Is the Total Station Obsolete? How GNSS Terminals Are Changing Surveying Sites

For many years, precision measurements using total stations (TS) have been indispensable in surveying. However, in recent years, the emergence of satellite positioning-based GNSS terminals has been dramatically changing conventional surveying practices. Expectations for labor reduction and efficiency on site have risen to the point where people ask, "Are total stations no longer necessary?" This article clearly compares traditional total station surveying with surveying using GNSS terminals and highlights the advantages of GNSS terminals—especially the latest LRTK technology. Following the actual workflow on site, it explains the innovations GNSS terminals bring in terms of operability, labor savings, cloud integration, AR-based guidance, photogrammetry, and point-cloud data acquisition. After reading this, your appreciation for the idea that "GNSS terminals might be sufficient for many field surveys from now on" will surely deepen.

Differences between Total Stations and GNSS Terminals

First, let’s grasp the basic differences between the total station (an optical conventional surveying instrument) and the GNSS terminal (a satellite-positioning surveying instrument). The two differ greatly in surveying methods and required conditions.

• Differences in surveying methods: A total station sights a reflector prism through the instrument’s telescope and measures angles and distances with high precision to calculate the target point’s position. It is essentially an application of triangulation, an optical method for determining three-dimensional coordinates to the target. GNSS surveying, on the other hand, identifies positions by receiving signals from artificial satellites. In particular, GNSS terminals using the RTK method cancel out satellite positioning errors by using correction information from a base station, achieving real-time centimeter-level accuracy (cm level accuracy (half-inch accuracy)).

• Required personnel and workflow: Surveying with a total station is typically done by a two-person team. One person operates the instrument while the other holds the prism at the survey point (recently, robotic TS allows single-person surveying but is very expensive). Starting a survey also requires setting the instrument on a tripod, precisely leveling it, and aligning coordinates using known points—preparation that needs time and skill. In contrast, surveying with a GNSS terminal is basically a one-person operation. A worker carrying the terminal walks to the point to be measured, sets the terminal (antenna) down, and presses a button to capture coordinates. Although initial setup involves base station installation and communications configuration, once connected you can move and record points consecutively without complex re-mounting work.

• Measurable range and environments: Because total stations measure optically, they can only measure within ranges with line-of-sight. If obstacles exist, you must detour to a spot where the prism is visible or set up intermediate points. On large sites, you may need to re-set the instrument every several tens of meters to expand the survey network. GNSS terminals, however, can directly position remote points without line-of-sight as long as satellites can be captured; multiple points several kilometers apart can be positioned simultaneously to obtain high relative accuracy. Conversely, GNSS positioning cannot, in principle, be performed where satellite signals cannot reach (inside tunnels, inside buildings, deep forests, etc.), in which case total stations and similar instruments remain necessary. In short, TSs are strong where "lines of sight" are available, while GNSS terminals excel where the "sky" is open.

• Measurement accuracy and coordinate systems: In terms of accuracy, total stations boast millimeter-level precision over short distances and are excellent for detailing dimensions and displacement measurements. For example, some remarkable models can measure a target 100 m (328.1 ft) away with an error on the order of 1 mm (0.04 in). However, in wide-area surveys, small errors accumulate each time the instrument is re-set, and errors grow as distances between control points increase. GNSS surveying (RTK) typically achieves about ±1–2 cm (±0.4–0.8 in) in horizontal position and ±2–3 cm (±0.8–1.2 in) in height. While it does not reach the millimeter precision of TSs, this is sufficiently practical accuracy for general civil engineering surveying and as-built control. Also, with GNSS, if the reference station is aligned to public coordinate systems (global geodetic systems or plane rectangular coordinate systems), observed points are obtained directly as global positioning coordinates. This eliminates the extra work of converting to local coordinates later and makes matching with design drawings and GIS data easier (with total station surveys, if no known ground points or control points exist at the survey points, separate survey computations or manual local→global coordinate transformations are often required).

• Equipment, cost, and learning curve: Total station units are expensive, precision instruments requiring regular calibration and maintenance. Also, frequent setup/adjustment and surveying tasks demand skill, and it often takes time for newcomers to become proficient. GNSS surveying used to require a pair of receivers costing several million yen, but nowadays low-cost GNSS terminals and public correction services (network RTK using electronic reference stations) have become widespread, lowering the barrier to equipment adoption. Moreover, the latest GNSS terminals that pair with smartphones or tablets allow intuitive app-based positioning, making them easier to handle for technicians with limited expertise. Overall, while equipment burden and initial investment vary case by case, GNSS terminals are often seen as economically advantageous over the medium to long term when labor savings are included.

As described above, total stations and GNSS terminals each have strengths and weaknesses. However, with technological progress, GNSS terminals are overcoming many former drawbacks and have the potential to become the mainstay of field surveying. The next chapters will look at the concrete benefits GNSS terminals—especially the latest LRTK technology—offer from a field perspective.

