gtsam::NoiseModelFactorN< ValueTypes > Class Template Reference

Detailed Description

template<class... ValueTypes>
class gtsam::NoiseModelFactorN< ValueTypes >

A convenient base class for creating your own NoiseModelFactor with n variables.

To derive from this class, implement evaluateError().

For example, a 2-way factor that computes the difference in x-translation between a Pose3 and Point3 could be implemented like so:

class MyFactor : public NoiseModelFactorN<Pose3, Point3> {
 public:
  using Base = NoiseModelFactorN<Pose3, Point3>;
 
  MyFactor(Key pose_key, Key point_key, const SharedNoiseModel& noiseModel)
      : Base(noiseModel, pose_key, point_key) {}
 
  Vector evaluateError(
      const Pose3& T, const Point3& p,
      boost::optional<Matrix&> H_T = boost::none,
      boost::optional<Matrix&> H_p = boost::none) const override {
    Matrix36 t_H_T;  // partial derivative of translation w.r.t. pose T
 
    // Only compute t_H_T if needed:
    Point3 t = T.translation(H_T ? &t_H_T : 0);
    double a = t(0); // a_H_t = [1, 0, 0]
    double b = p(0); // b_H_p = [1, 0, 0]
    double error = a - b; // H_a = 1, H_b = -1
 
    // H_T = H_a * a_H_t * t_H_T = the first row of t_H_T
    if (H_T) *H_T = (Matrix(1, 6) << t_H_T.row(0)).finished();
    // H_p = H_b * b_H_p = -1 * [1, 0, 0]
    if (H_p) *H_p = (Matrix(1, 3) << -1., 0., 0.).finished();
 
    return Vector1(error);
  }
};
 
// Unit Test
TEST(NonlinearFactor, MyFactor) {
  MyFactor f(X(1), X(2), noiseModel::Unit::Create(1));
  EXPECT_DOUBLES_EQUAL(-8., f.evaluateError(Pose3(), Point3(8., 7., 6.))(0),
                       1e-9);
  Values values;
  values.insert(X(1), Pose3(Rot3::RzRyRx(0.1, 0.2, 0.3), Point3(1, 2, 3)));
  values.insert(X(2), Point3(1, 2, 3));
  EXPECT_CORRECT_FACTOR_JACOBIANS(f, values, 1e-5, 1e-5);
}

These factors are templated on a values structure type. The values structures are typically more general than just vectors, e.g., Rot3 or Pose3, which are objects in non-linear manifolds (Lie groups).

Inheritance diagram for gtsam::NoiseModelFactorN< ValueTypes >:

