Movement monitoring now runs end to end in Birdi. You set the thresholds that matter on your site, and every prism movement report is banded against them automatically — so no one is re-checking figures against a number that only lives in someone's head.
This article covers:
Setting Warning and Action tolerances for a site
What each band means and how a movement is classified
Generating a prism movement report
Reading the report and exporting it as a PDF
Keeping a history of tolerance changes for audit
Note: Prism reference sets require an Ultimate plan.
When to use tolerances and movement reports
Geotechnical monitoring — you're tracking embankment, wall or dam movement between surveys and need consistent classification.
Reporting to a client or regulator — a banded report removes the argument about whether a figure is significant.
Handing over between shifts or crews — the thresholds sit with the site, not with the person who ran the last report.
Auditing an earlier decision — you need to show which tolerances were in force when a report was produced.
Different sites, different rules — a tailings embankment and a road batter don't warrant the same thresholds.
Step-by-step: setting your tolerances
1. Open the Tolerance levels tab
Go to the Site page and select the Tolerance levels tab, alongside Maps and Reference sets.
2. Set your four thresholds
Tolerances are set per site, in metres. There are four:
Horizontal (XY) — Warning
Horizontal (XY) — Action
Vertical (Z) — Warning
Vertical (Z) — Action
A movement is banded by the highest level it reaches. Anything below the lowest threshold is simply within tolerance.
Tip: Set Warning at the point you'd want someone to look, and Action at the point you'd want someone to respond. If they're the same number, you lose the early signal.
3. Check the band key before you save
A live key next to the fields shows the Within, Warning and Action bands with their ranges, updating as you type. Use it to sanity-check the effect on a report before committing to it.
Note: A site that's never been configured runs on Warning 0.075 m and Action 0.1 m, and shows those in the form. The numbers on screen are always the ones actually in force.
4. Save
Every save creates a new version rather than overwriting the last one. The card shows who last changed the values and when.
5. Review the history
Select View history to see every past version with its values and its author. Nothing is edited or deleted, so a version stays readable for as long as you need it — useful when you're asked why a report from six months ago was banded the way it was.
Who can change them: anyone with permission to edit the site — the same permission as renaming a site or setting a mark's status. Everyone else sees the values read-only.
Step-by-step: running a prism movement report
1. Add your prism set to the map
Your prisms need to be on the map before processing. Either bring them across when you create a map from inside the site, or add them later from workspace data — the Sites tag in the data panel lets you pull the set into an existing map.
Tip: Creating the map from inside the site is the quicker path — Birdi prompts you to bring across the site's prism and GCP sets, plus earlier DEMs, in one step.
2. Prism processing on the processing form
On the processing form, you'll see separate sections for Ground control points and Prisms. If the site already has reference sets, these auto-populate from your site data — you don't re-upload anything.
Note: GCPs and prisms are processed differently on purpose. GCPs pin your map to the ground. Prisms are read as checkpoints and deliberately excluded from that solution, so what they report is their movement rather than their contribution to the survey. That's what makes the movement report possible.
3. Confirm your tolerances before you process
Open the Tolerance levels tab on the Site page and check the values are the ones your project actually works to. The tolerances in force at the moment you generate a report are the ones recorded on it.
Tip: Set these once, up front. Changing them later doesn't re-band a report you've already generated — you'd need to regenerate it.
4. Generate the prism movement report
Once processing is complete, generate the report from the prism set — either from the export options in table view, or the right-click menu on the prism set folder in the Layer Panel.
5. Work through the report
The report is a trend report, and it runs from the whole network down to the individual prism:
Overview — a map of the prism network across the site.
Movement summary — the full prism dataset, with horizontal and vertical movement accuracy shown at the top.
By embankment — each embankment, the prisms it contains, and the movement across that group. This is what tells you whether a whole strip of the wall is moving, not just one point.
By prism — each individual prism and how much it has moved between captures, across every survey processed at that site.
Every movement is banded against the tolerances in force: within tolerance, warning, or action where the point has moved beyond your threshold.
6. Export the PDF
The new report will generate and create a layer in the tree.
Select the layer
Right click or select the ...
Select download
The report will open in a new tab for review
Note: Each report is a fixed record of the survey it was run on. Tolerance values are recorded on the report as generated. If you change your tolerances afterwards, regenerate the report to see the new banding.
Editable embankments
A prism's embankment — the label that groups it, like "A" — can now be set directly from the point inspector in the map toolbox. Previously it could only come in via CSV upload and was read-only once there.
The edit sticks to the physical mark, so if a later re-survey leaves the embankment column out, your grouping won't be wiped.
Tip: Get your embankment labels right before you run a report — they're what the report groups by.
Best practice tips
Agree tolerances with your geotechnical engineer before you set them. The numbers in Birdi should match the numbers in your monitoring plan.
Set tolerances once, per site. They carry across every report at that site, so no one has to remember them.
Use the band key before saving. It's faster to check the effect on screen than to regenerate a report.
Don't edit tolerances mid-campaign without noting why. The history records who and when — the reason still needs to live in your project notes.
Keep prism IDs consistent across re-surveys, so the same physical mark is tracked over time.
Check embankment labels after a re-survey upload, so the report groups the way you expect.