Struct TPose2D

Inheritance Relationships

Base Types

Struct Documentation

struct TPose2D : public mrpt::math::TPoseOrPoint, public mrpt::math::internal::ProvideStaticResize<TPose2D>

Lightweight 2D rigid-body pose — an element of SE(2).

Parameterises the group SE(2) = SO(2) ⋉ R² as the triplet (x, y, φ):

  • (x, y) — translation in metres.

  • φ (phi) — counter-clockwise rotation angle in radians, measured from the global X axis.

The equivalent 3x3 homogeneous matrix is: 

*   T = | cos(phi)  -sin(phi)  x |
*       | sin(phi)   cos(phi)  y |
*       |    0          0      1 |
*

**Composition (operator+)** implements the SE(2) group product: (this ⊕ b) maps a point expressed in frame b into the frame of this.

**Inverse composition (operator-)** implements (this ⊖ b) = b⁻¹ ⊕ this, i.e. the pose of this expressed in the frame of b.

This is a lightweight type without serialization or caching of trig values. Prefer mrpt::poses::CPose2D when composition is called repeatedly with the same pose (it caches cos/sin and supports serialization).

Coordinate access: operator[] with index 0→x, 1→y, 2→phi.

See also

mrpt::poses::CPose2D, TPose3D, TPoint2D

Public Functions

explicit TPose2D(const TPoint2D &p)

Constructor from TPoint2D: copies (x,y), sets phi=0 (pure translation, no rotation).

explicit TPose2D(const TPoint3D &p)

Constructor from TPoint3D: copies (x,y), sets phi=0; the z coordinate is discarded.

explicit TPose2D(const TPose3D &p)

Constructor from TPose3D: copies (x,y), maps yaw→phi; z, pitch and roll are discarded. This is a projection from SE(3) onto SE(2); information is irreversibly lost when pitch ≠ 0 or roll ≠ 0.

See also

TPose3D

inline constexpr TPose2D(double xx, double yy, double Phi)

Constructor from coordinates.

constexpr TPose2D() = default

Default fast constructor. Initializes to zeros.

inline double &operator[](size_t i)

Coordinate access using operator[]. Order: x,y,phi

inline constexpr double operator[](size_t i) const

Coordinate access using operator[]. Order: x,y,phi

template<typename Vector>
inline void asVector(Vector &v) const

Gets the pose as a vector of doubles.

Template Parameters:

Vector – It can be std::vector<double>, Eigen::VectorXd, etc.

template<typename Vector>
inline Vector asVector() const

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

void asString(std::string &s) const

Returns a human-readable textual representation of the object (eg: “[x y

yaw]”, yaw in degrees)

See also

fromString

inline std::string asString() const
mrpt::math::TPose2D operator+(const mrpt::math::TPose2D &b) const

SE(2) group composition — “⊕” operator: ret = this ⊕ b.

Computes the pose obtained by first applying transformation this, then b. In matrix form: T_ret = T_this · T_b. If this is the pose of frame A in the world W, and b is the pose of frame B in frame A, then ret is the pose of B in W.

See also

CPose2D, inverseComposeFrom

mrpt::math::TPose2D operator-(const mrpt::math::TPose2D &b) const

SE(2) inverse composition — “⊖” operator: ret = this ⊖ b = b⁻¹ ⊕ this.

Returns the pose of this expressed in the reference frame of b. In matrix form: T_ret = T_b⁻¹ · T_this. Useful for computing relative poses: if both this and b are poses in the world frame, ret is the pose of this as seen from b.

See also

CPose2D

mrpt::math::TPoint2D composePoint(const TPoint2D l) const

Transforms a point from the local frame of this pose into the global (world) frame. Equivalent to g = T_this · [l.x l.y 1]ᵀ (homogeneous coords).

See also

inverseComposePoint

Parameters:

l – Point in the local frame.

Returns:

Point in the global frame.

mrpt::math::TPoint2D operator+(const mrpt::math::TPoint2D &b) const

Alias for composePoint(): pose + point applies the SE(2) transformation to the point.

mrpt::math::TPoint2D inverseComposePoint(const TPoint2D g) const

Transforms a point from the global (world) frame into the local frame of this pose. Equivalent to l = T_this⁻¹ · [g.x g.y 1]ᵀ (homogeneous coords).

See also

composePoint

Parameters:

g – Point in the global frame.

Returns:

Point in the local frame of this pose.

inline const mrpt::math::TPoint2D translation() const

Returns the (x,y) translational part of the SE(2) transformation.

inline double norm() const

Euclidean norm of the translational part: |(x,y)|. The angle phi is ignored.

inline void normalizePhi()

Wraps phi to the canonical range (-pi, pi].

void fromString(const std::string &s)

Set the current object value from a string generated by ‘asString’ (eg: “[0.02 1.04 -45.0]” )

See also

asString

Throws:

std::exception – On invalid format

Public Members

double x = {.0}

Translation along the global X axis (metres).

double y = {.0}

Translation along the global Y axis (metres).

double phi = {.0}

Heading angle phi in radians, counter-clockwise from the global X axis. Range: any real value; use normalizePhi() to wrap to (-pi, pi].

Public Static Functions

static inline constexpr TPose2D Identity()

Returns the identity transformation

template<typename Vector>
static inline TPose2D FromVector(const Vector &v)

Builds from the first 3 elements of a vector-like object: [x y phi]

Template Parameters:

Vector – It can be std::vector<double>, Eigen::VectorXd, etc.

static inline TPose2D FromString(const std::string &s)

Public Static Attributes

static constexpr std::size_t static_size = 3