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vpCameraParameters Class Reference
Mathematics » Transformations » Other related transformations » Camera modelsComputer Vision » | Camera models

#include <vpCameraParameters.h>

Public Types

enum  vpCameraParametersProjType { perspectiveProjWithoutDistortion, perspectiveProjWithDistortion }
 

Public Member Functions

 vpCameraParameters ()
 
 vpCameraParameters (const vpCameraParameters &c)
 
 vpCameraParameters (const double px, const double py, const double u0, const double v0)
 
 vpCameraParameters (const double px, const double py, const double u0, const double v0, const double kud, const double kdu)
 
vpCameraParameters & operator= (const vpCameraParameters &c)
 
virtual ~vpCameraParameters ()
 
void init ()
 
void init (const vpCameraParameters &c)
 
void initFromCalibrationMatrix (const vpMatrix &_K)
 
void initPersProjWithoutDistortion (const double px, const double py, const double u0, const double v0)
 
void initPersProjWithDistortion (const double px, const double py, const double u0, const double v0, const double kud, const double kdu)
 
double get_px () const
 
double get_px_inverse () const
 
double get_py_inverse () const
 
double get_py () const
 
double get_u0 () const
 
double get_v0 () const
 
double get_kud () const
 
double get_kdu () const
 
vpCameraParametersProjType get_projModel () const
 
vpMatrix get_K () const
 
void printParameters ()
 

Friends

class vpMeterPixelConversion
 
class vpPixelMeterConversion
 
VISP_EXPORT std::ostream & operator<< (std::ostream &os, const vpCameraParameters &cam)
 

Detailed Description

Generic class defining intrinsic camera parameters.

Two kinds of camera modelisation are implemented:

  • Camera parameters for a perspective projection without distortion model,
  • Camera parameters for a perspective projection with distortion model.

The main intrinsic camera parameters are $(p_x, p_y)$ the ratio between the focal length and the size of a pixel, and $(u_0, v_0)$ the coordinates of the principal point in pixel. The lens distorsion can also be considered by two additional parameters $(k_{ud}, k_{du})$.

1. Camera parameters for a perspective projection without distortion model

In this modelisation, only $u_0,v_0,p_x,p_y$ parameters are used. If we denote $(u,v)$ the position of a pixel in the digitized image, this position is related to the corresponding coordinates $(x,y)$ in the normalized space (in meter) by:

\[ \left\{ \begin{array}{l} u = u_0 + p_x x \\ v = v_0 + p_y y \end{array}\right. \]

The conversion from pixel coordinates $(u,v)$ in the normalized space $(x,y)$ is implemented in vpPixelMeterConversion, whereas the conversion from normalized coordinates into pixel is implemented in vpMeterPixelConversion.

2. Camera parameters for a perspective projection with distortion model

In this modelisation, $u_0,v_0,p_x,p_y,k_{ud},k_{du}$ parameters are used. If a model with distortion is considered, we got:

\[ \left\{ \begin{array}{l} u = u_0 + p_x x + \delta_u \\ v = v_0 + p_y y + \delta_v \end{array}\right. \]

where $\delta_u$ and $\delta_v$ are geometrical distortions introduced in the camera model. These distortions are due to imperfections in the lenses design and assembly there usually are some positional errors that have to be taken into account. $\delta_u$ and $\delta_v$ can be modeled as follow:

  • with an undistorted to distorted model

    \[ \left\{ \begin{array}{l} \delta_u(x,y) = k_{ud} \;r^2\; p_x x \\ \\ \delta_v(x,y) = k_{ud}\; r^2\; p_y y \end{array}\right. \]

    with

    \[ r^2 = x^2 + y^2 \]

    This model is useful to convert meter to pixel coordinates because in this case :

    \[ \left\{ \begin{array}{l} u = f_u(x,y) = u_0 + p_x x\left(1+k_{ud}\left(x^2 + y^2\right)\right) \\ \\ v = f_v(x,y) = v_0 + p_y y\left(1+k_{ud}\left(x^2 + y^2\right)\right) \end{array}\right. \]

