cm-level accuracy (half-inch accuracy) × pocket-size! The latest compact surveying device is amazing

In recent construction and civil engineering sites, the use of ICT has advanced, and the way surveying is conducted has also changed significantly. When you hear surveying, you may imagine large-scale equipment such as transits and total stations being operated by specialized surveyors. However, today, compact surveying devices that offer centimeter-level positioning accuracy (cm level accuracy (half-inch accuracy)) while being pocket-sized have appeared, bringing an era in which anyone on site can easily carry out surveying. A representative example is the latest compact surveying system "LRTK". This article provides a detailed explanation—from the evolution of surveying equipment and the challenges faced on site, to the requirements demanded of compact surveying devices, the mechanism of high-precision positioning using smartphones and RTK technology, and the configuration and features of LRTK, as well as concrete use cases and the benefits of adopting it.

Evolution of Surveying Equipment and the Background of On-site Challenges

The construction industry is experiencing a chronic labor shortage, with the aging of personnel responsible for surveying and a lack of younger staff in particular becoming a significant issue. Moreover, despite increasing demand for surveying—such as maintenance and disaster-response measures due to aging infrastructure—there is a shortage of specialized surveying technicians. Conventional surveying work requires handling specialized equipment and advanced knowledge, and is often outsourced to external specialists, so even in routine on-site situations where people want to take measurements easily there has been a specialization barrier.

Furthermore, conventional surveying instruments are large and heavy, making them cumbersome to transport and set up on site. For example, surveying with total stations or GNSS receivers requires erecting a tripod and mounting the instrument, which took multiple people and time. For site agents juggling many tasks with limited staff, preparing equipment and securing specialized operators was a burden. The low portability made surveying in mountainous areas or on confined sites difficult, and it was a factor that made even minor measurements feel burdensome.

Against this backdrop, there has been a growing demand on-site for new surveying tools that are "easy for anyone to use, capable of immediate measurements, and highly accurate." The promotion of ICT construction has introduced new technologies such as drone aerial photography and 3D scanning, but when drones cannot be flown in urban areas or when detailed ground-level measurements are required, the need for compact, easy-to-use surveying instruments is increasing. To solve on-site challenges, surveying equipment is evolving ever more toward being both compact and simple and high-performance.

Requirements for compact surveying instruments: high accuracy, ease of use, and compactness

When considering compact surveying instruments for on-site use, there are three non-negotiable requirements. They are “high accuracy”, “easy operation”, and “portability (compact and lightweight)”.

• High accuracy: If the precision of survey results is low, it will affect construction quality and the reliability of land boundaries. Even when miniaturized, it is essential to ensure centimeter-level accuracy (cm level accuracy (half-inch accuracy)), with errors of a few centimeters or less. Traditionally, more precise equipment tended to be larger, but high accuracy must be realized in small devices through advances in GNSS and sensor technology.

• Easy operation: Simplicity that can be handled by non-experts is important. It should allow intuitive measurement via button operations or a smartphone app, and automatically handle difficult settings and calculations. The key point is an interface that on-site personnel can start using right away without having to thoroughly read the manual.

• Portability: It should be compact and lightweight enough to be carried at all times on daily job sites. If it fits in a pocket or a workwear chest pocket, it can be quickly taken out for measurement when needed. If it is light in weight, carrying it for long periods will not be burdensome. It is desirable to have a built-in battery so it can be used without worrying about power, and an integrated design with few cables.

If there is a surveying instrument that satisfies these three-in-one conditions, even non-specialist staff on site can easily "take a quick measurement". So how are the compact surveying instruments that have emerged in recent years achieving these conditions? The key technology is the combination of smartphones and RTK positioning.

Centimeter-level accuracy with smartphone + RTK positioning

In recent years, smartphones have supported multiple satellite positioning systems (GNSS), including GPS, and their positioning accuracy has improved. However, the GPS accuracy of typical smartphones is on the order of a few meters and does not reach the centimeter-level accuracy required in construction and surveying. The technology attracting attention for this is RTK (Real Time Kinematic) positioning.

