A convenience wrapper class for ROS's native TF2 API to simplify transforming of various messages. More...

#include <transformer.h>

Public Member Functions
	Transformer ()
	A convenience constructor that doesn't initialize anything.

	Transformer (const rclcpp::Node::SharedPtr &node)
	The main constructor that actually initializes stuff.

	Transformer (const rclcpp::Node::SharedPtr &node, const rclcpp::Clock::SharedPtr &clock, const rclcpp::Duration &cache_time=rclcpp::Duration(tf2::BUFFER_CORE_DEFAULT_CACHE_TIME), const rclcpp::QoS &qos=rclcpp::ServicesQoS())
	The main constructor that actually initializes stuff.

Transformer &	operator= (Transformer &&other)
	A convenience move assignment operator.

void	setDefaultFrame (const std::string &frame_id)
	Sets the default frame ID to be used instead of any empty frame ID.

void	setDefaultPrefix (const std::string &prefix)
	Sets the default frame ID prefix to be used if no prefix is present in the frame.

void	setLatLon (const double lat, const double lon)
	Sets the curret lattitude and longitude for UTM zone calculation.

void	setLookupTimeout (const rclcpp::Duration timeout=rclcpp::Duration(0, 0))
	Set a timeout for transform lookup.

void	retryLookupNewest (const bool retry=true)
	Enable/disable retry of a failed transform lookup with `rclcpp::Time(0)`.

void	beQuiet (const bool quiet=true)
	Enable/disable some prints that may be too noisy.

std::string	resolveFrame (const std::string &frame_id)
	Deduce the full frame ID from a shortened or empty string using current default prefix and default frame rules.

template<class T >
std::optional< T >	transformSingle (const T &what, const std::string &to_frame)
	Transforms a single variable to a new frame and returns it or `std::nullopt` if transformation fails.

template<class T >
std::optional< std::shared_ptr< T > >	transformSingle (const std::shared_ptr< T > &what, const std::string &to_frame)
	Transforms a single variable to a new frame.

template<class T >
std::optional< std::shared_ptr< T > >	transformSingle (const std::shared_ptr< const T > &what, const std::string &to_frame)
	Transforms a single variable to a new frame.

template<class T >
std::optional< T >	transformSingle (const std::string &from_frame, const T &what, const std::string &to_frame, const rclcpp::Time &time_stamp=rclcpp::Time(0))
	Transforms a single variable to a new frame and returns it or `std::nullopt` if transformation fails.

template<class T >
std::optional< std::shared_ptr< T > >	transformSingle (const std::string &from_frame, const std::shared_ptr< T > &what, const std::string &to_frame, const rclcpp::Time &time_stamp=rclcpp::Time(0))
	Transforms a single variable to a new frame and returns it or `std::nullopt` if transformation fails.

template<class T >
std::optional< std::shared_ptr< T > >	transformSingle (const std::string &from_frame, const std::shared_ptr< const T > &what, const std::string &to_frame, const rclcpp::Time &time_stamp=rclcpp::Time(0))
	Transforms a single variable to a new frame and returns it or `std::nullopt` if transformation fails.

template<class T >
std::optional< T >	transform (const T &what, const geometry_msgs::msg::TransformStamped &tf)
	Transform a variable to new frame using a particular transformation.

template<class T >
std::optional< std::shared_ptr< T > >	transform (const std::shared_ptr< const T > &what, const geometry_msgs::msg::TransformStamped &tf)
	Transform a variable to new frame using a particular transformation.

template<class T >
std::optional< std::shared_ptr< T > >	transform (const std::shared_ptr< T > &what, const geometry_msgs::msg::TransformStamped &tf)
	Transform a variable to new frame using a particular transformation.

std::optional< Eigen::Vector3d >	transformAsVector (const Eigen::Vector3d &what, const geometry_msgs::msg::TransformStamped &tf)
	Transform an Eigen::Vector3d (interpreting it as a vector).

std::optional< Eigen::Vector3d >	transformAsVector (const std::string &from_frame, const Eigen::Vector3d &what, const std::string &to_frame, const rclcpp::Time &time_stamp=rclcpp::Time(0))
	Transform an Eigen::Vector3d (interpreting it as a vector).

std::optional< Eigen::Vector3d >	transformAsPoint (const Eigen::Vector3d &what, const geometry_msgs::msg::TransformStamped &tf)
	Transform an Eigen::Vector3d (interpreting it as a point).

std::optional< Eigen::Vector3d >	transformAsPoint (const std::string &from_frame, const Eigen::Vector3d &what, const std::string &to_frame, const rclcpp::Time &time_stamp=rclcpp::Time(0))
	Transform an Eigen::Vector3d (interpreting it as a point).

std::optional< geometry_msgs::msg::TransformStamped >	getTransform (const std::string &from_frame, const std::string &to_frame, const rclcpp::Time &time_stamp=rclcpp::Time(0))
	Obtains a transform between two frames in a given time.

std::optional< geometry_msgs::msg::TransformStamped >	getTransform (const std::string &from_frame, const rclcpp::Time &from_stamp, const std::string &to_frame, const rclcpp::Time &to_stamp, const std::string &fixed_frame)
	Obtains a transform between two frames in a given time.

