Smartphone surveying completed with the compact LRTK survey instrument! The on-site revolution begins

In recent years, compact surveying instruments that can be used in combination with smartphones have been attracting attention at construction sites. With labor shortages and an aging workforce becoming increasingly serious, improving the efficiency and reducing the labor of surveying work is an industry-wide challenge. In this context, the benefits that a new surveying method leveraging smartphones and compact surveying instruments brings to the field are drawing attention. This article focuses on the device "LRTK", which opens up the possibilities of smartphone surveying, and explains in detail its market background, the innovations it brings to the field, its mechanism and features, use cases, comparisons with conventional methods, and the effects of its introduction.

Market Background of Small Surveying Instruments

In the construction industry, labor shortages are a major challenge. In particular, in the fields of surveying and construction management, the aging of skilled workers and the lack of younger personnel are making it difficult to maintain traditional methods. Moreover, the "personalization" of surveying work—its dependence on certain experienced individuals—often means that site progress is influenced by individual skills and circumstances.

To break through this situation, the construction industry is accelerating the shift to DX (digital transformation). Led by the Ministry of Land, Infrastructure, Transport and Tourism’s *i-Construction*, construction management that leverages ICT and 3D data is being promoted, and the introduction of new technologies such as drone surveying, 3D scanners, and machine guidance is advancing. As part of this, expectations are rising for compact surveying instruments that can be easily used on site. Even precision surveying, which traditionally required fixed-mounted total stations or expensive GNSS equipment, has become feasible with small, inexpensive devices thanks to technological advances. Compact surveying instruments have emerged in the market as a solution to improve the efficiency and sophistication of surveying work while offsetting labor shortages.

On-site Innovation with Smartphones and Compact Surveying Instruments: Labor Savings, Efficiency Improvements, and Enhanced Safety

Combining smartphones with compact surveying instruments has brought about a change in surveying work that could be called an on-site revolution. First, there is labor savings. Traditionally, surveying required teams of two or more, but with a smartphone and a compact surveying instrument, one person can complete surveying. For example, previously one person had to operate the surveying instrument while another held the staff (level rod). With smartphone surveying, a single operator can measure points and display and record the results on the screen as needed. Not only does this reduce staffing, it also shortens waiting times for surveying and improves the efficiency of the overall operation.

Next, in terms of efficiency, the process from data collection to sharing is accelerated dramatically. Because measurement data is automatically saved in a smartphone app and can be shared to the cloud immediately, information obtained on site can be shared on the spot with office staff and other teams. This allows verification of survey results and incorporation into drawings to be done in real time, helping prevent rework. Also, the intuitive operation of smartphones makes them easy to use even for people without specialist knowledge, contributing to a reduction in training costs. If an environment is established where anyone on site can acquire and utilize survey data, improved efficiency across the entire workflow can be expected.

Furthermore, the effect of improved safety should not be overlooked. The need to carry heavy tripods and surveying equipment into hazardous areas is reduced, and there are increasing cases where surveying can be done from a safe distance using compact devices and smartphones. For example, in road surveying work that traditionally required placing personnel to guide traffic, replacing that with quick smartphone surveying reduces workers' exposure time and is safer. Also, because AR functions allow positioning remotely without approaching hazardous spots, a shift from "going to measure" to "measuring from a safe place" is realized. The use of smartphones and compact surveying instruments not only streamlines labor and increases efficiency but also greatly contributes to ensuring worker safety.

Mechanism and Features of LRTK: RTK Positioning, Point Clouds, AR, Reports, Cloud

Now, as a representative example of a compact surveying instrument that enables smartphone surveying, let's take a look at the mechanism and features of LRTK. LRTK is an ultra-compact RTK positioning device that attaches to smartphones such as the iPhone. Compact enough to fit in a pocket (weighing about 165 g; thickness about 1 cm (0.4 in)), it nevertheless offers accuracy and a wide range of functions comparable to professional surveying equipment. Below are LRTK's main features.

• High-precision RTK positioning: LRTK uses RTK technology based on GNSS (Global Navigation Satellite System) to achieve centimeter-level positioning accuracy. While typical smartphone built-in GPS has an error of about 5-10 m (16.4-32.8 ft), LRTK can measure positions with horizontal 1-2 cm (0.4-0.8 in) and vertical 3 cm (1.2 in) accuracy. It supports the high-precision positioning service (CLAS) provided by Japan’s Quasi-Zenith Satellite System Michibiki, and a strength is that stable high-precision positioning can be performed even at sites outside cellular coverage, such as mountainous areas. This enables vertical surveying, which was previously difficult, to be carried out easily.

