Log Files and Transformations

Analyze rosbags, transformation trees, and time series data

ROS topics are stored in log files called rosbags. You can access and filter information from these rosbags in MATLAB®. For an example of working with rosbags, see Work with rosbag Logfiles.

You can access transformations between coordinate systems as ROS topics and use them to transform data in MATLAB. For more information see, Access the tf Transformation Tree in ROS.


rosbagOpen and parse rosbag log file
readMessagesRead messages from rosbag
selectSelect subset of messages in rosbag
timeseriesCreates a time series object for selected message properties
rostimeAccess ROS time functionality
rosdurationCreate a ROS duration object
secondsReturns seconds of a time or duration
rostfReceive, send, and apply ROS transformations
applyTransform message entities into target frame
canTransformVerify if transformation is available
transformTransform message entities into target coordinate frame
waitForTransformWait until a transformation is available
getTransformRetrieve transformation between two coordinate frames
sendTransformSend transformation to ROS network


BagSelection Object for storing rosbag selection
TransformStampedCreate transformation message


Read DataPlay back data from log file


ROS Log Files (rosbags)

Summary of the structure of rosbags and the workflow for selecting subsets of messages in a rosbag.

Work with rosbag Logfiles

A rosbag or bag is a file format in ROS for storing message data.

Access the tf Transformation Tree in ROS

The tf system in ROS keeps track of multiple coordinate frames and maintains the relationship between them in a tree structure.