Table of Contents

• Main use cases of GNSS receiver rentals and their limitations

• The advancement of centimeter-level positioning via CLAS support and RTK methods

• Unique advanced features offered by LRTK

• Differences from conventional GNSS receiver rental equipment

• On-site improvements expected from LRTK adoption

• Conclusion: The future opened by the simple surveying tool LRTK

Main use cases of GNSS receiver rentals and their limitations

When professional surveyors or construction technicians require high-precision position information, they often consider using a GNSS receiver rental. For example, in civil engineering when establishing control points or checking as-built conditions, GNSS surveying equipment capable of centimeter-level accuracy is indispensable. However, renting and using conventional GNSS receivers involves several hurdles.

First, typical GNSS surveying equipment (such as RTK-GNSS receivers) requires not only the main unit and antenna and a dedicated controller (information terminal), but also large, heavy accessories such as tripods and poles. On surveying sites, carrying, assembling, and preparing these for installation and calibration at control points takes time. For high-precision positioning, it is also necessary to set up a base station to transmit correction information via radio, or to connect to a network RTK service via mobile communications, which requires securing communications environments and device configuration—tasks that demand specialized knowledge. Therefore, even with rental equipment, training is required to operate it effectively, and situations often call for surveying experts familiar with the site.

Moreover, rentals are limited by available time and the number of units. Problems often occur where equipment is not immediately available when needed, causing waiting time at the site. In mountainous surveys, the burden of carrying heavy equipment over long distances is also non-negligible. As described above, while renting GNSS receivers is effective in terms of accuracy, it comes with constraints such as size and weight, complexity of preparation, and low responsiveness. In addition, conventional GNSS surveying equipment is primarily designed to obtain position coordinates and generally does not include additional functions like point cloud scanning or AR-based site visualization. Therefore, when detailed 3D information or visual data sharing of the site is required—not just measuring coordinates—users have had to prepare separate laser scanners or perform photography and drawing comparisons outside the surveying workflow, which added burdens to site work.

The advancement of centimeter-level positioning via CLAS support and RTK methods

In recent years, a technology attracting attention as a solution to these positioning challenges is the RTK method combined with Japan’s quasi-zenith satellite system’s CLAS (centimeter-level augmentation service). RTK (Real Time Kinematic) is a technique that corrects satellite positioning errors in real time, reducing errors that can be several meters with standalone GPS to a few centimeters. Historically, using RTK required setting up a base station receiver on site and performing relative positioning to that control point for corrections, or connecting to a network correction service known as Ntrip.

On the other hand, CLAS is the latest augmentation signal service provided by Japan’s satellite positioning system Michibiki. With a CLAS-capable GNSS receiver, centimeter-level correction information can be received directly from satellites overhead, enabling high-precision positioning even in environments without mobile coverage or internet connection. In other words, even in mountainous areas, at sea, or in disaster zones where communication infrastructure is down, positioning accuracy can be maintained using only satellite signals. The arrival of CLAS-compatible devices that enable positioning nationwide without a base station is an advanced development that dramatically increases the mobility of positioning operations.

Combining the RTK method and CLAS, today’s most advanced GNSS devices can achieve centimeter-level positioning with the press of a button. The ability to perform high-precision surveying without relying on specialized contractors is revolutionary for the surveying and construction industries. Next, let’s look in detail at the unique advanced features offered by the smartphone-integrated positioning device “LRTK” that supports RTK and CLAS.

Unique advanced features offered by LRTK

LRTK is a pocket-sized RTK-GNSS receiver designed to be attached to a smartphone. Developed by a startup originating from Tokyo Institute of Technology, it is compact—weighing only about 150–160 g and about 1 cm thick—yet enables surveying accuracy comparable to conventional surveying instruments. It supports CLAS satellite signals and network RTK (Ntrip), and its strength lies in providing centimeter-level positioning across Japan without the dedicated base stations that were previously required. By using LRTK, the following advanced functions—unavailable with traditional GNSS receiver rentals—can be realized on site.

• Centimeter-level high-precision positioning: LRTK incorporates a multi-band high-precision GNSS antenna and receives RTK corrections and CLAS signals to continuously provide centimeter-level position information. For example, horizontal accuracy can be about ±1–2 cm and vertical accuracy within several centimeters, securing precision comparable to conventional large surveying equipment. Latitude, longitude, and elevation can be checked in real time on the dedicated app, and plane rectangular coordinates and geoid heights in the Geospatial Information Authority coordinate system (JGD2011/2020) are automatically calculated, enabling immediate use of surveying results on site. The device also includes a function to repeat measurements and average them, allowing one-tap accuracy enhancement—practical for fieldwork.

• Excellent portability as an iPhone-integrated device: While conventional GNSS receivers were bulky or came with dedicated controllers, LRTK integrates with a smartphone and is therefore highly portable. It can be attached to an iPhone with a dedicated smartphone attachment in one touch, and when not in use it fits in a pocket. It contains an internal battery that can run continuously for up to about 6 hours, and can be USB-charged from a mobile battery for extended surveying. The convenience of site staff carrying one per person and being able to take it out whenever needed is an advantage unique to LRTK that rental equipment lacks. In fact, at major construction companies, site managers carrying LRTK-equipped smartphones have reported that “waiting for the surveying team is gone and work stoppages during construction have drastically decreased.” Always having a high-precision positioning tool at hand dramatically improves on-site agility.

