Represents an incremental surface element (surfel) that tracks the sufficient statistics of a 3D point set for online surface estimation. More...

#include <lib/core/include/ufo/core/surfel.hpp>

Public Member Functions
constexpr	Surfel ()=default
	Default-constructs an empty surfel with no points.

template<std::input_iterator InputIt> requires std::constructible_from<Vec<3, float>, std::iter_value_t<InputIt>>
constexpr	Surfel (InputIt first, InputIt last)
	Constructs a surfel by adding all points in `[first, last)`.

template<std::ranges::input_range Points> requires std::constructible_from<Vec<3, float>, std::ranges::range_value_t<Points>>
constexpr	Surfel (Points const &points)
	Constructs a surfel by adding all points in `points`.

constexpr	Surfel (std::initializer_list< Vec< 3, float > > points)
	Constructs a surfel from a brace-enclosed list of `Vec3f` points.

constexpr	Surfel (Vec< 3, float > position, Mat< 3, 3, float > scatter={})
	Constructs a surfel from a single position and optional scatter matrix.

constexpr	Surfel (Vec< 3, float > sum, std::array< float, 6 > sum_squares, std::uint32_t num_points)
	Constructs a surfel directly from its raw sufficient statistics.

template<std::input_iterator InputIt> requires std::constructible_from<Vec<3, float>, std::iter_value_t<InputIt>>
constexpr void	add (InputIt first, InputIt last)
	Adds all points in `[first, last)` using a batch algorithm.

template<std::ranges::input_range Points> requires std::constructible_from<Vec<3, float>, std::ranges::range_value_t<Points>>
constexpr void	add (Points const &points)
	Adds all points in `points` using the batch algorithm.

constexpr void	add (std::initializer_list< Vec< 3, float > > points) noexcept
	Adds points from a brace-enclosed initializer list.

constexpr void	add (Surfel const &surfel) noexcept
	Merges another surfel into this one using a numerically stable parallel update rule.

constexpr void	add (Vec< 3, float > point) noexcept
	Adds a single 3D point using an online (Welford-like) update rule.

constexpr void	clear () noexcept
	Clears the surfel to an empty state (no points, zero statistics).

constexpr Mat< 3, 3, double >	covariance () const noexcept
	Returns the 3×3 sample covariance matrix.

constexpr bool	empty () const noexcept
	Returns true if no points have been added.

constexpr Vec< 3, double >	mean () const noexcept
	Returns the centroid (mean position) of all accumulated points.

constexpr Vec3d	normal () const noexcept
	Returns the surface normal as the eigenvector of the covariance matrix corresponding to the smallest eigenvalue.

constexpr std::uint32_t	numPoints () const noexcept
	Returns the number of points currently represented by this surfel.

constexpr Surfel &	operator+= (Surfel const &rhs) noexcept
	Merges another surfel into this one using a numerically stable parallel update rule.

constexpr Surfel &	operator+= (Vec< 3, float > rhs) noexcept
	Adds a single 3D point to this surfel using an online (Welford-like) update rule.

constexpr Surfel &	operator-= (Surfel const &rhs) noexcept
	Removes another surfel's contribution from this one using a numerically stable parallel update rule.

constexpr Surfel &	operator-= (Vec< 3, float > rhs) noexcept
	Removes a single 3D point from this surfel and returns `*this`.

constexpr bool	operator== (Surfel const &) const noexcept=default
	Equality comparison on all three stored statistics.

constexpr double	planarity () const noexcept
	Returns a planarity measure in [0, 1].

template<std::input_iterator InputIt> requires std::constructible_from<Vec<3, float>, std::iter_value_t<InputIt>>
constexpr void	remove (InputIt first, InputIt last)
	Removes all points in `[first, last)` using a batch algorithm.

template<std::ranges::input_range Points> requires std::constructible_from<Vec<3, float>, std::ranges::range_value_t<Points>>
constexpr void	remove (Points const &points)
	Removes all points in `points` using the batch algorithm.

constexpr void	remove (std::initializer_list< Vec< 3, float > > points) noexcept
	Removes all points in a brace-enclosed initializer list.

constexpr void	remove (Surfel const &surfel) noexcept
	Removes a previously-added surfel's contribution from this one.

constexpr void	remove (Vec< 3, float > point) noexcept
	Removes a single previously-added 3D point.

constexpr Vec< 3, float >	sum () const noexcept
	Returns the raw sum of all point positions.

constexpr std::array< float, 6 >	sumSquares () const noexcept
	Returns the raw scatter matrix upper triangle (Sxx, Sxy, Sxz, Syy, Syz, Szz).

