MbTracker¶

class MbTracker¶

Bases: pybind11_object

Main methods for a model-based tracker.

This class provides the main methods for a model based tracker. This pure virtual class must be used in inheritance for a tracker that compute the interaction matrix and the residu vector using a defined information (edge, points of interest, patch, …)

This class intends to define a common basis for object tracking. This is realised by implementing the main functions:

init() : Initialisation of the tracker (it includes re-initialisation). This method is called at the end of the initClick() method.
initFaceFromCorners() : Initialisation of the lines that has to be tracked.
track() : Tracking on the current image
testTracking() : Test the tracking. This method throws exception if the tracking failed.
display() : Display the model and eventually other information.

Methods

`__init__`
`computeCurrentProjectionError`	Compute projection error given an input image and camera pose, parameters.
`getAngleAppear`	Return the angle used to test polygons appearance.
`getAngleDisappear`	Return the angle used to test polygons disappearance.
`getCameraParameters`	Get the camera parameters.
`getClipping`	Get the clipping used and defined in vpPolygon3D::vpMbtPolygonClippingType.
`getCovarianceMatrix`	Get the covariance matrix.
`getEstimatedDoF`	Get a 1x6 vpColVector representing the estimated degrees of freedom.
`getFaces`	Return a reference to the faces structure.
`getFarClippingDistance`	Get the far distance for clipping.
`getInitialMu`	Get the initial value of mu used in the Levenberg Marquardt optimization loop.
`getLambda`	Get the value of the gain used to compute the control law.
`getMaxIter`	Get the maximum number of iterations of the virtual visual servoing stage.
`getNbPolygon`	Get the number of polygons (faces) representing the object to track.
`getNearClippingDistance`	Get the near distance for clipping.
`getOptimizationMethod`	Get the optimization method used during the tracking.
`getPolygonFaces`	Get the list of polygons faces (a vpPolygon representing the projection of the face in the image and a list of face corners in 3D), with the possibility to order by distance to the camera or to use the visibility check to consider if the polygon face must be retrieved or not.
`getPose`	Overloaded function.
`getProjectionError`	Get the error angle between the gradient direction of the model features projected at the resulting pose and their normal.
`getStopCriteriaEpsilon`
`initClick`	Overloaded function.
`initFromPoints`	Overloaded function.
`initFromPose`	Overloaded function.
`loadConfigFile`	Load a config file to parameterise the behavior of the tracker.
`loadModel`	Load a 3D model from the file in parameter.
`savePose`	Save the pose in the given filename
`setAngleAppear`	Set the angle used to test polygons appearance.
`setAngleDisappear`	Set the angle used to test polygons disappearance.
`setCameraParameters`	Set the camera parameters.
`setClipping`	Specify which clipping to use.
`setCovarianceComputation`	Set if the covariance matrix has to be computed.
`setDisplayFeatures`	Enable to display the features.
`setEstimatedDoF`	Set a 6-dim column vector representing the degrees of freedom in the object frame that are estimated by the tracker.
`setFarClippingDistance`	Set the far distance for clipping.
`setInitialMu`	Set the initial value of mu for the Levenberg Marquardt optimization loop.
`setLambda`	Set the value of the gain used to compute the control law.
`setLod`	Set the flag to consider if the level of detail (LOD) is used.
`setMask`
`setMaxIter`	Set the maximum iteration of the virtual visual servoing stage.
`setMinLineLengthThresh`	Set the threshold for the minimum line length to be considered as visible in the LOD case.
`setMinPolygonAreaThresh`	Set the minimum polygon area to be considered as visible in the LOD case.
`setNearClippingDistance`	Set the near distance for clipping.
`setOgreShowConfigDialog`	Enable/Disable the appearance of Ogre config dialog on startup.
`setOgreVisibilityTest`	Use Ogre3D for visibility tests
`setOptimizationMethod`
`setPoseSavingFilename`	Set the filename used to save the initial pose computed using the initClick() method.
`setProjectionErrorComputation`	Set if the projection error criteria has to be computed.
`setProjectionErrorDisplay`	Display or not gradient and model orientation when computing the projection error.
`setProjectionErrorDisplayArrowLength`	Arrow length used to display gradient and model orientation for projection error computation.
`setProjectionErrorDisplayArrowThickness`	Arrow thickness used to display gradient and model orientation for projection error computation.
`setProjectionErrorKernelSize`	Set kernel size used for projection error computation.
`setProjectionErrorMovingEdge`	Set Moving-Edges parameters for projection error computation.
`setScanLineVisibilityTest`
`setStopCriteriaEpsilon`	Set the minimal error (previous / current estimation) to determine if there is convergence or not.

