Visual Servoing Platform  version 3.6.1 under development (2024-11-21)
Public Types | Public Member Functions | Static Public Member Functions | Static Public Attributes | Protected Attributes | List of all members
vpFeatureTranslation Class Reference
visual_features: Visual features module » Visual features

#include <visp3/visual_features/vpFeatureTranslation.h>

+ Inheritance diagram for vpFeatureTranslation:

Public Types

enum  vpFeatureTranslationRepresentationType { cdMc , cMcd , cMo }
 
enum  vpBasicFeatureSelect { FEATURE_ALL = 0xffff }
 
enum  vpBasicFeatureDeallocatorType { user , vpServo }
 

Public Member Functions

 vpFeatureTranslation ()
 
VP_EXPLICIT vpFeatureTranslation (vpFeatureTranslationRepresentationType r)
 
 vpFeatureTranslation (vpHomogeneousMatrix &f2Mf1, vpFeatureTranslationRepresentationType r)
 
vpFeatureTranslation & buildFrom (const vpHomogeneousMatrix &f2Mf1)
 
void display (const vpCameraParameters &cam, const vpImage< unsigned char > &I, const vpColor &color=vpColor::green, unsigned int thickness=1) const VP_OVERRIDE
 
void display (const vpCameraParameters &cam, const vpImage< vpRGBa > &I, const vpColor &color=vpColor::green, unsigned int thickness=1) const VP_OVERRIDE
 
vpFeatureTranslation * duplicate () const VP_OVERRIDE
 
vpColVector error (const vpBasicFeature &s_star, unsigned int select=FEATURE_ALL) VP_OVERRIDE
 
vpFeatureTranslationRepresentationType getFeatureTranslationType () const
 
double get_Tx () const
 
double get_Ty () const
 
double get_Tz () const
 
void init () VP_OVERRIDE
 
vpMatrix interaction (unsigned int select=FEATURE_ALL) VP_OVERRIDE
 
void print (unsigned int select=FEATURE_ALL) const VP_OVERRIDE
 
void set_Tx (double t_x)
 
void set_Ty (double t_y)
 
void set_Tz (double t_z)
 
void setFeatureTranslationType (const vpFeatureTranslationRepresentationType r)
 

Static Public Member Functions

static unsigned int selectTx ()
 
static unsigned int selectTy ()
 
static unsigned int selectTz ()
 

Static Public Attributes

static const unsigned int FEATURE_LINE [32]
 

Protected Attributes

vpColVector s
 
unsigned int dim_s
 
bool * flags
 
unsigned int nbParameters
 

Inherited functionalities from vpBasicFeature

unsigned int dimension_s ()
 
vpColVector get_s (unsigned int select=FEATURE_ALL) const
 
vpBasicFeatureDeallocatorType getDeallocate ()
 
unsigned int getDimension (unsigned int select=FEATURE_ALL) const
 
virtual double operator[] (unsigned int i) const
 
void setDeallocate (vpBasicFeatureDeallocatorType d)
 
void setFlags ()
 
static unsigned int selectAll ()
 
vpBasicFeatureDeallocatorType deallocate
 
void resetFlags ()
 

Detailed Description

Class that defines the translation visual feature $s=(t_x,t_y,t_z)$.

It is convenient to consider two coordinate frames noted here $ {\cal{F}}_1 $ and $ {\cal{F}}_{2} $.

Let $^{{\cal{F}}_2}M_{{\cal{F}}_1} $ be the homogeneous matrix that gives the orientation and the translation of the frame $ {\cal{F}}_1 $ with respect to the frame $ {\cal{F}}_2 $.

\[ ^{{\cal{F}}_2}M_{{\cal{F}}_1} = \left(\begin{array}{cc} ^{{\cal{F}}_2}R_{{\cal{F}}_1} & ^{{\cal{F}}_2}t_{{\cal{F}}_1} \\ {\bf 0}_{1\times 3} & 1 \end{array} \right) \]

with $^{{\cal{F}}_2}R_{{\cal{F}}_1} $ the rotation matrix that gives the orientation of the frame $ {\cal{F}}_1 $ relative to the frame $ {\cal{F}}_2 $ and $^{{\cal{F}}_2}t_{{\cal{F}}_1} $ the translation vector that gives the position of the frame $ {\cal{F}}_1 $ relative to the frame $ {\cal{F}}_2 $. To know more about homogeneous matrices see vpHomogeneousMatrix documentation.

This class can be used to manipulate three kind of visual features:

  • This class can be used to manipulate the translation visual feature $s= ^{c^*}t_c$ which gives the position of the current camera frame relative to the desired camera frame. It is composed by the three components $(t_x,t_y,t_z)$. The desired visual feature $ s^* $ is equal to zero. The corresponding error is than equal to $ e=(s-s^*) = ^{c^*}t_c $. In this case, the interaction matrix related to $ s $ is given by

    \[ L = [ ^{c^*}R_c \;\; 0_3] \]

  • This class can also be used to manipulate the translation visual feature $s= ^{c}t_{c^*}$ which gives the position of the desired camera frame relative to the current camera frame. It is composed by the three components $(t_x,t_y,t_z)$. The desired visual feature $ s^* $ is equal to zero. The corresponding error is than equal to $ e=(s-s^*) = ^{c}t_{c^*} $. In this case, the interaction matrix related to $ s $ is given by

    \[ L = [ -I_3 \;\; [^{c}t_{c^*}]_\times] \]

  • Actually, this class can also be used to manipulate the translation visual feature $s= ^{c}t_o$ which gives the position of the object frame relative to the current camera frame. It is composed by the three components $(t_x,t_y,t_z)$ too. The desired visual feature $ s^* $ is the translation visual feature $s^*= ^{c^*}t_o$ which gives the position of the object frame relative to the desired camera frame. The corresponding error is than equal to $ e=(s-s^*) = ^{c}t_o - ^{c^*}t_o $. In this case, the interaction matrix related to $ s $ is given by

    \[ L = [ -I_3 \;\; [^{c}t_o]_\times] \]

To initialize the feature $(t_x, t_y, t_z)$ you may use member functions like set_Tx(), set_Ty(), set_Tz(), or also build() functions.

