Represents a node in RTAB-Map's pose graph. More...

#include <Signature.h>

Public Member Functions
	Signature ()
	Default constructor.

	Signature (int id, int mapId=-1, int weight=0, double stamp=0.0, const std::string &label=std::string(), const Transform &pose=Transform(), const Transform &groundTruthPose=Transform(), const SensorData &sensorData=SensorData())
	Constructor with explicit parameters.

	Signature (const SensorData &data)
	Constructor from sensor data.

virtual	~Signature ()
	Virtual destructor.

float	compareTo (const Signature &signature) const
	Compares this signature to another signature.

bool	isBadSignature () const
	Checks if this signature is considered "bad".

int	id () const
	Returns the signature ID.

int	mapId () const
	Returns the map ID.

void	setWeight (int weight)
	Sets the weight/importance of this signature.

int	getWeight () const
	Returns the weight/importance of this signature.

void	setLabel (const std::string &label)
	Sets a label/name for this signature.

const std::string &	getLabel () const
	Returns the label/name of this signature.

double	getStamp () const
	Returns the timestamp of this signature.

void	addLinks (const std::list< Link > &links)
	Adds multiple links from a list.

void	addLinks (const std::map< int, Link > &links)
	Adds multiple links from a map.

void	addLink (const Link &link)
	Adds a single link to this signature.

bool	hasLink (int idTo, Link::Type type=Link::kUndef) const
	Checks if this signature has a link to a target signature.

void	changeLinkIds (int idFrom, int idTo)
	Changes all link target IDs from one value to another.

void	removeLinks (bool keepSelfReferringLinks=false)
	Removes all links from this signature.

void	removeLink (int idTo)
	Removes a specific link to a target signature.

void	removeVirtualLinks ()
	Removes all virtual links from this signature.

void	addLandmark (const Link &landmark)
	Adds a landmark observation to this signature.

const std::map< int, Link > &	getLandmarks () const
	Returns all landmark observations.

void	removeLandmarks ()
	Removes all landmark observations.

void	removeLandmark (int landmarkId)
	Removes a specific landmark observation.

void	setSaved (bool saved)
	Sets whether this signature has been saved to the database.

void	setModified (bool modified)
	Sets the modification flag for this signature.

const std::multimap< int, Link > &	getLinks () const
	Returns all links from this signature.

bool	isSaved () const
	Checks if this signature has been saved to the database.

bool	isModified () const
	Checks if this signature has been modified.

bool	isLinksModified () const
	Checks if the links have been modified.

void	removeAllWords ()
	Removes all visual words from this signature.

void	changeWordsRef (int oldWordId, int activeWordId)
	Changes visual word references from one word ID to another.

void	setWords (const std::multimap< int, int > &words, const std::vector< cv::KeyPoint > &keypoints, const std::vector< cv::Point3f > &words3, const cv::Mat &descriptors)
	Sets all visual words for this signature.

bool	isEnabled () const
	Checks if this signature is enabled.

void	setEnabled (bool enabled)
	Sets whether this signature is enabled.

const std::multimap< int, int > &	getWords () const
	Returns the visual words map.

const std::vector< cv::KeyPoint > &	getWordsKpts () const
	Returns the keypoints associated with visual words.

int	getInvalidWordsCount () const
	Returns the count of invalid visual words.

const std::map< int, int > &	getWordsChanged () const
	Returns the word ID change mapping.

const cv::Mat &	getWordsDescriptors () const
	Returns the feature descriptors for visual words.

void	setWordsDescriptors (const cv::Mat &descriptors)
	Sets the feature descriptors for visual words.

void	setPose (const Transform &pose)
	Sets the pose of this signature.

void	setGroundTruthPose (const Transform &pose)
	Sets the ground truth pose for evaluation.

void	setVelocity (float vx, float vy, float vz, float vroll, float vpitch, float vyaw)
	Sets the velocity of this signature.

const std::vector< cv::Point3f > &	getWords3 () const
	Returns the 3D points of visual words.

const Transform &	getPose () const
	Returns the pose of this signature.

cv::Mat	getPoseCovariance () const
	Gets the pose covariance matrix.

const Transform &	getGroundTruthPose () const
	Returns the ground truth pose.

const std::vector< float > &	getVelocity () const
	Returns the velocity of this signature.

