PrincipalAxes< DIM, FT > Class Template Reference

Computes the principal axes for a set of 2D or 3D points. More...

#include <easy3d/core/principal_axes.h>

Public Member Functions
	PrincipalAxes ()
	Default constructor.
	~PrincipalAxes ()=default
	Destructor.
void	begin ()
	Begins adding points.
template<typename FT2>
void	add (const Vec< DIM, FT2 > &p, FT2 weight=FT2(1))
	Adds a point p with a weight.
void	end ()
	Ends adding points.
template<typename InputIterator>
void	add (InputIterator first, InputIterator last)
	Adds a set of points (internally it iteratively calls add()).
template<typename FT2>
Vec< DIM, FT2 >	center () const
	The weighted average of the points.
template<typename FT2>
Vec< DIM, FT2 >	axis (int i) const
	The i_th axis.
FT	eigen_value (int i) const
	The i_th eigenvalue.

Detailed Description

template<int DIM, typename FT = double>
class easy3d::PrincipalAxes< DIM, FT >

Computes the principal axes for a set of 2D or 3D points.

Template Parameters

DIM	The spatial dimension (must be either 2 or 3).
FT	The floating-point type used for computations (float or double). Defaults to 'double'.

Note

Using 'float' may lead to significant numerical errors, especially when processing a large number of points with varying coordinate scales, due to floating-point precision limitations.

Todo

Test support for 2D cases.

Member Function Documentation

add() [1/2]

template<int DIM, typename FT>

template<typename FT2>

void add	(	const Vec< DIM, FT2 > &	p,
		FT2	weight = FT2(1) )

Adds a point p with a weight.

This function supports different types of vectors, e.g. vec3, dvec3, and ivec3.

Template Parameters

FT2	The type of the point's coordinates.

Parameters

p	The point to be added.
weight	The weight of the point (default is 1).

add() [2/2]

template<int DIM, typename FT>

template<typename InputIterator>

void add	(	InputIterator	first,
		InputIterator	last )

Adds a set of points (internally it iteratively calls add()).

Template Parameters

InputIterator

The type of the input iterator.

Parameters

first	The beginning of the range of points.
last	The end of the range of points.

axis()

template<int DIM, typename FT>

template<typename FT2>

Vec< DIM, FT2 > axis

(

int

i

)

const

The i_th axis.

This function supports different types of vectors, e.g. vec3 and dvec. To call this function, use

normal = pca.axis<float>(2);

Template Parameters

FT2	The type of the floating-point number for the result.

Parameters

i	The index of the axis.

Returns

The i_th axis.

Note

The eigenvectors are sorted in accordance with eigenvalues stored in the descending order.

center()

template<int DIM, typename FT>

template<typename FT2>

Vec< DIM, FT2 > center

(

)

const

The weighted average of the points.

This function supports different types of vectors, e.g. vec3, dvec3. To call this function, use

center = pca.center<float>();

Template Parameters

FT2	The type of the floating-point number for the result.

Returns

The center of the points.

eigen_value()

template<int DIM, typename FT>

FT eigen_value

(

int

i

)

const

The i_th eigenvalue.

Parameters

i	The index of the eigenvalue.

Returns

The i_th eigenvalue.

Note

The eigenvalues are sorted in descending order.

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The documentation for this class was generated from the following file:

• G:/3_code/Easy3D/easy3d/core/principal_axes.h