RTK positioning corrects positions in real time using error-correction information from a reference station, allowing high accuracy down to errors of a few centimeters (a few inches). Previously, expensive dedicated GNSS receivers and communication devices for RTK positioning were required, but now, by combining a smartphone and a compact RTK-capable receiver, individuals can easily perform RTK surveying. The smartphone functions as a platform that uses its communication capabilities to receive network-based RTK correction information (such as VRS), perform positioning computations, and display data. Meanwhile, the small RTK-GNSS receiver captures high-precision satellite signals that the smartphone cannot receive and transmits the data to the smartphone.

For example, in Japan, by using the satellite-delivered augmentation signal called CLAS（centimeter-level positioning augmentation service） provided by the Quasi-Zenith Satellite System Michibiki, RTK positioning is possible even in mountainous areas outside internet coverage. The latest compact surveying instruments also support reception of this CLAS, enabling high-precision positioning using only correction information from satellites without installing a base station. Also, because smartphones and receivers connect via Bluetooth, they are cable-free and easy to handle.

In short, the combination of "smartphone + RTK" has made it possible for one person to achieve centimeter-level positioning that previously required specialized equipment and personnel. On the smartphone screen, you can check your position in real time while recording points or being guided to the location you want to measure, making surveying work dramatically more efficient and simpler.

The Latest Compact Surveying Instrument LRTK: Configuration, Features, and How to Use

One of the latest compact surveying instruments garnering attention for leveraging smartphone + RTK technology is LRTK. LRTK is a surveying system developed by a startup spun out of Tokyo Institute of Technology, and it consists of a pocket-sized RTK-GNSS receiver, a smartphone app, and a cloud service. By attaching the dedicated compact receiver to a smartphone or connecting it via Bluetooth and simply launching the app, the smartphone itself transforms into a high-precision surveying instrument.

The LRTK receiver main unit features a slim, lightweight design weighing approximately 165 g and measuring about 10 mm (0.39 in) thick, making it possible to carry in a workwear pocket. It is powered by a built-in battery and can be used continuously on site for several hours. The equipment configuration is simple; for example, for iPhone there is a dedicated smartphone case that allows the receiver to be attached with a one-touch mount, so setup is completed immediately when you want to take a measurement. An optional small pole (a monopod) is also available, and when measuring ground points more precisely the receiver is attached to the tip of the pole and used wirelessly in conjunction with the smartphone.

Main features of LRTK:

• Pocket-sized integrated surveying instrument: Achieves functions equivalent to a full set of conventional surveying equipment with just a smartphone + receiver. Because you only need to carry a device of about 165 g, you can always carry one device per person at the site and take measurements immediately when needed.

• Centimeter-class high-precision positioning: A multi-GNSS RTK receiver provides positioning errors within a few centimeters (cm-level accuracy, half-inch accuracy) through real-time corrections. It also supports reception of Japan's L6 signal (Michibiki's CLAS), enabling stable high-precision positioning even at sites outside communication coverage.

• Easy operation and multifunction app: On the dedicated app screen, just press the "Measure" button to record position coordinates. The acquired data are automatically calculated and displayed not only as latitude, longitude, and elevation but also as coordinates in Japan's Plane Rectangular Coordinate System. Point names, date/time, and notes are saved together, so the app handles tedious recordkeeping. Functions in high demand on-site, such as distance and area measurement and height-difference calculations between measured points, are also well supported.

• Layout marking and AR functions: LRTK not only measures but also supports layout marking (positioning/staking out) and navigation based on measured points. For example, if you want to move to a pre-set coordinate, the app shows the current position and the target point and guides you there. It is also possible to display the target point in AR through the smartphone screen, allowing intuitive marking of the intended position.

• Point cloud measurement and 3D scanning: By linking with the smartphone's built-in LiDAR scanner, surrounding structures and terrain can be captured as 3D point clouds. Single-smartphone LiDAR scans sometimes produced positional shifts and distortions, but combining them with LRTK assigns accurate geographic coordinates to each point, so even when walking to scan wide areas you obtain high-precision point cloud data with little distortion. From the acquired point cloud you can measure the distance between any two points or calculate the volume of fills/excavations on-site, enabling immediate earthwork quantity management and as-built verification.