Inherited Methods

Operators

`__annotations__`
`__doc__`
`__init__`
`__module__`

Attributes

`GAUSS_NEWTON_OPT`
`LEVENBERG_MARQUARDT_OPT`
`__annotations__`

class MbtOptimizationMethod(self, value: int)¶

Bases: pybind11_object

Values:

GAUSS_NEWTON_OPT
LEVENBERG_MARQUARDT_OPT

__and__(self, other: object) → object¶

__eq__(self, other: object) → bool¶

__ge__(self, other: object) → bool¶

__getstate__(self) → int¶

__gt__(self, other: object) → bool¶

__hash__(self) → int¶

__index__(self) → int¶

__init__(self, value: int)¶

__int__(self) → int¶

__invert__(self) → object¶

__le__(self, other: object) → bool¶

__lt__(self, other: object) → bool¶

__ne__(self, other: object) → bool¶

__or__(self, other: object) → object¶

__rand__(self, other: object) → object¶

__ror__(self, other: object) → object¶

__rxor__(self, other: object) → object¶

__setstate__(self, state: int) → None¶

__xor__(self, other: object) → object¶

property name : str¶

__init__(*args, **kwargs)¶

computeCurrentProjectionError(self, I: visp._visp.core.ImageGray, _cMo: visp._visp.core.HomogeneousMatrix, _cam: visp._visp.core.CameraParameters) → float¶

Compute projection error given an input image and camera pose, parameters. This projection error uses locations sampled exactly where the model is projected using the camera pose and intrinsic parameters. You may want to use

Note

See setProjectionErrorComputation

Note

See getProjectionError

to get a projection error computed at the ME locations after a call to track() . It works similarly to vpMbTracker::getProjectionError function:Get the error angle between the gradient direction of the model features projected at the resulting pose and their normal. The error is expressed in degree between 0 and 90.

Parameters:

I: visp._visp.core.ImageGray¶: Input grayscale image.
_cMo: visp._visp.core.HomogeneousMatrix¶: Camera pose.
_cam: visp._visp.core.CameraParameters¶: Camera parameters.

getAngleAppear(self) → float¶: Return the angle used to test polygons appearance.

getAngleDisappear(self) → float¶: Return the angle used to test polygons disappearance.

getCameraParameters(self, cam: visp._visp.core.CameraParameters) → None¶

Get the camera parameters.

Parameters:

cam: visp._visp.core.CameraParameters¶: copy of the camera parameters used by the tracker.

getClipping(self) → int¶

Get the clipping used and defined in vpPolygon3D::vpMbtPolygonClippingType.

Returns:: Clipping flags.

getCovarianceMatrix(self) → visp._visp.core.Matrix¶: Get the covariance matrix. This matrix is only computed if setCovarianceComputation() is turned on.

Note

See setCovarianceComputation()

getEstimatedDoF(self) → visp._visp.core.ColVector¶

Get a 1x6 vpColVector representing the estimated degrees of freedom. vpColVector [0] = 1 if translation on X is estimated, 0 otherwise; vpColVector [1] = 1 if translation on Y is estimated, 0 otherwise; vpColVector [2] = 1 if translation on Z is estimated, 0 otherwise; vpColVector [3] = 1 if rotation on X is estimated, 0 otherwise; vpColVector [4] = 1 if rotation on Y is estimated, 0 otherwise; vpColVector [5] = 1 if rotation on Z is estimated, 0 otherwise;

Returns:: 1x6 vpColVector representing the estimated degrees of freedom.

getFaces(self) → vpMbHiddenFaces<vpMbtPolygon>¶: Return a reference to the faces structure.

getFarClippingDistance(self) → float¶

Get the far distance for clipping.

