Before starting a new measurement, select from the New Measurement Settings if a Distance, an Angle or Angle and Distance should be measured.

To start measuring, click with the left mouse button at the position where the measurement should start.

If Distance is chosen, end the measurement by left-clicking again at the desired end point.

If an Angle is measured, you first draw on side of the angle. After the second mouse click, the second side of the angle is displayed and you can move it around to the desired endpoint, where you click again to finish the measurement. The arrows indicate in which direction the angle is measured.

When choosing Angle and Distance, the distance will be measured on the first drawn side of the angle.

In the Editing Settings part of the panel, choose Lock Measurements to move the whole line of a measured distance and/or angle to another location. If Lock Measurements is unchecked, the end points of a measurement can be modified.

In Snap to grid, define if points should be selected freely in the structure (Free Placement), or be snapped to the nearest Voxel Centers, Voxel Corners, or Edge Centers. This means that when you click into the structure the nearest voxel center, voxel corner, or edge center (depending on the selection) is set as starting point (or end point) for the measurement.

In the example shown here, the diameter of the red fiber in X-direction is measured.

The differences between the snap options can be observed if the visibility of the grid is turned on. Look at the start or end points of the measurements to detect the difference. If a Snap mode is active, the measurements can be more precise than placing the points by hand (Free Placement).

Each measurement gets a number and all of them are listed in the drop-down menu under Active Measurement. The last measurement is usually the active one, but you can choose a previous measurement from the list or by clicking on the endpoints of the measurement in the visualization area.

Below, the measured distance and/or measured angle is shown.

Check Hide to hide the measurement and the text in the visualization area, uncheck Show Distance to hide only the text of distance measurement, or uncheck Show Angle to hide the text of the measured angle. The angle is measured and shown counterclockwise, when Counterclockwise Angle is checked. Uncheck to switch measuring and visualization to Clockwise, there is no need to redo the measurement, see also the example below.

With Delete Measurement, the currently active measurement is deleted from the panel.

Clicking Adjust Voxel Length opens a dialog to change the voxel length of the structure accordingly to the measured distance. Enter the desired length of the measured line (in the example 8.5 µm instead of the 8 µm measured in Measurement 1) and click OK. The voxel length of the whole structure is rescaled to match the desired length. Check Rescale all volume fields, to rescale also the volume fields to the new voxel length.

The old measurements remain in the structure and their metrical position is maintained. But due to the adjusted voxel length, the voxel position of the measurement changes.

In the All Measurements part of the panel, all available measurements can be hidden by checking Hide All or deleted with Delete All Measurements.

Write the resulting distances and angles into a *.gdr file by clicking Save Measurements. A dialog opens, where you enter the desired result file name.

In the Visualization Settings, choose the Line Thickness and Color for the visualization of the measurements. This can also be done after the measurements were conducted and it applies to all measurements. The font size of the measurements can be changed in the visualization settings tab of the sidebar.

Edit a selected measurement with a right click on one of the endpoints. The selected point can be snapped to the grid as explained above. The measured distance is adapted accordingly.

The options Hide, Adjust Voxel Length, and Delete Measurement are the same as explained above. If needed, you can Copy the Distance in meters to the clipboard.

For the example we re-measure the length of the gray fiber segment and its angle to the X-axis. For this, we set the options for this new measurement to Angle and Distance. As snap mode Snap to Edge Centers was chosen.

First, the desired distance is measured, then this measure line is taken as first angle leg, and the angle can be measured with a third click.

Unchecking Counterclockwise Angle changes the visualization and value of the measured angle as it is measured clockwise.

Unchecking Show Distance makes the distance disappear from the visualization area. It is still shown in the Metrology tab of the sidebar.