Labor reduction and work efficiency: fast surveying by one person

The greatest advantage of GNSS terminals is that they can dramatically reduce personnel requirements for surveying tasks. As noted above, total station work traditionally required teams of 2–3 people, whereas GNSS terminals allow one person to complete surveying. A worker carrying the terminal walks the site and taps the button at the desired point, instantly recording coordinates. Since line-of-sight checks and coordination with another person are unnecessary, daily work efficiency improves dramatically, especially when measuring many points over a wide site.

Specifically, with total stations, time was consumed per point by re-setting equipment and transporting prisms. GNSS terminals can record points continuously, so the number of points that can be collected increases dramatically. For example, cases have been reported where topographic surveys that used to take several days were completed in just half a day to one day using GNSS terminals. Shorter surveying times allow subsequent construction and analysis work to start earlier, contributing to shorter project schedules and cost reductions.

Also, requiring fewer personnel is very attractive to the construction industry, which suffers from labor shortages. Even if experienced surveyors are scarce, if one person can operate a GNSS terminal, surveying tasks on site can be maintained, making it possible to cover multiple sites with limited resources. Single-person surveying also reduces communication errors during work and offers safety advantages. Introducing GNSS terminals is becoming a trump card for labor reduction and productivity improvement.

Intuitive operability and digital integration

Another appeal of GNSS terminals is that device operation and data processing have become intuitive and smart. The latest GNSS terminals connect to smartphones and tablets, allowing surveying operations from dedicated apps. Craftsman-like tasks such as precisely leveling an instrument with a spirit level or aligning crosshairs to a prism in an optical telescope are unnecessary. You set the antenna at the survey point and follow on-screen instructions to press a button. Once positioning stabilizes to centimeter precision (cm level accuracy (half-inch accuracy), FIX solution), that point’s coordinates are automatically recorded.

This simple operability can be learned relatively quickly even by inexperienced young technicians. For the smartphone generation, familiar tap operations lower the barrier to equipment operation. For example, dedicated apps can automatically calculate plane rectangular coordinates in the Japanese geodetic system and geoid corrections for height with a single tap. Metadata such as observation time and satellite capture status are recorded simultaneously, and functions like automatic point numbering and site memo input are provided. This eliminates the need to scribble point records in a field notebook and transcribe them later in the office. With all data managed digitally in one place, human errors are greatly reduced.

Furthermore, coordinate data obtained by GNSS terminals can be output in formats easily used by various software. Traditionally, coordinate calculations and data conversion after surveying were unavoidable, but with GNSS terminals you get coordinate data that can be treated as deliverables the moment you measure them. You no longer need to carry paper field books or calculators—just the terminal and a smartphone are enough to complete necessary field surveying. This digital integration is extremely valuable on modern sites that require ICT construction and BIM compatibility.

Immediate information sharing via the cloud

One notable change GNSS terminals bring to job sites is the speed of information sharing through cloud integration. The latest GNSS terminal apps have functions linked to cloud services, allowing survey data observed on site to be uploaded to the cloud with a single tap. For example, if you press the sync button upon finishing observations, the list of point coordinates and survey deliverables can be checked on the office PC within seconds. Considering the previous hassle of bringing data back on USB drives or entering them manually, this real-time connection between field and office is revolutionary.

Survey data aggregated in the cloud are stored and shared plotted on maps. Everyone involved can immediately view the coordinates, heights, and memo information of points collected on site, enabling speedy acceptance checks and decisions for subsequent steps. For instance, a construction manager in the office can check point positions and as-built results uploaded from the field and instruct whether additional measurements are needed. This reduces communication loss and helps prevent rework.

Cloud integration also excels at bringing design data into the field. If prepared design coordinates, drawings, or BIM/CIM 3D models are synchronized to the GNSS terminal via the cloud, that data can be displayed as background maps or reference models on site. Tasks that used to require carrying paper drawings or coordinate tables can now be done on a tablet, comparing current position with design points as you work. Two-way data use via the cloud enables seamless collaboration between field and office.

AR-based guidance and layout marking

An emerging technology combined with GNSS terminals is AR (augmented reality) guidance and layout marking. Using AR to overlay information on camera images from a smartphone, you can intuitively show where to measure or place elements on site. For example, when moving toward a target coordinate registered in a surveying app, arrows and guide lines are displayed on the screen to guide the worker. As you approach the target, distance and direction such as "X cm remaining" are shown, so even inexperienced personnel can reach the designated point without confusion.

Layout marking (stump-out) is also being revolutionized by AR. Previously, the procedure was to set a prism directly over the point determined by a total station and have another person mark it. With GNSS terminals and AR, the terminal’s position itself becomes the reference. You move the terminal to the specified coordinate and confirm with a virtual stake or mark shown on the screen. It’s like "driving a stake in AR" and enables layout marking even on concrete surfaces where physical stakes can’t be placed or on dangerous slopes, making it possible to indicate reference points safely and to mark multiple points quickly in succession.