• Detailed 3D point cloud scanning: LRTK not only measures positions but also supports 3D scanning using the smartphone’s camera and LiDAR sensor. On the latest iPhones, LiDAR-based laser measurement or photogrammetry that reconstructs 3D from multiple photos can convert the surrounding terrain and structures into point cloud data on the spot. When used with LRTK, all captured point clouds are assigned absolute public coordinates in real time, so the scanned data immediately becomes a high-precision 3D surveying deliverable (for example, scanning slopes or bridge piers with an iPhone generates a 3D model with latitude, longitude, and elevation attached to the point cloud on site). Where as-built measurements previously using laser scanners or drone surveys could take days, with LRTK it can be completed simply by walking while scanning with a smartphone. From acquired point clouds you can calculate the distance between any two points, areas, and embankment or excavation volumes on site in real time, enabling immediate earthwork assessment and cross-section checks. For instance, in embankment work, scanning with LRTK and instantly calculating the fill volume helps determine the number of dump trucks and revise embankment plans.

• As-built management and visualization with AR functions: LRTK incorporates augmented reality (AR) technology so surveying data and design information can be visually used on site. For example, inputting coordinates from drawings displays arrows or markers on the smartphone screen to guide you to those points via an AR positioning guide. This allows one person to accurately stake out positions. You can also overlay acquired point clouds or BIM/CIM design 3D models on the smartphone and compare design and as-built in AR. It is easy to compare the finish of a slope against the design model on the spot or display scanned buried objects in AR to avoid obstacles during excavation. Because LRTK constantly knows its position with centimeter precision via GNSS, AR overlays remain stable even as the user moves, which is a major advantage. Sharing the completed image with stakeholders on a tablet at the site or comparing current views with past inspection photos in the same perspective using AR helps LRTK serve as a communication tool that contributes to site management.

• Indoor positioning and performance in areas without coverage: Even where GNSS signals cannot reach, LRTK can continue positioning and recording through clever measures. For instance, in places where GPS signals drop out such as under bridges or inside tunnels, the LRTK app’s indoor positioning mode can account for movement from the last temporarily measured position, enabling centimeter-level position tracking for short periods. This allows acquiring survey points in global coordinates or tagging photos with accurate location information even under bridges. Furthermore, CLAS support enables receiving correction signals directly from satellites in remote mountains without mobile phone coverage, maintaining high-precision positioning and proving powerful in disaster situations where infrastructure is cut. In fact, during the 2024 Noto Peninsula earthquake, technicians used LRTK-equipped smartphones to rapidly scan collapsed buildings in communication-unstable disaster areas, and their high-precision point cloud models were immediately shared via the cloud. The ability to comprehensively record and distribute disaster conditions with a single smartphone allowed remote headquarters to instantly grasp measurements such as “how many centimeters a utility pole has subsided” or “the width of a crack,” aiding initial response.

• Cloud integration for data sharing and report output: Positioning and point cloud data acquired with LRTK can be automatically uploaded to the cloud. By accessing the dedicated cloud platform (LRTK Cloud), office staff can view site survey data via a browser and share information in real time with remote supervisors and clients. On the cloud, you can list and search plotted survey points on a map, display point clouds in a 3D viewer, and measure distances, areas, and cross-sections. As needed, measurement results can be downloaded as CSV or SIMA formats for import into drawing software, and volumes or cross-section diagrams derived from point clouds can be output as reports with one click. There is also a function to issue data sharing links via URL, so sending it to subcontractors or stakeholders allows anyone to view 3D data without logging in. Information that used to be exchanged flatly by email or drawings can be conveyed three-dimensionally and intuitively using LRTK Cloud, improving communication accuracy and the efficiency of consultations.

As described above, LRTK completes “measure, record, and share” with a single device and dramatically simplifies tasks that used to require multiple devices and procedures. It is truly a solution that turns a smartphone into an all-purpose surveying instrument.

Differences from conventional GNSS receiver rental equipment

So, what specifically changes with the advent of LRTK? Compared with traditional GNSS surveying equipment available for rental, LRTK has suggestive yet clear points of differentiation.

First, the difference in portability and speed is obvious. Conventional rented GNSS receivers required operating equipment that could weigh several kilograms, including stationary base stations, pole-top antennas, and dedicated controller terminals. In contrast, LRTK completes tasks with only a smartphone and a slim antenna device and can be operated one-handed while walking the site. Eliminating the need to allocate heavy equipment or personnel to transport and set up gear means you can measure whenever you want, matching the site’s pace.