Returns:: Far clipping value.

getInitialMu(self) → float¶

Get the initial value of mu used in the Levenberg Marquardt optimization loop.

Returns:: the initial mu value.

getLambda(self) → float¶

Get the value of the gain used to compute the control law.

Returns:: the value for the gain.

getMaxIter(self) → int¶

Get the maximum number of iterations of the virtual visual servoing stage.

Returns:: the number of iteration

getNbPolygon(self) → int¶

Get the number of polygons (faces) representing the object to track.

Returns:: Number of polygons.

getNearClippingDistance(self) → float¶

Get the near distance for clipping.

Returns:: Near clipping value.

getOptimizationMethod(self) → visp._visp.mbt.MbTracker.MbtOptimizationMethod¶

Get the optimization method used during the tracking. 0 = Gauss-Newton approach. 1 = Levenberg-Marquardt approach.

Returns:: Optimization method.

getPolygonFaces(self, orderPolygons: bool = true, useVisibility: bool = true, clipPolygon: bool = false) → tuple[list[visp._visp.core.Polygon], list[list[visp._visp.core.Point]]]¶

Get the list of polygons faces (a vpPolygon representing the projection of the face in the image and a list of face corners in 3D), with the possibility to order by distance to the camera or to use the visibility check to consider if the polygon face must be retrieved or not.

Parameters:

orderPolygons: bool = true¶: If true, the resulting list is ordered from the nearest polygon faces to the farther.
useVisibility: bool = true¶: If true, only visible faces will be retrieved.
clipPolygon: bool = false¶: If true, the polygons will be clipped according to the clipping flags set in vpMbTracker .

Returns:

A pair object containing the list of vpPolygon and the list of face corners.

getPose(*args, **kwargs)¶

Overloaded function.

getPose(self: visp._visp.mbt.MbTracker, cMo: visp._visp.core.HomogeneousMatrix) -> None

Get the current pose between the object and the camera. cMo is the matrix which can be used to express coordinates from the object frame to camera frame.

Parameters:

cMo: the pose

getPose(self: visp._visp.mbt.MbTracker) -> visp._visp.core.HomogeneousMatrix

Get the current pose between the object and the camera. cMo is the matrix which can be used to express coordinates from the object frame to camera frame.

Returns:: the current pose

getProjectionError(self) → float¶

Get the error angle between the gradient direction of the model features projected at the resulting pose and their normal. The error is expressed in degree between 0 and 90. This value is computed if setProjectionErrorComputation() is turned on.

Note

See setProjectionErrorComputation()

Returns:: the value for the error.

getStopCriteriaEpsilon(self) → float¶

initClick(*args, **kwargs)¶

Overloaded function.

initClick(self: visp._visp.mbt.MbTracker, I: visp._visp.core.ImageGray, initFile: str, displayHelp: bool = false, T: visp._visp.core.HomogeneousMatrix = vpHomogeneousMatrix()) -> None
initClick(self: visp._visp.mbt.MbTracker, I_color: visp._visp.core.ImageRGBa, initFile: str, displayHelp: bool = false, T: visp._visp.core.HomogeneousMatrix = vpHomogeneousMatrix()) -> None
initClick(self: visp._visp.mbt.MbTracker, I: visp._visp.core.ImageGray, points3D_list: list[visp._visp.core.Point], displayFile: str = ) -> None
initClick(self: visp._visp.mbt.MbTracker, I_color: visp._visp.core.ImageRGBa, points3D_list: list[visp._visp.core.Point], displayFile: str = ) -> None

initFromPoints(*args, **kwargs)¶

Overloaded function.

initFromPoints(self: visp._visp.mbt.MbTracker, I: visp._visp.core.ImageGray, initFile: str) -> None

Initialise the tracker by reading 3D point coordinates and the corresponding 2D image point coordinates from a file. Comments starting with # character are allowed. 3D point coordinates are expressed in meter in the object frame with X, Y and Z values. 2D point coordinates are expressied in pixel coordinates, with first the line and then the column of the pixel in the image. The structure of this file is the following.

