Random sampling search for minimization of a robust objective function. More...

#include <rrel_ran_sam_search.h>

Inheritance diagram for rrel_ran_sam_search:

Public Member Functions
	rrel_ran_sam_search ()
	Constructor using a non-deterministic random-sampling seed.
	rrel_ran_sam_search (int seed)
	Constructor using a given random-sampling seed.
virtual	~rrel_ran_sam_search ()
void	set_gen_all_samples ()
	Indicate that all possible minimal subset samples should be tried.
void	set_sampling_params (double max_outlier_frac=0.5, double desired_prob_good=0.99, unsigned int max_populations_expected=1, unsigned int min_samples=0)
	Set the parameters for random sampling.
virtual bool	estimate (const rrel_estimation_problem problem, const rrel_objective obj_fcn)
	Estimation for an "ordinary" estimation problem.
double	scale () const
	Get the scale estimate.
const vnl_vector< double > &	params () const
	Get the parameter estimate.
const vcl_vector< int > &	index () const
	Get the indices of best data sample.
const vcl_vector< double > &	residuals () const
	Get the residuals for best sample.
double	cost () const
	Get the cost for best sample returned by rrel_objective function.
int	samples_tested () const
	Get the number of samples tested in during estimation.
void	print_params () const
	Print the sampling parameters. Used for debugging.
void	set_trace_level (int level)
Protected Member Functions
virtual void	calc_num_samples (const rrel_estimation_problem *problem)
	Calculate number of samples --- non-unique matching estimation problems.
virtual void	next_sample (unsigned int taken, unsigned int num_points, vcl_vector< int > &sample, unsigned int points_per_sample)
	Determine the next random sample, filling in the "sample" vector.
Protected Attributes
double	max_outlier_frac_
double	desired_prob_good_
unsigned int	max_populations_expected_
unsigned int	min_samples_
bool	generate_all_
vnl_random *	generator_
	Random number generator.
bool	own_generator_
vnl_vector< double >	params_
double	scale_
vcl_vector< int >	indices_
vcl_vector< double >	residuals_
double	min_obj_
unsigned int	samples_to_take_
int	trace_level_
Private Member Functions
void	trace_sample (const vcl_vector< int > &point_indices) const
void	trace_residuals (const vcl_vector< double > &residuals) const

Detailed Description

Random sampling search for minimization of a robust objective function.

The code organization follows the design of the rrel library where there is a separation between objective function (M-estimator, LMS, etc), search technique, and estimation problem. See discussion in rrel_estimation_problem.

The algorithm implemented was discovered independently by Fischler and Bolles in the CACM RANSAC paper from 1981 and Rousseeuw in a Journal of the American Statistical Association paper from 1984. The implementation follows Rousseeuw's approach by not allowing the short-circuiting of RANSAC, which can cause incorrect results for a large number of outliers.

The number of samples taken is computed to accommodate the possibility of more than one population in the data, as described in Stewart, PAMI 1995. It is a relatively straightforward generalization of the ordinary method for calculating the number of samples.

Using this class requires calling set_sampling_params (or set_gen_all_samples, which can be quite expensive), and then calling estimate(). Results may be obtained through the functions params() and scale().

Definition at line 40 of file rrel_ran_sam_search.h.

Constructor & Destructor Documentation

rrel_ran_sam_search::rrel_ran_sam_search ( )

Constructor using a non-deterministic random-sampling seed.

Definition at line 20 of file rrel_ran_sam_search.cxx.

rrel_ran_sam_search::rrel_ran_sam_search ( int seed )

Constructor using a given random-sampling seed.

Definition at line 31 of file rrel_ran_sam_search.cxx.

rrel_ran_sam_search::~rrel_ran_sam_search ( ) [virtual]

Definition at line 43 of file rrel_ran_sam_search.cxx.

Member Function Documentation

void rrel_ran_sam_search::calc_num_samples ( const rrel_estimation_problem * problem ) [protected, virtual]

Calculate number of samples --- non-unique matching estimation problems.

Definition at line 186 of file rrel_ran_sam_search.cxx.

double rrel_ran_sam_search::cost ( ) const [inline]

Get the cost for best sample returned by rrel_objective function.

Definition at line 90 of file rrel_ran_sam_search.h.

bool rrel_ran_sam_search::estimate	(	const rrel_estimation_problem *	problem,
		const rrel_objective *	obj_fcn
	)		`[virtual]`

Estimation for an "ordinary" estimation problem.

Reimplemented in rrel_wgted_ran_sam_search.

Definition at line 75 of file rrel_ran_sam_search.cxx.

const vcl_vector<int>& rrel_ran_sam_search::index ( ) const [inline]

Get the indices of best data sample.

Definition at line 84 of file rrel_ran_sam_search.h.

void rrel_ran_sam_search::next_sample	(	unsigned int	taken,
		unsigned int	num_points,
		vcl_vector< int > &	sample,
		unsigned int	points_per_sample
	)		`[protected, virtual]`

Determine the next random sample, filling in the "sample" vector.

Reimplemented in rrel_wgted_ran_sam_search.

Definition at line 220 of file rrel_ran_sam_search.cxx.

const vnl_vector<double>& rrel_ran_sam_search::params ( ) const [inline]

Get the parameter estimate.

Definition at line 81 of file rrel_ran_sam_search.h.

void rrel_ran_sam_search::print_params ( ) const

Print the sampling parameters. Used for debugging.

Definition at line 282 of file rrel_ran_sam_search.cxx.

const vcl_vector<double>& rrel_ran_sam_search::residuals ( ) const [inline]

Get the residuals for best sample.

Definition at line 87 of file rrel_ran_sam_search.h.

int rrel_ran_sam_search::samples_tested ( ) const [inline]

Get the number of samples tested in during estimation.

Definition at line 93 of file rrel_ran_sam_search.h.

double rrel_ran_sam_search::scale ( ) const [inline]

Get the scale estimate.

Definition at line 78 of file rrel_ran_sam_search.h.

void rrel_ran_sam_search::set_gen_all_samples ( )

Indicate that all possible minimal subset samples should be tried.

Definition at line 52 of file rrel_ran_sam_search.cxx.

void rrel_ran_sam_search::set_sampling_params	(	double	max_outlier_frac = `0.5`,
		double	desired_prob_good = `0.99`,
		unsigned int	max_populations_expected = `1`,
		unsigned int	min_samples = `0`
	)