ROS Log Files and Specialized Messages

Analyze rosbags, ros2bags, and access messages from specialized sensors and inputs

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.

Specialized message functions enable you to create and access sensors and data types using specific ROS and ROS 2 message types. You can use the same functions to work with specific ROS and ROS 2 specialized message types. For examples of accessing data from these sensors, see Work with Specialized ROS Messages.

Functions

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ROS bag Log Files

`rosbag`	Open and parse rosbag log file
`readMessages`	Read messages from rosbag
`rosbagreader`	Access rosbag log file information
`rosbagwriter`	Create and write logs to rosbag log file
`write`	Write logs to rosbag log file
`select`	Select subset of messages in rosbag
`timeseries`	Create time series object for selected message properties

ROS 2 bag Log Files

`ros2bagreader`	Access ROS 2 bag log file information
`readMessages`	Read messages from ros2bagreader object
`select`	Select subset of messages in ros2bagreader
`ros2bagwriter`	Create and write logs to ROS 2 bag log file
`write`	Write logs to ROS 2 bag log file
`delete`	Remove ros2bagwriter object from memory

Images

`rosReadImage`	Convert ROS or ROS 2 image data into MATLAB image
`rosWriteImage`	Write MATLAB image to ROS or ROS 2 image message
`rosWriteCameraInfo`	Write monocular or stereo camera parameters to ROS or ROS 2 message structure

Laser Scans

`rosReadLidarScan`	Display lidar scan or point cloud from ROS or ROS 2 message structure
`rosReadCartesian`	Read laser scan ranges in Cartesian coordinates from ROS or ROS 2 message structure
`rosReadScanAngles`	Return scan angles from ROS or ROS 2 message structure
`rosPlot`	Display lidar scan or point cloud from ROS or ROS 2 message structures

Point Clouds

`rosReadXYZ`	Extract XYZ coordinates from ROS or ROS 2 point cloud message structure
`rosReadRGB`	Extract RGB color values from ROS or ROS 2 point cloud message structure
`rosReadAllFieldNames`	Get all available field names from ROS or ROS 2 point cloud message structure
`rosReadField`	Read point cloud data from ROS or ROS 2 message structure based on field name
`rosPlot`	Display lidar scan or point cloud from ROS or ROS 2 message structures

Quaternions

rosReadQuaternion Create MATLAB quaternion object from ROS or ROS 2 message structure

Velodyne ROS Messages

`velodyneROSMessageReader`	Read Velodyne ROS messages
`hasFrame`	Determine if another Velodyne point cloud is available in the ROS messages
`readFrame`	Read point cloud frame from ROS message
`reset`	Reset `CurrentTime` property of `velodyneROSMessageReader` object to default value

Occupancy Maps

`rosReadBinaryOccupancyGrid`	Read binary occupancy grid data from ROS or ROS 2 message structure
`rosReadOccupancyGrid`	Read occupancy grid data from ROS or ROS 2 message structure
`rosReadOccupancyMap3D`	Read 3-D map from ROS or ROS 2 `Octomap` message structure
`rosWriteBinaryOccupancyGrid`	Write values from binary occupancy grid to ROS or ROS 2 message structure
`rosWriteOccupancyGrid`	Write values from occupancy grid to ROS or ROS 2 message structure

Objects

BagSelection Object for storing rosbag selection

Blocks

Read Data	Play back data from log file
Read Image	Extract image from ROS Image message
Read Scan	Extract scan data from ROS or ROS 2 laser scan message
Read Point Cloud	Extract point cloud from ROS PointCloud2 message
Write Image	Write image data to a ROS or ROS 2 message
Write Point Cloud	Write point cloud data to a ROS or ROS 2 message

Topics

ROS Log Files (rosbags)
Summary of the structure of rosbags and the workflow for selecting subsets of messages in a rosbag.
Log ROS Messages from Simulink to a Rosbag Logfile
Save ROS message data from Simulink^® to a rosbag file.
Work with rosbag Logfiles
A rosbag or bag is a file format in ROS for storing message data.
Work with Specialized ROS Messages
Some commonly used ROS messages store data in a format that requires some transformation before it can be used for further processing.
Work with Velodyne ROS Messages
Velodyne ROS messages store data in a format that requires some interpretation before it can be used for further processing.
Improve Performance of ROS Using Message Structures
This example demonstrates the use of ROS message structures, and their benefits and differences from message objects.