Load and Play ROS or ROS 2 Bag File

Load ROS or ROS 2 Bag File

Load the ROS or ROS 2 bag file by opening it from the File tab in ROS Data Analyzer app toolstrip. The toolstrip also contains the list of supported visualizers under the Visualize tab, and allows you to choose the layout between Default and Grid.

Grid Layout of ROS Bag Viewer App

You can open multiple instances of the app to play multiple ROS or ROS 2 bag files simultaneously.

View Bag File Details

The details of bag file content are found on the left side under the app toolstrip.

The Topic List shows the available topics in the ROS or ROS 2 bag file.
The Source Details list the Name, Start time, End time, Duration and Message count of the bag file.

Create Visualizers and Play Bag File

Types of Viewer

Viewer	Viewer Icon	Interface	Description
Image Viewer			Load a bag file containing `sensor_msgs/Image` or `sensor_msgs/CompressedImage` message type. Select Image Viewer from the toolstrip and choose the data source from the drop down to visualize the image. Use the top-right corner options to zoom in and out, and pan the image in all directions.
Point Cloud Viewer			Load a bag file containing `sensor_msgs/PointCloud2` message type. Select Point Cloud Viewer from the toolstrip and choose the data source from the drop down to visualize the point cloud message. Use the top-right corner options to zoom in and out, pan, and rotate the message in 3D.
Laser Scan Viewer			Load a bag file containing `sensor_msgs/LaserScan` message type. Select Laser Scan Viewer from the toolstrip and choose the data source from the drop down to visualize the laser scan message. Use the options on the top to zoom in and out, pan, and rotate the message 3D.
Odometry Viewer			Load a bag file containing `nav_msgs/Odometry` message type. Select Odometry Viewer from the toolstrip and choose the data source from the drop down to visualize the odometry message. See the indicator to view the instantaneous location of the robot in the trajectory. Use the top-right corner options to zoom in and out, and pan in all directions.
XY Plot Viewer			Load a bag file containing `geometry_msgs/Point` or `nav_msgs/Odometry` message type. Select XY Plot Viewer from the toolstrip and choose the data source from the drop down to visualize how the numeric message field changes across the XY axes. See the indicator to view the instantaneous location of the robot across the XY axes. Use the top-right corner options to zoom in and out, and pan in all directions.
Time Plot Viewer			Load a bag file containing `geometry_msgs/Point` or `nav_msgs/Odometry` message type. Select Time Plot Viewer from the toolstrip and choose the data source from the drop down to visualize how the numeric message field changes with respect to time. See the indicator to view the instantaneous location of the robot. Use the top-right corner options to zoom in and out, and pan in all directions.
Message Viewer			Load a bag file containing any message type. Select Message Viewer from the toolstrip and choose the data source from the drop down to visualize the raw message stored in the rosbag.
Map Viewer			Load a bag file containing `sensor_msgs/NavSatFix` or `gps_common/GPSFix` message types. Select Map Viewer from the toolstrip and choose the data source from the drop down to visualize the GPS message. See the indicator to view the instantaneous location of the GPS coordinate in the trajectory. Use the top-right corner options to zoom in and out, and pan in all directions.
Marker Viewer			Load a bag file containing `visualization_msgs/Marker` or `visualization_msgs/MarkerArray` message types. Select Marker Viewer from the toolstrip and choose the data source from the drop down to visualize the marker message. Also, specify the frame ID which you want to be the global frame for marker visualization. Use the top-right corner options to zoom in and out, pan, and rotate the message in 3D. From the Tools section on the app toolstrip, you can: Toggle the marker visualizer view between 2-D and 3-D axes. Select two marker points and measure distance between them. Use the data tips option in the top-right corner to select the two points of interest.

The ROS Bag Viewer app enables you to visualize messages in ROS and ROS 2 bag files. You can create multiple viewers within the app and visualize different ROS and ROS 2 messages simultaneously. For each viewer, you can filter the supported messages in the bag file and press the Play button from the Playback panel for visualization.

Playback panel of ROS Bag Viewer

You can choose to display the Elapsed Time or the Timestamp values associated with the bag file along the slider tick labels. You can visualize the messages by putting a specific numeric value or drag the slider to a particular value of the elapsed time or the time stamp. You can also take a snapshot and export the information for further use.