# 3D point coordinates
4                 # Number of 3D points in the file (minimum is four)
0.01 0.01 0.01    #  \
...               #  | 3D coordinates in meters in the object frame
0.01 -0.01 -0.01  # /
# corresponding 2D point coordinates
4                 # Number of image points in the file (has to be the same
as the number of 3D points)
100 200           #  \
...               #  | 2D coordinates in pixel in the image
50 10             #  /

Parameters:

I: Input grayscale image
initFile: Path to the file containing all the points.

initFromPoints(self: visp._visp.mbt.MbTracker, I_color: visp._visp.core.ImageRGBa, initFile: str) -> None

# 3D point coordinates
4                 # Number of 3D points in the file (minimum is four)
0.01 0.01 0.01    #  \
...               #  | 3D coordinates in meters in the object frame
0.01 -0.01 -0.01  # /
# corresponding 2D point coordinates
4                 # Number of image points in the file (has to be the same
as the number of 3D points)
100 200           #  \
...               #  | 2D coordinates in pixel in the image
50 10             #  /

Parameters:

I_color: Input color image
initFile: Path to the file containing all the points.

initFromPoints(self: visp._visp.mbt.MbTracker, I: visp._visp.core.ImageGray, points2D_list: list[visp._visp.core.ImagePoint], points3D_list: list[visp._visp.core.Point]) -> None

Initialise the tracking with the list of image points (points2D_list) and the list of corresponding 3D points (object frame) (points3D_list).

Parameters:

I: Input grayscale image
points2D_list: List of image points.
points3D_list: List of 3D points (object frame).

initFromPoints(self: visp._visp.mbt.MbTracker, I_color: visp._visp.core.ImageRGBa, points2D_list: list[visp._visp.core.ImagePoint], points3D_list: list[visp._visp.core.Point]) -> None

Initialise the tracking with the list of image points (points2D_list) and the list of corresponding 3D points (object frame) (points3D_list).

Parameters:

I_color: Input color grayscale image
points2D_list: List of image points.
points3D_list: List of 3D points (object frame).

initFromPose(*args, **kwargs)¶

Overloaded function.

initFromPose(self: visp._visp.mbt.MbTracker, I: visp._visp.core.ImageGray, initFile: str) -> None

Initialise the tracking thanks to the pose in vpPoseVector format, and read in the file initFile. The structure of this file is (without the comments):

// The six value of the pose vector
0000    //  \
0000    //  |
0000    //  | Example of value for the pose vector where Z = 1 meter
0000    //  |
0000    //  |
0000    //  /

Where the three firsts lines refer to the translation and the three last to the rotation in thetaU parametrisation (see vpThetaUVector ).

Parameters:

I: Input grayscale image
initFile: Path to the file containing the pose.

initFromPose(self: visp._visp.mbt.MbTracker, I_color: visp._visp.core.ImageRGBa, initFile: str) -> None

Initialise the tracking thanks to the pose in vpPoseVector format, and read in the file initFile. The structure of this file is (without the comments):

// The six value of the pose vector
0000    //  \
0000    //  |
0000    //  | Example of value for the pose vector where Z = 1 meter
0000    //  |
0000    //  |
0000    //  /

Where the three firsts lines refer to the translation and the three last to the rotation in thetaU parametrisation (see vpThetaUVector ).

Parameters:

I_color: Input color image
initFile: Path to the file containing the pose.

initFromPose(self: visp._visp.mbt.MbTracker, I: visp._visp.core.ImageGray, cMo: visp._visp.core.HomogeneousMatrix) -> None

Initialise the tracking thanks to the pose.

Parameters:

I: Input grayscale image
cMo: Pose matrix.

initFromPose(self: visp._visp.mbt.MbTracker, I_color: visp._visp.core.ImageRGBa, cMo: visp._visp.core.HomogeneousMatrix) -> None

Initialise the tracking thanks to the pose.

Parameters:

I_color: Input color image
cMo: Pose matrix.

initFromPose(self: visp._visp.mbt.MbTracker, I: visp._visp.core.ImageGray, cPo: visp._visp.core.PoseVector) -> None

Initialise the tracking thanks to the pose vector.