Static Public Member Functions
static constexpr const std::string &	frame_from (const geometry_msgs::msg::TransformStamped &msg)
	A convenience function that returns the frame from which the message transforms.

static constexpr std::string &	frame_from (geometry_msgs::msg::TransformStamped &msg)
	A convenience function that returns the frame from which the message transforms.

static constexpr const std::string &	frame_to (const geometry_msgs::msg::TransformStamped &msg)
	A convenience function that returns the frame to which the message transforms.

static constexpr std::string &	frame_to (geometry_msgs::msg::TransformStamped &msg)
	A convenience function that returns the frame to which the message transforms.

static geometry_msgs::msg::TransformStamped	inverse (const geometry_msgs::msg::TransformStamped &msg)
	A convenience function implements returns the inverse of the transform message as a one-liner.

Detailed Description

A convenience wrapper class for ROS's native TF2 API to simplify transforming of various messages.

Implements optional automatic frame prefix deduction, seamless transformation lattitude/longitude coordinates and UTM coordinates, simple transformation of MRS messages etc.

Constructor & Destructor Documentation

◆ Transformer() [1/3]

mrs_lib::Transformer::Transformer ( )

A convenience constructor that doesn't initialize anything.

This constructor is just to enable usign the Transformer as a member variable of nodelets etc. To actually initialize the class, use the alternative constructor.

Note: This constructor doesn't initialize the TF2 transform listener and all calls to the transformation-related methods of an object constructed using this method will fail.

◆ Transformer() [2/3]

mrs_lib::Transformer::Transformer ( const rclcpp::Node::SharedPtr & node )

The main constructor that actually initializes stuff.

This constructor initializes the class and the TF2 transform listener.

Parameters

node	the node handle to be used for subscribing to the transformations.

◆ Transformer() [3/3]

mrs_lib::Transformer::Transformer	(	const rclcpp::Node::SharedPtr &	node,
		const rclcpp::Clock::SharedPtr &	clock,
		const rclcpp::Duration &	cache_time = `rclcpp::Duration(tf2::BUFFER_CORE_DEFAULT_CACHE_TIME)`,
		const rclcpp::QoS &	qos = `rclcpp::ServicesQoS()`
	)

The main constructor that actually initializes stuff.

This constructor initializes the class and the TF2 transform listener.

Parameters

node	the node handle to be used for subscribing to the transformations.
cache_time	duration of the transformation buffer's cache into the past that will be kept.

The main constructor that actually initializes stuff.

This constructor initializes the class and the TF2 transform listener.

Parameters

node	the node handle to be used for subscribing to the transformations.
cache_time	duration of the transformation buffer's cache into the past that will be kept.

Member Function Documentation

◆ beQuiet()

void mrs_lib::Transformer::beQuiet ( const bool quiet = true )

inline

Enable/disable some prints that may be too noisy.

Parameters

quiet enables or disables quiet mode.

Note: Disabled by default.

◆ frame_from() [1/2]

static constexpr const std::string & mrs_lib::Transformer::frame_from ( const geometry_msgs::msg::TransformStamped & msg )

inlinestaticconstexpr

A convenience function that returns the frame from which the message transforms.

Parameters

msg	the message representing the transformation.

Returns: the frame from which the transformation in \msg transforms.

◆ frame_from() [2/2]

static constexpr std::string & mrs_lib::Transformer::frame_from ( geometry_msgs::msg::TransformStamped & msg )

inlinestaticconstexpr

A convenience function that returns the frame from which the message transforms.

This overload returns a reference to the string in the message representing the frame id so that it can be modified.

Parameters

msg	the message representing the transformation.

Returns: a reference to the field in the message containing the string with the frame id from which the transformation in \msg transforms.

◆ frame_to() [1/2]

static constexpr const std::string & mrs_lib::Transformer::frame_to ( const geometry_msgs::msg::TransformStamped & msg )

inlinestaticconstexpr

A convenience function that returns the frame to which the message transforms.

Parameters

msg	the message representing the transformation.

Returns: the frame to which the transformation in \msg transforms.

