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MobilityGen Package and Recordings#

Isaac Sim 6.0 deprecates the isaacsim.replicator.mobility_gen extension. Enable and import isaacsim.replicator.experimental.mobility_gen for new code. The examples extension remains isaacsim.replicator.mobility_gen.examples and now depends on the experimental MobilityGen package.

Update extension dependencies or command-line enables from:

"isaacsim.replicator.mobility_gen" = {}

to:

"isaacsim.replicator.experimental.mobility_gen" = {}

Update Python imports in scripts and custom robot/scenario implementations:

Isaac Sim 5.x:

from isaacsim.replicator.mobility_gen.impl.writer import MobilityGenWriter

writer = MobilityGenWriter("/tmp/mobility_gen_recording")

Isaac Sim 6.0:

from isaacsim.replicator.experimental.mobility_gen import MobilityGenWriter

writer = MobilityGenWriter("/tmp/mobility_gen_recording")

If your robot classes use the packaged examples, continue enabling isaacsim.replicator.mobility_gen.examples alongside the experimental core extension.

Recordings made with Isaac Sim 5.x store robot state in state/common/*.npy files (pickled Python dicts). Starting with Isaac Sim 6.0, MobilityGen switched to state/common/*.npz (named NumPy arrays). The reader only supports the new format, so convert older recordings before replay.

To convert all recordings in a directory tree in-place, run:

./python.sh \
    standalone_examples/replicator/mobility_gen/migrate_recordings.py \
    ~/MobilityGenData/recordings --recursive

The script takes a positional recording path; pass --recursive when the path is a parent directory containing multiple recordings.

If a recording still uses the old format, the reader logs an error and produces zero steps — convert it with the script above before replaying.

Validation Checklist#

Verify the following after converting recordings:

  • Run the migration script on a copy of representative recordings before deleting the original data.

  • Confirm that *.npz files exist for every old state/common/*.npy file.

  • Replay at least one converted recording and verify that the reader produces nonzero steps.

  • Verify that custom robot or scenario classes import from isaacsim.replicator.experimental.mobility_gen.

  • Re-run the downstream writer or SDG pipeline that consumes the recording.

For the MobilityGen tutorial, see Data Generation with MobilityGen.

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