Protected Member Functions
constexpr void	add (std::array< double, 6 > ss, Vec< 3, double > const &sum, std::uint32_t num_points)
	Helper to add a batch of points represented by their scatter statistics.

constexpr void	remove (std::array< double, 6 > ss, Vec< 3, double > const &sum, std::uint32_t num_points)
	Helper to remove a batch of points represented by their scatter statistics.

Static Protected Member Functions
static constexpr void	addOuter (std::array< double, 6 > &ss, Vec< 3, double > const &v, double scale) noexcept
	Helper to add the outer product correction term in the parallel update.

template<std::input_iterator InputIt> requires std::constructible_from<Vec<3, double>, std::iter_value_t<InputIt>>
static constexpr std::tuple< std::array< double, 6 >, Vec< 3, double >, std::uint32_t >	batchScatter (InputIt first, InputIt last) noexcept
	Computes scatter statistics `(ss, sum, n)` for a batch of points.

static constexpr std::array< double, 6 >	toDouble (std::array< float, 6 > const &arr) noexcept
	Converts an array of six `float`s to `double`s for intermediate calculations.

static constexpr void	toFloat (std::array< double, 6 > const &src, std::array< float, 6 > &dst) noexcept
	Converts an array of six `double`s to `float`s for storage.

Protected Attributes
std::uint32_t	num_points_ {}
	The number of contributing points. This is used to compute the mean and covariance from the raw sums. If this is zero, the surfel is considered empty and all statistics are zero. If this is one, the mean is equal to the single point and the covariance is undefined (but treated as zero). For two or more points, the mean and covariance are computed from the sums as described in the method documentation.

Vec< 3, float >	sum_ {}
	The sum of all point positions (a `Vec<3, float>`). This is the unnormalized sum; the mean can be obtained by dividing this sum by `numPoints()`, or by calling the `mean()` method directly.

std::array< float, 6 >	sum_squares_ {}
	Upper triangle of the scatter matrix S, stored as six `float`s in the order (Sxx, Sxy, Sxz, Syy, Syz, Szz). S accumulates the sum of squared deviations from the running mean; the sample covariance is S / (n − 1).

Friends
Surfel	operator+ (Surfel lhs, Surfel const &rhs) noexcept
	Returns a new surfel that is the merge of `lhs` and `rhs`.

Surfel	operator+ (Surfel lhs, Vec< 3, float > rhs) noexcept
	Returns a new surfel that is the result of adding point `rhs` to `lhs`.

Surfel	operator- (Surfel lhs, Surfel const &rhs) noexcept
	Returns a new surfel that is the result of removing `rhs` from `lhs`.

Surfel	operator- (Surfel lhs, Vec< 3, float > rhs) noexcept
	Returns a new surfel that is the result of removing point `rhs` from `lhs`.

Detailed Description

Represents an incremental surface element (surfel) that tracks the sufficient statistics of a 3D point set for online surface estimation.

A Surfel maintains three quantities that together allow the mean, full 3×3 covariance matrix, eigenvalues, eigenvectors, surface normal, and planarity of an arbitrary set of 3D points to be computed at any time, without storing the individual points:

sum_ — the sum of all point positions (a Vec<3, float>).
sum_squares_ — the upper triangle of the scatter matrix S, stored as six floats in the order (Sxx, Sxy, Sxz, Syy, Syz, Szz). S accumulates the sum of squared deviations from the running mean; the sample covariance is S / (n − 1).
num_points_ — the number of contributing points.