The interaction() method allows to compute the interaction matrix $ L$ associated to the translation visual feature, while the error() method computes the error vector $(s - s^*)$ between the current visual feature and the desired one.

The code below shows how to create a eye-in hand visual servoing task using a 3D translation feature $(t_x,t_y,t_z)$ that correspond to the 3D translation between the desired camera frame and the current camera frame. To control six degrees of freedom, at least three other features must be considered like vpFeatureThetaU visual features. First we create a current ( $s$) and desired ( $s^*$) 3D translation feature, set the task to use the interaction matrix associated to the current feature $L_s$ and than compute the camera velocity $v=-\lambda \; L_s^+ \; (s-s^*)$. The current feature $s$ is updated in the while() loop while $s^*$ is set to zero.

#include <visp3/core/vpHomogeneousMatrix.h>
#include <visp3/visual_features/vpFeatureTranslation.h>
#include <visp3/vs/vpServo.h>
#ifdef ENABLE_VISP_NAMESPACE
using namespace VISP_NAMESPACE_NAME;
#endif
int main()
{
vpServo task; // Visual servoing task
vpHomogeneousMatrix cdMc;
// ... cdMc need here to be initialized from for example a pose estimation.
// Creation of the current visual feature s
vpFeatureTranslation s(vpFeatureTranslation::cdMc);
s.buildFrom(cdMc); // Initialization of the current feature s=(tx,ty,tz)
// Set eye-in-hand control law.
// The computed velocities will be expressed in the camera frame
task.setServo(vpServo::EYEINHAND_CAMERA);
// Interaction matrix is computed with the current visual features s
task.setInteractionMatrixType(vpServo::CURRENT);
// Set the constant gain
double lambda = 0.8;
task.setLambda(lambda);
// Add the 3D translation feature to the task
task.addFeature(s); // s* is here considered as zero
// Control loop
for ( ; ; ) {
// ... cdMc need here to be initialized from for example a pose estimation.
// Update the current 3D translation visual feature
s.buildFrom(cdMc);
// compute the control law
vpColVector v = task.computeControlLaw(); // camera velocity
}
}
vpBasicFeature::s
vpColVector s
State of the visual feature.
Definition: vpBasicFeature.h:92
vpColVector
Implementation of column vector and the associated operations.
Definition: vpColVector.h:191
vpFeatureTranslation
Class that defines the translation visual feature .
Definition: vpFeatureTranslation.h:282
vpHomogeneousMatrix
Implementation of an homogeneous matrix and operations on such kind of matrices.
Definition: vpHomogeneousMatrix.h:221
vpServo::setInteractionMatrixType
void setInteractionMatrixType(const vpServoIteractionMatrixType &interactionMatrixType, const vpServoInversionType &interactionMatrixInversion=PSEUDO_INVERSE)
Definition: vpServo.cpp:380
vpServo::EYEINHAND_CAMERA
@ EYEINHAND_CAMERA
Definition: vpServo.h:161
vpServo::addFeature
void addFeature(vpBasicFeature &s_cur, vpBasicFeature &s_star, unsigned int select=vpBasicFeature::FEATURE_ALL)
Definition: vpServo.cpp:331
vpServo::setLambda
void setLambda(double c)
Definition: vpServo.h:986
vpServo::setServo
void setServo(const vpServoType &servo_type)
Definition: vpServo.cpp:134
vpServo::computeControlLaw
vpColVector computeControlLaw()
Definition: vpServo.cpp:705
vpServo::CURRENT
@ CURRENT
Definition: vpServo.h:202
VISP_NAMESPACE_NAME
Definition: vpEigenConversion.h:44

If you want to deal only with the $(t_x,t_y)$ subset feature from the 3D translation, you have just to modify the addFeature() call in the previous example by the following line. In that case, the dimension of $s$ is two.

// Add the (tx,ty) subset features from 3D translation to the task
task.addFeature(s, vpFeatureTranslation::selectTx() | vpFeatureTranslation::selectTy());
vpFeatureTranslation::selectTx
static unsigned int selectTx()
Definition: vpFeatureTranslation.cpp:682
vpFeatureTranslation::selectTy
static unsigned int selectTy()
Definition: vpFeatureTranslation.cpp:727

If you want to build your own control law, this other example shows how to create a current ( $s$) and desired ( $s^*$) 3D translation visual feature, compute the corresponding error vector $(s-s^*)$ and finally build the interaction matrix $L_s$.

#include <visp3/core/vpHomogeneousMatrix.h>
#include <visp3/core/vpMatrix.h>
#include <visp3/visual_features/vpFeatureTranslation.h>
#ifdef ENABLE_VISP_NAMESPACE
using namespace VISP_NAMESPACE_NAME;
#endif
int main()
{
vpHomogeneousMatrix cdMc;
// ... cdMc need here to be initialized from for example a pose estimation.
// Creation of the current feature s
vpFeatureTranslation s(vpFeatureTranslation::cdMc);
s.buildFrom(cdMc); // Initialization of the feature
// Creation of the desired feature s*. By default this feature is
// initialized to zero
vpFeatureTranslation s_star(vpFeatureTranslation::cdMc);
// Compute the interaction matrix for the translation feature
vpMatrix L = s.interaction();
// Compute the error vector (s-s*) for the translation feature
vpColVector e = s.error(s_star); // e = (s-s*)
}
vpMatrix
Implementation of a matrix and operations on matrices.
Definition: vpMatrix.h:169

The code below shows how to create an eye-in hand visual servoing task using a 3D translation feature $(t_x,t_y,t_z)$ that correspond to the 3D translation between the current camera frame and the object frame. Like with the previous examples, to control six degrees of freedom, at least three other features must be considered like vpFeatureThetaU visual features. The way to initialize the visual features is quite the same as before. The difference is that the cMo method must be precised and the desired feature is note necessary equal to zero.