◆ frame_to() [2/2]

static constexpr std::string & mrs_lib::Transformer::frame_to ( geometry_msgs::msg::TransformStamped & msg )

inlinestaticconstexpr

A convenience function that returns the frame to which the message transforms.

This overload returns a reference to the string in the message representing the frame id so that it can be modified.

Parameters

msg	the message representing the transformation.

Returns: a reference to the field in the message containing the string with the frame id to which the transformation in \msg transforms.

◆ getTransform() [1/2]

std::optional< geometry_msgs::msg::TransformStamped > mrs_lib::Transformer::getTransform	(	const std::string &	from_frame,
		const rclcpp::Time &	from_stamp,
		const std::string &	to_frame,
		const rclcpp::Time &	to_stamp,
		const std::string &	fixed_frame
	)

Obtains a transform between two frames in a given time.

This overload enables the user to select a different time of the source frame and the target frame.

Parameters

from_frame	The original frame of the transformation.
from_stamp	The time at which the original frame should be evaluated. (0 will get the latest)
to_frame	The target frame of the transformation.
to_stamp	The time to which the data should be transformed. (0 will get the latest)
fixed_frame	The frame that may be assumed constant in time (the "world" frame).

Returns: std::nullopt if failed, optional containing the requested transformation otherwise.

Note: An example of when this API may be useful is explained here: http://wiki.ros.org/tf2/Tutorials/Time%20travel%20with%20tf2%20%28C%2B%2B%29

◆ getTransform() [2/2]

std::optional< geometry_msgs::msg::TransformStamped > mrs_lib::Transformer::getTransform	(	const std::string &	from_frame,
		const std::string &	to_frame,
		const rclcpp::Time &	time_stamp = `rclcpp::Time(0)`
	)

Obtains a transform between two frames in a given time.

Parameters

from_frame	The original frame of the transformation.
to_frame	The target frame of the transformation.
time_stamp	The time stamp of the transformation. (0 will get the latest)

Returns: std::nullopt if failed, optional containing the requested transformation otherwise.

◆ inverse()

static geometry_msgs::msg::TransformStamped mrs_lib::Transformer::inverse ( const geometry_msgs::msg::TransformStamped & msg )

inlinestatic

A convenience function implements returns the inverse of the transform message as a one-liner.

Parameters

msg	the message representing the transformation.

Returns: a new message representing an inverse of the original transformation.

◆ operator=()

Transformer & mrs_lib::Transformer::operator= ( Transformer && other )

A convenience move assignment operator.

This operator moves all data from the object that is being assigned from, invalidating it.

Parameters

other the object to assign from. It will be invalid after this method returns.

Returns: a reference to the object being assigned to.

◆ resolveFrame()

std::string mrs_lib::Transformer::resolveFrame ( const std::string & frame_id )

inline

Deduce the full frame ID from a shortened or empty string using current default prefix and default frame rules.

Example assuming default prefix is "uav1" and default frame is "uav1/gps_origin": "" -> "uav1/gps_origin" "local_origin" -> "uav1/local_origin"

Parameters

frame_id The frame ID to be resolved.

Returns: The resolved frame ID.

◆ retryLookupNewest()

void mrs_lib::Transformer::retryLookupNewest ( const bool retry = true )

inline

Enable/disable retry of a failed transform lookup with rclcpp::Time(0).

If enabled, a failed transform lookup will be retried. The new try will ignore the requested timestamp and will attempt to fetch the latest transformation between the two frames.

Note: Disabled by default.

Parameters

retry enables or disables retry.

◆ setDefaultFrame()

void mrs_lib::Transformer::setDefaultFrame ( const std::string & frame_id )

inline

Sets the default frame ID to be used instead of any empty frame ID.

If you call e.g. the transform() method with a message that has an empty header.frame_id field, this value will be used instead.

Parameters

frame_id the default frame ID. Use an empty string to disable default frame ID deduction.

Note: Disabled by default.

◆ setDefaultPrefix()

void mrs_lib::Transformer::setDefaultPrefix ( const std::string & prefix )

inline

Sets the default frame ID prefix to be used if no prefix is present in the frame.

If you call any method with a frame ID that doesn't begin with this string, it will be automatically prefixed including a forward slash between the prefix and raw frame ID. The forward slash should therefore not be included in the prefix.

Example frame ID resolution assuming default prefix is "uav1": "local_origin" -> "uav1/local_origin"

Parameters

prefix the default frame ID prefix (without the forward slash at the end). Use an empty string to disable default frame ID prefixing.

Note: Disabled by default. The prefix will be applied as a namespace (with a forward slash between the prefix and raw frame ID).

