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optimizePoses

Optimize absolute poses using relative pose constraints

Description

example

vSetOptim = optimizePoses(vSet) returns a point cloud view set whose absolute poses are optimized. vSetOptim and vSet are pcviewset objects.

The optimizePoses function performs pose graph optimization on the absolute poses for the Views in the view set using the relative pose constraints established by the Connections property. You can use optimizePoses to correct drift in odometry after detecting loop closures.

vSetOptim = optimizePoses(vSet,Name,Value) specifies options using one or more name-value pair arguments. For example, 'Tolerance',0.2 sets the tolerance of the optimization cost function to 0.2.

Examples

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Create a view set.

vSet = pcviewset;

Add four nodes and specify absolute poses.

absPoses = repelem(rigid3d, 4, 1);   

absPoses(1).Translation = [ 0   0 0];
absPoses(2).Translation = [ 1   0 0];
absPoses(3).Translation = [ 2   0 0];
absPoses(4).Translation = [ 0.1 0 0];

vSet = addView(vSet, 1, absPoses(1));
vSet = addView(vSet, 2, absPoses(2));
vSet = addView(vSet, 3, absPoses(3));
vSet = addView(vSet, 4, absPoses(4));

Define 4 edges, 3 odometry and 1 loop closure.

relPoses = repelem(rigid3d, 4, 1);

relPoses(1).Translation = [ 1   0 0];
relPoses(2).Translation = [ 1   0 0];
relPoses(3).Translation = [-1.9 0 0];
relPoses(4).Translation = [ 0.2 0 0];

vSet = addConnection(vSet, 1, 2, relPoses(1)); % odometry
vSet = addConnection(vSet, 2, 3, relPoses(2)); % odometry
vSet = addConnection(vSet, 3, 4, relPoses(3)); % odometry
vSet = addConnection(vSet, 4, 1, relPoses(4)); % loop closure

Optimize view set.

vSetOptim = optimizePoses(vSet);

DIsplay original and optimized locations.

disp('Original absolute translations:')
Original absolute translations:
disp(vertcat(vSet.Views.AbsolutePose.Translation))
         0         0         0
    1.0000         0         0
    2.0000         0         0
    0.1000         0         0
disp('Optimized absolute translations:')
Optimized absolute translations:
disp(vertcat(vSetOptim.Views.AbsolutePose.Translation))
         0         0         0
    0.9250         0         0
    1.8500         0         0
   -0.1250         0         0

Input Arguments

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Point cloud view set, specified as a pcviewset object.

Name-Value Arguments

Specify optional pairs of arguments as Name1=Value1,...,NameN=ValueN, where Name is the argument name and Value is the corresponding value. Name-value arguments must appear after other arguments, but the order of the pairs does not matter.

Before R2021a, use commas to separate each name and value, and enclose Name in quotes.

Example: 'MaxIterations',300 sets the maximum number of iterations to 300.

Maximum number of iterations before the function terminates optimization, specified as the comma-separated pair consisting of 'MaxIterations' and a positive integer. Increase this value for greater accuracy in the results. Decrease this value for faster results.

Tolerance of the optimization cost function between two consecutive iterations, specified as the comma-separated pair consisting of 'Tolerance' and a positive scalar. If the cost function changes by less than the 'Tolerance' value between two consecutive iterations, the function terminates optimization.

Display progress information, specified as the comma-separated pair consisting of Verbose and a numeric or logical 0 (false) or 1 (true). To display the progress information, set 'Verbose' to true.

Output Arguments

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Point cloud view set that contains optimized absolute poses, specified as a pcviewset object.

Tips

  • To update a view set with optimized poses, use the updateView object function.

  • The optimizePoses object function holds the first view fixed.

Algorithms

The optimizePoses function uses the Levenberg-Marquardt optimization algorithm with sparse Cholesky decomposition from the general (hyper) graph optimization (G2o) library, [1].

References

[1] Kümmerle, Rainer, Giorgio Grisetti, Hauke Strasdat, Kurt Konolige, and Wolfram Burgard. “G2o: A General Framework for Graph Optimization.” In 2011 IEEE International Conference on Robotics and Automation, 3607–13, 2011. https://doi.org/10.1109/ICRA.2011.5979949.

Extended Capabilities

Version History

Introduced in R2020a

See Also

Functions

Objects