More advanced uses include overlaying the design model on the actual site via AR. If you load the planned structure’s 3D model into the GNSS terminal app, you can project that model to scale through the camera on site and check its relationship with the surroundings and existing structures. Thanks to GNSS’s high-precision positioning, the model will not be misaligned, which is a major advantage. Viewing the AR model with owners and construction teams enables smoother image sharing and reduces rework due to misunderstandings. AR-based intuitive guidance and layout marking create an environment where anyone can accurately set out points and communicate smoothly, making them next-generation on-site tools.

Photogrammetry and point-cloud scanning for 3D data utilisation

The advent of GNSS terminals has also made it dramatically easier to obtain 3D data such as photogrammetry and point-cloud scans. Traditionally, recording the three-dimensional shape of terrain or structures required calling a specialized photogrammetry team for drone flights or using expensive 3D laser scanners. Today, site technicians can acquire 3D point clouds with just a smartphone. What supports this capability behind the scenes is the high-precision positioning provided by GNSS terminals.

For example, using the camera and LiDAR sensor built into a smartphone or tablet to scan the surroundings can generate point cloud data (a collection of many measured points) in a short time. Latest apps perform scanning while the GNSS terminal supplements the scanner’s real-time position, enabling accurate global coordinates to be assigned to each individual point in the point cloud. This makes large-scale point-cloud measurements that single smartphones previously struggled with possible, and automatically corrects the positional shifts and distortions that often occur during scanning. By simply walking around the site, you can obtain detailed 3D models of terrain and structures.

Moreover, the point clouds and photos obtained can be used immediately for earthwork volume calculations and as-built management. For example, scanning a pile of excavated soil allows on-the-spot volume calculation to quantify earthworks; comparing ground surfaces before and after paving enables progress calculation. Even non-specialist personnel can perform these analyses through intuitive app operations, making it a time when anyone on site can harness 3D data. It is also easy to overlay orthophotos from photogrammetry (detailed overhead images) on cloud maps to share site conditions among stakeholders.

By combining accurate GNSS positioning with 3D measurement technologies, GNSS terminals streamline field investigation and documentation. Using point-cloud data facilitates comparisons between design and as-built conditions and aids in preparing construction planning materials. In short, GNSS terminals make it easy to build a digital twin of the site—an advantage unique to the GNSS terminal era.

Conclusion: Simple surveying enabled by LRTK

As we have seen, GNSS terminals offer tremendous benefits to surveying sites. Of course, it is prudent not to categorically declare total stations unnecessary—indoor work and setup surveys requiring millimeter precision still favor TSs. However, it is undeniable that for typical outdoor surveying tasks, cases where GNSS terminals alone suffice have increased dramatically. In particular, a solution called LRTK, which evolves the latest RTK technology, realizes the goal of making GNSS surveying easier and faster to use on site.

With LRTK-capable GNSS terminals, even the formerly necessary base station installation can be eliminated. By receiving dedicated correction information via satellite communications or proprietary networks, you can achieve real-time centimeter-level accuracy while minimizing equipment. As a result, the gear you bring to site can be a pocket-sized GNSS terminal and a smartphone. Power on, launch the app, and you get the convenience of starting surveying immediately. LRTK combines high accuracy with mobility, making it a true "universal surveying instrument anyone can use anywhere."

Sites that have actually adopted LRTK report results such as finishing surveys that used to take several days in just a few hours and detecting structural displacements in real time with worker-carried terminals. The style of surveying where a single worker covers a wide area and shares and makes decisions on results on the spot enables the formerly difficult combination of labor reduction and immediacy. With prices becoming far more affordable than traditional equipment, the shift is moving from "one surveying instrument per team" to "one instrument per person." If everyone on site carries a high-precision positioning tool and can measure whenever needed, productivity will surge.

The Ministry of Land, Infrastructure, Transport and Tourism’s *i-Construction* initiative (DX of construction sites) also encourages GNSS use as part of ICT civil engineering. Simple surveying terminals like LRTK are emblematic solutions that support construction sites with digital technology. From now on, surveying may no longer be the domain of a specialized department alone, as site supervisors and construction managers themselves may measure and make immediate decisions. A portable GNSS terminal will be a major enabler of that change.

"Maybe we don’t need to rely on total stations anymore"—that future is becoming realistic. By leveraging GNSS terminals, especially cutting-edge devices like LRTK, anyone can perform high-accuracy surveying easily. If you are considering labor savings or speeding up surveying on your site, you might want to try this new surveying style. GNSS terminals, which combine accuracy comparable to total stations with unprecedented convenience, are sure to change conventional wisdom on site.