A distance or angle can look clear in a molecular view and still be easy to lose track of. You may be comparing atoms, adjusting a structure, or running an interactive minimization—and the number you noted a moment ago may no longer describe the current geometry. The useful distinction is between a temporary measurement for a quick check and a saved measurement label that stays with your document.
Measure the geometry you need
In SAMSON, open the Measure editor from the left-side menu in the viewport, or use Ctrl/Cmd + M. Then click the relevant structure elements:
- Click a bond to show its length.
- Click two atoms to show the distance between them.
- Click three atoms to show the angle between them.
- Click four atoms to show the torsion between them.
This gives you a quick way to inspect local geometry without leaving the molecular view. For example, use a two-atom distance when checking whether a pair of atoms is moving closer together, or a four-atom torsion when you want to keep an eye on a rotation around part of a structure.
Temporary or saved? Choose before moving on
A measurement that you have not saved is temporary. It remains visible at any zoom level, which is convenient while you focus on one value. But it disappears when you create the next measurement. If you need to keep several measurements visible at once—or want the measurement to be part of the document—press Enter to save it as a label.
This small step can prevent a common workflow frustration: measuring several features in sequence and then realizing that only the last temporary measurement remains on screen. Saved measurement labels behave like other labels in the document. They can be inspected and adjusted, and labels are preserved when you save in SAMSON’s .sam or .samx formats.
Keep measurements useful while the structure moves
Saved measurements are not just snapshots of the value at the moment you created them. When the associated atoms change position, their measurements update automatically in the viewport, Document view, and Inspector. That means a saved distance or angle can help you follow a structure while using Move editors or interactive minimization, rather than forcing you to repeatedly delete and recreate annotations.
For atom-to-atom distance labels, the Inspector also provides additional measurements for projections on planes. If you want to see which atoms a saved annotation refers to, select its label and open the Inspector. This is especially useful when a busy structure makes it hard to tell which atoms an annotation belongs to.
Make the annotation readable
Saved measurement labels follow label visibility behavior: their visibility can change with zoom level. You can adjust label font, color, and offset using the labeling tools. The Inspector also lets you change the colors of distance lines, angle planes, and related measurement elements. If a color change is no longer useful, the Inspector provides ways to restore defaults: double-click the associated color text to reset it, or use the clear button next to Text color to reset the text color.
For consistency across a document, you can set a font for an individual label in the Inspector, or adjust the default font for labels that do not have one specified. In Preferences > Rendering > Labels, you can also set the number of decimal places shown for angles and distances created with the Measure editor. Choose a precision that makes comparisons readable without suggesting more certainty than you need.
For the complete measurement workflow and related settings, see the SAMSON Measuring documentation.
Note: SAMSON and all SAMSON Extensions are free for non-commercial use. Get SAMSON.