Public Member Functions
template<int I = 1>
Key	key () const
	Returns a key.
Constructors
	NoiseModelFactorN ()
	Default Constructor for I/O.
	NoiseModelFactorN (const SharedNoiseModel &noiseModel, KeyType< ValueTypes >... keys)
	Constructor.
template<typename CONTAINER = std::initializer_list<Key>, typename = IsContainerOfKeys<CONTAINER>>
	NoiseModelFactorN (const SharedNoiseModel &noiseModel, CONTAINER keys)
	Constructor.
NoiseModelFactor methods
Vector	unwhitenedError (const Values &x, boost::optional< std::vector< Matrix > & > H=boost::none) const override
	This implements the unwhitenedError virtual function by calling the n-key specific version of evaluateError, which is pure virtual so must be implemented in the derived class.
Virtual methods
virtual Vector	evaluateError (const ValueTypes &... x, OptionalMatrix< ValueTypes >... H) const =0
	Override evaluateError to finish implementing an n-way factor.
Convenience method overloads
Vector	evaluateError (const ValueTypes &... x) const
	No-Jacobians requested function overload.
template<typename... OptionalJacArgs, typename = IndexIsValid<sizeof...(OptionalJacArgs) + 1>>
Vector	evaluateError (const ValueTypes &... x, OptionalJacArgs &&... H) const
	Some (but not all) optional Jacobians are omitted (function overload).
Shortcut functions <tt>key1()</tt> -> <tt>key\<1\>()</tt>
Key	key1 () const
template<int I = 2>
Key	key2 () const
template<int I = 3>
Key	key3 () const
template<int I = 4>
Key	key4 () const
template<int I = 5>
Key	key5 () const
template<int I = 6>
Key	key6 () const
Public Member Functions inherited from gtsam::NoiseModelFactor
	NoiseModelFactor ()
	Default constructor for I/O only.
	~NoiseModelFactor () override
	Destructor.
template<typename CONTAINER>
	NoiseModelFactor (const SharedNoiseModel &noiseModel, const CONTAINER &keys)
	Constructor.
void	print (const std::string &s="", const KeyFormatter &keyFormatter=DefaultKeyFormatter) const override
	Print.
bool	equals (const NonlinearFactor &f, double tol=1e-9) const override
	Check if two factors are equal.
size_t	dim () const override
	get the dimension of the factor (number of rows on linearization)
const SharedNoiseModel &	noiseModel () const
	access to the noise model
Vector	whitenedError (const Values &c) const
	Vector of errors, whitened This is the raw error, i.e., i.e.
Vector	unweightedWhitenedError (const Values &c) const
	Vector of errors, whitened, but unweighted by any loss function.
double	weight (const Values &c) const
	Compute the effective weight of the factor from the noise model.
double	error (const Values &c) const override
	Calculate the error of the factor.
boost::shared_ptr< GaussianFactor >	linearize (const Values &x) const override
	Linearize a non-linearFactorN to get a GaussianFactor, \( Ax-b \approx h(x+\delta x)-z = h(x) + A \delta x - z \) Hence \( b = z - h(x) = - \mathtt{error\_vector}(x) \).
shared_ptr	cloneWithNewNoiseModel (const SharedNoiseModel newNoise) const
	Creates a shared_ptr clone of the factor with a new noise model.
	NonlinearFactor ()
	Default constructor for I/O only.
template<typename CONTAINER>
	NonlinearFactor (const CONTAINER &keys)
	Constructor from a collection of the keys involved in this factor.
void	print (const std::string &s="", const KeyFormatter &keyFormatter=DefaultKeyFormatter) const override
	print
virtual	~NonlinearFactor ()
	Destructor.
double	error (const HybridValues &c) const override
	All factor types need to implement an error function.
virtual bool	active (const Values &) const
	Checks whether a factor should be used based on a set of values.
virtual shared_ptr	clone () const
	Creates a shared_ptr clone of the factor - needs to be specialized to allow for subclasses.
virtual shared_ptr	rekey (const std::map< Key, Key > &rekey_mapping) const
	Creates a shared_ptr clone of the factor with different keys using a map from old->new keys.
virtual shared_ptr	rekey (const KeyVector &new_keys) const
	Clones a factor and fully replaces its keys.
virtual bool	sendable () const
	Should the factor be evaluated in the same thread as the caller This is to enable factors that has shared states (like the Python GIL lock).
Public Member Functions inherited from gtsam::Factor
virtual	~Factor ()=default
	Default destructor.
bool	empty () const
	Whether the factor is empty (involves zero variables).
Key	front () const
	First key.
Key	back () const
	Last key.
const_iterator	find (Key key) const
	find
const KeyVector &	keys () const
	Access the factor's involved variable keys.
const_iterator	begin () const
	Iterator at beginning of involved variable keys.
const_iterator	end () const
	Iterator at end of involved variable keys.
size_t	size () const
virtual void	printKeys (const std::string &s="Factor", const KeyFormatter &formatter=DefaultKeyFormatter) const
	print only keys
bool	equals (const This &other, double tol=1e-9) const
	check equality
KeyVector &	keys ()
iterator	begin ()
	Iterator at beginning of involved variable keys.
iterator	end ()
	Iterator at end of involved variable keys.

Public Types
enum	{ N = sizeof...(ValueTypes) }
	N is the number of variables (N-way factor).
template<int I, typename = IndexIsValid<I>>
using	ValueType
	The type of the I'th template param can be obtained as ValueType.
Public Types inherited from gtsam::NoiseModelFactor
typedef boost::shared_ptr< This >	shared_ptr
	Noise model.
Public Types inherited from gtsam::NonlinearFactor
typedef boost::shared_ptr< This >	shared_ptr
Public Types inherited from gtsam::Factor
typedef KeyVector::iterator	iterator
	Iterator over keys.
typedef KeyVector::const_iterator	const_iterator
	Const iterator over keys.