Note

Upon loading a ROS or ROS 2 bag file, the app toolstrip updates with the added features of adding and managing bookmarks and tags, and exporting data from topics or bookmarks.

Add and Manage Bookmarks

During the bag file playback, you can add bookmarks at desired time points. To add a bookmark, follow these steps:

Click Add in the Bookmark section of the app toolstrip. This opens the Add bookmark details dialog.
Add the duration of the bookmark in seconds and specify a label. You can also tune the start time of the bookmark.
Click OK. The app now adds a bookmark to the bag file starting from the start time for the specified duration.

You can always view all the bookmarks that you have added as a table by clicking Manage in the Bookmark section of the app toolstrip. Alternatively, you can also access the bookmark table by clicking the Bookmarks tab at the top-right edge of the app canvas. From the bookmark table, you can switch between different bookmarks, modify the bookmark parameters by double-clicking the entries, or delete bookmarks.

Add and Manage Tags

You can add tags to bag file that is currently open in the app. Tags serve as identifiers about the overall content in the bag file. Tags can also provide a quick understanding of the use-cases and applications of the bag file. To add a tag, follow these steps:

Click Add Tag in the Tags section of the app toolstrip. This opens the Tags panel.
Add the desired tag and press Enter.

Save and Restore Session

If you close the app with a bag file loaded or load a different bag file, this automatically saves the current session. The app saves these visualization session elements and restores them when you open the same bag file next time:

All visualizers
Visualizer layout
Bookmarks
Tags

Export Data from Topics and Bookmarks

The ROS Data Analyzer app enables you to capture the data of specific instances from a large database of bag files and export the data using topics and bookmarks. You can then save the data to a BAG or MCAP file for further analysis.

ROS Data Analyzer export icon

Export Data from Topics

To export data from topics, follow these steps:

From the app toolstrip, click Export and select Export data from Topics. This opens the export dialog specific to exporting data from topics.
Select one or multiple topics from the list under Select Topic.
Use slider to select the timestamp range for which you want to export the data. You can also enter Start time and Duration as alternatives to update the minimum and maximum thumbs of the slider respectively.
Click the drop down to select .bag to save the data exported from a ROS bag file. To save the data exported from a ROS 2 bag file, you can choose .bag or .mcap from the drop down.
Click Export to export data based on the chosen parameters.

For example, you can export message types like nav_msgs/Odometry and gps_common/GPSFix to a new bag file for path planning. Or, you can export sensor_msgs/Image and sensor_msgs/PointCloud2 message types to a different bag file for simultaneous localization and mapping (SLAM).

Export Data Using Bookmarks

To export data using bookmarks, follow these steps:

From the app toolstrip, click Export and select Export data using Bookmarks. This opens the export dialog specific to exporting data using Bookmarks.
Select one or multiple bookmarks from the list under Select Bookmark.
Click the drop down to select .bag to save the data exported from a ROS bag file. To save the data exported from a ROS 2 bag file, you can choose .bag or .mcap from the drop down.
Click Export to export data based on the chosen parameters.

For example, you can use this functionality to mark specific sections in deployed algorithms to capture certain instances of segmentation, pose and so on, and save them to a new bag file for further analysis.

Search Bag Files Using Tags, Bookmarks and Visualizers and Export Search Results

The ROS Data Analyzer app allows you to search across all previously opened bag files using filters or the associated metadata such as the tags, bookmarks and visualizers. You can then export the search results of the required metadata to a CSV file and share across a team for further analysis.

To search across previously opened bag files and export the search results, follow these steps:

From the app toolstrip, click Open > Search Bag File. This opens the search dialog.
Under Search Filters panel:
- Select the desired tags. You can search manually across all the tags using the search bar.
- Select the desired bookmarks. You can search manually across all the bookmarks using the search bar.
- Select the desired visualizers. This filter denotes the visualizers that were open during the bag file visualization.
All selected filters will appear in the Active Filters panel.
The Search Results panel shows the list of bag files which satisfy at least one criterion from the Active Filters panel.
You can export the search results to a CSV file by clicking the Export icon on the top right corner just above the Search Results panel.