    The conversion from normalized coordinates $(x,y)$ into pixel $(u,v)$ is implemented in vpMeterPixelConversion.
  • or with a distorted to undistorted model

    \[ \left\{ \begin{array}{l} \delta_u(u,v) = -k_{du} \;r^2\; \left(u-u_0\right) \\ \\ \delta_v(u,v) = -k_{du}\; r^2\; \left(v-v_0\right) \end{array}\right. \]

    with

    \[ r^2 = {\left(\frac{u-u_0}{p_{x}}\right)}^2 + {\left(\frac{v-v_0}{p_{y}}\right)}^2 \]

    This model is useful to convert pixel to meter coordinates because in this case :

    \[ \left\{ \begin{array}{l} x = f_x(u,v) = \frac{u-u_0}{p_x}\left(1+k_{du}\left( {\left(\frac{u-u_0}{p_{x}}\right)}^2 + {\left(\frac{v-v_0}{p_{y}}\right)}^2 \right)\right) \\ \\ y = f_y(u,v) = \frac{v-v_0}{p_y}\left(1+k_{du}\left( {\left(\frac{u-u_0}{p_{x}}\right)}^2 + {\left(\frac{v-v_0}{p_{y}}\right)}^2 \right)\right) \end{array}\right. \]

    The conversion from pixel coordinates $(u,v)$ in the normalized space $(x,y)$ is implemented in vpPixelMeterConversion.

The selection of one of these modelisations is done during vpCameraParameters initialisation.

Here an example of camera initialisation, for a model without distortion:

double px = 600;
double py = 600;
double u0 = 320;
double v0 = 240;
// Create a camera parameter container
vpCameraParameters cam;
// Camera initialization with a perspective projection without distortion model
cam.initPersProjWithoutDistortion(px,py,u0,v0);
// It is also possible to print the current camera parameters
std::cout << cam << std::endl;

Here an example of camera initialisation, for a model with distortion:

double px = 600;
double py = 600;
double u0 = 320;
double v0 = 240;
double kud = -0.19;
double kdu = 0.20;
// Create a camera parameter container
vpCameraParameters cam;
// Camera initialization with a perspective projection without distortion model
cam.initPersProjWithDistortion(px,py,u0,v0,kud,kdu);

The code below shows how to know the currently used projection model:

vpCameraParameters cam;
...
vpCameraParameters::vpCameraParametersProjType projModel;
projModel = cam.get_projModel(); // Get the projection model type

An XML parser for camera parameters is also provided in vpXmlParserCamera.