#include <visp3/core/vpHomogeneousMatrix.h>
#include <visp3/visual_features/vpFeatureTranslation.h>
#include <visp3/vs/vpServo.h>
#ifdef ENABLE_VISP_NAMESPACE
using namespace VISP_NAMESPACE_NAME;
#endif
int main()
{
vpServo task; // Visual servoing task
vpHomogeneousMatrix cdMo;
// ... cdMo need here to be initialized from for example a pose estimation.
// Creation of the desired visual feature s*
vpFeatureTranslation s_star(vpFeatureTranslation::cMo);
s_star.buildFrom(cdMo); // Initialization of the desired feature s*=(tx*,ty*,tz*)
vpHomogeneousMatrix cMo;
// ... cMo need here to be computed.
// Creation of the current visual feature s
vpFeatureTranslation s(vpFeatureTranslation::cMo);
s.buildFrom(cMo); // Initialization of the current feature s=(tx,ty,tz)
// Set eye-in-hand control law.
// The computed velocities will be expressed in the camera frame
task.setServo(vpServo::EYEINHAND_CAMERA);
// Interaction matrix is computed with the current visual features s
task.setInteractionMatrixType(vpServo::CURRENT);
// Set the constant gain
double lambda = 0.8;
task.setLambda(lambda);
// Add the 3D translation feature to the task
task.addFeature(s, s_star); // s* is here considered as zero
// Control loop
for ( ; ; ) {
// ... cMo need here to be computed from for example a pose estimation.
// Update the current 3D translation visual feature
s.buildFrom(cMo);
// compute the control law
vpColVector v = task.computeControlLaw(); // camera velocity
}
}
Examples
servoAfma6AprilTagPBVS.cpp, servoAfma6MegaposePBVS.cpp, servoFrankaPBVS.cpp, servoSimu3D_cMcd_CamVelocity.cpp, servoSimu3D_cdMc_CamVelocity.cpp, servoSimuPoint2DhalfCamVelocity3.cpp, and servoUniversalRobotsPBVS.cpp.

Definition at line 281 of file vpFeatureTranslation.h.

Member Enumeration Documentation

◆ vpBasicFeatureDeallocatorType

enum vpBasicFeature::vpBasicFeatureDeallocatorType
inherited

Indicates who should deallocate the feature.

Enumerator
user 
vpServo 

Definition at line 88 of file vpBasicFeature.h.

◆ vpBasicFeatureSelect

enum vpBasicFeature::vpBasicFeatureSelect
inherited
Enumerator
FEATURE_ALL 

Definition at line 83 of file vpBasicFeature.h.

◆ vpFeatureTranslationRepresentationType

enum vpFeatureTranslation::vpFeatureTranslationRepresentationType

Kind of implemented 3D translation feature.

Enumerator
cdMc 

Selector used to manipulate the visual feature $s= ^{c^*}t_c$ which gives the position of the current camera frame relative to the desired camera frame.

cMcd 

Selector used to manipulate the visual feature $s= ^{c}t_{c^*}$ which gives the position of the desired camera frame relative to the current camera frame.

cMo 

Selector used to manipulate the visual feature $s= ^{c}t_o$ which gives the position of the object frame relative to the current camera frame.

Definition at line 288 of file vpFeatureTranslation.h.

Constructor & Destructor Documentation

◆ vpFeatureTranslation() [1/3]

vpFeatureTranslation::vpFeatureTranslation ( )

Default constructor that builds a visual feature and initialize it to zero. The type of the translation feature will be vpFeatureTranslation::cdMc by default. Use the function setFeatureTranslationType() to set the desired type of feature.

Definition at line 86 of file vpFeatureTranslation.cpp.

References init().

Referenced by duplicate().

◆ vpFeatureTranslation() [2/3]

vpFeatureTranslation::vpFeatureTranslation ( vpFeatureTranslationRepresentationType  r)

Default constructor that builds a visual feature and initialize it to zero specifying the type.

Parameters
r: Type of considered 3D translation feature.

Definition at line 95 of file vpFeatureTranslation.cpp.

References init().

◆ vpFeatureTranslation() [3/3]

vpFeatureTranslation::vpFeatureTranslation ( vpHomogeneousMatrix &  f2Mf1_,
vpFeatureTranslationRepresentationType  r 
)

Constructor that builds a 3D visual feature from an homogeneous matrix $ ^{{\cal{F}}_2}M_{{\cal{F}}_1} $ that represent the 3D transformation between two frames ${\cal{F}}_1$ and ${\cal{F}}_2$.

Parameters
f2Mf1_[in] : 3D displacement that the camera has to achieve to move from the frame ${\cal{F}}_2$ to the frame ${\cal{F}}_1$ ( $ ^{{\cal{F}}_2}M_{{\cal{F}}_1} $).
r: type of feature. It can be vpFeature::cdMc or vpFeature::cMo.

Definition at line 112 of file vpFeatureTranslation.cpp.

References buildFrom(), and init().

Member Function Documentation

◆ buildFrom()

vpFeatureTranslation & vpFeatureTranslation::buildFrom ( const vpHomogeneousMatrix &  f2Mf1_)

Build a 3D translation visual feature from an homogeneous matrix $ ^{{\cal{F}}_2}M_{{\cal{F}}_1} $ that represent the 3D transformation between two frames ${\cal{F}}_1$ and ${\cal{F}}_2$.

Parameters
f2Mf1_[in] : 3D displacement that the camera has to achieve to move from the frame ${\cal{F}}_2$ to the frame ${\cal{F}}_1$ ( $ ^{{\cal{F}}_2}M_{{\cal{F}}_1} $).

Definition at line 129 of file vpFeatureTranslation.cpp.

References vpBasicFeature::flags, and vpBasicFeature::s.

Referenced by vpFeatureTranslation().

◆ dimension_s()

unsigned int vpBasicFeature::dimension_s ( )
inlineinherited

Return the dimension of the feature vector $\bf s$.

Definition at line 110 of file vpBasicFeature.h.

