Use the Ruler Tool

Use this when

You want to measure the distance between two points on the sonar. The Ruler works on both the standard 2D/down-imaging view and the side-scan view. On side-scan, it measures horizontal ground-plane distance across the swath.

Before you start

Open a recording in the viewer. At least one channel must be loaded and visible.

Activate the Ruler tool

1. Click the Ruler button in the toolbar on the left side of the viewer, or press R.
2. The cursor changes to indicate the tool is ready.

Take a measurement

1. Click the first point on the sonar. A dot appears where you clicked, and a dashed line follows your cursor as you move.
2. Click the second point. The line locks in and a readout appears on the canvas showing the measured distance.

The distance is calculated in real-world meters (or feet, depending on your units setting), using the sonar's recorded depth and range data to convert pixel positions to ground distances.

Save or dismiss the result

After the second click you have two options:

• Add Contact — click this button in the readout to create a new contact at the measurement location with the length pre-filled.
• Click elsewhere — clicking anywhere else on the canvas clears the measurement and returns to cursor mode.

Saved measurements also appear in the Measurements list in the sidebar. Each entry shows the tool icon and the recorded distance.

What you should see

A dashed line between the two points with a distance readout. The readout shows the value in your current units. If you click Add Contact, the Contact dialog opens with the length field already populated.

If it does not work

• Second click clears the first point instead of completing the measurement — you may have accidentally pressed Esc or switched tools. Press R to reactivate the Ruler and start again.
• Distance reads much larger or smaller than expected — on the 2D view, the ruler measures along the depth axis. For horizontal (along-track) distances on side-scan, use the Ruler in the side-scan panel.
• No readout appears after the second click — the frames at those positions may not have valid depth data. Try two points in a section of the recording with a clear sonar return.