Parameters:

I: Input grayscale image
cPo: Pose vector.

initFromPose(self: visp._visp.mbt.MbTracker, I_color: visp._visp.core.ImageRGBa, cPo: visp._visp.core.PoseVector) -> None

Initialise the tracking thanks to the pose vector.

Parameters:

I_color: Input color image
cPo: Pose vector.

loadConfigFile(self, configFile: str, verbose: bool = true) → None¶

Load a config file to parameterise the behavior of the tracker.

Virtual method to adapt to each tracker.

Parameters:

configFile: str¶: An xml config file to parse.
verbose: bool = true¶: verbose flag.

loadModel(self, modelFile: str, verbose: bool = false, T: visp._visp.core.HomogeneousMatrix = vpHomogeneousMatrix()) → None¶

Load a 3D model from the file in parameter. This file must either be a vrml file (.wrl) or a CAO file (.cao). CAO format is described in the loadCAOModel() method.

Parameters:

modelFile: str¶: the file containing the the 3D model description. The extension of this file is either .wrl or .cao.
verbose: bool = false¶: verbose option to print additional information when loading CAO model files which include other CAO model files.

savePose(self, filename: str) → None¶

Save the pose in the given filename

Parameters:

filename: str¶: Path to the file used to save the pose.

setAngleAppear(self, a: float) → None¶

Set the angle used to test polygons appearance. If the angle between the normal of the polygon and the line going from the camera to the polygon center has a value lower than this parameter, the polygon is considered as appearing. The polygon will then be tracked.

Parameters:

a: float¶: new angle in radian.

setAngleDisappear(self, a: float) → None¶

Set the angle used to test polygons disappearance. If the angle between the normal of the polygon and the line going from the camera to the polygon center has a value greater than this parameter, the polygon is considered as disappearing. The tracking of the polygon will then be stopped.

Parameters:

a: float¶: new angle in radian.

setCameraParameters(self, cam: visp._visp.core.CameraParameters) → None¶

Set the camera parameters.

Parameters:

cam: visp._visp.core.CameraParameters¶: The new camera parameters.

setClipping(self, flags: int) → None¶

Specify which clipping to use.

Note

See vpMbtPolygonClipping

Parameters:

flags: int¶: New clipping flags.

setCovarianceComputation(self, flag: bool) → None¶

Set if the covariance matrix has to be computed.

Note

See getCovarianceMatrix()

Parameters:

flag: bool¶: True if the covariance has to be computed, false otherwise. If computed its value is available with getCovarianceMatrix()

setDisplayFeatures(self, displayF: bool) → None¶

Enable to display the features. By features, we meant the moving edges (ME) and the klt points if used.

Note that if present, the moving edges can be displayed with different colors:

If green : The ME is a good point.
If blue : The ME is removed because of a contrast problem during the tracking phase.
If purple : The ME is removed because of a threshold problem during the tracking phase.
If red : The ME is removed because it is rejected by the robust approach in the virtual visual servoing scheme.

Parameters:

displayF: bool¶: set it to true to display the features.

setEstimatedDoF(self, v: visp._visp.core.ColVector) → None¶

Set a 6-dim column vector representing the degrees of freedom in the object frame that are estimated by the tracker. When set to 1, all the 6 dof are estimated.

Below we give the correspondence between the index of the vector and the considered dof:

v[0] = 1 if translation along X is estimated, 0 otherwise;
v[1] = 1 if translation along Y is estimated, 0 otherwise;
v[2] = 1 if translation along Z is estimated, 0 otherwise;
v[3] = 1 if rotation along X is estimated, 0 otherwise;
v[4] = 1 if rotation along Y is estimated, 0 otherwise;
v[5] = 1 if rotation along Z is estimated, 0 otherwise;

setFarClippingDistance(self, dist: float) → None¶

Set the far distance for clipping.

Parameters:

dist: float¶: Far clipping value.

setInitialMu(self, mu: float) → None¶

Set the initial value of mu for the Levenberg Marquardt optimization loop.

Parameters:

mu: float¶: initial mu.

setLambda(self, gain: float) → None¶

Set the value of the gain used to compute the control law.

Parameters:

gain: float¶: the desired value for the gain.

setLod(self: visp._visp.mbt.MbTracker, useLod: bool, name: str =) → None¶

Set the flag to consider if the level of detail (LOD) is used.