◆ display() [1/2]

void vpFeatureTranslation::display ( const vpCameraParameters &  cam,
const vpImage< unsigned char > &  I,
const vpColor &  color = vpColor::green,
unsigned int  thickness = 1 
) const
virtual

Not implemented.

Implements vpBasicFeature.

Definition at line 608 of file vpFeatureTranslation.cpp.

◆ display() [2/2]

void vpFeatureTranslation::display ( const vpCameraParameters &  cam,
const vpImage< vpRGBa > &  I,
const vpColor &  color = vpColor::green,
unsigned int  thickness = 1 
) const
virtual

Not implemented.

Implements vpBasicFeature.

Definition at line 625 of file vpFeatureTranslation.cpp.

◆ duplicate()

vpFeatureTranslation * vpFeatureTranslation::duplicate ( ) const
virtual

Feature duplication.

Create an object with the same type.

vpBasicFeature *s_star;
vpFeatureTranslation s(vpFeatureTranslation::cdMc); //or
vpFeatureTranslation s(vpFeatureTranslation::cMo);
s_star = s.duplicate();
// s_star is now a vpFeatureTranslation
vpBasicFeature
class that defines what is a visual feature
Definition: vpBasicFeature.h:79

Implements vpBasicFeature.

Definition at line 591 of file vpFeatureTranslation.cpp.

References cdMc, cMcd, cMo, and vpFeatureTranslation().

◆ error()

vpColVector vpFeatureTranslation::error ( const vpBasicFeature &  s_star,
unsigned int  select = FEATURE_ALL 
)
virtual

Compute the error $ (s-s^*)$ between the current and the desired visual features from a subset of the possible features.

  • With the feature type cdMc: Since this visual feature $ s $ represent the 3D translation from the desired camera frame to the current one $^{c^*}t_{c} $, the desired visual feature $ s^* $ should be zero. Thus, the error is here equal to the current visual feature $ s $.
  • With the feature type cMo: In this case the desired feature is not necessary equal to zero. Thus, the error is here equal to $ s-s^* $.
Parameters
s_star: Desired visual feature.
select: The error can be computed for a selection of a subset of the possible translation features.
  • To compute the error for all the three translation vector coordinates use vpBasicFeature::FEATURE_ALL. In that case the error vector is a 3 dimension column vector.
  • To compute the error for only one of the translation vector coordinate feature $(t_x, t_y, t_z)$ use one of the corresponding function selectTx(), selectTy() or selectTz(). In that case the error vector is a 1 dimension column vector.
Returns
The error $ (s-s^*)$ between the current and the desired visual feature.
Exceptions
vpFeatureException::badInitializationError: If the desired visual feature $ s^* $ is not equal to zero in the case of the feature type is cdMc or cMcd.

The code below shows how to use this method to manipulate the $ t_z $ subset in the case of the cdMc feature type. It can be used also with the cMo feature type. In that case just change vpFeatureTranslation::cdMc by vpFeatureTranslation::cMo during the declaration of the two vpFeatureTranslation features.

// Creation of the current feature s
vpFeatureTranslation s(vpFeatureTranslation::cdMc);
s.set_TUz(0.3); // Initialization of the feature
// Creation of the desired feature s*. By default this feature is
// initialized to zero
vpFeatureTranslation s_star(vpFeatureTranslation::cdMc);
// Compute the interaction matrix for the t_z translation feature
vpMatrix L_z = s.interaction( vpFeatureTranslation::selectTz() );
// Compute the error vector (s-s*) for the t_z feature
s.error(s_star, vpFeatureTranslation::selectTz());
vpFeatureTranslation::selectTz
static unsigned int selectTz()
Definition: vpFeatureTranslation.cpp:772

To manipulate the subset features $s=(t_y, t_z)$, the code becomes:

// Compute the interaction matrix for the t_y, t_z features
vpMatrix L_yz = s.interaction( vpFeatureTranslation::selectTy() | vpFeatureTranslation::selectTz() );
// Compute the error vector e = (s-s*) for the t_y, t_z feature
vpColVector e = s.error(s_star, vpFeatureTranslation::selectTy() | vpFeatureTranslation::selectTz());

Reimplemented from vpBasicFeature.

Definition at line 508 of file vpFeatureTranslation.cpp.

References vpFeatureException::badInitializationError, cdMc, cMcd, vpBasicFeature::get_s(), vpBasicFeature::s, selectTx(), selectTy(), selectTz(), vpColVector::stack(), and vpColVector::sumSquare().

◆ get_s()

vpColVector vpBasicFeature::get_s ( unsigned int  select = FEATURE_ALL) const
inherited

Get the feature vector $\bf s$.

Examples
servoAfma6Ellipse2DCamVelocity.cpp.

Definition at line 115 of file vpBasicFeature.cpp.

References vpBasicFeature::dim_s, vpBasicFeature::FEATURE_LINE, vpBasicFeature::s, and vpColVector::stack().

Referenced by vpServo::computeError(), vpBasicFeature::error(), vpFeatureDepth::error(), vpFeatureThetaU::error(), error(), and vpGenericFeature::error().

◆ get_Tx()

double vpFeatureTranslation::get_Tx ( ) const

Return the $t_x $ subset value of the visual feature $s$.

Definition at line 204 of file vpFeatureTranslation.cpp.

References vpBasicFeature::s.

◆ get_Ty()

double vpFeatureTranslation::get_Ty ( ) const

Return the $t_y $ subset value of the visual feature $s$.

Definition at line 211 of file vpFeatureTranslation.cpp.

References vpBasicFeature::s.

◆ get_Tz()

double vpFeatureTranslation::get_Tz ( ) const

Return the $t_z $ subset value of the visual feature $s$.

Definition at line 218 of file vpFeatureTranslation.cpp.

References vpBasicFeature::s.

◆ getDeallocate()

vpBasicFeatureDeallocatorType vpBasicFeature::getDeallocate ( )
inlineinherited

Definition at line 123 of file vpBasicFeature.h.

◆ getDimension()

unsigned int vpBasicFeature::getDimension ( unsigned int  select = FEATURE_ALL) const
inherited

Get the feature vector dimension.