Next, there is a major difference in the breadth of functionality. Conventional devices could perform high-precision coordinate measurements but were limited in other functions. If you wanted to acquire point clouds or visualize with AR, you had to prepare separate 3D scanners, AR markers, tablets, etc., and different devices produced different data formats, complicating post-processing. With LRTK, surveying, point cloud generation, photo and memo recording, and even AR display are integrated on one platform, so data flows seamlessly. For example, you can view photos taken on the spot linked to the point cloud recorded by LRTK or immediately compare measured coordinates with drawing models—one-stop operations that were not possible when renting single-function receivers. This integration translates into improved work efficiency.

The dependence on specialist knowledge and experience also differs significantly. Operating traditional precision surveying equipment required experienced surveyors to handle device settings, verify positioning results, and avoid coordinate conversion errors. LRTK is designed so that guides appear on the smartphone app and beginners can operate it intuitively. Features like automatic coordinate conversion and averaged positioning help reduce human error, making it easier for non-experts to secure the required precision. This changes the situation where surveying had to be outsourced to a specialized department and enables site personnel to independently perform necessary measurements.

Additionally, there is an implicit difference in cost structure. Renting expensive GNSS receivers repeatedly can accumulate substantial costs as usage increases. New-generation devices like LRTK are more affordable, making it realistic for organizations to procure multiple units and keep them on hand. This enables a shift from “renting when needed” to “always available,” which not only prevents delays in site work but also contributes to long-term cost-effectiveness.

Overall, LRTK brings portability, multifunctionality, and ease of use not found in conventional GNSS receiver rentals, with the potential to transform on-site surveying practices.

On-site improvements expected from LRTK adoption

By adopting such advanced tools on site, what concrete improvements can be expected? Here are several examples.

• Significant reduction in work waiting times: Even in situations where previously one had to wait for a surveying team to arrive or for equipment setup, if each person carries LRTK they can measure on the spot as soon as the need arises. For example, when a major general contractor equipped all site managers with LRTK-enabled smartphones, they reported that “idle time due to waiting for surveying was eliminated, and overall site progress became smoother.” Being able to measure and check at a moment’s notice reduces stoppages and improves productivity.

• Promotion of solo work and labor savings: Because LRTK is lightweight, compact, and easy for anyone to handle, surveying tasks that used to require two to three people can now be completed by one person. For instance, checking control points or as-built inspections can be done by mounting LRTK on a monopod and pressing a button on the smartphone to get results immediately. This reduces the need for role divisions like having another person hold a staff rod, allowing efficient work even on understaffed sites. The ease of pulling a smartphone from a pocket instead of carrying a heavy total station to high places reduces worker burden in mountainous surveys and high-altitude inspections.

• Improvement in surveying accuracy and quality: Automatic digital recording and real-time sharing reduce human error and standardize measurement quality. With LRTK, survey point data are immediately saved to the cloud, making omissions and transcription errors unlikely. Also, less experienced technicians can obtain accurate measurements by following app guidance, reducing mistakes due to inexperience. As a result, the reliability of surveying data increases and rework or re-measurements are suppressed. Using acquired point cloud data allows checking details that were previously overlooked on 3D models, improving as-built management accuracy.

• Enhanced safety: LRTK’s non-contact and remote measurement capabilities contribute to on-site safety. For example, measurements at dangerous locations such as cliff edges or deep excavations can be taken without having personnel enter those areas, using remote target measurement functions. This reduces occasions where workers must stand on unstable footing or remain on busy roads for long periods, lowering accident risk. In disaster response, LRTK’s agility enables rapid situational assessment, contributing to secondary-disaster prevention and swift evacuation decisions.

• Smooth information sharing and faster decision-making: Traditionally, data measured on site had to be taken back to the office, converted into drawings and reports, and then shared with stakeholders. With LRTK, data are uploaded to the cloud from the site, allowing clients and designers to view and review data simultaneously from multiple locations. For example, sharing daily as-built information as point clouds enables remote offices to confirm progress in 3D and issue corrective or additional instructions within the same day. Faster decisions lead to shorter schedules and improved quality, fostering a stronger connection between site and office.

As shown above, introducing LRTK on site brings not only time and labor savings but also many benefits in terms of accuracy control and safety management. This is more than a mere replacement of equipment; it has the potential to transform the workflow on site.

Conclusion: The future opened by the simple surveying tool LRTK

The emergence of the new option of “simple surveying” using a smartphone and a small GNSS receiver in a field that used to require specialists is accelerating on-site digital transformation (DX). LRTK offers many advanced features not found in GNSS receiver rentals and integrates the processes of measuring, recording, and communicating seamlessly. As a result, it succeeds in meeting both precision and efficiency—requirements that were previously at odds—while lowering the barriers to surveying.

If a high-precision surveying device per person becomes commonplace, site planning and management methods will become even faster and more flexible. Such solutions align with the Ministry of Land, Infrastructure, Transport and Tourism’s push for i-Construction and are expected to bring new value to construction and civil engineering sites.

Take this opportunity to experience the convenient and advanced “simple surveying” made possible by LRTK. As high-precision measurement that used to be difficult becomes accessible to anyone with a handy tool, the possibilities on site expand dramatically. Your smartphone can evolve into the next-generation surveying and measurement platform. Why not take this new step forward?