Points and entire surfels can be added or removed incrementally. The addition algorithm uses a numerically stable parallel / online update rule (analogous to Welford's algorithm for variance) so that the scatter matrix remains accurate as the point count grows. Batch addition uses a two-pass algorithm for improved numerical conditioning. All intermediate arithmetic is performed in double precision; results are stored as float.

Intended for use as a per-point or per-node attribute in surface reconstruction, mapping, or point cloud processing.

Derived quantities

Method	Description
`mean()`	Centroid of the point set.
`covariance()`	3×3 sample covariance matrix.
`normal()`	Unit surface normal = eigenvector of the smallest eigenvalue.
`planarity()`	Planarity measure in [0, 1]; 1 means perfectly planar.

Definition at line 96 of file surfel.hpp.

Constructor & Destructor Documentation

◆ Surfel() [1/5]

constexpr ufo::Surfel::Surfel	(	Vec< 3, float >	sum,
		std::array< float, 6 >	sum_squares,
		std::uint32_t	num_points
	)

inlineconstexpr

Constructs a surfel directly from its raw sufficient statistics.

Parameters

[in]	sum	Sum of all point positions.
[in]	sum_squares	Upper triangle of the scatter matrix (Sxx, Sxy, Sxz, Syy, Syz, Szz).
[in]	num_points	Number of points represented by this surfel.

Intended for deserialization or copying internal state.

Definition at line 119 of file surfel.hpp.

◆ Surfel() [2/5]

constexpr ufo::Surfel::Surfel	(	Vec< 3, float >	position,
		Mat< 3, 3, float >	scatter = `{}`
	)

inlineconstexpr

Constructs a surfel from a single position and optional scatter matrix.

Parameters

[in]	position	The point position.
[in]	scatter	Optional scatter matrix.

Definition at line 130 of file surfel.hpp.

◆ Surfel() [3/5]

template<std::input_iterator InputIt>
requires std::constructible_from<Vec<3, float>, std::iter_value_t<InputIt>>

constexpr ufo::Surfel::Surfel	(	InputIt	first,
		InputIt	last
	)

inlineconstexpr

Constructs a surfel by adding all points in [first, last).

Template Parameters

InputIt std::input_iterator whose value type is convertible to Vec3d.

Parameters

[in]	first	The beginning of the input range.
[in]	last	The end of the input range.

Definition at line 147 of file surfel.hpp.

◆ Surfel() [4/5]

template<std::ranges::input_range Points>
requires std::constructible_from<Vec<3, float>, std::ranges::range_value_t<Points>>

constexpr ufo::Surfel::Surfel ( Points const & points )

inlineconstexpr

Constructs a surfel by adding all points in points.

Template Parameters

Points std::ranges::input_range whose elements are convertible to Vec3d.

Parameters

[in] points The range of points to add.

Definition at line 160 of file surfel.hpp.

◆ Surfel() [5/5]

constexpr ufo::Surfel::Surfel ( std::initializer_list< Vec< 3, float > > points )

inlineconstexpr

Constructs a surfel from a brace-enclosed list of Vec3f points.

Parameters

[in] points The list of points to add.

Definition at line 168 of file surfel.hpp.

Member Function Documentation

◆ add() [1/6]

template<std::input_iterator InputIt>
requires std::constructible_from<Vec<3, float>, std::iter_value_t<InputIt>>

constexpr void ufo::Surfel::add	(	InputIt	first,
		InputIt	last
	)

inlineconstexpr

Adds all points in [first, last) using a batch algorithm.

Template Parameters

InputIt std::input_iterator whose value type is convertible to Vec3d.

Parameters

[in]	first	The beginning of the input range.
[in]	last	The end of the input range.

Accumulates raw second moments in a single pass, then applies a centering correction before merging with the parallel update rule.

Definition at line 297 of file surfel.hpp.

◆ add() [2/6]

template<std::ranges::input_range Points>
requires std::constructible_from<Vec<3, float>, std::ranges::range_value_t<Points>>

constexpr void ufo::Surfel::add ( Points const & points )

inlineconstexpr

Adds all points in points using the batch algorithm.

Template Parameters

Points std::ranges::input_range whose elements are convertible to Vec3d.

Parameters

[in] points The input range of points.