SensorData &	sensorData ()
	Returns mutable access to the sensor data.

const SensorData &	sensorData () const
	Returns const access to the sensor data.

unsigned long	getMemoryUsed (bool withSensorData=true) const
	Computes the memory usage of this signature.

Detailed Description

Represents a node in RTAB-Map's pose graph.

The Signature class is a fundamental building block of RTAB-Map's graph-based mapping system. Each signature represents a unique location or pose in the map and contains:

Visual words: Bag-of-words representation using visual features (keypoints, descriptors, 3D points) for place recognition
Links: Connections to other signatures (neighbors, loop closures, landmarks)
Pose information: Current pose, ground truth pose, velocity
Sensor data: Images, depth, laser scans, etc. captured at this location
Metadata: ID, map ID, timestamp, label, weight, modification flags

Signatures are used for:

Place recognition: Comparing signatures to detect loop closures
Graph construction: Building the pose graph through links
Localization: Matching current observations to stored signatures
Mapping: Storing sensor data, visual features and local occupancy grid for each location

The class tracks modification state to optimize database updates, and provides methods to manage visual words, links, landmarks, and pose information.

Note: Signatures are typically managed by the Memory class, which handles storage, retrieval, and graph operations.

See also: Link; SensorData; Memory

Definition at line 83 of file Signature.h.

Constructor & Destructor Documentation

◆ Signature() [1/3]

rtabmap::Signature::Signature ( )

Default constructor.

Creates an empty signature with invalid ID (0), default map ID (-1), and all fields initialized to default values.

◆ Signature() [2/3]

rtabmap::Signature::Signature	(	int	id,
		int	mapId = `-1`,
		int	weight = `0`,
		double	stamp = `0.0`,
		const std::string &	label = `std::string()`,
		const Transform &	pose = `Transform()`,
		const Transform &	groundTruthPose = `Transform()`,
		const SensorData &	sensorData = `SensorData()`
	)

Constructor with explicit parameters.

Creates a signature with the specified parameters. The sensor data ID will be automatically set to match the signature ID if not already set.

Parameters

id	Unique signature ID (must be > 0 for valid signature)
mapId	Map ID this signature belongs to (default: -1 for no map)
weight	Weight/importance of this signature (default: 0)
stamp	Timestamp in seconds (default: 0.0)
label	Optional label/name for this signature (default: empty)
pose	Current pose of the signature (default: identity null transform)
groundTruthPose	Ground truth pose for evaluation (default: null transform)
sensorData	Sensor data captured at this location (default: empty)

Note: The signature is marked as modified and not saved by default.

◆ Signature() [3/3]

rtabmap::Signature::Signature ( const SensorData & data )

Constructor from sensor data.

Creates a signature from sensor data. The signature ID is taken from the sensor data ID, and the ground truth pose is extracted from the sensor data if available.

Parameters

data	Sensor data to create signature from

Note: The signature pose is initialized to identity transform.

Member Function Documentation

◆ compareTo()

float rtabmap::Signature::compareTo ( const Signature & signature ) const

Compares this signature to another signature.

Computes a similarity score between this signature and another signature based on their visual words. The comparison uses bag-of-words matching to determine how similar the two locations are.

Parameters

signature The signature to compare against

Returns: Similarity score between 0.0 and 1.0, where 1.0 means 100% similarity

Note: This method is used for loop closure detection and place recognition.

◆ isBadSignature()

bool rtabmap::Signature::isBadSignature ( ) const

Checks if this signature is considered "bad".

A signature is considered bad if it has no valid visual words (all words are invalid or the signature has no words at all). Bad signatures cannot be used for place recognition.

Returns: True if the signature has no valid visual words, false otherwise

◆ id()

int rtabmap::Signature::id ( ) const

inline

Returns the signature ID.