Examples:
AROgre.cpp, AROgreBasic.cpp, calibrate2dGrid.cpp, HelloWorldOgre.cpp, HelloWorldOgreAdvanced.cpp, manGeometricFeatures.cpp, manServo4PointsDisplay.cpp, manSimu4Dots.cpp, manSimu4Points.cpp, mbtTracking.cpp, photometricVisualServoing.cpp, poseVirtualVS.cpp, servoAfma4Point2DArtVelocity.cpp, servoAfma4Point2DCamVelocity.cpp, servoAfma4Point2DCamVelocityKalman.cpp, servoAfma62DhalfCamVelocity.cpp, servoAfma6Cylinder2DCamVelocity.cpp, servoAfma6Cylinder2DCamVelocitySecondaryTask.cpp, servoAfma6Ellipse2DCamVelocity.cpp, servoAfma6FourPoints2DArtVelocity.cpp, servoAfma6FourPoints2DCamVelocityInteractionCurrent.cpp, servoAfma6FourPoints2DCamVelocityInteractionDesired.cpp, servoAfma6Line2DCamVelocity.cpp, servoAfma6Point2DArtVelocity.cpp, servoAfma6Point2DCamVelocity.cpp, servoAfma6Points2DCamVelocityEyeToHand.cpp, servoAfma6Segment2DCamVelocity.cpp, servoAfma6SquareLines2DCamVelocity.cpp, servoAfma6TwoLines2DCamVelocity.cpp, servoBiclopsPoint2DArtVelocity.cpp, servoMomentImage.cpp, servoMomentPoints.cpp, servoMomentPolygon.cpp, servoPioneerPanSegment3D.cpp, servoPioneerPoint2DDepth.cpp, servoPioneerPoint2DDepthWithoutVpServo.cpp, servoPtu46Point2DArtVelocity.cpp, servoSimu4Points.cpp, servoSimuAfma6FourPoints2DCamVelocity.cpp, servoSimuCircle2DCamVelocityDisplay.cpp, servoSimuCylinder.cpp, servoSimuCylinder2DCamVelocityDisplay.cpp, servoSimuCylinder2DCamVelocityDisplaySecondaryTask.cpp, servoSimuFourPoints2DCamVelocityDisplay.cpp, servoSimuFourPoints2DPolarCamVelocityDisplay.cpp, servoSimuLine2DCamVelocityDisplay.cpp, servoSimuSphere.cpp, servoSimuSquareLine2DCamVelocityDisplay.cpp, servoSimuViper850FourPoints2DCamVelocity.cpp, servoViper850FourPoints2DArtVelocityInteractionCurrent.cpp, servoViper850FourPoints2DArtVelocityInteractionDesired.cpp, servoViper850FourPoints2DCamVelocityInteractionCurrent.cpp, servoViper850FourPointsKinect.cpp, servoViper850Point2DArtVelocity-jointAvoidance-basic.cpp, servoViper850Point2DArtVelocity-jointAvoidance-gpa.cpp, servoViper850Point2DArtVelocity.cpp, servoViper850Point2DCamVelocity.cpp, servoViper850Point2DCamVelocityKalman.cpp, simulateCircle2DCamVelocity.cpp, simulateFourPoints2DCartesianCamVelocity.cpp, simulateFourPoints2DPolarCamVelocity.cpp, testAfma6.cpp, testFeatureSegment.cpp, testRobotAfma6.cpp, testRobotAfma6Pose.cpp, testRobotViper850.cpp, testRobotViper850Pose.cpp, testTrackDot.cpp, testUndistortImage.cpp, testViper850.cpp, trackMeLine.cpp, and wireframeSimulator.cpp.

Definition at line 197 of file vpCameraParameters.h.

Member Enumeration Documentation

enum vpCameraParameters::vpCameraParametersProjType
Enumerator
perspectiveProjWithoutDistortion 

Perspective projection without distortion model.

perspectiveProjWithDistortion 

Perspective projection with distortion model.

Definition at line 202 of file vpCameraParameters.h.

Constructor & Destructor Documentation

vpCameraParameters::vpCameraParameters ( )

Default constructor. By default, a perspective projection without distortion model is set.

See also
init()

Definition at line 73 of file vpCameraParameters.cpp.

References init().

vpCameraParameters::vpCameraParameters ( const vpCameraParameters &  c)

Copy constructor

Definition at line 81 of file vpCameraParameters.cpp.

References init().

vpCameraParameters::vpCameraParameters ( const double  px,
const double  py,
const double  u0,
const double  v0 
)

Constructor for perspective projection without distortion model

Parameters
px,py: pixel size
u0,v0: principal points

Definition at line 93 of file vpCameraParameters.cpp.

References initPersProjWithoutDistortion().

vpCameraParameters::vpCameraParameters ( const double  px,
const double  py,
const double  u0,
const double  v0,
const double  kud,
const double  kdu 
)

Constructor for perspective projection with distortion model

Parameters
px,py: pixel size
u0,v0: principal points
kud: undistorted to distorted radial distortion
kdu: distorted to undistorted radial distortion

Definition at line 108 of file vpCameraParameters.cpp.

References initPersProjWithDistortion().

vpCameraParameters::~vpCameraParameters ( )
virtual

destructor

nothing much to destroy...

Definition at line 224 of file vpCameraParameters.cpp.

Member Function Documentation

vpMatrix vpCameraParameters::get_K ( ) const

return the calibration matrix K

K is 3x3 matrix given by:

$ K = \left(\begin{array}{ccc} p_x & 0 & u_0 \\ 0 & p_y & v_0 \\ 0 & 0 & 1 \end{array} \right) $

Warning
: this function is useful only in the case of perspective projection without distortion.

Definition at line 299 of file vpCameraParameters.cpp.