◆ setLatLon()

void mrs_lib::Transformer::setLatLon	(	const double	lat,
		const double	lon
	)

Sets the curret lattitude and longitude for UTM zone calculation.

The Transformer uses this to deduce the current UTM zone used for transforming stuff to latlon_origin.

Parameters

lat	the latitude in degrees.
lon	the longitude in degrees.

Note: Any transformation to latlon_origin will fail if this function is not called first!

◆ setLookupTimeout()

void mrs_lib::Transformer::setLookupTimeout ( const rclcpp::Duration timeout = rclcpp::Duration(0, 0) )

inline

Set a timeout for transform lookup.

The transform lookup operation will block up to this duration if the transformation is not available immediately.

Note: Disabled by default.

Parameters

timeout the lookup timeout. Set to zero to disable blocking.

◆ transform() [1/3]

template<class T >

std::optional< std::shared_ptr< T > > mrs_lib::Transformer::transform	(	const std::shared_ptr< const T > &	what,
		const geometry_msgs::msg::TransformStamped &	tf
	)

inline

Transform a variable to new frame using a particular transformation.

A convenience override for shared pointers to const.

Parameters

tf	The transformation to be used.
what	The object to be transformed.

Returns: std::nullopt if failed, optional containing the transformed object otherwise.

◆ transform() [2/3]

template<class T >

std::optional< std::shared_ptr< T > > mrs_lib::Transformer::transform	(	const std::shared_ptr< T > &	what,
		const geometry_msgs::msg::TransformStamped &	tf
	)

inline

Transform a variable to new frame using a particular transformation.

A convenience override for shared pointers.

Parameters

tf	The transformation to be used.
what	The object to be transformed.

Returns: std::nullopt if failed, optional containing the transformed object otherwise.

◆ transform() [3/3]

template<class T >

std::optional< T > mrs_lib::Transformer::transform	(	const T &	what,
		const geometry_msgs::msg::TransformStamped &	tf
	)

Transform a variable to new frame using a particular transformation.

Parameters

tf	The transformation to be used.
what	The object to be transformed.

Returns: std::nullopt if failed, optional containing the transformed object otherwise.

◆ transformAsPoint() [1/2]

std::optional< Eigen::Vector3d > mrs_lib::Transformer::transformAsPoint	(	const Eigen::Vector3d &	what,
		const geometry_msgs::msg::TransformStamped &	tf
	)

Transform an Eigen::Vector3d (interpreting it as a point).

Both the rotation and translation will be applied to the variable.

Parameters

tf	The transformation to be used.
what	The object to be transformed.

Returns: std::nullopt if failed, optional containing the transformed object otherwise.

◆ transformAsPoint() [2/2]

std::optional< Eigen::Vector3d > mrs_lib::Transformer::transformAsPoint	(	const std::string &	from_frame,
		const Eigen::Vector3d &	what,
		const std::string &	to_frame,
		const rclcpp::Time &	time_stamp = `rclcpp::Time(0)`
	)

Transform an Eigen::Vector3d (interpreting it as a point).

Both the rotation and translation will be applied to the variable.

Parameters

from_frame	The current frame of `what`.
what	The object to be transformed.
to_frame	The desired frame of `what`.
time_stamp	From which time to take the transformation (use `rclcpp::Time(0)` for the latest time).

Returns: std::nullopt if failed, optional containing the transformed object otherwise.

◆ transformAsVector() [1/2]

std::optional< Eigen::Vector3d > mrs_lib::Transformer::transformAsVector	(	const Eigen::Vector3d &	what,
		const geometry_msgs::msg::TransformStamped &	tf
	)

Transform an Eigen::Vector3d (interpreting it as a vector).

Only the rotation will be applied to the variable.

Parameters

tf	The transformation to be used.
what	The vector to be transformed.

Returns: std::nullopt if failed, optional containing the transformed object otherwise.

◆ transformAsVector() [2/2]

std::optional< Eigen::Vector3d > mrs_lib::Transformer::transformAsVector	(	const std::string &	from_frame,
		const Eigen::Vector3d &	what,
		const std::string &	to_frame,
		const rclcpp::Time &	time_stamp = `rclcpp::Time(0)`
	)

Transform an Eigen::Vector3d (interpreting it as a vector).

Only the rotation will be applied to the variable.

Parameters

from_frame	The current frame of `what`.
what	The vector to be transformed.
to_frame	The desired frame of `what`.
time_stamp	From which time to take the transformation (use `rclcpp::Time(0)` for the latest time).

Returns: std::nullopt if failed, optional containing the transformed object otherwise.