Examples
testPoint.cpp.

Definition at line 102 of file vpBasicFeature.cpp.

References vpBasicFeature::dim_s, vpBasicFeature::FEATURE_LINE, vpArray2D< Type >::getRows(), and vpBasicFeature::s.

◆ getFeatureTranslationType()

vpFeatureTranslation::vpFeatureTranslationRepresentationType vpFeatureTranslation::getFeatureTranslationType ( ) const

Get the type of translation feature.

Returns
Type of translation feature. It can be vpFeatureTranslation::cdMc, vpFeatureTranslation::cMcd or vpFeatureTranslation::cMo.
See also
setFeatureTranslationType()

Definition at line 194 of file vpFeatureTranslation.cpp.

◆ init()

BEGIN_VISP_NAMESPACE void vpFeatureTranslation::init ( void  )
virtual

Initialise the memory space requested for 3D translation visual feature.

Implements vpBasicFeature.

Definition at line 66 of file vpFeatureTranslation.cpp.

References vpBasicFeature::dim_s, vpBasicFeature::flags, vpBasicFeature::nbParameters, vpColVector::resize(), and vpBasicFeature::s.

Referenced by vpFeatureTranslation().

◆ interaction()

vpMatrix vpFeatureTranslation::interaction ( unsigned int  select = FEATURE_ALL)
virtual

Compute and return the interaction matrix $ L $ from a subset $(t_x, t_y, t_z)$ of the possible translation features that represent the 3D transformation $ ^{{\cal{F}}_2}M_{{\cal{F}}_1} $.

As it exists three different features, the computation of the interaction matrix is diferent for each one.

  • With the feature type cdMc:

    \[ L = [ ^{c^*}R_c \;\; 0_3] \]

where $^{c^*}R_c$ is the rotation the camera has to achieve to move from the desired camera frame to the current camera frame.

  • With the feature type cMcd:

    \[ L = [ -I_3 \;\; [^{c}t_{c^*}]_\times] \]

where $^{c}R_{c^*}$ is the rotation the camera has to achieve to move from the current camera frame to the desired camera frame.

  • With the feature type cMo:

    \[ L = [ -I_3 \;\; [^{c}t_o]_\times] \]

where $^{c}t_o $ is the position of the object frame relative to the current camera frame.

Parameters
select: Selection of a subset of the possible translation features.
  • To compute the interaction matrix for all the three translation subset features $(t_x,t_y,t_y)$ use vpBasicFeature::FEATURE_ALL. In that case the dimension of the interaction matrix is $ [3 \times 6] $
  • To compute the interaction matrix for only one of the translation subset ( $t_x, t_y, t_z$) use one of the corresponding function selectTx(), selectTy() or selectTz(). In that case the returned interaction matrix is $ [1 \times 6] $ dimension.
Returns
The interaction matrix computed from the translation features.

The code below shows how to compute the interaction matrix associated to the visual feature $s = t_x $ using the cdMc feature type.

vpHomogeneousMatrix cdMc;
...
// Creation of the current feature s
vpFeatureTranslation s(vpFeatureTranslation::cdMc);
s.buildFrom(cdMc);
vpMatrix L_x = s.interaction( vpFeatureTranslation::selectTx() );

The code below shows how to compute the interaction matrix associated to the $s = (t_x, t_y) $ subset visual feature:

vpMatrix L_xy = s.interaction( vpFeatureTranslation::selectTx() | vpFeatureTranslation::selectTy() );

L_xy is here now a 2 by 6 matrix. The first line corresponds to the $ t_x $ visual feature while the second one to the $ t_y $ visual feature.

It is also possible to build the interaction matrix from all the translation components by:

vpMatrix L_xyz = s.interaction( vpBasicFeature::FEATURE_ALL );

In that case, L_xyz is a 3 by 6 interaction matrix where the last line corresponds to the $ t_z $ visual feature.

Implements vpBasicFeature.

Definition at line 301 of file vpFeatureTranslation.cpp.

References cdMc, cMcd, cMo, vpBasicFeature::deallocate, vpBasicFeature::flags, vpBasicFeature::nbParameters, vpBasicFeature::resetFlags(), vpBasicFeature::s, selectTx(), selectTy(), selectTz(), vpMatrix::stack(), and vpBasicFeature::user.

◆ operator[]()

virtual double vpBasicFeature::operator[] ( unsigned int  i) const
inlinevirtualinherited

Return element i in the state vector (usage : x = s[i] )

Definition at line 130 of file vpBasicFeature.h.

◆ print()

void vpFeatureTranslation::print ( unsigned int  select = FEATURE_ALL) const
virtual

Print to stdout the values of the current visual feature $ s $.

Parameters
select: Selection of a subset of the possible translation features.
vpHomogeneousMatrix cdMc; // Homogeneous transformation between the desired
camera frame and the current camera frame.
// Creation of the current feature s
vpFeatureTranslation s(vpFeatureTranslation::cdMc);
s.buildFrom(cdMc);
s.print(); // print all the 3 components of the translation feature
s.print(vpBasicFeature::FEATURE_ALL); // same behavior then previous line
s.print(vpFeatureTranslation::selectTz()); // print only the t_z component
vpColVector::print
int print(std::ostream &s, unsigned int length, char const *intro=0) const
Definition: vpColVector.cpp:802

Implements vpBasicFeature.

Definition at line 563 of file vpFeatureTranslation.cpp.

References vpBasicFeature::s, selectTx(), selectTy(), and selectTz().

◆ resetFlags()

void vpBasicFeature::resetFlags ( )
protectedinherited

Definition at line 132 of file vpBasicFeature.cpp.

References vpBasicFeature::flags, and vpBasicFeature::nbParameters.

Referenced by vpFeatureVanishingPoint::interaction(), vpFeatureDepth::interaction(), vpFeatureEllipse::interaction(), vpFeatureLine::interaction(), vpFeaturePoint::interaction(), vpFeaturePoint3D::interaction(), vpFeaturePointPolar::interaction(), vpFeatureThetaU::interaction(), and interaction().