• Cloud integration: Measurement data can be uploaded to the cloud with one tap and shared immediately with the office or other team members. On the cloud map screen you can check point locations and notes or display point cloud data in 3D for analysis. Data stored in the cloud can be exported as CSV or industry-standard formats as described below, and can be handled in the same way as conventional survey deliverables.

Basic usage is also very simple. Take the LRTK receiver to the point you want to measure and just press the measurement button on your smartphone screen. If it is mounted on the tip of a pole, touch the tip to the ground point and operate the button. A single point recording takes only a few seconds, and the measurement results are displayed and saved on the smartphone screen on the spot. You can, if necessary, take photos to link to the measured point and add notes. Previously there was the hassle of recording coordinates in a notebook after surveying and then entering them into a PC at the office, but with LRTK everything is completed on site, and because calculations and saving are automatic, handwriting errors and input mistakes do not occur.

Practical Use Cases

The compact surveying instrument LRTK is useful in a variety of field operations. Below are representative use cases and their benefits.

• Field surveying (construction management): LRTK is highly effective for as-built control and elevation measurements at construction sites. For example, it enables a single person to quickly check formwork heights before concrete placement or to measure excavation and fill volumes. Tasks that used to be handled by craftsmen’s intuition or simple leveling instruments can be captured with accurate numerical values using LRTK, leading to improved construction accuracy and prevention of rework.

• Land surveying (boundary surveying): Compact RTK surveying instruments are effective at sites where land and building surveyors perform boundary confirmations and lot-boundary surveys. If you measure the coordinates of boundary markers to the centimeter level (cm level accuracy (half-inch accuracy)), it will help with later boundary restoration and prevent boundary disputes. Because LRTK can position in public coordinate systems (e.g., JGD2011), it can also be applied to producing official surveying results. Even in situations such as subdividing forest land while carrying heavy equipment, the portability of LRTK provides mobility.

• ICT construction: In the context of ICT construction such as i-Construction, three-dimensional management of construction data is required. It is possible to overlay the coordinate-attached point cloud data acquired by LRTK onto the design’s 3D data to check the as-built condition of the work on site. For example, in road construction you can compare the design model and the current terrain on the cloud and instantly calculate the required fill volume. As-built surveys and earthwork quantity calculations that were previously outsourced to specialists can be carried out daily by site staff using LRTK, improving process efficiency.

• Boundary confirmation and maintenance: LRTK is also useful in infrastructure inspection and maintenance tasks. When an anomaly is discovered during inspections of roads or bridges, accurately measuring and recording its location helps with future repair planning. Using AR functions, you can visualize prior information about underground buried utilities and boundary lines on site, contributing to safety checks for excavation work. Converting inspection tasks that were previously done by visual estimation into quantitative data increases the credibility of reporting materials.

Beyond these, LRTK's use cases are diverse, including recording damage at disaster sites, parcel surveying of farmland, and even 3D surveys of existing conditions in urban areas where drones cannot be flown. From site supervisors to surveying professionals, it can be widely used as a tool that allows you to measure immediately when needed.

Ease of Use, App UI, and Report Output Usable by Beginners

The advantage of LRTK is that it is highly functional while being intuitive to operate. The smartphone app's UI is simply designed, and even first-time users can complete surveying just by following the on-screen instructions. Because it uses easy-to-understand Japanese-language displays and icons instead of obscure technical terms, staff without surveying expertise won’t be confused.

Recording of survey points is also automated. As mentioned above, the app automatically converts the coordinates of measured points into plane rectangular coordinates and elevation systems, and survey point numbers and timestamps are also automatically assigned. If you want to leave notes on site, you can enter text on the screen and save it linked to the data. There is no need to carry a paper field notebook; your smartphone serves as a digital field notebook.

In addition, the LRTK system makes exporting survey results easy. Data uploaded to the cloud can be downloaded to a PC in CSV format or exported in formats that are easy to import into professional software, such as the Geospatial Information Authority of Japan’s SIMA format or DXF format. Because coordinate data required for creating survey maps and reports can be reused as-is, compilation work in the office is also streamlined. There is also a feature to generate PDF reports from the app, making it possible to issue simple survey reports immediately from the field.