• 3D point cloud scan: By integrating with a smartphone camera and built-in LiDAR sensor, you can capture surrounding structures and terrain as 3D point cloud data. A key feature is that by combining positioning coordinates from LRTK with the smartphone’s sensors, absolute coordinates (geodetic coordinates) can be added to the point cloud data. This allows the captured point cloud to be overlaid with drawings and other survey data for practical use. It also helps in understanding the shapes of complex structures and excavation areas and in as-built management, and can be used for analyses on the cloud described later, such as volume calculations and cross-section creation.

• AR feature: LRTK also includes an position-guidance and construction-support function that leverages AR (augmented reality) technology. Through a smartphone screen, you can project 3D models and markings onto pre-set coordinates, allowing intuitive on-site layout marking work (indicating pile-driving positions). Tasks that were traditionally laid out using drawings and a tape measure can now display a mark on the smartphone screen that clearly shows “drive the pile here,” preventing misalignment. By overlaying the design model onto live site imagery, it can also be used for as-built verification and interference checks, helping to improve on-site understanding and prevent mistakes.

• Automated data recording and report output: The LRTK app automatically records the positioned location information along with the date/time and measurement conditions. The obtained coordinates are converted in real time to the Japanese geodetic system and the plane rectangular coordinate system, and point names and numbers are auto-assigned, eliminating the need for manual calculations or handwritten records in the field. Photos and notes can be attached to each survey point, and report generation of survey results is completed with a single button press. This removes the paper records and data transcription errors that used to occur with every survey, helping reduce site supervisors’ workload and improve data reliability. It truly feels like the smartphone itself becomes a field notebook, and because the app automatically performs advanced calculations, accurate survey results can be obtained even without specialized knowledge.

• Cloud sharing and utilization: Positioning data and point cloud data acquired with LRTK can be uploaded instantly from the field to the cloud-based LRTK Cloud. Uploaded data can be viewed on maps and 3D views in a web browser, allowing you to grasp field survey results in real time while in the office. The cloud offers robust analysis functions—distance measurement between survey points and calculation of areas and volumes—so all stakeholders can utilize the data without installing dedicated software. Also, by sharing a generated URL, clients and partner companies can view and download data without logging in, facilitating smooth information sharing both within and outside the team. By integrating with the cloud, data coordination between the field⇔office becomes seamless, and the preparation of reports and inspection documents is also streamlined.

As described above, LRTK is a multifunctional, compact surveying instrument that, when combined with a single smartphone, can complete all "positioning, measurement, recording, and sharing" on-site. Its mechanism and features provide an environment in which not only professionals but anyone can perform high-precision surveying.

Use cases: Site supervisors, ICT personnel, surveyors, etc.

By introducing LRTK, field stakeholders in a variety of roles are benefiting from it. Below we introduce the main use cases and the target users.

• Site Manager / Construction Supervision: For supervisors at construction sites, LRTK is a powerful support tool for daily operations. Because they can quickly perform tasks such as surveying and setting out control points, verifying as-built conditions, and laying out the positions of buried utilities themselves, they can reduce the time spent waiting after requesting the surveying department. They can measure areas of concern on the spot during construction and confirm them immediately, which helps with early detection of construction errors and prevents rework. Additionally, for progress management they can measure earth volumes using point cloud measurement to calculate quantities and overlay design drawings with current conditions in AR to check as-built conditions, contributing to on-site quality control and efficiency improvements.

• Land and building surveyors: For surveyors who conduct boundary surveys and investigations of land and buildings, compact RTK surveying instruments are a powerful tool for their work. With LRTK, high-precision positioning is possible via satellite corrections without installing control points, so boundary restoration and determining building locations can be carried out quickly. Even on sites that traditionally required time-consuming transit or traverse surveys, the necessary coordinates can be obtained in a short time. The acquired data can be output in the plane rectangular coordinate system, so it can be used directly to create drawings for submission to municipal authorities. By combining the surveyor’s expertise with the ease of compact surveying instruments, improvements in operational efficiency and service quality can be expected.