References vpException::notImplementedError, perspectiveProjWithDistortion, perspectiveProjWithoutDistortion, vpMatrix::resize(), and vpERROR_TRACE.

Referenced by vpMbEdgeTracker::downScale(), vpPose::poseFromRectangle(), and vpMbEdgeTracker::upScale().

double vpCameraParameters::get_kdu ( ) const
inline

Definition at line 236 of file vpCameraParameters.h.

Referenced by vpCalibration::computeStdDeviation_dist().

double vpCameraParameters::get_kud ( ) const
inline

Definition at line 235 of file vpCameraParameters.h.

Referenced by vpCalibration::computeStdDeviation_dist(), vpCalibration::displayGrid(), and vpImageTools::undistort().

vpCameraParametersProjType vpCameraParameters::get_projModel ( ) const
inline

Definition at line 238 of file vpCameraParameters.h.

Referenced by vpXmlParserCamera::save().

double vpCameraParameters::get_px ( ) const
inline
Examples:
calibrate2dGrid.cpp, servoPioneerPanSegment3D.cpp, servoPioneerPoint2DDepth.cpp, and servoPioneerPoint2DDepthWithoutVpServo.cpp.

Definition at line 229 of file vpCameraParameters.h.

Referenced by vpFeatureLuminance::buildFrom(), vpCalibration::computeStdDeviation(), vpCalibration::computeStdDeviation_dist(), vpMbEdgeTracker::computeVVS(), vpCalibration::displayGrid(), vpSimulatorAfma6::initDisplay(), vpSimulatorViper850::initDisplay(), vpSimulatorAfma6::setCameraParameters(), vpSimulatorViper850::setCameraParameters(), vpSimulator::setExternalCameraParameters(), vpWireFrameSimulator::setExternalCameraParameters(), vpSimulator::setInternalCameraParameters(), vpWireFrameSimulator::setInternalCameraParameters(), vpImageTools::undistort(), and vpAROgre::updateCameraProjection().

double vpCameraParameters::get_px_inverse ( ) const
inline

Definition at line 230 of file vpCameraParameters.h.

double vpCameraParameters::get_py ( ) const
inline
Examples:
servoPioneerPanSegment3D.cpp, servoPioneerPoint2DDepth.cpp, and servoPioneerPoint2DDepthWithoutVpServo.cpp.

Definition at line 232 of file vpCameraParameters.h.

Referenced by vpFeatureLuminance::buildFrom(), vpCalibration::computeStdDeviation(), vpCalibration::computeStdDeviation_dist(), vpCalibration::displayGrid(), vpSimulatorAfma6::initDisplay(), vpSimulatorViper850::initDisplay(), vpSimulatorAfma6::setCameraParameters(), vpSimulatorViper850::setCameraParameters(), vpSimulator::setExternalCameraParameters(), vpWireFrameSimulator::setExternalCameraParameters(), vpSimulator::setInternalCameraParameters(), vpWireFrameSimulator::setInternalCameraParameters(), vpImageTools::undistort(), and vpAROgre::updateCameraProjection().

double vpCameraParameters::get_py_inverse ( ) const
inline

Definition at line 231 of file vpCameraParameters.h.

double vpCameraParameters::get_u0 ( ) const
inline
Examples:
servoAfma4Point2DCamVelocityKalman.cpp, and servoPioneerPanSegment3D.cpp.

Definition at line 233 of file vpCameraParameters.h.

Referenced by vpCalibration::computeStdDeviation(), vpCalibration::computeStdDeviation_dist(), vpCalibration::displayGrid(), vpImageTools::undistort(), and vpAROgre::updateCameraProjection().

double vpCameraParameters::get_v0 ( ) const
inline
Examples:
servoAfma4Point2DCamVelocityKalman.cpp.

Definition at line 234 of file vpCameraParameters.h.

Referenced by vpCalibration::computeStdDeviation(), vpCalibration::computeStdDeviation_dist(), vpCalibration::displayGrid(), vpImageTools::undistort(), and vpAROgre::updateCameraProjection().

void vpCameraParameters::init ( )

basic initialization with the default parameters

Examples:
AROgre.cpp, and AROgreBasic.cpp.