Returns: The unique signature ID (0 if invalid/uninitialized)

Definition at line 168 of file Signature.h.

◆ mapId()

int rtabmap::Signature::mapId ( ) const

inline

Returns the map ID.

Returns: The map ID this signature belongs to (-1 if no map assigned)

Definition at line 174 of file Signature.h.

◆ setWeight()

void rtabmap::Signature::setWeight ( int weight )

inline

Sets the weight/importance of this signature.

The weight represents the importance or priority of this signature, typically set by Rehearsal mechanism (see Memory::rehearsal). Higher weights may be used to prioritize certain signatures during memory management or loop closure detection.

Parameters

weight The weight value

Note: Marks the signature as modified if the weight changes. A signature already flagged as modified stays modified.

Definition at line 189 of file Signature.h.

◆ getWeight()

int rtabmap::Signature::getWeight ( ) const

inline

Returns the weight/importance of this signature.

Returns: The weight value

Definition at line 195 of file Signature.h.

◆ setLabel()

void rtabmap::Signature::setLabel ( const std::string & label )

inline

Sets a label/name for this signature.

Labels are optional text identifiers that can be used to tag or categorize signatures (e.g., "room1", "corridor", "entrance").

Parameters

label The label string

Note: Marks the signature as modified if the label changes. A signature already flagged as modified stays modified.

Definition at line 208 of file Signature.h.

◆ getLabel()

const std::string & rtabmap::Signature::getLabel ( ) const

inline

Returns the label/name of this signature.

Returns: The label string (empty if not set)

Definition at line 214 of file Signature.h.

◆ getStamp()

double rtabmap::Signature::getStamp ( ) const

inline

Returns the timestamp of this signature.

Returns: Timestamp in seconds (typically seconds since epoch)

Definition at line 220 of file Signature.h.

◆ addLinks() [1/2]

void rtabmap::Signature::addLinks ( const std::list< Link > & links )

Adds multiple links from a list.

Adds all links from the provided list to this signature's link collection.

Parameters

links List of links to add

Note: Each link must have from() equal to this signature's ID.; Automatically marks links as modified.

See also: addLink()

◆ addLinks() [2/2]

void rtabmap::Signature::addLinks ( const std::map< int, Link > & links )

Adds multiple links from a map.

Adds all links from the provided map to this signature's link collection.

Parameters

links Map of target IDs to links

Note: Each link must have from() equal to this signature's ID.; The map's keys are the target IDs (to() values of the links).; Automatically marks links as modified.

See also: addLink()

◆ addLink()

void rtabmap::Signature::addLink ( const Link & link )

Adds a single link to this signature.

Adds a link connecting this signature to another signature. The link represents a constraint in the pose graph (e.g., neighbor, loop closure).

Parameters

link	The link to add

Note: The link's from() must equal this signature's ID.; The link's to() must be different from this signature's ID (except for self-referring links like pose priors or gravity).; Duplicate links to the same target are not allowed (assertion failure).; Automatically marks links as modified.

◆ hasLink()

bool rtabmap::Signature::hasLink	(	int	idTo,
		Link::Type	type = `Link::kUndef`
	)		const

Checks if this signature has a link to a target signature.

Parameters

idTo	Target signature ID (0 to check for any link of the specified type)
type	Link type to check for (default: Link::kUndef to check any type)

Returns: True if a matching link exists, false otherwise

◆ changeLinkIds()

void rtabmap::Signature::changeLinkIds	(	int	idFrom,
		int	idTo
	)

Changes all link target IDs from one value to another.

Updates all links that point to idFrom to point to idTo instead. This is useful when merging or reorganizing the graph.

Parameters

idFrom	Original target ID
idTo	New target ID

Note: Automatically marks links as modified.

◆ removeLinks()

void rtabmap::Signature::removeLinks ( bool keepSelfReferringLinks = false )

Removes all links from this signature.

Parameters

keepSelfReferringLinks If true, preserves self-referring links (pose priors, gravity) that have from() == to()

Note: Automatically marks links as modified.

◆ removeLink()

void rtabmap::Signature::removeLink ( int idTo )

Removes a specific link to a target signature.

