This is part III of our III part cover story. Catch up on part I, Minnesota company develops new system for mapping underground utilities and part II, Review benefits of GNSS rover accuracy.
Scanning capabilities, in one form or another, have been added to models of robotic total station (RTS) since 2007 — for instance, on the Trimble VX. Such capabilities were limited to a pattern of individual shots, as the RTS would “nod.” While not designed to compete with traditional scanners, even such painfully slow “pseudo-scanning” capabilities demonstrate the value of new options for capturing detailed features.
It was not long before nearly all RTS offered limited (nodding scanning) capabilities, though at rates as slow as 15 shots per second. By 2013, the release of the Leica MS50 took the nodding scan to the next level, with a rate of up to 1,000 points per second, and then up to 30,000 in the subsequent MS60 model (which now also supports a tilting prism pole).
The end of 2016 saw the release of Trimble’s SX10 (and SX12 more recently). This routed the laser through a pair of rotating prisms to capture a swath of points as it nodded. In 2019, Topcon took the approach of adding a piggy-backed compact conventional scanner to the top of an RTS: the GTL-1000 and GTL-1200 models.
All these implementations were built upon high-quality RTS. Foremost, they can be operated as an RTS, with all the same integrated surveying capabilities as instruments with which surveyors were familiar, and in the same field software.
This includes all the integrated GNSS workflows: resections, combining optical and GNSS captured points in the same survey, and adding a rover to the prism pole for track-on-GNSS methods. One huge advantage of scanning total stations is instant deliverables already fully registered, as adopters of these new systems quickly realized.
Some initial users seemed skeptical of the relatively slow scan rates of these various models: 12 to 30 minutes for full-dome scans, and then a photo capture pass. Others, though, discovered that the time did not necessarily need to go to waste.
First, it is not necessary to do a full-dome scan and image pass every time; it is sufficient to pre-select specific areas to scan and image.
The real kicker is that while the RTS is scanning, it is possible to fire up the GNSS rover and capture points that the RTS cannot see, such as behind curbs, cars and vegetation. This is true especially now, with the advent of no-compensation tilt capabilities on nearly every new GNSS rover system.
This can be done in the same project, using the same software and field controller. This struck this writer as one of the coolest lateral features of scanning total stations when he first tried out an SX10 in 2017.
Considering the benefits scanning total stations deliver (especially with the integrated GNSS bonus), what has the reception been like among surveyors and other segments of the architecture, engineering and construction (AEC) community?
“As an industry, we’re getting better at tying solutions and workflow elements together, and not seeing them, or treating them, as individual functions or pieces of hardware,” said Derek Shanks, director of Geospatial Optical Product Management for Trimble. “We bring the system aspect, a case of using the best tool, using the strengths of each tool to their fullest.”
Accoring to multiple manufacturers, sales numbers indicate that the adoption of scanning total stations for AEC applications — and not just surveying — has exceeded expectations.