Definition at line 314 of file surfel.hpp.

◆ add() [3/6]

constexpr void ufo::Surfel::add	(	std::array< double, 6 >	ss,
		Vec< 3, double > const &	sum,
		std::uint32_t	num_points
	)

inlineconstexprprotected

Helper to add a batch of points represented by their scatter statistics.

Parameters

[in]	ss	The scatter matrix upper triangle of the batch to add.
[in]	sum	The sum of all point positions in the batch.
[in]	num_points	The number of points in the batch.

Definition at line 716 of file surfel.hpp.

◆ add() [4/6]

constexpr void ufo::Surfel::add ( std::initializer_list< Vec< 3, float > > points )

inlineconstexprnoexcept

Adds points from a brace-enclosed initializer list.

Parameters

[in] points The initializer list of points to add.

Definition at line 324 of file surfel.hpp.

◆ add() [5/6]

constexpr void ufo::Surfel::add ( Surfel const & surfel )

inlineconstexprnoexcept

Merges another surfel into this one using a numerically stable parallel update rule.

Parameters

surfel The surfel to merge in.

If this surfel is empty the other surfel's statistics are copied directly. Otherwise the scatter matrix is updated with the cross-term correction:

S += S_other + (n * n_other / (n + n_other)) * outer(mu - mu_other)

where mu and mu_other are the current means. This is the parallel variant of Welford's algorithm.

Definition at line 258 of file surfel.hpp.

◆ add() [6/6]

constexpr void ufo::Surfel::add ( Vec< 3, float > point )

inlineconstexprnoexcept

Adds a single 3D point using an online (Welford-like) update rule.

Parameters

point The point to incorporate.

If this surfel is empty the point initializes the sum and the scatter matrix remains zero. Otherwise the scatter matrix is updated with:

S += (n / (n + 1)) * outer(sum/n - point)

ufo::Surfel::sum

constexpr Vec< 3, float > sum() const noexcept

Returns the raw sum of all point positions.

Definition surfel.hpp:584

Definition at line 279 of file surfel.hpp.

◆ addOuter()

static constexpr void ufo::Surfel::addOuter	(	std::array< double, 6 > &	ss,
		Vec< 3, double > const &	v,
		double	scale
	)

inlinestaticconstexprprotectednoexcept

Helper to add the outer product correction term in the parallel update.

Parameters

[in,out]	ss	The scatter matrix upper triangle to update.
[in]	v	The vector used in the outer product correction.
[in]	scale	The scaling factor for the correction term.

Definition at line 645 of file surfel.hpp.

◆ batchScatter()

template<std::input_iterator InputIt>
requires std::constructible_from<Vec<3, double>, std::iter_value_t<InputIt>>

static constexpr std::tuple< std::array< double, 6 >, Vec< 3, double >, std::uint32_t > ufo::Surfel::batchScatter	(	InputIt	first,
		InputIt	last
	)

inlinestaticconstexprprotectednoexcept

Computes scatter statistics (ss, sum, n) for a batch of points.

Template Parameters

InputIt std::input_iterator whose value type is convertible to Vec3d.

Parameters

[in]	first	The beginning of the input range.
[in]	last	The end of the input range.

Returns

A tuple containing:

ss: An array of six doubles representing the upper triangle of the scatter matrix.
sum: The sum of all point positions as a Vec<3, double>.
n: The number of points in the batch as a std::uint32_t.

Accumulates raw second moments in a single pass, then subtracts the centering correction s[i]*s[j]/n to produce the scatter matrix.

Definition at line 676 of file surfel.hpp.

◆ clear()

constexpr void ufo::Surfel::clear ( )

inlineconstexprnoexcept

Clears the surfel to an empty state (no points, zero statistics).

After calling this method, empty() will return true and all statistics will be reset to zero.

Definition at line 473 of file surfel.hpp.

◆ covariance()

constexpr Mat< 3, 3, double > ufo::Surfel::covariance ( ) const

inlineconstexprnoexcept

Returns the 3×3 sample covariance matrix.

Returns: The sample covariance matrix of the accumulated points.