Parameters

idTo	Target signature ID of the link to remove

Note: Automatically marks links as modified.

◆ removeVirtualLinks()

void rtabmap::Signature::removeVirtualLinks ( )

Removes all virtual links from this signature.

Virtual links are links of type Link::kVirtualClosure.

Note: Automatically marks links as modified.

◆ addLandmark()

void rtabmap::Signature::addLandmark ( const Link & landmark )

Adds a landmark observation to this signature.

Landmarks are persistent features in the environment that can be observed from multiple locations. This method adds a link representing the observation of a landmark from this signature's location.

Parameters

landmark Link representing the landmark observation

Note: Landmark IDs are typically negative to distinguish them from regular nodes.

◆ getLandmarks()

const std::map< int, Link > & rtabmap::Signature::getLandmarks ( ) const

inline

Returns all landmark observations.

Returns: Const reference to the map of landmark IDs to landmark links

Definition at line 332 of file Signature.h.

◆ removeLandmark()

void rtabmap::Signature::removeLandmark ( int landmarkId )

Removes a specific landmark observation.

Parameters

landmarkId The landmark ID to remove

◆ setSaved()

void rtabmap::Signature::setSaved ( bool saved )

inline

Sets whether this signature has been saved to the database.

Parameters

saved True if saved, false otherwise

Definition at line 349 of file Signature.h.

◆ setModified()

void rtabmap::Signature::setModified ( bool modified )

inline

Sets the modification flag for this signature.

Marks the signature as modified (or unmodified). When set to true, also marks links as modified.

Parameters

modified True if modified, false otherwise

Definition at line 359 of file Signature.h.

◆ getLinks()

const std::multimap< int, Link > & rtabmap::Signature::getLinks ( ) const

inline

Returns all links from this signature.

Returns: Const reference to the multimap of target IDs to links

Definition at line 365 of file Signature.h.

◆ isSaved()

bool rtabmap::Signature::isSaved ( ) const

inline

Checks if this signature has been saved to the database.

Returns: True if saved, false otherwise

Definition at line 371 of file Signature.h.

◆ isModified()

bool rtabmap::Signature::isModified ( ) const

inline

Checks if this signature has been modified.

Returns true if either the signature data or links have been modified.

Returns: True if modified, false otherwise

Definition at line 380 of file Signature.h.

◆ isLinksModified()

bool rtabmap::Signature::isLinksModified ( ) const

inline

Checks if the links have been modified.

Returns: True if links are modified, false otherwise

Definition at line 386 of file Signature.h.

◆ removeAllWords()

void rtabmap::Signature::removeAllWords ( )

Removes all visual words from this signature.

Clears all visual words, keypoints, 3D points, and descriptors. The signature will be disabled after this operation.

◆ changeWordsRef()

void rtabmap::Signature::changeWordsRef	(	int	oldWordId,
		int	activeWordId
	)

Changes visual word references from one word ID to another.

Updates all occurrences of oldWordId to activeWordId in the visual words. This is used when words are merged or reorganized in the dictionary.

Parameters

oldWordId	The original word ID to replace
activeWordId	The new word ID to use

Note: Tracks word ID changes in _wordsChanged for reference.

◆ setWords()

void rtabmap::Signature::setWords	(	const std::multimap< int, int > &	words,
		const std::vector< cv::KeyPoint > &	keypoints,
		const std::vector< cv::Point3f > &	words3,
		const cv::Mat &	descriptors
	)

Sets all visual words for this signature.

Sets the complete visual word representation including word IDs, keypoints, 3D points, and descriptors. All arrays must have matching sizes.

Parameters

words	Multimap of word IDs to keypoint indices (allows duplicate words). The keypoint indices match the keypoints, points and descriptors.
keypoints	Vector of 2D keypoints in image coordinates. The keypoints must be in the same order as the words.
words3	Vector of 3D points in base_link frame (with localTransform applied). The points must be in the same order as the words.
descriptors	Feature descriptors matrix (one row per word). The descriptors must be in the same order as the words.

