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This page assumes knowledge of ROS.

In Formant, ROS data which relates to /tf messages is encapsulated in a single data type called transform tree.

ROS message type	Formant datapoint type
`tf2_msgs/TFMessage` (`/tf` and `/tf_static` topics only)	Transform tree

This guide will teach you how to add a Transform tree telemetry stream from the /tf and /tf_static ROS topics.

Step 1: Create a ROS transform tree stream

In Formant, in the upper-left corner, open the menu and click Settings.
Click Devices, and then click on the device you want to configure.
Click the Telemetry tab, and then click Add Stream.
Click ROS Transform Tree. This will open the New ROS Transform Tree Stream configuration window:

Property	Usage
Telemetry stream name	Give the stream a name.
On demand	If ON, this stream will store data locally on your device, and only upload data to Formant when you click Retrieve on-demand data. `Rate limit` controls the rate at which datapoints are added to the on-device buffer. For more information, see On demand streams. If OFF, this stream will ingest periodically. `Rate limit` controls the rate of data ingestion.
Video encoding	Only applicable for `sensor_msgs/Image` and `sensor_msgs/CompressedImage` streams. Choose whether you want images ingested on this stream to be encoded as a video.
Validation schema	Only applicable for JSON and text streams. Choose a configuration schema for this stream.
Base reference frame	The base reference frame must be included in `/tf` or `/tf_static` (e.g., `base_link`).
Add tags (e.g. `key: value`) (optional)	Add tags to each datapoint of this stream. For more information on tags, see Configure access levels.
Rate limit (Hz) (optional)	If `On demand` is ON: Set the rate at which data is added to the on-device buffer. Data in the on-device buffer will be ingested by the agent when you click Retrieve on-demand data. For more information, see On demand streams. If `On demand` is OFF: Set the rate at which data is ingested. The default rate is 0.5 Hz.

When you're finished configuring your stream, click Done, and then Save.

Step 2: Add stream to a view

Once you've added a stream to your device, your next step is to add it to a view in Formant.

Add the streams you want to visualize, and then move on to Viewing data in Formant.

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