◆ selectAll()

static unsigned int vpBasicFeature::selectAll ( )
inlinestaticinherited

Select all the features.

Examples
testPoint.cpp.

Definition at line 142 of file vpBasicFeature.h.

◆ selectTx()

unsigned int vpFeatureTranslation::selectTx ( )
static

Function used to select the $ t_x$ subset of the translation visual feature.

This function is to use in conjunction with interaction() in order to compute the interaction matrix associated to $ t_x$.

See the interaction() method for an usage example.

This function is also useful in the vpServo class to indicate that a subset of the visual feature is to use in the control law:

See also
selectTy(), selectTz()

Definition at line 682 of file vpFeatureTranslation.cpp.

References vpBasicFeature::FEATURE_LINE.

Referenced by error(), interaction(), and print().

◆ selectTy()

unsigned int vpFeatureTranslation::selectTy ( )
static

Function used to select the $ t_y$ subset of the translation visual feature.

This function is to use in conjunction with interaction() in order to compute the interaction matrix associated to $ t_y$.

See the interaction() method for an usage example.

This function is also useful in the vpServo class to indicate that a subset of the visual feature is to use in the control law:

See also
selectTx(), selectTz()

Definition at line 727 of file vpFeatureTranslation.cpp.

References vpBasicFeature::FEATURE_LINE.

Referenced by error(), interaction(), and print().

◆ selectTz()

unsigned int vpFeatureTranslation::selectTz ( )
static

Function used to select the $ t_z$ subset of the translation visual feature.

This function is to use in conjunction with interaction() in order to compute the interaction matrix associated to $ t_z$.

See the interaction() method for an usage example.

This function is also useful in the vpServo class to indicate that a subset of the visual feature is to use in the control law:

See also
selectTx(), selectTy()

Definition at line 772 of file vpFeatureTranslation.cpp.

References vpBasicFeature::FEATURE_LINE.

Referenced by error(), interaction(), and print().

◆ set_Tx()

void vpFeatureTranslation::set_Tx ( double  t_x)

Initialise the $t_x $ subset value of the 3D visual feature $ s$.

Parameters
t_x: $t_x $ subset value to initialize.
See also
get_Tx()

Definition at line 163 of file vpFeatureTranslation.cpp.

References vpBasicFeature::s.

◆ set_Ty()

void vpFeatureTranslation::set_Ty ( double  t_y)

Initialise the $t_y $ subset value of the 3D visual feature $ s$.

Parameters
t_y: $t_y $ subset value to initialize.
See also
get_Ty()

Definition at line 173 of file vpFeatureTranslation.cpp.

References vpBasicFeature::s.

◆ set_Tz()

void vpFeatureTranslation::set_Tz ( double  t_z)

Initialise the $t_z $ subset value of the 3D visual feature $ s$.

Parameters
t_z: $t_z $ subset value to initialize.
See also
get_Tz()

Definition at line 183 of file vpFeatureTranslation.cpp.

References vpBasicFeature::s.

◆ setDeallocate()

void vpBasicFeature::setDeallocate ( vpBasicFeatureDeallocatorType  d)
inlineinherited

Definition at line 137 of file vpBasicFeature.h.

Referenced by vpServo::addFeature().

◆ setFeatureTranslationType()

void vpFeatureTranslation::setFeatureTranslationType ( const vpFeatureTranslationRepresentationType  r)

Set the type of translation feature.

Parameters
r: type of translation feature. It can be vpFeatureTranslation::cdMc, vpFeatureTranslation::cMcd or vpFeatureTranslation::cMo.
See also
getFeatureTranslationType()

Definition at line 149 of file vpFeatureTranslation.cpp.

◆ setFlags()

void vpBasicFeature::setFlags ( )
inherited

Set feature flags to true to prevent warning when re-computing the interaction matrix without having updated the feature.

Definition at line 142 of file vpBasicFeature.cpp.

References vpBasicFeature::flags, and vpBasicFeature::nbParameters.

Member Data Documentation

◆ deallocate

vpBasicFeatureDeallocatorType vpBasicFeature::deallocate
protectedinherited

Definition at line 148 of file vpBasicFeature.h.

Referenced by vpFeatureVanishingPoint::interaction(), vpFeatureDepth::interaction(), vpFeatureEllipse::interaction(), vpFeatureLine::interaction(), vpFeaturePoint::interaction(), vpFeaturePoint3D::interaction(), vpFeaturePointPolar::interaction(), vpFeatureSegment::interaction(), vpFeatureThetaU::interaction(), interaction(), and vpBasicFeature::operator=().

◆ dim_s

unsigned int vpBasicFeature::dim_s
protectedinherited

Dimension of the visual feature.

Definition at line 94 of file vpBasicFeature.h.

Referenced by vpFeatureMoment::duplicate(), vpGenericFeature::duplicate(), vpBasicFeature::error(), vpFeatureLuminanceMapping::error(), vpGenericFeature::error(), vpFeatureLuminance::error(), vpBasicFeature::get_s(), vpGenericFeature::get_s(), vpBasicFeature::getDimension(), vpFeatureMoment::getDimension(), vpFeatureDepth::init(), vpFeatureEllipse::init(), vpFeatureLine::init(), vpFeatureLuminanceMapping::init(), vpFeaturePoint::init(), vpFeaturePoint3D::init(), vpFeaturePointPolar::init(), vpFeatureSegment::init(), vpFeatureThetaU::init(), init(), vpFeatureVanishingPoint::init(), vpFeatureLuminance::init(), vpFeatureMoment::init(), vpFeatureLuminanceMapping::interaction(), vpFeatureMoment::interaction(), vpGenericFeature::interaction(), vpFeatureLuminance::interaction(), vpBasicFeature::operator=(), vpFeatureLuminance::operator=(), vpFeatureLuminanceMapping::operator=(), vpFeatureMoment::print(), vpGenericFeature::print(), vpGenericFeature::set_s(), vpGenericFeature::setError(), vpGenericFeature::setInteractionMatrix(), vpFeatureMoment::update(), vpFeatureLuminance::vpFeatureLuminance(), and vpGenericFeature::vpGenericFeature().