• ICT promotion officers: For ICT promotion officers at construction companies and local governments, LRTK can become a trump card for on-site DX. Because it is easy to operate and highly portable, deployment and training for field workers are simple. By equipping each person with one device and using them, you can build a system in which each worker proactively collects and shares site data. For example, if personnel perform smartphone surveying at various locations on a construction site and integrate the data in the cloud, it is also possible to visualize the progress of the entire site in real time. ICT promotion officers can, through the introduction of LRTK, promote the use of digital technologies within the company and work to optimize business processes across the board.

• Non-surveying field workers: Even general workers who have not received formal surveying training can find surveying with a smartphone and LRTK accessible. Because position measurement and point-cloud scanning can be performed through an intuitive smartphone app, for example a heavy equipment operator can measure the as-built condition of a work area by themselves, or a foreman can check dimensions before a rebar inspection, leading to a boost in on-site capabilities. Since measurement tasks can be carried out based on on-site decisions without relying on a specialized department, each field staff member can proactively take responsibility for quality control and safety checks.

• Other use cases: The convenience of LRTK is proving useful in fields beyond construction. For example, local governments have begun initiatives that use smartphone surveying to assess damage immediately after a disaster and quickly share 3D models of damaged locations. At disaster sites, where a limited number of personnel must cover wide areas, the mobility of small surveying devices and their real-time sharing capabilities are extremely effective. In this way, LRTK is being used by a wide range of users — from site supervisors to engineers, surveyors, and government officials — and is evolving from a "nice-to-have" to an "indispensable" tool.

Comparison with conventional methods: usability, implementation cost, training, accuracy, portability

What advantages does LRTK, which enables smartphone surveying, have compared with traditional surveying methods and equipment? Here we compare them from several perspectives.

• Usability: Traditional surveying instruments such as total stations and dedicated GNSS receivers required specialized knowledge and experience for initial setup and measurement operations. Operators had to perform coordinate calculations on the instrument's control panel and spend time on leveling, requiring proficiency. In contrast, LRTK runs on a smartphone app, and measurements and records can be made simply by following on-screen prompts and pressing buttons. Intuitive touch operation and automatic calculation functions mean that the hurdle to operating the equipment has been greatly reduced. With an interface that beginners can use without hesitation, even less-experienced staff can immediately obtain results with a certain level of accuracy.

• Initial cost: Assembling conventional high-precision surveying equipment required a substantial investment. GNSS surveying units cost several million yen per unit, total stations are also expensive, and labor costs for multiple personnel and subcontracting fees further add up. LRTK can be used with only a smartphone and is an affordable device, allowing deployment at a vastly lower cost compared with dedicated equipment. Traditionally, high-precision RTK positioning required base stations and communication fees, but LRTK can utilize correction signals provided free of charge by the Michibiki satellites, reducing running costs. As a result, a "one device per person" system—equipping each individual with surveying tools—becomes realistic and can promote DX across the entire site.

• Education and training: It takes a long time to teach newcomers the specialized techniques of surveying. Training in traditional methods such as transit instrument setup, observation procedures, and calculation methods has a high barrier, and without gaining experience they could not be used effectively in practice. Surveying with LRTK and smartphones is easier for young people who are accustomed to smartphones to accept, and its appeal is that they can be made operational through short-term training. Because apps automatically perform coordinate transformations and averaging, accurate results can be obtained even without fully understanding the theory. As a result, it becomes easier to increase the number of personnel with surveying skills within an organization, offering significant benefits for human resource development.

• Measurement accuracy: Professional surveying instruments are characterized by millimeter-level high precision, but LRTK also secures sufficient accuracy required on site. As mentioned above, it achieves approximately ±1～2 cm (±0.4–0.8 in) in horizontal/planar position and about ±3 cm (±1.2 in) in the vertical direction, which is more than adequate for general construction surveying. In experiments, data show LRTK positioning results had errors of less than 5 mm (0.20 in) compared with first-class GNSS equipment, exhibiting accuracy comparable to professional-grade instruments. Furthermore, using the averaging positioning function can reduce measurement error per point to below 1 cm (below 0.4 in), yielding results comparable to conventional methods. However, in satellite positioning in heavily obstructed locations and in precision construction that demands very high accuracy, conventional equipment still has its role, but for many field operations LRTK accuracy is sufficient.