◆ transformSingle() [1/6]

template<class T >

std::optional< std::shared_ptr< T > > mrs_lib::Transformer::transformSingle	(	const std::shared_ptr< const T > &	what,
		const std::string &	to_frame
	)

inline

Transforms a single variable to a new frame.

A convenience override for shared pointers to const.

Parameters

what	The object to be transformed.
to_frame	The target fram ID.

Returns: std::nullopt if failed, optional containing the transformed object otherwise.

◆ transformSingle() [2/6]

template<class T >

std::optional< std::shared_ptr< T > > mrs_lib::Transformer::transformSingle	(	const std::shared_ptr< T > &	what,
		const std::string &	to_frame
	)

inline

Transforms a single variable to a new frame.

A convenience override for shared pointers.

Parameters

what	The object to be transformed.
to_frame	The target fram ID.

Returns: std::nullopt if failed, optional containing the transformed object otherwise.

◆ transformSingle() [3/6]

template<class T >

std::optional< std::shared_ptr< T > > mrs_lib::Transformer::transformSingle	(	const std::string &	from_frame,
		const std::shared_ptr< const T > &	what,
		const std::string &	to_frame,
		const rclcpp::Time &	time_stamp = `rclcpp::Time(0)`
	)

inline

Transforms a single variable to a new frame and returns it or std::nullopt if transformation fails.

A convenience overload for shared pointers to const headerless variables.

Parameters

from_frame	the original target frame ID.
what	the object to be transformed.
to_frame	the target frame ID.
time_stamp	the time of the transformation.

Returns: std::nullopt if failed, optional containing the transformed object otherwise.

◆ transformSingle() [4/6]

template<class T >

std::optional< std::shared_ptr< T > > mrs_lib::Transformer::transformSingle	(	const std::string &	from_frame,
		const std::shared_ptr< T > &	what,
		const std::string &	to_frame,
		const rclcpp::Time &	time_stamp = `rclcpp::Time(0)`
	)

inline

Transforms a single variable to a new frame and returns it or std::nullopt if transformation fails.

A convenience overload for shared pointers to headerless variables.

Parameters

from_frame	the original target frame ID.
what	the object to be transformed.
to_frame	the target frame ID.
time_stamp	the time of the transformation.

Returns: std::nullopt if failed, optional containing the transformed object otherwise.

◆ transformSingle() [5/6]

template<class T >

std::optional< T > mrs_lib::Transformer::transformSingle	(	const std::string &	from_frame,
		const T &	what,
		const std::string &	to_frame,
		const rclcpp::Time &	time_stamp = `rclcpp::Time(0)`
	)

Transforms a single variable to a new frame and returns it or std::nullopt if transformation fails.

A convenience overload for headerless variables.

Parameters

from_frame	the original target frame ID.
what	the object to be transformed.
to_frame	the target frame ID.
time_stamp	the time of the transformation.

Returns: std::nullopt if failed, optional containing the transformed object otherwise.

◆ transformSingle() [6/6]

template<class T >

std::optional< T > mrs_lib::Transformer::transformSingle	(	const T &	what,
		const std::string &	to_frame
	)

Transforms a single variable to a new frame and returns it or std::nullopt if transformation fails.

Parameters

what	the object to be transformed.
to_frame	the target frame ID.

Returns: std::nullopt if failed, optional containing the transformed object otherwise.

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

include/mrs_lib/transformer.h
include/mrs_lib/impl/transformer.hpp
src/transformer/transformer.cpp

Public Member Functions

Static Public Member Functions

Detailed Description

Constructor & Destructor Documentation

◆ Transformer() [1/3]

◆ Transformer() [2/3]

◆ Transformer() [3/3]

Member Function Documentation

◆ beQuiet()

◆ frame_from() [1/2]

◆ frame_from() [2/2]

◆ frame_to() [1/2]

◆ frame_to() [2/2]

◆ getTransform() [1/2]

◆ getTransform() [2/2]

◆ inverse()

◆ operator=()

◆ resolveFrame()

◆ retryLookupNewest()

◆ setDefaultFrame()

◆ setDefaultPrefix()

◆ setLatLon()

◆ setLookupTimeout()

◆ transform() [1/3]

◆ transform() [2/3]

◆ transform() [3/3]

◆ transformAsPoint() [1/2]

◆ transformAsPoint() [2/2]

◆ transformAsVector() [1/2]

◆ transformAsVector() [2/2]

◆ transformSingle() [1/6]

◆ transformSingle() [2/6]

◆ transformSingle() [3/6]

◆ transformSingle() [4/6]

◆ transformSingle() [5/6]

◆ transformSingle() [6/6]