LRTK Phone Opens a Future for Surveyors with Just a Smartphone

The role and challenges of surveyors required on site

Surveyors are indispensable on construction and civil engineering sites. Their primary role is to measure the precise positions and elevations of buildings and infrastructure so that construction proceeds according to design drawings. Because surveying errors can affect the safety and quality of structures, surveyors are always required to achieve high accuracy. However, several challenges in on-site surveying have become apparent.

First, there is a shortage of personnel and an aging workforce of technicians. While the number of experienced surveyors decreases year by year, there are too few younger successors, resulting in a chronic shortage of human resources. Traditional surveying work often involves carrying heavy equipment or working in pairs, which has efficiency issues. Carrying a heavy total station, setting up a tripod, and precisely mounting the instrument is time- and labor-intensive, and it imposes a burden and safety risks on workers. Furthermore, in the current situation where a limited number of people must handle many surveying tasks, methods that allow efficient surveying with few personnel are required. At some sites, the shortage of surveyors affects construction schedules, so reducing burden and improving efficiency are urgent. Surveying on roads or steep slopes is also inherently dangerous, and simplifying equipment and procedures to reduce work time is desirable from a safety standpoint. In this way, ensuring accuracy while addressing manpower shortages, work efficiency, and safety is a major challenge for surveyors on site.

Evolution of surveying technology: fusing traditional technology with smartphones

Traditional surveying technology has also evolved significantly in recent years. Total stations and GNSS surveying instruments are highly accurate, but their operation required dedicated equipment and skilled procedures. For example, to achieve centimeter accuracy (half-inch accuracy) with RTK (Real-Time Kinematic) positioning, it was essential to mount a base station antenna on a tripod and fix the rover to a pole to maintain verticality—stable installation was indispensable. The conventional wisdom for high-precision positioning was to “keep the equipment stationary and stable,” and the more precision required, the more bulky the equipment tended to become.

However, a new approach that fuses smartphones with cutting-edge positioning technology has emerged. By combining various sensors built into smartphones (GPS/GNSS, accelerometers/gyros, LiDAR cameras, etc.) with a high-precision GNSS receiver, and adding AR (augmented reality) and cloud services, surveying that used to require heavy equipment can be transformed. For example, a smartphone can receive correction information in real time for RTK positioning, display 3D models or survey points in AR on the camera screen, or easily capture surrounding point cloud data with built-in LiDAR. Measured data can be synchronized to the cloud and immediately checked or shared from an office PC. By fusing GNSS high-precision positioning technology with smartphone mobility and the convenience of AR and cloud services, surveying styles are undergoing major change.

What is LRTK Phone?

LRTK Phone is a smartphone surveying solution that embodies these new technologies. It is an ultra-compact RTK-GNSS receiver that attaches to a compatible smartphone (iPhone), condensing traditional surveying instruments into a smartphone-sized device. Its hardware is compact enough to carry in a pocket with a smartphone, weighing approximately 165 g and with a thickness of approximately 1 cm (0.4 in). Despite its small size, it is equipped with multi-band GNSS antennas and a high-performance receiver circuit, achieving positioning accuracy of only a few centimeters (a few inches) in both horizontal and vertical directions. It has an internal battery that allows about 6 hours of continuous operation and can be charged via USB Type-C, enabling power from a mobile battery. It connects wirelessly with the iPhone and acquires and utilizes positioning data via the dedicated “LRTK app.” The device is designed to attach to the back of the iPhone, integrating with the smartphone so it can be easily carried around the site and used for surveying whenever needed. Additionally, a slim monopod (pole) can be attached as needed. By placing the pole tip on the ground and holding the device vertically, more stable, high-precision positioning is possible. Even so, it is far easier than conventional tripod setups, and the flexibility to switch between handheld and pole use depending on the situation is an advantage.

A major point of LRTK Phone is that centimeter-level RTK positioning (half-inch accuracy) can be completed with just a smartphone and this device. There is no need to prepare a separate large base station, and because it supports Japan’s quasi-zenith satellite system “Michibiki” centimeter-level positioning augmentation service (CLAS) (half-inch accuracy), it can continue to receive correction information via satellite even at sites outside mobile communication coverage. Even in mountainous areas or disaster sites where radio signals are unstable, high-precision positioning can continue so work can proceed. In other words, with LRTK Phone, high-precision surveying that previously required specialized equipment and complex procedures can be easily realized by anyone with the feel of just a smartphone.

