ISAM2UpdateParams

ISAM2UpdateParams supplies per-update controls to iSAM2: factor removal, constrained ordering groups, relinearization exclusions, extra re-elimination keys, and full-solve overrides.

Authors: Frank Dellaert, et al. (see THANKS for the full author list)

See LICENSE for the license information

try:
    import google.colab
    %pip install --quiet gtsam-develop
except ImportError:
    pass

import gtsam
import numpy as np
from gtsam.symbol_shorthand import L, V, X

Creating update parameters¶

The default object requests an ordinary incremental update. Set only the fields needed for a particular call; persistent solver behavior belongs in ISAM2Params.

update_params = gtsam.ISAM2UpdateParams()
update_params.force_relinearize = True
update_params.forceFullSolve = False
update_params.removeFactorIndices = []
print("force relinearization:", update_params.force_relinearize)

Using the object with `ISAM2.update()`¶

The dedicated overload takes new factors, new values, and ISAM2UpdateParams. This example adds a prior in one update and a relative-pose factor in the next.

isam = gtsam.ISAM2()
model = gtsam.noiseModel.Diagonal.Sigmas(np.array([0.1, 0.1, 0.05]))

first_graph = gtsam.NonlinearFactorGraph()
first_graph.add(gtsam.PriorFactorPose2(X(0), gtsam.Pose2(), model))
first_values = gtsam.Values()
first_values.insert(X(0), gtsam.Pose2(0.1, 0.0, 0.01))
isam.update(first_graph, first_values)

second_graph = gtsam.NonlinearFactorGraph()
second_graph.add(
    gtsam.BetweenFactorPose2(X(0), X(1), gtsam.Pose2(1.0, 0.0, 0.0), model)
)
second_values = gtsam.Values()
second_values.insert(X(1), gtsam.Pose2(1.1, 0.1, 0.02))
result = isam.update(second_graph, second_values, update_params)
print("estimate for X1:", isam.calculateEstimatePose2(X(1)))

Advanced fields¶

constrainedKeys groups variables for constrained COLAMD ordering. noRelinKeys protects selected variables from relinearization, while extraReelimKeys forces selected variables through re-elimination. removeFactorIndices uses the indices returned by earlier ISAM2Result.getNewFactorsIndices() calls. forceFullSolve performs a full back-substitution after the incremental update.

Source¶

ISAM2UpdateParams.h

AI assistance caveat¶

AI was used to help draft this documentation, and inaccuracies could be present.

Creating update parameters¶

Using the object with ISAM2.update()¶

Advanced fields¶

Source¶

AI assistance caveat¶

Using the object with `ISAM2.update()`¶