Computed as sum_squares_ / (n − 1) where n = numPoints(). The matrix is symmetric; both upper and lower triangles are filled.

Precondition: numPoints() >= 2.

Definition at line 511 of file surfel.hpp.

◆ empty()

constexpr bool ufo::Surfel::empty ( ) const

inlineconstexprnoexcept

Returns true if no points have been added.

Returns: True if empty.

Definition at line 187 of file surfel.hpp.

◆ mean()

constexpr Vec< 3, double > ufo::Surfel::mean ( ) const

inlineconstexprnoexcept

Returns the centroid (mean position) of all accumulated points.

Returns: The mean position of the points in the surfel.

Precondition: !empty() - behavior is undefined if the surfel contains no points.

Definition at line 491 of file surfel.hpp.

◆ normal()

constexpr Vec3d ufo::Surfel::normal ( ) const

inlineconstexprnoexcept

Returns the surface normal as the eigenvector of the covariance matrix corresponding to the smallest eigenvalue.

Returns: Unit vector normal to the local surface.

Precondition: numPoints() >= 2.

Definition at line 532 of file surfel.hpp.

◆ numPoints()

constexpr std::uint32_t ufo::Surfel::numPoints ( ) const

inlineconstexprnoexcept

Returns the number of points currently represented by this surfel.

Returns: The number of points in the surfel.

Definition at line 569 of file surfel.hpp.

◆ operator+=() [1/2]

constexpr Surfel & ufo::Surfel::operator+= ( Surfel const & rhs )

inlineconstexprnoexcept

Merges another surfel into this one using a numerically stable parallel update rule.

Parameters

[in] rhs The surfel to merge in.

Returns: Reference to *this after merging.

Definition at line 200 of file surfel.hpp.

◆ operator+=() [2/2]

constexpr Surfel & ufo::Surfel::operator+= ( Vec< 3, float > rhs )

inlineconstexprnoexcept

Adds a single 3D point to this surfel using an online (Welford-like) update rule.

Parameters

[in] rhs The point to add.

Returns: Reference to *this after adding the point.

Definition at line 213 of file surfel.hpp.

◆ operator-=() [1/2]

constexpr Surfel & ufo::Surfel::operator-= ( Surfel const & rhs )

inlineconstexprnoexcept

Removes another surfel's contribution from this one using a numerically stable parallel update rule.

Parameters

[in] rhs The surfel to remove.

Returns: Reference to *this after removal.

Definition at line 340 of file surfel.hpp.

◆ operator-=() [2/2]

constexpr Surfel & ufo::Surfel::operator-= ( Vec< 3, float > rhs )

inlineconstexprnoexcept

Removes a single 3D point from this surfel and returns *this.

Parameters

[in] rhs The point to remove.

Returns: Reference to *this after removal.

Definition at line 352 of file surfel.hpp.

◆ operator==()

constexpr bool ufo::Surfel::operator== ( Surfel const & ) const

constexprdefaultnoexcept

Equality comparison on all three stored statistics.

Returns: True if all statistics are equal, false otherwise.

◆ planarity()

constexpr double ufo::Surfel::planarity ( ) const

inlineconstexprnoexcept

Returns a planarity measure in [0, 1].

Returns: Planarity measure in [0, 1], where 1 indicates a perfectly planar arrangement and 0 indicates an isotropic distribution.

Computed as 2 * (e1 - e0) / (e0 + e1 + e2) where e0 <= e1 <= e2 are the sorted eigenvalues of the covariance matrix. A value of 1 indicates a perfectly planar arrangement; 0 indicates an isotropic distribution.

Precondition: numPoints() >= 2.

Definition at line 554 of file surfel.hpp.

◆ remove() [1/6]

template<std::input_iterator InputIt>
requires std::constructible_from<Vec<3, float>, std::iter_value_t<InputIt>>

constexpr void ufo::Surfel::remove	(	InputIt	first,
		InputIt	last
	)

inlineconstexpr

Removes all points in [first, last) using a batch algorithm.

Template Parameters

InputIt std::input_iterator whose value type is convertible to Vec3d.

