SLAM LiDAR vs cavity monitoring system (CMS)
A cavity monitoring system extends a laser head past the brow on a boom and rotates it: it records what is in a straight line from that point. A SLAM LiDAR scanner goes into the void — lowered, on a pole or on a drone — and records the cavity from inside.
The difference is the part of the stope the boom cannot see, and that is the part the reconciliation has been inferring.
SLAM LiDAR or a CMS for stope surveying?
SLAM LiDAR for the complete void — it enters the stope and records every wall at ±10 mm; a CMS for a quick line-of-sight check on a simple cavity.
How they compare
Both measure stopes; the criteria are what each records and what the reconciliation gets.
| SLAM LiDAR (Artec Jet)Enters the void on a pole, in a cage or on a self-navigating drone. | Cavity monitoring systemA laser head on a boom, extended past the brow and rotated. | |
|---|---|---|
| Where the sensor is | Inside the cavity, moving through it | At the end of a boom, fixed at the access |
| What is recorded | Every wall in a 360° × 290° view — the far wall, the back, behind shoulders | What is in line of sight from that point; shadows behind shoulders are gaps |
| Accuracy | ±10 mm underground; ±5 mm change detection between scans | Centimetre-class typical; depends on range and set-up |
| Irregular or large voids | The drone plans its own path through them; occlusion is not a limit | Occlusion grows with irregularity; large voids exceed range from one position |
| Beyond stopes | The same scanner surveys headings, shafts, ore passes, old workings and surface | Stopes only; a dedicated instrument |
| Output | Closed solid and point cloud; LAS, LAZ, E57 into the planning package | Point cloud from one position; gaps interpolated when closed |
| Choose this when | Choose this for reconciliation, dilution, irregular voids and anything the brow cannot see. | Choose this for a fast line-of-sight check on a simple cavity where a boom is already rigged. |
A CMS survey remains a valid check where the void is simple and the boom has line of sight to all of it. The comparison is about the void it does not have line of sight to.
The wall the boom cannot see
A CMS records from one point, so everything behind a shoulder, above a ledge or around a bend is a gap. On a clean, simple stope that may be very little. On a real one — an irregular back, a shoulder where a ring underbroke, a cavity that has unravelled — the gaps are exactly where the reconciliation question is. The software closes them by interpolation, and the solid that reaches the planning package is partly measured and partly drawn. Dilution and overbreak are then reported from the drawn parts as much as the measured ones.
A scanner inside the void has no line-of-sight problem, because it moves. Artec Jet on a drone plans its own path through the cavity and records every wall in a 360° × 290° view at ±10 mm; on a pole or in a cage it is lowered past the brow and records from inside. The solid that Artec Twins closes is measured everywhere. Where the CMS keeps its place is the simple, clean stope where a boom is already rigged and a fast check is all that is wanted — and where entering the void with anything is not permitted. There the CMS is quick and adequate, and this page says so.
The figures behind the verdict
See a stope flown from the drawpoint and reconciled against design with no interpolated walls — book a demo for your survey and planning teams.
Book a demoWhat people ask when choosing
Can we keep using the CMS alongside?
Yes. Where a boom is rigged and the void is simple, a CMS check is fast. Where reconciliation, dilution or an irregular cavity is at stake, the SLAM scanner goes in. Many mines run the CMS less and the drone more over time.
Is entering the void with a drone safe?
Nobody enters; the drone does, planning its own path around obstacles as fine as 2 mm wires, in the dark, positioned by SLAM. If it is lost, a 1.57 kg scanner is lost — not a person, and not a boom rig.
How does the accuracy compare?
Jet records at ±10 mm underground everywhere in the void; a CMS is typically centimetre-class from its single position and, more importantly, records nothing at all where it has no line of sight.
Does the SLAM scanner do anything else?
Everything else underground: headings at walking pace, shafts on the conveyance, ore passes on a line, old workings by drone, and surface from a vehicle. A CMS is a stope instrument; Jet is the mine’s survey scanner that also does stopes.
Other comparisons
Tell us how you survey stopes today
Describe the stoping method, the CMS you run and where the reconciliation is contested. A mining specialist will come back with what a scan from inside the void would change.