A variety of functions completed with a single smartphone

With the LRTK Phone system, a smartphone alone can perform various surveying-related functions. Here are some of the main features:

• Centimeter-level high-precision positioning (half-inch accuracy): Using GNSS and RTK technology, latitude, longitude, and elevation can be obtained in real time at centimeter-level accuracy (half-inch accuracy). This allows survey point coordinates to be recorded instantly, and traditional handwritten field notes can be completed on the smartphone.

• 3D point cloud scanning: By utilizing the iPhone’s LiDAR scanner and camera, surrounding structures and terrain can be captured as 3D point cloud data. The acquired point clouds are assigned absolute coordinates (geodetic coordinates), so their positions can be accurately confirmed on a map later.

• AR-assisted stake-out: Using AR (augmented reality), stake-out positions and reference points based on design drawings can be displayed on the camera screen. When driving stakes on site, a single operator can accurately locate positions by following markers shown on the smartphone screen.

• On-the-spot measurement of distance, area, and volume: Without measuring tapes or heavy machinery, distance, area, and volume can be measured on the smartphone. On the acquired point cloud data, distances between two points, enclosed areas, and earthwork volumes (fill or excavation volumes) can be calculated instantly. Specialized calculations are automated within the app, so anyone can easily perform earthwork calculations.

• Geotagged photos: Simply taking photos with the smartphone camera automatically records the coordinates of the shooting location with each photo. For drawings and reports, it becomes possible to accurately determine where each photo was taken, improving the accuracy of site records.

• Coordinate navigation (position guidance): By entering coordinates specified in the design, the smartphone will guide the user to that point. The screen displays the direction and distance to the destination, so even for points without visible markers, buried object checks or surveying tasks can be completed without getting lost.

• Cloud integration and data sharing: Survey data captured in the field is automatically saved and synchronized to the cloud. Data can be viewed as 2D drawings or 3D models in the cloud, and distances and areas can be measured there as well. There is no need to bring collected information back to the office, and instant sharing with stakeholders enables smooth reporting and analysis.

Use cases of LRTK Phone

The advantage of being able to perform high-precision surveying with a single smartphone is being utilized across various field operations. Here are several concrete use scenarios:

• Stake-out work: LRTK Phone is powerful in pre-construction stake-out (layout) tasks. Traditionally, surveyors used total stations to measure angles and distances and installed stakes with multiple people, but by using smartphone AR and coordinate navigation, one person can accurately drive stakes into the designated positions. The smartphone guides the user to pre-set coordinates, and by confirming the on-screen marker while installing the stake, efficient and error-free layout can be achieved.

• As-built management: Smartphone surveying is also useful for as-built management of fills and slopes. Scanning the post-construction terrain with LRTK Phone allows rapid acquisition of point cloud data needed for as-built checks. By overlaying the acquired point cloud with design data and comparing them, you can instantly confirm whether fills have reached the design elevation or excavations have been performed as instructed. Advanced checks such as displaying differences between point clouds and design surfaces as heat maps and color-coding areas of deficiency or excess can be completed with a single smartphone.

• Inspections: LRTK Phone is useful for inspections of infrastructure facilities and structures. For regular inspections of bridges and roads, if photos taken with a smartphone retain position coordinates, the exact locations where cracks or deformations were found can be accurately recorded. If the site is scanned as needed and the situation—previously assessed by visual inspection and scale measurement—is saved as 3D data, it will be useful for later comparisons and analysis. Such digital records are expected to improve the reliability of inspection results and work efficiency.

• Disaster response: In disaster sites such as earthquakes and landslides, smartphone-based surveying is highly effective. Lightweight smartphone surveying allows rapid entry into dangerous areas immediately after damage to record terrain and damage conditions. Photos and point cloud data acquired with LRTK Phone are instantly synchronized to the cloud with location information, enabling remote situational awareness and use in planning emergency responses. Since positioning is possible with satellite augmentation even in mountain areas outside communication coverage, stable surveying operations can be maintained in emergencies.