Definition at line 119 of file vpCameraParameters.cpp.

References vpException::divideByZeroError, and vpERROR_TRACE.

Referenced by vpCameraParameters().

void vpCameraParameters::init ( const vpCameraParameters &  c)

initialization from another vpCameraParameters object

Definition at line 232 of file vpCameraParameters.cpp.

void vpCameraParameters::initFromCalibrationMatrix ( const vpMatrix &  _K)

initialise the camera from a calibration matrix. Using a calibration matrix leads to a camera without distorsion

The K matrix in parameters must be like:

$ K = \left(\begin{array}{ccc} p_x & 0 & u_0 \\ 0 & p_y & v_0 \\ 0 & 0 & 1 \end{array} \right) $

Parameters
_K: the 3by3 calibration matrix

Definition at line 253 of file vpCameraParameters.cpp.

References vpException::badValue, vpException::dimensionError, vpMatrix::getCols(), vpMatrix::getRows(), and initPersProjWithoutDistortion().

Referenced by vpMbEdgeTracker::downScale(), and vpMbEdgeTracker::upScale().

void vpCameraParameters::initPersProjWithDistortion ( const double  px,
const double  py,
const double  u0,
const double  v0,
const double  kud,
const double  kdu 
)

Initialization with specific parameters using perpective projection with distortion model.

Parameters
px,py: pixel size
u0,v0: principal points
kud: undistorted to distorted radial distortion
kdu: distorted to undistorted radial distortion
Examples:
testUndistortImage.cpp.

Definition at line 190 of file vpCameraParameters.cpp.

References vpException::divideByZeroError, perspectiveProjWithDistortion, and vpERROR_TRACE.

Referenced by vpViper850::getCameraParameters(), vpAfma6::getCameraParameters(), vpKinect::start(), and vpCameraParameters().

void vpCameraParameters::initPersProjWithoutDistortion ( const double  px,
const double  py,
const double  u0,
const double  v0 
)

Initialization with specific parameters using perpective projection without distortion model.

Parameters
px,py: pixel size
u0,v0: principal point
Examples:
calibrate2dGrid.cpp, servoPioneerPanSegment3D.cpp, servoPioneerPoint2DDepth.cpp, and servoPioneerPoint2DDepthWithoutVpServo.cpp.

Definition at line 153 of file vpCameraParameters.cpp.

References vpException::divideByZeroError, perspectiveProjWithoutDistortion, and vpERROR_TRACE.

Referenced by vpViper850::getCameraParameters(), vpServolens::getCameraParameters(), vpAfma6::getCameraParameters(), vpSimulatorAfma6::getCameraParameters(), vpSimulatorViper850::getCameraParameters(), vpSimulatorAfma6::initDisplay(), vpSimulatorViper850::initDisplay(), initFromCalibrationMatrix(), and vpCameraParameters().

vpCameraParameters & vpCameraParameters::operator= ( const vpCameraParameters &  cam)

copy operator

Definition at line 269 of file vpCameraParameters.cpp.

void vpCameraParameters::printParameters ( )

Print the camera parameters on the standard output

See also
operator <<
Examples:
servoViper850FourPoints2DArtVelocityInteractionCurrent.cpp, servoViper850FourPoints2DArtVelocityInteractionDesired.cpp, servoViper850FourPoints2DCamVelocityInteractionCurrent.cpp, and servoViper850FourPointsKinect.cpp.

Definition at line 330 of file vpCameraParameters.cpp.

References perspectiveProjWithDistortion, and perspectiveProjWithoutDistortion.

Referenced by vpCalibration::computeCalibration(), and vpCalibration::computeCalibrationMulti().

Friends And Related Function Documentation

VISP_EXPORT std::ostream& operator<< ( std::ostream &  os,
const vpCameraParameters &  cam 
)
friend

Print on the output stream os the camera parameters.

Parameters
os: Output stream.
cam: Camera parameters.

Definition at line 358 of file vpCameraParameters.cpp.

friend class vpMeterPixelConversion
friend

Definition at line 199 of file vpCameraParameters.h.

friend class vpPixelMeterConversion
friend

Definition at line 200 of file vpCameraParameters.h.