Measuring
Measuring is usually the first thing anyone does on a virtual outcrop, and VRGS offers five tools that all look similar in the ribbon. The difference between them is which component of the separation they report, and whether the result is kept.
The five tools
All five live on the Annotations panel (and on the Home ribbon in the basic layouts). Click the tool to arm it, then pick points in the 3D view.
| Tool | Reports | Keeps a record |
|---|---|---|
| Measure Vertical | The elevation difference between two points | Yes |
| Measure Horizontal | The map distance between two points, ignoring elevation | Yes |
| Measure 3D | The true 3D separation between two points | Yes |
| Measure Multi 3D | Cumulative 3D distance along a path of many points | Yes |
| Tape Measure | Live distance, components and angles while you drag | No |
The first four create a measurement object in the Interpretation tree, which means the number survives the session, appears in the spreadsheet view, and can be exported. The Tape Measure is a read-out only — nothing is stored.
"How thick is this bed?" is usually Measure Vertical — but only if the bedding is horizontal. On dipping beds, a vertical measurement is not thickness; use a sedimentary log with a dip domain set, which converts to true stratigraphic thickness properly.
The Tape Measure read-out
The tape measure is the tool to reach for when you are exploring rather than recording. Drag between two points and it draws a live line over the model — deliberately over the top of it, so the tape is never hidden inside the geometry — with a label showing:
- Distance, in units chosen automatically: millimetres below 1 cm,
centimetres below 1 m, metres above. The number of decimal places increases as
the distance shrinks, so a small measurement does not read as
0.00. - DX, DY and DZ — the separation broken into project axes.
- Elevation and Azimuth — the orientation of the line between the two points.
That last pair makes the tape measure a quick orientation check as well as a ruler: drag along a bedding trace and read the azimuth off directly.
Trackway Analysis
Trackway Analysis is a specialised mode for measuring a sequence of footprints or similar repeated features, capturing the geometry of the trackway rather than one isolated distance.
Trackway Analysis is handled by the OpenGL view. The button is inert in a Vulkan view — switch renderer in Project Properties if you need it, or use Measure Multi 3D for a simple cumulative path.
Working with measurements once you have them
Each measurement is an object in the Interpretation tree → Measurements, with the usual right-click menu.
| Command | What it does |
|---|---|
| Navigate To | Fly the camera to the measurement. |
| Set Dip Azimuth | Attach an orientation to the measurement, so it can feed the structural tools. |
| Convert → To Polyline | Turn the measurement into a polyline you can extend, edit and use as interpretation. |
| Group / Ungroup | Organise measurements into folders in the tree. |
| Export | Write the group out — see below. |
Right-click the Measurements group and open its Spreadsheet. You get a tabular window of every measurement in the project — usually all you need when the question is just "what were those numbers?". Polylines, faults and geopolygons have the same view.
Virtual scale objects
Numbers are one way to convey scale; an object of known size in the picture is another, and often better for a figure or a presentation.
Display → Add Virtual Scale Object drops a synthetic object of a known dimension into the scene, in four sizes:
| Command | Size |
|---|---|
| Add Virtual Scale Object | 5 m |
| (1 m variant) | 1 m |
| (10 cm variant) | 10 cm |
| (triaxial variant) | A three-axis marker showing all three directions at once |
Place one beside the feature you are photographing and it does the same job as the geological hammer in a field photograph — see Figures and Images.
The Scale Bar overlay (Home ribbon → Overlays → Scale Bar) is the other half of this: a dynamic bar at the bottom-left of the view that rescales itself as you zoom. Use the overlay for a screen figure and a virtual scale object for something embedded in the scene itself.
Cross-sections
Cross Section on the Annotations panel defines a vertical section plane through the scene, which is how you get from a surface interpretation to a section view. The section appears in the Interpretation tree, where you can import an image onto it, and it works with the polylines and surfaces you have already interpreted — see Basic Interpretation.
Getting the numbers out
Right-click the Measurements group → Export opens the shared interpretation export dialog. Four formats work reliably — XML, GeoJSON, CSV and GlobalMapper ASCII — and the tick-boxes down the side of the dialog control what each record carries: record IDs, vertices, orientations, attributes, errors, stratigraphy, tree path, and whether to convert coordinates to WGS 84.
Tick Export displayed items only if you want just the measurements currently switched on in the tree rather than the whole group.
See Getting Data In and Out for the full export reference.
Tips and troubleshooting
- The measurement is wrong by a constant factor. The project's linear unit is probably feet where the data is metres, or the other way round. See Coordinate Systems.
- Elevations look wrong but horizontal distances are right. The vertical datum, or Vertical Scale in the display properties is not 1.0 — vertical exaggeration changes what you see, not what is measured, but it makes a wrong reading look plausible.
- The pick lands behind the surface. You are picking through a transparent or hidden object. Switch off what you are not measuring on.
- The tool does not do anything when I click. It needs two picks; the first sets the anchor. Press Esc to disarm and start again.
- Measure Vertical between two beds is not the bed thickness. Only where the beds are horizontal. Use a log with a dip domain instead.
See also
- Basic Interpretation — the interpretation tools these sit alongside.
- Sedimentary Logging — measuring stratigraphic thickness properly.
- Figures and Images — putting a scale into a figure.
- Getting Data In and Out — exporting measurements.