• Portability: The difference in transporting surveying equipment is also significant. Conventional equipment required transporting tripods, targets, and mounting units by vehicle and then assembling and installing them on site. On rough sites with heavy machinery, simply carrying the equipment can be labor-intensive. The LRTK is palm-sized and small enough to hold in one hand even when paired with a smartphone, and the convenience of being able to carry it in a worker's pocket at all times is appealing. The agility to quickly take it out and measure when needed is a major advantage over conventional equipment. For example, when surveying in mountainous areas and heading to rugged locations, you can move with lighter gear and reduce the burden. It can flexibly handle measurements in confined or elevated locations as well as sudden additional survey points, and its "measure anywhere, anytime" portability lightens on-site mobility.

Benefits of implementation: Reduced rework・Reduced measurement time・Support for inspections・Improved reliability

Finally, we summarize the specific benefits of introducing LRTK on-site. Surveying with compact surveying instruments and smartphones is not merely a substitute for conventional workflows; it contributes to project success across multiple dimensions.

• Reduction of rework: Being able to verify measurement results with high accuracy and in real time makes it easier to detect construction mistakes and inconsistencies with the design on the spot. For example, if each dimension is checked with smartphone-based surveying before concrete pouring, any discrepancies can be corrected in advance. This reduces major rework that would require redoing work after construction and leads to prevention of quality defects. In addition, reviewing point cloud scan data helps prevent oversights, which ultimately reduces the number of rework instances and additional dispatches.

• Shorter measurement times: The speed of the surveying work itself increases dramatically. Traditionally, arranging a survey team and preparing equipment took time, but with LRTK you can take measurements immediately whenever you need. Acquiring the coordinates of a single point takes only tens of seconds, and even point cloud scans can be completed in a few minutes, allowing you to finish data processing right away. This reduces construction interruptions due to waiting for measurements and contributes to shortening the overall construction schedule. In particular, when the number of measurement points is large or for periodic as-built measurements, point cloud surveying—which can quickly measure many points at once—proves powerful and leads to significant time savings.

• Improving inspection responsiveness: Smartphone surveying data also functions effectively during inspections and site visits conducted by supervisory offices and clients. For each inspection item during construction, presenting the numerical values and point cloud models obtained with LRTK makes it easier to explain as objective evidence. For example, in as-built inspections, measurement data can be shared immediately via the cloud, allowing inspectors in remote locations to confirm conditions in real time. In addition, because surveying results are systematically stored as digital data, document preparation and the creation of reporting materials are expedited. This reduces the effort required to prepare materials for inspection while demonstrating accurate data, enabling highly reliable inspection handling.

• Improved deliverable reliability: Traditionally, field surveying results relied on manual recording and data entry, creating a risk of human error. After introducing LRTK, measurement data are automatically recorded and stored in the cloud, enabling highly reliable deliverables free from data tampering and transcription errors. Position coordinates and as-built records are retained with timestamps and latitude/longitude, making later verification and traceability easy. When combined with visual records such as point cloud data and photographs, information that is hard to convey on paper can be transmitted accurately. This increase in reliability raises evaluations from clients and stakeholders, and in turn contributes to showcasing a company's technical capabilities and strengthening competitiveness in winning contracts.

Summary: Benefits of Simplified Surveying Brought by LRTK

Smartphone surveying, which combines a smartphone with a compact surveying device, has breathed new life into traditional field surveying and is becoming a practical solution to challenges such as labor shortages and work efficiency. Among these, LRTK combines high-precision RTK positioning and the ease of smartphone apps, enabling "simple surveying" that anyone can use. Despite being small and lightweight, it delivers performance comparable to professional-grade equipment, and its benefits—directly contributing to labor savings on-site, improved safety, and quality assurance—are immeasurable.

By enabling onsite surveying to be completed with a single smartphone, each person in charge can autonomously collect and utilize data without relying on specialized departments. This not only improves operational efficiency but also promotes DX (digitalization) across the entire site, representing the first step toward a new form of construction management. In fact, at sites that have adopted LRTK, we have heard comments such as "there is less waiting for surveys and things run more smoothly" and "errors have decreased, and we can be confident in quality," and the benefits are steadily becoming apparent.

From now on at construction sites, the style of each worker carrying a compact surveying device and taking measurements immediately when needed may become the norm. The easy-to-use, high-precision surveying environment that LRTK brings can truly be called a reform in on-site work practices. Companies struggling with labor shortages and the transfer of skills should leverage this on-site revolution of smartphone-based surveying as a tailwind to pursue productivity improvements and stronger safety management. By actively adopting new technologies, you can take a step ahead in creating the construction sites of the future and build solid results and trust. Make the most of the benefits of simple surveying with LRTK, and please consider bringing this wave of revolution to your company’s sites as well.