◆ FEATURE_LINE

BEGIN_VISP_NAMESPACE const unsigned int vpBasicFeature::FEATURE_LINE
staticinherited
Initial value:
= {
(unsigned int)(1 << 0), (unsigned int)(1 << 1), (unsigned int)(1 << 2), (unsigned int)(1 << 3),
(unsigned int)(1 << 4), (unsigned int)(1 << 5), (unsigned int)(1 << 6), (unsigned int)(1 << 7),
(unsigned int)(1 << 8), (unsigned int)(1 << 9), (unsigned int)(1 << 10), (unsigned int)(1 << 11),
(unsigned int)(1 << 12), (unsigned int)(1 << 13), (unsigned int)(1 << 14), (unsigned int)(1 << 15),
(unsigned int)(1 << 16), (unsigned int)(1 << 17), (unsigned int)(1 << 18), (unsigned int)(1 << 19),
(unsigned int)(1 << 20), (unsigned int)(1 << 21), (unsigned int)(1 << 22), (unsigned int)(1 << 23),
(unsigned int)(1 << 24), (unsigned int)(1 << 25), (unsigned int)(1 << 26), (unsigned int)(1 << 27),
(unsigned int)(1 << 28), (unsigned int)(1 << 29), (unsigned int)(1 << 30), (unsigned int)(1 << 31) }

Definition at line 81 of file vpBasicFeature.h.

Referenced by vpBasicFeature::error(), vpGenericFeature::error(), vpBasicFeature::get_s(), vpBasicFeature::getDimension(), vpFeatureMoment::getDimension(), vpFeatureMoment::interaction(), vpGenericFeature::interaction(), vpFeatureMoment::print(), vpGenericFeature::print(), vpFeatureEllipse::select_n02(), vpFeatureEllipse::select_n11(), vpFeatureEllipse::select_n20(), vpFeatureSegment::selectAlpha(), vpFeatureVanishingPoint::selectAlpha(), vpFeatureVanishingPoint::selectAtanOneOverRho(), vpFeatureSegment::selectL(), vpFeatureVanishingPoint::selectOneOverRho(), vpFeatureLine::selectRho(), vpFeaturePointPolar::selectRho(), vpFeatureLine::selectTheta(), vpFeaturePointPolar::selectTheta(), vpFeatureThetaU::selectTUx(), vpFeatureThetaU::selectTUy(), vpFeatureThetaU::selectTUz(), selectTx(), selectTy(), selectTz(), vpFeatureEllipse::selectX(), vpFeaturePoint::selectX(), vpFeaturePoint3D::selectX(), vpFeatureVanishingPoint::selectX(), vpFeatureSegment::selectXc(), vpFeatureEllipse::selectY(), vpFeaturePoint::selectY(), vpFeaturePoint3D::selectY(), vpFeatureVanishingPoint::selectY(), vpFeatureSegment::selectYc(), and vpFeaturePoint3D::selectZ().

◆ flags

bool* vpBasicFeature::flags
protectedinherited

Ensure that all the parameters needed to compute the interaction matrix are set.

Definition at line 98 of file vpBasicFeature.h.

Referenced by vpFeatureLine::buildFrom(), vpFeaturePointPolar::buildFrom(), vpFeatureEllipse::buildFrom(), vpFeaturePoint::buildFrom(), vpFeatureDepth::buildFrom(), buildFrom(), vpFeaturePoint3D::buildFrom(), vpFeatureThetaU::buildFrom(), vpFeatureMoment::duplicate(), vpFeatureDepth::init(), vpFeatureEllipse::init(), vpFeatureLine::init(), vpFeatureLuminance::init(), vpFeaturePoint::init(), vpFeaturePoint3D::init(), vpFeaturePointPolar::init(), vpFeatureSegment::init(), vpFeatureThetaU::init(), init(), vpFeatureVanishingPoint::init(), vpFeatureMoment::init(), vpFeatureVanishingPoint::interaction(), vpFeatureDepth::interaction(), vpFeatureEllipse::interaction(), vpFeatureLine::interaction(), vpFeaturePoint::interaction(), vpFeaturePoint3D::interaction(), vpFeaturePointPolar::interaction(), vpFeatureSegment::interaction(), vpFeatureThetaU::interaction(), interaction(), vpBasicFeature::operator=(), vpBasicFeature::resetFlags(), vpFeaturePointPolar::set_rho(), vpFeaturePointPolar::set_rhoThetaZ(), vpFeaturePointPolar::set_theta(), vpFeatureThetaU::set_TUx(), vpFeatureThetaU::set_TUy(), vpFeatureThetaU::set_TUz(), vpFeatureDepth::set_x(), vpFeatureEllipse::set_x(), vpFeaturePoint::set_x(), vpFeaturePoint3D::set_X(), vpFeatureVanishingPoint::set_x(), vpFeatureEllipse::set_xy(), vpFeaturePoint::set_xyZ(), vpFeaturePoint3D::set_XYZ(), vpFeatureDepth::set_xyZLogZoverZstar(), vpFeatureDepth::set_y(), vpFeatureEllipse::set_y(), vpFeaturePoint::set_y(), vpFeaturePoint3D::set_Y(), vpFeatureVanishingPoint::set_y(), vpFeatureDepth::set_Z(), vpFeatureLuminance::set_Z(), vpFeaturePoint::set_Z(), vpFeaturePoint3D::set_Z(), vpFeaturePointPolar::set_Z(), vpFeatureEllipse::setABC(), vpFeatureLine::setABCD(), vpFeatureVanishingPoint::setAlpha(), vpFeatureVanishingPoint::setAtanOneOverRho(), vpBasicFeature::setFlags(), vpFeatureEllipse::setMoments(), vpFeatureVanishingPoint::setOneOverRho(), vpFeatureLine::setRhoTheta(), vpFeatureMoment::update(), vpFeatureLuminance::vpFeatureLuminance(), and vpBasicFeature::~vpBasicFeature().

