IntrinsicProjection::IntrinsicProjection(double const *).....

I must have missed something really basic. Can someone help?

Thanks,
Minh.

[Minh Vo]

I realized that if I don't call:

double dummy[2];
CostFunction* cost_function = new AutoDiffCostFunction<CameraProjection, 2, 3, 3, 3, 5>(new CameraProjection(dummy));
problem.AddResidualBlock(cost_function, NULL, dummy, dummy, dummy, dummy);

It can compile without error.

[Chris Sweeney]

Maybe I'm wrong here (c++ gurus feel free to chime in)... but you are trying to call a virtual function (run time decision) in a templated method which requires the call to be known at compile time. You can try to use something like a curiously recurring template pattern to get around this.

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[Sameer Agarwal]

also you cannot pass the same ptr to AddResidualBlock.

Sameer

[William Rucklidge]

It's something very simple; you'll hit yourself. You declared, but never defined, IntrinsicProjection's ctor.

        IntrinsicProjection(const double* observations);

should be

        IntrinsicProjection(const double* observations) {}

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[Minh Vo]

William: Ahh, it is really a silly error. That's for pointing that out!

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