Bagmetti

BAG file utility for MEssage, Tf, and TIme.

What's This?

Bagmetti is a collection of utility scripts for filtering and modifying existing bag files. You can use Bagmetti, for example, when:

rosbag record -a takes up too much storage and you want a more lightweight bag file with fewer topics
you want to exclude certain TF transformations
creating a bag file for only a certain time range
you want to rename existing TF frame names

But what about...

Yes, there are existing alternatives, but sometimes they aren't good enough.

`rosbag filter`

Problem: rosbag filter only accepts one argument for filtering messages.

The argument is a Python one-liner. When you have multiple topics and TF transformations to consider, this becomes a huge string full of ands and ors.

Using rosbag filter also makes it harder to track down what was used for filtering a certain bag file. Depending on your shell configuration the command you executed can be lost, and even if you have the command history you may not be able to tell what expression was used last. What's more, one-line expressions are hard to read.

Bagmetti lets you manage filtering rules in a YAML file. Therefore, you could put it in the same directory as the bag file so that you can later look back at what was used to filter the original bag file.

`rosbag play -s 42 -u 60 foo.bag`

Problem: The format is start time + delta

You can specify what time to start and how long to play instead of what time to end. Most of the times you know the start and end time of the section you want to cut out. In these cases it's more intuitive to specify the start and end time, and Bagmetti let's you do that.

`rosbag play foo.bag some_topic:=new_topic_name`

Problem: Can't rename TF transformations

You can rename topic names using the remapping command line arguments or <remap from="some_topic" to="new_topic_name" /> in launch files. However, you can't rename TF transformations with this method. Also, often times you forget to do this, and it could be a pain in the neck to specify these remapping arguments every time.

Running

Filter in or out certain messages from a bag file and output to a different bag file.

rosrun bagmetti filter.py <bag file path> <output file path> <config file path>

Rename topic names and TF transformations.

rosrun bagmetti rename.py <bag file path> <output file path> <config file path>

Config File Format

Formats are different depending on what script you use (don't worry; they're really simple and written in YAML).

Also check out the sample config files.

TODO

Unit tests
Python expression feature for filter.py

topic:
  -:
    # Exclude if message matches the expression
    - name: /imu/data
      expr: msg.linear_acceleration.x < 1.5
    - velodyne_points

tf:
  +:
    # Include if transformation matches the expression
    - name: map -> odom
      expr: tf.translation.x > 0.5

License

MIT

Author

Naoki Mizuno (mizuno.naoki@rm.is.tohoku.ac.jp)

tanay-bits/bagmetti