Note: The signature is disabled after setting words (must be explicitly enabled).; Invalid words (ID <= 0) are counted in _invalidWordsCount.; All arrays must have the same size (number of words).

◆ isEnabled()

bool rtabmap::Signature::isEnabled ( ) const

inline

Checks if this signature is enabled.

Enabled signatures can be used for place recognition and loop closure detection. More explicitly, it means that the signature is registered to the VWDictionary (see Memory::enableWordsRef).

Returns: True if enabled, false otherwise

Definition at line 436 of file Signature.h.

◆ setEnabled()

void rtabmap::Signature::setEnabled ( bool enabled )

inline

Sets whether this signature is enabled.

Parameters

enabled True to enable, false to disable

Definition at line 442 of file Signature.h.

◆ getWords()

const std::multimap< int, int > & rtabmap::Signature::getWords ( ) const

inline

Returns the visual words map.

Returns a multimap of word IDs to keypoint indices. The multimap allows duplicate word IDs (a word can appear multiple times in the signature).

Returns: Const reference to the words multimap

Definition at line 452 of file Signature.h.

◆ getWordsKpts()

const std::vector< cv::KeyPoint > & rtabmap::Signature::getWordsKpts ( ) const

inline

Returns the keypoints associated with visual words.

Returns: Const reference to the vector of 2D keypoints

Definition at line 458 of file Signature.h.

◆ getInvalidWordsCount()

int rtabmap::Signature::getInvalidWordsCount ( ) const

inline

Returns the count of invalid visual words.

Invalid words are those with ID <= 0. These words cannot be used for place recognition. However, they are still used for transform estimation after loop closures are detected with the valid words.

Returns: Number of invalid words

Definition at line 469 of file Signature.h.

◆ getWordsChanged()

const std::map< int, int > & rtabmap::Signature::getWordsChanged ( ) const

inline

Returns the word ID change mapping.

Returns a map of old word IDs to new word IDs, tracking changes made through changeWordsRef().

Returns: Const reference to the word ID change map

Definition at line 479 of file Signature.h.

◆ getWordsDescriptors()

const cv::Mat & rtabmap::Signature::getWordsDescriptors ( ) const

inline

Returns the feature descriptors for visual words.

Returns: Const reference to the descriptors matrix (one row per word)

Definition at line 485 of file Signature.h.

◆ setWordsDescriptors()

void rtabmap::Signature::setWordsDescriptors ( const cv::Mat & descriptors )

Sets the feature descriptors for visual words.

Updates the descriptors matrix. The number of rows must match the number of visual words.

Parameters

descriptors Descriptors matrix (one row per word)

◆ setPose()

void rtabmap::Signature::setPose ( const Transform & pose )

inline

Sets the pose of this signature.

The pose represents the position and orientation of this signature in the odometry coordinate frame. To get the pose in map coordinate frame, use the map correction transform computed by graph optimization and apply it to this pose.

Parameters

pose	The transform representing the pose in the odometry coordinate frame.

// Get pose in map coordinate frame
Statistics stats;
Transform poseInMapFrame = stats.mapCorrection() * signature.getPose();
// poseInMapFrame is the pose in map coordinate frame
// signature.getPose() returns the pose in odometry coordinate frame

See also: Statistics::mapCorrection(); getPose()

Definition at line 519 of file Signature.h.

◆ setGroundTruthPose()

void rtabmap::Signature::setGroundTruthPose ( const Transform & pose )

inline

Sets the ground truth pose for evaluation.

Ground truth poses are used for evaluating localization accuracy and comparing against the estimated pose.

Parameters

pose	The ground truth transform

Definition at line 529 of file Signature.h.

◆ setVelocity()

void rtabmap::Signature::setVelocity	(	float	vx,
		float	vy,
		float	vz,
		float	vroll,
		float	vpitch,
		float	vyaw
	)

inline

Sets the velocity of this signature.

Sets the 6DOF velocity (linear and angular) at the time this signature was captured.