Protected Types
using	Base = NoiseModelFactor
using	This = NoiseModelFactorN<ValueTypes...>
template<typename T>
using	OptionalMatrix = boost::optional<Matrix&>
template<typename T>
using	KeyType = Key
SFINAE aliases
template<typename From, typename To>
using	IsConvertible
template<int I>
using	IndexIsValid
template<typename Container>
using	ContainerElementType
template<typename Container>
using	IsContainerOfKeys = IsConvertible<ContainerElementType<Container>, Key>
Protected Types inherited from gtsam::NoiseModelFactor
typedef NonlinearFactor	Base
typedef NoiseModelFactor	This
Protected Types inherited from gtsam::NonlinearFactor
typedef Factor	Base
typedef NonlinearFactor	This

Friends
class	boost::serialization::access
	Serialization function.

Additional Inherited Members
Protected Member Functions inherited from gtsam::NoiseModelFactor
	NoiseModelFactor (const SharedNoiseModel &noiseModel)
	Constructor - only for subclasses, as this does not set keys.
	Factor ()
	Default constructor for I/O.
template<typename CONTAINER>
	Factor (const CONTAINER &keys)
	Construct factor from container of keys.
template<typename ITERATOR>
	Factor (ITERATOR first, ITERATOR last)
	Construct factor from iterator keys.
template<typename CONTAINER>
static Factor	FromKeys (const CONTAINER &keys)
	Construct factor from container of keys.
template<typename ITERATOR>
static Factor	FromIterators (ITERATOR first, ITERATOR last)
	Construct factor from iterator keys.
Protected Attributes inherited from gtsam::NoiseModelFactor
SharedNoiseModel	noiseModel_
Protected Attributes inherited from gtsam::Factor
KeyVector	keys_
	The keys involved in this factor.

Member Typedef Documentation

ContainerElementType

template<class... ValueTypes>

template<typename Container>

using gtsam::NoiseModelFactorN< ValueTypes >::ContainerElementType

protected

Initial value:

 
typename std::decay<decltype(*std::declval<Container>().begin())>::type

IndexIsValid

template<class... ValueTypes>

template<int I>

using gtsam::NoiseModelFactorN< ValueTypes >::IndexIsValid

protected

Initial value:

typename std::enable_if<(I >= 1) && (I <= N),
                                              void>::type

IsConvertible

template<class... ValueTypes>

template<typename From, typename To>

using gtsam::NoiseModelFactorN< ValueTypes >::IsConvertible

protected

Initial value:

 
typename std::enable_if<std::is_convertible<From, To>::value, void>::type

ValueType

template<class... ValueTypes>

template<int I, typename = IndexIsValid<I>>

using gtsam::NoiseModelFactorN< ValueTypes >::ValueType

Initial value:

 
typename std::tuple_element<I - 1, std::tuple<ValueTypes...>>::type

The type of the I'th template param can be obtained as ValueType.

I is 1-indexed for backwards compatibility/consistency! So for example,

using Factor = NoiseModelFactorN<Pose3, Point3>;
Factor::ValueType<1>  // Pose3
Factor::ValueType<2>  // Point3
// Factor::ValueType<0> // ERROR!  Will not compile.
// Factor::ValueType<3> // ERROR!  Will not compile.

You can also use the shortcuts X1, ..., X6 which are the same as ValueType<1>, ..., ValueType<6> respectively (see detail::NoiseModelFactorAliases).

Note that, if your class is templated AND you want to use ValueType<1> inside your class, due to dependent types you need the template keyword: typename MyFactor<T>::template ValueType<1>.

Constructor & Destructor Documentation

NoiseModelFactorN() [1/2]

template<class... ValueTypes>

gtsam::NoiseModelFactorN< ValueTypes >::NoiseModelFactorN ( const SharedNoiseModel & noiseModel, KeyType< ValueTypes >... keys )

inline

Constructor.

Example usage: NoiseModelFactorN(noise, key1, key2, ..., keyN)

Parameters

noiseModel	Shared pointer to noise model.
keys	Keys for the variables in this factor, passed in as separate arguments.