Note

See setMinLineLengthThresh() , setMinPolygonAreaThresh()

Parameters:

useLod: true if the level of detail must be used, false otherwise. When true, two parameters can be set, see setMinLineLengthThresh() and setMinPolygonAreaThresh() .
name: name of the face we want to modify the LOD parameter.

setMask(self: visp._visp.mbt.MbTracker, mask: vpImage<bool>) → None¶

setMaxIter(self, max: int) → None¶

Set the maximum iteration of the virtual visual servoing stage.

Parameters:

max: int¶: the desired number of iteration

setMinLineLengthThresh(self: visp._visp.mbt.MbTracker, minLineLengthThresh: float, name: str =) → None¶

Set the threshold for the minimum line length to be considered as visible in the LOD case.

Note

See setLod() , setMinPolygonAreaThresh()

Parameters:

minLineLengthThresh: threshold for the minimum line length in pixel.
name: name of the face we want to modify the LOD threshold.

setMinPolygonAreaThresh(self: visp._visp.mbt.MbTracker, minPolygonAreaThresh: float, name: str =) → None¶

Set the minimum polygon area to be considered as visible in the LOD case.

Note

See setLod() , setMinLineLengthThresh()

Parameters:

minPolygonAreaThresh: threshold for the minimum polygon area in pixel.
name: name of the face we want to modify the LOD threshold.

setNearClippingDistance(self, dist: float) → None¶

Set the near distance for clipping.

Parameters:

dist: float¶: Near clipping value.

setOgreShowConfigDialog(self, showConfigDialog: bool) → None¶

Enable/Disable the appearance of Ogre config dialog on startup.

Warning

This method has only effect when Ogre is used and Ogre visibility test is enabled using setOgreVisibilityTest() with true parameter.

Parameters:

showConfigDialog: bool¶: if true, shows Ogre dialog window (used to set Ogre rendering options) when Ogre visibility is enabled. By default, this functionality is turned off.

setOgreVisibilityTest(self, v: bool) → None¶

Use Ogre3D for visibility tests

Warning

This function has to be called before the initialization of the tracker.

Parameters:

v: bool¶: True to use it, False otherwise

setOptimizationMethod(self, opt: visp._visp.mbt.MbTracker.MbtOptimizationMethod) → None¶

setPoseSavingFilename(self, filename: str) → None¶

Set the filename used to save the initial pose computed using the initClick() method. It is also used to read a previous pose in the same method. If the file is not set then, the initClick() method will create a .0.pos file in the root directory. This directory is the path to the file given to the method initClick() used to know the coordinates in the object frame.

Parameters:

filename: str¶: The new filename.

setProjectionErrorComputation(self, flag: bool) → None¶

Set if the projection error criteria has to be computed. This criteria could be used to detect the quality of the tracking. It computes an angle between 0 and 90 degrees that is available with getProjectionError() . Closer to 0 is the value, better is the tracking.

Note

See getProjectionError()

Parameters:

flag: bool¶: True if the projection error criteria has to be computed, false otherwise.

setProjectionErrorDisplay(self, display: bool) → None¶: Display or not gradient and model orientation when computing the projection error.

setProjectionErrorDisplayArrowLength(self, length: int) → None¶: Arrow length used to display gradient and model orientation for projection error computation.

setProjectionErrorDisplayArrowThickness(self, thickness: int) → None¶: Arrow thickness used to display gradient and model orientation for projection error computation.

setProjectionErrorKernelSize(self, size: int) → None¶

Set kernel size used for projection error computation.

Parameters:

size: int¶: Kernel size computed as kernel_size = size*2 + 1.

setProjectionErrorMovingEdge(self, me: visp._visp.me.Me) → None¶

Set Moving-Edges parameters for projection error computation.

Parameters:

me: visp._visp.me.Me¶: Moving-Edges parameters.

setScanLineVisibilityTest(self, v: bool) → None¶

setStopCriteriaEpsilon(self, eps: float) → None¶

Set the minimal error (previous / current estimation) to determine if there is convergence or not.

Parameters:

eps: float¶: Epsilon threshold.