A distance or angle can look precise in a screenshot and still become misleading after the structure changes. If you move atoms, refine a pose, or run an interactive minimization, the old number may no longer describe the geometry you are looking at. In SAMSON, saved measurement labels can update with their associated atoms, so the annotation stays connected to the structure rather than becoming a static note.
Here is a practical workflow for measuring a geometry, keeping it visible, and preserving it with your document.
Choose the measurement by the number of atoms
Open the Measure editor from the left-side menu in the viewport, or use Ctrl+M on Windows/Linux and Cmd+M on macOS. Then select the feature you want to inspect:
- Click a bond to show or hide its length.
- Click two atoms to measure the distance between them.
- Click three atoms to measure an angle.
- Click four atoms to measure a torsion.
This gives you a quick way to check a contact, a local bond geometry, or a torsional arrangement without manually calculating coordinates. For an atom-to-atom distance, the saved label can also expose projections on planes in the Inspector, which can help when a single distance does not tell the whole spatial story.
Temporary readout or persistent annotation?
A measurement you have not saved is temporary. It remains visible regardless of zoom, which is useful while checking a value, but it disappears when you make another measurement. SAMSON allows only one temporary measurement at a time.
To keep the readout, press Enter. The measurement is saved as a label in the document. This small step is easy to miss when you are exploring several candidate geometries: save the values you want to compare or revisit, and leave quick checks temporary. Saved labels can be viewed and edited like other labels, and they are preserved when you save the document in SAMSON’s .sam or .samx formats.
Follow geometry changes instead of remeasuring
Saved measurements update automatically when their associated atoms change position or charge. That makes them useful during interactive editing: keep a distance or torsion label in place while moving atoms or performing interactive minimization, and watch the value respond to the changing structure.
If an annotation does not update as you expect, select its label and inspect it in the Inspector. A saved measurement label keeps access to the atoms associated with the measurement, which helps you verify that the annotation refers to the intended part of the model.
Make labels readable without changing the data
Saved measurement labels follow the usual label visibility behavior, including changes with zoom. You can adjust label font, color, and offset, and the Inspector also lets you change the colors of distance lines and angle planes. If a custom line or angle color becomes distracting, double-click its associated color entry in the Inspector to restore the default. To reset text color, use the clear button next to the Text color setting.
For consistent readouts across a project, set the default label font and the number of decimal places for distances and angles in Preferences > Rendering > Labels. A useful rule is to keep precision appropriate to the question: extra decimal places can make a label harder to scan without adding meaningful information.
Keep charge labels distinct
Measurements are not the only useful labels. You can also add formal- or partial-charge labels to atoms using the context toolbar for selected nodes: Label > Add label to… > Atoms (formal charges). These annotations can make it easier to read structural geometry alongside atom properties.
For the complete instructions, see the SAMSON Measuring documentation.
Note: SAMSON and all SAMSON Extensions are free for non-commercial use. Get SAMSON.