• Infrastructure maintenance and management: Smartphone surveying is expected to be effective in infrastructure maintenance and management, such as roads and water/sewer pipes. For example, when verifying the location of aging pipes by trial excavation, scanning an exposed pipe with LRTK Phone records the pipe’s 3D position accurately in the cloud. For future repairs, the recorded coordinates can be used with coordinate navigation to quickly find the buried location, reducing unnecessary excavation. Also, by overlaying management drawings (CAD or GIS data) on the LRTK cloud and referencing them on site, discrepancies between drawings and reality can be checked on the spot.

Comparison with traditional methods: personnel, equipment, time, safety, reproducibility

So, what specifically changes with smartphone RTK surveying compared to traditional methods? The main differences are summarized below:

• Required personnel: Traditional surveying required at least two people for instrument operation and holding targets. With LRTK Phone, a single person can complete all surveying tasks, greatly reducing the burden of personnel arrangement.

• Equipment used: Traditional methods required many dedicated pieces of equipment such as total stations, large GNSS units, tripods, and prisms, but LRTK Phone only requires a smartphone, a small device, and a monopod if needed. The effort of transporting and maintaining equipment is reduced, and bringing equipment to the site is easier.

• Preparation and work time: Time spent on tripod setup and instrument calibration is eliminated, so the time from arrival on site to the start of measurement is drastically shortened. Because you can move flexibly while continuously acquiring survey points, surveying can be completed efficiently in a short time even on large sites.

• Safety and burden: Lightweight equipment reduces the physical burden on workers, and surveying at heights or in confined spaces becomes easier. Reducing the need to carry heavy equipment or have two people enter dangerous areas reduces the risk of accidents.

• Data reproducibility: Digitally acquired point cloud data and coordinates are accumulated in the cloud, allowing rechecks and additional analysis at any time. Compared to relying solely on paper field notes, it is easier to detect measurement errors and verify measurements later, making it easier to reproduce the same results regardless of who performed the measurement. Past data can be compared as needed, offering advantages in quality control.

Impact on young surveyors, DX promotion, and future prospects

The new surveying method using smartphones has a significant impact on young technicians and those aspiring to become surveyors. Traditional surveying equipment required specialized knowledge and experience and involved hard labor, but intuitive interfaces familiar to the smartphone generation allow beginners to perform basic surveying after short training. This promotes digital transformation (DX) on site and shifts the surveyor’s role from “measuring accurately” to “supporting on-site decision-making by utilizing data.” The fusion of veteran expertise and young people’s IT skills contributes to both productivity improvement and the passing on of skills. Also, by reducing equipment burdens, veterans can continue working on site without overexertion, creating opportunities to pass valuable knowledge to younger staff.

Furthermore, initiatives such as the Ministry of Land, Infrastructure, Transport and Tourism’s i-Construction are accelerating ICT and DX across the construction industry. Smartphone RTK surveying like LRTK Phone is a cutting-edge approach that rides this wave. For small-to-medium sites where large investments or increases in personnel are difficult, solutions that utilize existing smartphones have low barriers to adoption and can raise the overall level of the industry. In the future, not only dedicated surveyors but also construction managers and designers may increasingly obtain and use surveying data themselves, enabling faster and more accurate on-site decision-making. Surveying DX that starts with a single smartphone has ample potential to greatly change the way surveyors work and the landscape of construction sites.

Conclusion: the future opened by smartphone RTK surveying

Finally, smartphone RTK surveying technologies represented by LRTK Phone are bringing innovation to on-site surveying. They address the accuracy, personnel, and safety challenges faced by surveyors and make it possible for each individual to easily obtain high-quality surveying data. The vision of surveying completed with just a smartphone is no longer a pipe dream; it is already within reach. By proactively adopting such new technologies, site productivity and safety will dramatically improve, and the way surveyors work will evolve into more creative and higher-value roles. The future of surveyors that LRTK Phone opens is sure to be an indispensable step in the coming era of labor-saving and DX in the construction industry. For sites troubled by manpower shortages and skill succession, smartphone RTK surveying can be a trump card for solving problems. By adopting advanced tools, you can quickly realize a new surveying style that will become the future standard. A single smartphone is all you need—this future of surveying is already beginning.