Measuring the distance between two or more points

The Tape measure tool is used to measure the two-dimensional distance between two or more points on an active echogram. On multibeam target echograms, the measurement can be stored in the EV file as a target property.

There are two measuring modes for the Tape measure tool: a single click, drag and release for a simple two point measurement; or a multi-point distance measurement using a click for each progressive point. Distances are displayed in meters by default. To display distances in nautical miles (nmi), apply a distance grid in (nmi) to the echogram on the Grid page of the Variable Properties dialog box.

To clear the current measurement, press ESC. To stop using the Tape measure tool, select another tool. To see the distance measurement, press SHIFT as you drag the mouse or as you move the mouse between points. Cumulative distance is displayed for multi-point measurements. Refer to About measuring distance for a discussion on the limitations of this tool.

• Single beam echograms
• Multibeam echograms
• Storing manual target lengths

To use the Tape measure tool on a single beam echogram

For a simple two point measurement:

1. Click on a single beam echogram.
2. On the Echogram tools toolbar, select the Tape measure tool
3. Use the mouse pointer to select a point on the echogram, drag to the second point, and release. Distance measurements between the two points will be displayed.

For a distance measurement with multiple points:

1. Click on a single beam echogram.
2. On the Echogram tools toolbar, select the Tape measure tool
3. Use the mouse pointer to select a point on the echogram and click.
4. Click in a new position for second and subsequent points. The displayed sum of distance measurements are progressively updated.
5. To obtain the perimeter distance of an enclosed shape, right-click and select Close perimeter.

Notes:

• Five distances are calculated and displayed on single beam echograms when the tape measure tool is used: the length straight-line distance, the length along-track distance, the GPS straight-line distance, the GPS along-track distance and the Range.

To use the Tape measure tool on a multibeam echogram

For a simple two point measurement:

1. Click on a multibeam echogram.
2. On the Echogram tools toolbar, select the Tape measure tool
3. Use the mouse pointer to select a point on the echogram, drag to the second point, and release. Distance measurement between the two points will be displayed.

For a distance measurement with multiple points:

1. Click on a multibeam echogram.
2. On the Echogram tools toolbar, select the Tape measure tool
3. Use the mouse pointer to select a point on the echogram and click.
4. Click in a new position for second and subsequent points. The displayed distance sum measurement is progressively updated.
5. To obtain the perimeter distance of an enclosed shape, right-click and select Close perimeter.

Storing manual target lengths

On a multibeam target echogram, you can store a distance measurement (made by the Tape measure tool) to a particular target on the echogram. The stored target property is called the manual target length and can be viewed on the Details dialog box and the Target Metadata window, and is exported from associated single target and target length echograms.

Measure a target manually and store its length

1. View a multibeam target echogram.
2. Zoom in to the target.
3. Click on the Tape measure tool .
4. Click, drag and release for a straight line measure.
   - OR-
   Click and click again for a multi-point measurement.
5. Move the cursor over the target you are measuring.
6. Right click and choose Store target length.
   - OR-
   Press the L shortcut key.
   
   Targets with manual target lengths are displayed with a green outline.

Notes:

• To view samples that contribute to the target select Show target sample outlines on the Echogram Display page of the Variable Properties dialog box.
• To display all target lengths (estimated and manual measurements) in one echogram refer to View target length and manual target length together.

Viewing manual target lengths

• Display the Details dialog box and see Length (manual) as you move the cursor over targets.
• Open the Target Metadata window.
• Create a Target conversion virtual variable and export the data.
• Create a TS substitution virtual variable using manual target length data.

Note: Display settings for multibeam targets are on the Echogram Display page of the Variable Properties dialog box. Refer to the discussion on the multibeam targets echogram for more information.

See also

About measuring distance
Multibeam echogram window shortcuts