◆ nbParameters

unsigned int vpBasicFeature::nbParameters
protectedinherited

Number of parameters needed to compute the interaction matrix.

Definition at line 100 of file vpBasicFeature.h.

Referenced by vpFeatureLine::buildFrom(), vpFeaturePointPolar::buildFrom(), vpFeatureEllipse::buildFrom(), vpFeaturePoint::buildFrom(), vpFeatureDepth::buildFrom(), vpFeaturePoint3D::buildFrom(), vpFeatureThetaU::buildFrom(), vpFeatureMoment::duplicate(), vpFeatureDepth::init(), vpFeatureEllipse::init(), vpFeatureLine::init(), vpFeatureLuminance::init(), vpFeaturePoint::init(), vpFeaturePoint3D::init(), vpFeaturePointPolar::init(), vpFeatureSegment::init(), vpFeatureThetaU::init(), init(), vpFeatureVanishingPoint::init(), vpFeatureMoment::init(), vpFeatureVanishingPoint::interaction(), vpFeatureDepth::interaction(), vpFeatureEllipse::interaction(), vpFeatureLine::interaction(), vpFeaturePoint::interaction(), vpFeaturePoint3D::interaction(), vpFeaturePointPolar::interaction(), vpFeatureSegment::interaction(), vpFeatureThetaU::interaction(), interaction(), vpBasicFeature::operator=(), vpBasicFeature::resetFlags(), vpFeaturePointPolar::set_rhoThetaZ(), vpFeaturePoint::set_xyZ(), vpFeaturePoint3D::set_XYZ(), vpFeatureDepth::set_xyZLogZoverZstar(), vpFeatureEllipse::setABC(), vpFeatureLine::setABCD(), vpBasicFeature::setFlags(), vpFeatureMoment::update(), and vpFeatureLuminance::vpFeatureLuminance().

◆ s

vpColVector vpBasicFeature::s
protectedinherited

State of the visual feature.

Definition at line 92 of file vpBasicFeature.h.

Referenced by vpFeatureLine::buildFrom(), vpFeaturePointPolar::buildFrom(), vpFeatureEllipse::buildFrom(), vpFeaturePoint::buildFrom(), vpFeatureDepth::buildFrom(), buildFrom(), vpFeaturePoint3D::buildFrom(), vpFeatureThetaU::buildFrom(), vpFeatureLuminance::buildFrom(), vpFeatureLuminanceMapping::buildFrom(), vpFeatureEllipse::display(), vpFeatureMoment::duplicate(), vpFeatureVanishingPoint::error(), vpBasicFeature::error(), vpFeatureDepth::error(), vpFeatureEllipse::error(), vpFeatureLine::error(), vpFeatureMomentAlpha::error(), vpFeaturePoint::error(), vpFeaturePoint3D::error(), vpFeaturePointPolar::error(), vpFeatureThetaU::error(), error(), vpGenericFeature::error(), vpFeatureLuminance::error(), vpFeatureLuminanceMapping::error(), vpFeatureDepth::get_LogZoverZstar(), vpFeaturePointPolar::get_rho(), vpBasicFeature::get_s(), vpGenericFeature::get_s(), vpFeaturePointPolar::get_theta(), vpFeatureThetaU::get_TUx(), vpFeatureThetaU::get_TUy(), vpFeatureThetaU::get_TUz(), get_Tx(), get_Ty(), get_Tz(), vpFeaturePoint::get_x(), vpFeaturePoint3D::get_X(), vpFeatureVanishingPoint::get_x(), vpFeaturePoint::get_y(), vpFeaturePoint3D::get_Y(), vpFeatureVanishingPoint::get_y(), vpFeaturePoint3D::get_Z(), vpFeatureVanishingPoint::getAlpha(), vpFeatureVanishingPoint::getAtanOneOverRho(), vpBasicFeature::getDimension(), vpFeatureVanishingPoint::getOneOverRho(), vpFeatureDepth::init(), vpFeatureEllipse::init(), vpFeatureLine::init(), vpFeaturePoint::init(), vpFeaturePoint3D::init(), vpFeaturePointPolar::init(), vpFeatureSegment::init(), vpFeatureThetaU::init(), init(), vpFeatureVanishingPoint::init(), vpGenericFeature::init(), vpFeatureLuminanceMapping::init(), vpFeatureLuminance::init(), vpFeatureMoment::init(), vpFeatureEllipse::interaction(), vpFeatureLine::interaction(), vpFeatureThetaU::interaction(), interaction(), vpFeatureLuminanceMapping::interaction(), vpBasicFeature::operator=(), vpFeatureLuminance::operator=(), vpFeatureLuminanceMapping::operator=(), vpFeatureEllipse::print(), vpFeatureLine::print(), vpFeatureLuminanceMapping::print(), vpFeatureMoment::print(), vpFeatureSegment::print(), vpFeatureThetaU::print(), print(), vpGenericFeature::print(), vpFeatureDepth::set_LogZoverZstar(), vpFeaturePointPolar::set_rho(), vpGenericFeature::set_s(), vpFeaturePointPolar::set_theta(), vpFeatureThetaU::set_TUx(), vpFeatureThetaU::set_TUy(), vpFeatureThetaU::set_TUz(), set_Tx(), set_Ty(), set_Tz(), vpFeatureEllipse::set_x(), vpFeaturePoint::set_x(), vpFeaturePoint3D::set_X(), vpFeatureVanishingPoint::set_x(), vpFeatureEllipse::set_xy(), vpFeatureEllipse::set_y(), vpFeaturePoint::set_y(), vpFeaturePoint3D::set_Y(), vpFeatureVanishingPoint::set_y(), vpFeaturePoint3D::set_Z(), vpFeatureVanishingPoint::setAlpha(), vpFeatureVanishingPoint::setAtanOneOverRho(), vpFeatureEllipse::setMoments(), vpFeatureVanishingPoint::setOneOverRho(), vpFeatureLine::setRhoTheta(), vpFeatureMoment::update(), and vpGenericFeature::vpGenericFeature().