A distance or angle can look correct in a static structure and change as soon as you move an atom or run an interactive minimization. Repeating measurements by hand interrupts the work—and makes it harder to see whether a geometric change is meaningful. In SAMSON, saved measurements can follow the atoms they refer to, so you can monitor geometry while editing.
Measure first, then keep the result
Open the Measure editor from the left-side menu in the viewport, or use Ctrl+M on Windows/Linux and Cmd+M on macOS. The number of atoms you click determines the measurement:
- Click a bond to show its length.
- Click two atoms to show their distance.
- Click three atoms to show the angle.
- Click four atoms to show the torsion.
The first result is temporary. It stays visible at any zoom level, but disappears when you make another measurement. That is handy for a quick check, but it is not enough if you want to compare several geometric features or watch one during a longer editing step. Press Enter to save a measurement as a label in the document. You can then create and retain more measurements.
Let measurements follow your edits
Once a measurement is saved, SAMSON automatically updates it when the associated atoms change position or charge. The updated value is shown in the viewport, Document view, and Inspector. This makes saved measurements useful during operations such as moving atoms or interactive minimization: instead of measuring again after each change, you can follow the same geometric relationship as the structure evolves.
A practical workflow is to identify the atoms that define the feature you care about, create the measurement, press Enter to save it, and then make your structural changes. Keep the label visible while editing and check how its value responds. For a distance, this can help you track whether two atoms are moving closer together or farther apart; for an angle or torsion, it lets you monitor changes in the defined geometry.
Inspect what the label records
Select a saved measurement label and open the Inspector to access the atoms associated with it and inspect its measurement properties. A saved atom-to-atom distance also provides additional measurements for projections onto planes. This can be useful when a single distance does not tell the whole story about how two atoms are positioned relative to the surrounding coordinate planes.
Keep the annotation readable
Saved measurements behave like other labels: their visibility depends on zoom level, and you can adjust their font, color, and offset. In the Inspector, measurement labels also let you change the colors of distance lines and angle planes. If you want a consistent level of detail in displayed values, Preferences > Rendering > Labels lets you set the number of decimal places for angles and distances created with the Measure editor. Remember that this setting applies to labels whose font or other relevant properties have not been specified directly on the label.
When you save the document in SAMSON’s .sam or .samx format, measurement labels are saved with it. That means your geometry checks can remain part of the working document rather than being lost as temporary viewport annotations.
For the full guide to measuring, updating, and styling measurements, see the SAMSON Measuring documentation.
Note: SAMSON and all SAMSON Extensions are free for non-commercial use. Get SAMSON.