Parameters

[in]	first	The beginning of the input range.
[in]	last	The end of the input range.

Computes the batch's scatter statistics then reverses the parallel merge.

Definition at line 430 of file surfel.hpp.

◆ remove() [2/6]

template<std::ranges::input_range Points>
requires std::constructible_from<Vec<3, float>, std::ranges::range_value_t<Points>>

constexpr void ufo::Surfel::remove ( Points const & points )

inlineconstexpr

Removes all points in points using the batch algorithm.

Template Parameters

Points std::ranges::input_range whose elements are convertible to Vec3d.

Parameters

[in] points The input range of points.

Definition at line 447 of file surfel.hpp.

◆ remove() [3/6]

constexpr void ufo::Surfel::remove	(	std::array< double, 6 >	ss,
		Vec< 3, double > const &	sum,
		std::uint32_t	num_points
	)

inlineconstexprprotected

Helper to remove a batch of points represented by their scatter statistics.

Parameters

[in]	ss	The scatter matrix upper triangle of the batch to remove.
[in]	sum	The sum of all point positions in the batch.
[in]	num_points	The number of points in the batch.

Definition at line 746 of file surfel.hpp.

◆ remove() [4/6]

constexpr void ufo::Surfel::remove ( std::initializer_list< Vec< 3, float > > points )

inlineconstexprnoexcept

Removes all points in a brace-enclosed initializer list.

Parameters

[in] points The input range of points.

Definition at line 457 of file surfel.hpp.

◆ remove() [5/6]

constexpr void ufo::Surfel::remove ( Surfel const & surfel )

inlineconstexprnoexcept

Removes a previously-added surfel's contribution from this one.

Parameters

[in] surfel The surfel to subtract.

If surfel contains at least as many points as this surfel, the surfel is cleared entirely. Otherwise the scatter matrix is updated by reversing the parallel merge formula:

S -= S_other + (n_other * n_result / (n_other + n_result)) * outer(mu_result -

mu_other)

Definition at line 396 of file surfel.hpp.

◆ remove() [6/6]

constexpr void ufo::Surfel::remove ( Vec< 3, float > point )

inlineconstexprnoexcept

Removes a single previously-added 3D point.

Parameters

[in] point The point to remove.

Clears the surfel if it is empty or contains exactly one point. Otherwise reverses the online update rule used in add(Vec3f):

S -= (n / (n - 1)) * outer(sum/n - point)

Definition at line 413 of file surfel.hpp.

◆ sum()

constexpr Vec< 3, float > ufo::Surfel::sum ( ) const

inlineconstexprnoexcept

Returns the raw sum of all point positions.

Returns: The sum of all point positions.

This is the unnormalized sum of all point positions. The mean can be obtained by dividing this sum by numPoints(), or by calling the mean() method directly.

Definition at line 584 of file surfel.hpp.

◆ sumSquares()

constexpr std::array< float, 6 > ufo::Surfel::sumSquares ( ) const

inlineconstexprnoexcept

Returns the raw scatter matrix upper triangle (Sxx, Sxy, Sxz, Syy, Syz, Szz).

Returns: The upper triangle of the scatter matrix.

Dividing by (numPoints() − 1) yields the sample covariance upper triangle.

Definition at line 599 of file surfel.hpp.

◆ toDouble()

static constexpr std::array< double, 6 > ufo::Surfel::toDouble ( std::array< float, 6 > const & arr )

inlinestaticconstexprprotectednoexcept

Converts an array of six floats to doubles for intermediate calculations.

Parameters

[in] arr The input array of six floats representing the upper triangle of the scatter matrix.

Returns: An array of six doubles converted from the input floats.

Definition at line 616 of file surfel.hpp.

◆ toFloat()

static constexpr void ufo::Surfel::toFloat	(	std::array< double, 6 > const &	src,
		std::array< float, 6 > &	dst
	)

inlinestaticconstexprprotectednoexcept

Converts an array of six doubles to floats for storage.

Parameters

[in]	src	The input array of six `double`s.
[out]	dst	The output array of six `float`s.

Definition at line 631 of file surfel.hpp.