Overall, the LRTK's usability and app UI are beginner-friendly, while also offering the flexibility to meet professional demands. Without spending time becoming proficient, you can start using it on-site from the day it's introduced, so there’s no worry it will go unused. Because anyone on-site can collect and share data, it also contributes to improving productivity across the entire organization.

Conveniences unique to LRTK, such as cloud sharing and AR

Points that set LRTK apart from conventional surveying instruments include robust cloud integration and AR capabilities. Positioning data and point cloud data can be automatically synchronized with cloud services, enabling real-time information sharing with engineers in the office and clients. For example, immediately after surveying on site you can check the data on an office PC and give instructions on the spot to ensure no measurements were missed. Data you want to share can be made viewable simply by providing stakeholders with a URL on the cloud, and can be safely shared via password-protected links without requiring ID registration. This makes reporting to partner companies and clients smoother and dramatically reduces information transmission lag.

AR (augmented reality) features are another convenient function unique to LRTK. Because you can overlay measured points and lines from design drawings onto real-world scenes through a smartphone camera, intuitive consensus building and checks can be performed. For example, you can display invisible boundary lines on the ground within a site via AR to confirm with stakeholders, or composite a 3D model of a designed structure into on-site footage to share the finished image. The ability to present information that until now could only be seen on drawings in a way that anyone on site can visually understand is a major strength.

Furthermore, as an advanced use case combining the cloud and AR, issuing instructions from remote locations and progress monitoring can also be considered. It is already possible to overlay point-cloud scans uploaded from the field with the design model in the cloud, allowing the office to check for construction deviations. Because you can grasp the current conditions via AR without being on site and provide feedback to the field as needed, remote site management is becoming a realistic possibility.

In this way, LRTK functions not merely as a surveying instrument but as a hub that connects the field and the office, the physical and the digital. By leveraging cloud sharing and AR, it maximizes the value of surveying data and promotes collaboration among all stakeholders, offering a next-generation convenience not found in conventional products.

Benefits of Implementation: Labor savings, Reduced rework, Quality assurance, Safety

Finally, we summarize the effects of introducing a compact surveying instrument such as LRTK. The main benefits brought to the site are as follows.

• Labor savings: Surveying can be completed by a single person, reducing the effort of arranging personnel. The burden of transporting and setting up heavy equipment is also reduced, and working time is shortened. Even on sites with labor shortages, surveying operations can proceed without delay and efficiently.

• Reduced rework: Because high-precision data can be acquired and verified on site, the risk of later re-measurements or rework is lowered. Construction errors can be detected and corrected early, preventing rework caused by deviations in the as-built condition.

• Quality assurance: Proceeding based on quantitative measurement data improves the reliability of construction quality and surveying results. Records are automatically retained, ensuring traceability for quality management. In boundary surveys, high-precision coordinate records contribute to the preservation of boundary markers; in infrastructure inspections, accurately identifying the locations of deterioration enables appropriate repair planning.

• Safety: By enabling single-person operations with small, lightweight equipment, the need for multiple people to enter hazardous areas for surveying is reduced. Surveying alongside busy roads or performing prolonged work in extreme heat or cold can be completed in shorter time and with fewer personnel, thereby reducing worker risk. Additionally, AR visualization allows buried objects and hazardous areas to be identified in advance, helping to prevent near-miss incidents.

These effects improve overall productivity and safety levels on the site, and ultimately contribute to cost savings and shorter construction schedules. The introduction of compact surveying instruments can be said to contribute not only to replacing surveying tasks but also to on-site workstyle reform.

Conclusion

The latest compact surveying instrument, LRTK, which combines centimeter-class accuracy (cm level accuracy (half-inch accuracy)) and palm-sized portability, is transforming surveying work that was previously left to specialists into “routine tasks” that anyone on site can handle. In the construction and civil engineering sectors facing challenges such as labor shortages and the need to improve productivity, simple surveying with LRTK will be a powerful solution. With high-precision, highly reliable data easily obtainable, on-site decision-making and responsiveness will be dramatically enhanced. As a result, quality assurance, rigorous safety management, and reduction of waste can be achieved, improving the overall success rate of projects.

With the latest technology on your side, surveying no longer has to be a highly specialized, difficult task. By introducing LRTK, a pocket-sized partner, why not elevate the efficiency and accuracy of your field operations to the next level?