Parameters

vx	Linear velocity in x direction (m/s)
vy	Linear velocity in y direction (m/s)
vz	Linear velocity in z direction (m/s)
vroll	Angular velocity around x axis (rad/s)
vpitch	Angular velocity around y axis (rad/s)
vyaw	Angular velocity around z axis (rad/s)

Definition at line 544 of file Signature.h.

◆ getWords3()

const std::vector< cv::Point3f > & rtabmap::Signature::getWords3 ( ) const

inline

Returns the 3D points of visual words.

Returns the 3D coordinates of visual words in the base_link frame (with localTransform applied).

Returns: Const reference to the vector of 3D points

Definition at line 562 of file Signature.h.

◆ getPose()

const Transform & rtabmap::Signature::getPose ( ) const

inline

Returns the pose of this signature.

Returns: Const reference to the pose transform in the odometry coordinate frame.

See also: setPose() for an example of how to get the pose in map coordinate frame.

Definition at line 569 of file Signature.h.

◆ getPoseCovariance()

cv::Mat rtabmap::Signature::getPoseCovariance ( ) const

Gets the pose covariance matrix.

Gets the covariance matrix representing the uncertainty between the current pose and the previous pose (e.g, from the odometry link with the previous signature).

Returns: 6x6 covariance matrix (3x3 for translation, 3x3 for rotation)

◆ getGroundTruthPose()

const Transform & rtabmap::Signature::getGroundTruthPose ( ) const

inline

Returns the ground truth pose.

Returns: Const reference to the ground truth transform

Definition at line 585 of file Signature.h.

◆ getVelocity()

const std::vector< float > & rtabmap::Signature::getVelocity ( ) const

inline

Returns the velocity of this signature.

Returns: Const reference to the velocity vector [vx, vy, vz, vroll, vpitch, vyaw]

Definition at line 591 of file Signature.h.

◆ sensorData() [1/2]

SensorData & rtabmap::Signature::sensorData ( )

inline

Returns mutable access to the sensor data.

Returns: Reference to the sensor data

Definition at line 597 of file Signature.h.

◆ sensorData() [2/2]

const SensorData & rtabmap::Signature::sensorData ( ) const

inline

Returns const access to the sensor data.

Returns: Const reference to the sensor data

Definition at line 603 of file Signature.h.

◆ getMemoryUsed()

unsigned long rtabmap::Signature::getMemoryUsed ( bool withSensorData = true ) const

Computes the memory usage of this signature.

Calculates the approximate memory footprint of this signature, including visual words, links, sensor data, and other internal structures.

Parameters

withSensorData If true, includes sensor data in the calculation

Returns: Memory usage in bytes

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

corelib/include/rtabmap/core/Signature.h

Public Member Functions

Detailed Description

Constructor & Destructor Documentation

◆ Signature() [1/3]

◆ Signature() [2/3]

◆ Signature() [3/3]

Member Function Documentation

◆ compareTo()

◆ isBadSignature()

◆ id()

◆ mapId()

◆ setWeight()

◆ getWeight()

◆ setLabel()

◆ getLabel()

◆ getStamp()

◆ addLinks() [1/2]

◆ addLinks() [2/2]

◆ addLink()

◆ hasLink()

◆ changeLinkIds()

◆ removeLinks()

◆ removeLink()

◆ removeVirtualLinks()

◆ addLandmark()

◆ getLandmarks()

◆ removeLandmark()

◆ setSaved()

◆ setModified()

◆ getLinks()

◆ isSaved()

◆ isModified()

◆ isLinksModified()

◆ removeAllWords()

◆ changeWordsRef()

◆ setWords()

◆ isEnabled()

◆ setEnabled()

◆ getWords()

◆ getWordsKpts()

◆ getInvalidWordsCount()

◆ getWordsChanged()

◆ getWordsDescriptors()

◆ setWordsDescriptors()

◆ setPose()

◆ setGroundTruthPose()

◆ setVelocity()

◆ getWords3()

◆ getPose()

◆ getPoseCovariance()

◆ getGroundTruthPose()

◆ getVelocity()

◆ sensorData() [1/2]

◆ sensorData() [2/2]

◆ getMemoryUsed()