Friends And Related Symbol Documentation

◆ operator+ [1/2]

Surfel operator+	(	Surfel	lhs,
		Surfel const &	rhs
	)

friend

Returns a new surfel that is the merge of lhs and rhs.

Parameters

[in]	lhs	The left-hand side surfel.
[in]	rhs	The right-hand side surfel.

Returns: Surfel The merged surfel.

Definition at line 226 of file surfel.hpp.

◆ operator+ [2/2]

Surfel operator+	(	Surfel	lhs,
		Vec< 3, float >	rhs
	)

friend

Returns a new surfel that is the result of adding point rhs to lhs.

Parameters

[in]	lhs	The left-hand side surfel.
[in]	rhs	The point to add.

Returns: Surfel The resulting surfel.

Definition at line 238 of file surfel.hpp.

◆ operator- [1/2]

Surfel operator-	(	Surfel	lhs,
		Surfel const &	rhs
	)

friend

Returns a new surfel that is the result of removing rhs from lhs.

Parameters

[in]	lhs	The left-hand side surfel.
[in]	rhs	The surfel to remove.

Returns: A new surfel with rhs removed from lhs.

Definition at line 365 of file surfel.hpp.

◆ operator- [2/2]

Surfel operator-	(	Surfel	lhs,
		Vec< 3, float >	rhs
	)

friend

Returns a new surfel that is the result of removing point rhs from lhs.

Parameters

[in]	lhs	The left-hand side surfel.
[in]	rhs	The point to remove.

Returns: A new surfel with point rhs removed from lhs.

Definition at line 377 of file surfel.hpp.

Member Data Documentation

◆ num_points_

std::uint32_t ufo::Surfel::num_points_ {}

protected

The number of contributing points. This is used to compute the mean and covariance from the raw sums. If this is zero, the surfel is considered empty and all statistics are zero. If this is one, the mean is equal to the single point and the covariance is undefined (but treated as zero). For two or more points, the mean and covariance are computed from the sums as described in the method documentation.

Definition at line 792 of file surfel.hpp.

◆ sum_

Vec<3, float> ufo::Surfel::sum_ {}

protected

The sum of all point positions (a Vec<3, float>). This is the unnormalized sum; the mean can be obtained by dividing this sum by numPoints(), or by calling the mean() method directly.

Definition at line 783 of file surfel.hpp.

◆ sum_squares_

std::array<float, 6> ufo::Surfel::sum_squares_ {}

protected

Upper triangle of the scatter matrix S, stored as six floats in the order (Sxx, Sxy, Sxz, Syy, Syz, Szz). S accumulates the sum of squared deviations from the running mean; the sample covariance is S / (n − 1).

Definition at line 776 of file surfel.hpp.

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

lib/core/include/ufo/core/surfel.hpp

Public Member Functions

Protected Member Functions

Static Protected Member Functions

Protected Attributes

Friends

Detailed Description

Constructor & Destructor Documentation

◆ Surfel() [1/5]

◆ Surfel() [2/5]

◆ Surfel() [3/5]

◆ Surfel() [4/5]

◆ Surfel() [5/5]

Member Function Documentation

◆ add() [1/6]

◆ add() [2/6]

◆ add() [3/6]

◆ add() [4/6]

◆ add() [5/6]

◆ add() [6/6]

◆ addOuter()

◆ batchScatter()

◆ clear()

◆ covariance()

◆ empty()

◆ mean()

◆ normal()

◆ numPoints()

◆ operator+=() [1/2]

◆ operator+=() [2/2]

◆ operator-=() [1/2]

◆ operator-=() [2/2]

◆ operator==()

◆ planarity()

◆ remove() [1/6]

◆ remove() [2/6]

◆ remove() [3/6]

◆ remove() [4/6]

◆ remove() [5/6]

◆ remove() [6/6]

◆ sum()

◆ sumSquares()

◆ toDouble()

◆ toFloat()

Friends And Related Symbol Documentation

◆ operator+ [1/2]

◆ operator+ [2/2]

◆ operator- [1/2]

◆ operator- [2/2]

Member Data Documentation

◆ num_points_

◆ sum_

◆ sum_squares_