Helper functions

Functions
template<class It >
void	tag::getProjectiveHomography (It begin, It end, TooN::Matrix< 3 > &H)
template<class It >
TooN::Matrix< 3 >	tag::getProjectiveHomography (It begin, It end)
int	tag::find_quartic_real_roots (double B, double C, double D, double E, double r[])

Detailed Description

This group contains various helper functions used throughout tag. Most functions come in pairs where one version writes the result to a passed in parameter and the second uses the first to return a new result to the caller.

Function Documentation

int tag::find_quartic_real_roots	(	double	B,
		double	C,
		double	D,
		double	E,
		double	r[]
	)

A function to find the real roots of a quartic polynomial x^4 + Bx^3 + Cx^2 + Dx + E. It efficiently implements the quartic formula as given by Cardano, Harriot, et al. The precision of the resulting roots depends on the nature of the coefficients. Sufficient precision can be ensured by refining the resulting roots using Newton's method.

Parameters

[in]	B	the coefficient of the cubic term
[in]	C	the coefficient of the quadratic term
[in]	D	the coefficient of the linear term
[in]	E	the coefficient of the constant term
[out]	r	an array in which 0, 2, or 4 real roots will be stored

Returns

the number of real roots

References tag::depressed_cubic_real_roots().

Referenced by tag::three_point_pose().

template<class It >

void tag::getProjectiveHomography	(	It	begin,
		It	end,
		TooN::Matrix< 3 > &	H
	)

estimates a 2D homography between two sets of correspondences. The observations passed (via iterators) to the estimate method must allow:

TooN::Vector<2> a = first_point(*it); // default value is "(*it).first"
TooN::Vector<2> b = second_point(*it); // default value is "(*it).second"
double R = noise(*it); // default value is "1.0"

At least 4 correspondences are needed. The resulting H returned satisfies b = H a, where a, b are in homogenous coordinates.

Parameters

	begin	iterator pointing to the begin of the sequence
	end	iterator to the end of the sequence (after the last element)
[out]	H	resulting homography

References tag::first_point(), tag::noise(), and tag::second_point().

Referenced by tag::Homography::estimate(), and tag::getProjectiveHomography().

template<class It >

TooN::Matrix<3> tag::getProjectiveHomography	(	It	begin,
		It	end
	)

return version of the 2D homography estimation between two sets of correspondences. The observations passed (via iterators) to the estimate method must allow:

TooN::Vector<2> a = first_point(*it); // default value is "(*it).first"
TooN::Vector<2> b = second_point(*it); // default value is "(*it).second"
double R = noise(*it); // default value is "1.0"

At least 4 correspondences are needed. The resulting H returned satisfies b = H a, where a, b are in homogenous coordinates.

Parameters

begin	iterator pointing to the begin of the sequence
end	iterator to the end of the sequence (after the last element)

Returns

resulting homography

References tag::getProjectiveHomography().