NoiseModelFactorN() [2/2]

template<class... ValueTypes>

template<typename CONTAINER = std::initializer_list<Key>, typename = IsContainerOfKeys<CONTAINER>>

gtsam::NoiseModelFactorN< ValueTypes >::NoiseModelFactorN ( const SharedNoiseModel & noiseModel, CONTAINER keys )

inline

Constructor.

Example usage: NoiseModelFactorN(noise, {key1, key2, ..., keyN}) Example usage: NoiseModelFactorN(noise, keys) where keys is a vector<Key>

Parameters

noiseModel	Shared pointer to noise model.
keys	A container of keys for the variables in this factor.

Member Function Documentation

evaluateError() [1/3]

template<class... ValueTypes>

Vector gtsam::NoiseModelFactorN< ValueTypes >::evaluateError ( const ValueTypes &... x ) const

inline

No-Jacobians requested function overload.

This specializes the version below to avoid recursive calls since this is commonly used.

e.g. const Vector error = factor.evaluateError(pose, point);

evaluateError() [2/3]

template<class... ValueTypes>

template<typename... OptionalJacArgs, typename = IndexIsValid<sizeof...(OptionalJacArgs) + 1>>

Vector gtsam::NoiseModelFactorN< ValueTypes >::evaluateError ( const ValueTypes &... x, OptionalJacArgs &&... H ) const

inline

Some (but not all) optional Jacobians are omitted (function overload).

e.g. const Vector error = factor.evaluateError(pose, point, Hpose);

evaluateError() [3/3]

template<class... ValueTypes>

virtual Vector gtsam::NoiseModelFactorN< ValueTypes >::evaluateError ( const ValueTypes &... x, OptionalMatrix< ValueTypes >... H ) const

pure virtual

Override evaluateError to finish implementing an n-way factor.

Both the x and H arguments are written here as parameter packs, but when overriding this method, you probably want to explicitly write them out. For example, for a 2-way factor with variable types Pose3 and Point3, you should implement:

Vector evaluateError(
    const Pose3& x1, const Point3& x2,
    boost::optional<Matrix&> H1 = boost::none,
    boost::optional<Matrix&> H2 = boost::none) const override { ... }

If any of the optional Matrix reference arguments are specified, it should compute both the function evaluation and its derivative(s) in the requested variables.

Parameters

	x	The values of the variables to evaluate the error for. Passed in as separate arguments.
[out]	H	The Jacobian with respect to each variable (optional).

key()

template<class... ValueTypes>

template<int I = 1>

Key gtsam::NoiseModelFactorN< ValueTypes >::key ( ) const

inline

Returns a key.

Usage: key<I>() returns the I'th key. I is 1-indexed for backwards compatibility/consistency! So for example,

NoiseModelFactorN<Pose3, Point3> factor(noise, key1, key2);
key<1>()  // = key1
key<2>()  // = key2
// key<0>()  // ERROR!  Will not compile
// key<3>()  // ERROR!  Will not compile

Note that, if your class is templated AND you are trying to call key<1> inside your class, due to dependent types you need the template keyword: this->key1().

unwhitenedError()

template<class... ValueTypes>

Vector gtsam::NoiseModelFactorN< ValueTypes >::unwhitenedError ( const Values & x, boost::optional< std::vector< Matrix > & > H = boost::none ) const

inlineoverridevirtual

This implements the unwhitenedError virtual function by calling the n-key specific version of evaluateError, which is pure virtual so must be implemented in the derived class.

Example usage:

gtsam::Values values;
values.insert(...) // populate values
std::vector<Matrix> Hs(2); // this will be an optional output argument
const Vector error = factor.unwhitenedError(values, Hs);

Parameters

[in]	x	A Values object containing the values of all the variables used in this factor
[out]	H	A vector of (dynamic) matrices whose size should be equal to n. The Jacobians w.r.t. each variable will be output in this parameter.

Implements gtsam::NoiseModelFactor.

---

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

• /tmp/gtsam-4.2-docs.H5EUbA/src/gtsam/nonlinear/NonlinearFactor.h