A distance or angle can look clear at one moment and become hard to verify after a model changes. Perhaps you are moving atoms, refining a structure, or running an interactive minimization. Repeating the measurement each time interrupts the work—and a number that is no longer attached to the right atoms can be misleading.
SAMSON’s Measure editor offers a practical way to keep geometry visible while the associated atoms move. The key is to know when a measurement is temporary, when it should be saved as a label, and where to inspect the values afterward.
Choose the measurement by clicking atoms
Open the Measure editor from the left-side menu in the viewport, or use Ctrl+M on Windows/Linux or Cmd+M on macOS. Then click the relevant part of the structure:
- Click a bond to show its length.
- Click two atoms to show the distance between them.
- Click three atoms to show the angle.
- Click four atoms to show the torsion.
This makes it easy to ask a focused structural question—for example, whether two atoms remain close, or whether a local angle changes as you adjust the surrounding geometry.
Temporary or saved? Make the choice deliberately
A new measurement is temporary until you save it. Temporary measurements stay visible regardless of zoom, which is convenient while inspecting a structure. But SAMSON keeps only one temporary measurement: making another replaces the previous one.
If you want to retain several measurements, or keep one with the document, press Enter to save it as a label. That distinction is useful during a modeling session: use a temporary measurement for a quick check, and save it when it becomes part of the evidence or comparison you want to revisit. Labels are saved when you save the document in a SAMSON format (.sam or .samx).
Let the measurement follow the structure
Saved measurements update automatically when their associated atoms change position. The displayed measurement can therefore follow along as you use Move editors or interactive minimization, instead of forcing you to recreate the annotation after each adjustment. Measurements also update when associated atoms change charge.
This is especially useful for monitoring a structural change rather than recording a single snapshot. Keep a saved label on the geometry you care about, make the adjustment, and check how the value changes. The same measurement is visible in the viewport, Document view, and Inspector.
Use the Inspector to check what you measured
Select a saved measurement label and open the Inspector to access the atoms associated with it. For an atom-to-atom distance label, the Inspector also shows additional measurements for projections on planes. This can help when a single distance does not tell the whole story about how two atoms are oriented relative to the structure.
Saved measurement labels behave like other labels: their visibility depends on zoom, and you can adjust their font, color, and offset. The Inspector also lets you change the color of distance lines and angle planes. If you need consistent numeric precision across labels created with the Measure editor, adjust the number of decimal places in Preferences > Rendering > Labels.
A simple habit can prevent confusion: save measurements you intend to compare, then confirm the selected label and its associated atoms in the Inspector before interpreting the result. For the full instructions, see the SAMSON Measuring documentation.
Note: SAMSON and all SAMSON Extensions are free for non-commercial use. Get SAMSON.