Contents

• How Network RTK Works and the Basics of Error Correction

• How Smartphone RTK (LRTK) Changes Field Accuracy, Procedures, and Speed

• UX Design Enabling Solo Surveying (Apps, AR Guidance, Photo Positioning, etc.)

• Compatibility with Point Cloud Scanning, As-Built Management, CAD and Cloud Integration

• Real-Time Office–Field Integration (Cloud Maps, Shared Survey Points, Coordinate Navigation)

• Time Savings, Removal of Skill Dependency, Improved Safety, and Applications to Disaster Response

• Natural Introduction and Guidance for Introducing Simple Surveying with LRTK

• FAQ (Frequently Asked Questions)

The fusion of smartphones and RTK (Real-Time Kinematic) technology is driving a major transformation in the surveying world. Surveying tasks that once required multiple people can now be performed by a single person with centimeter-level accuracy using smartphone RTK. By leveraging network-based RTK correction services, users can begin positioning on site without installing dedicated base stations, dramatically shortening surveying procedures and required time. This article starts with how network RTK works and its advantages, then explains how smartphone-mounted RTK systems (referred to as LRTK) improve accuracy and work efficiency on site. It also covers UX designs that support solo surveying, the compatibility with point cloud scanning, cloud integration, AR guidance and other modern features, and applications for productivity gains, safety, and disaster response. Finally, an FAQ addresses common questions about adopting smartphone RTK.

How Network RTK Works and the Basics of Error Correction

First, RTK (Real-Time Kinematic) is a technique that corrects GPS and GNSS positioning errors in real time to dramatically improve positional accuracy. Standalone GPS positioning typically has errors of several meters due to satellite signal errors, but RTK computes error information using a reference station (base station) whose coordinates are known precisely in advance, and applies corrections to the rover’s positioning data. This reduces typical meter-level errors to on the order of a few centimeters.

In conventional RTK surveying, operators had to install their own base station near the site and transmit correction data via radio. This required setup time to mount tripods and antennas before surveying, and if the measurement area was large the base station had to be moved and reinstalled, consuming time and effort. Also, correction effectiveness diminishes as base-to-rover distance increases, so to maintain high accuracy there was a baseline distance constraint of a few kilometers. High-performance RTK equipment was also very expensive and required specialized knowledge, so the technology was not easily accessible to everyone.

Network RTK addresses these issues. Network RTK uses networks of many reference points (continuously operating reference stations) installed by government or private entities, and provides correction information by creating a “virtual reference station” near the user. The user device sends its approximate position to a server over mobile data, and the server integrates and analyzes data from multiple surrounding reference stations to generate error information (corrections) as if there were a base station at the user’s location. This mechanism, also called the VRS (Virtual Reference Station) method, makes it possible to position as if “a base station were right next to you,” enabling centimeter-level positioning without placing a physical base station on site.

The advantages of network RTK go beyond eliminating per-site base station setup. Because correction data is calculated and provided close to the user at all times, accuracy degradation while moving is suppressed, and uniform high accuracy can be maintained over wide-area surveys. When properly operated, the achievable accuracy is essentially equivalent to conventional local RTK (both can be centimeter-level), and the major difference is the superior operational cost-effectiveness and convenience of network RTK. In recent years, network RTK that can be used nationwide wherever mobile networks exist has become the mainstream for high-precision positioning, and in the field it has become common to “try VRS first.” Optical total stations and standalone GNSS positioning are still used as needed, but in many cases network RTK supports the field in both accuracy and efficiency.

Note that using network RTK requires subscription to a correction data distribution service and a communication environment. In Japan, the Geospatial Information Authority (GSI) provides services using approximately 1,300 continuously operating reference stations nationwide (GNSS Continuous Operating Reference Stations), and mobile carriers and surveying companies offer commercial correction data distribution services. Users connect their smartphones or positioning devices to these services via the internet and receive correction data (the Ntrip protocol is commonly used). As long as you are within network coverage you can obtain precise coordinates in the World Geodetic System in real time anywhere in the country, but in mountainous areas or places with unstable connectivity it can be difficult to maintain accuracy. As a countermeasure, methods have emerged to receive correction information directly from satellites, such as the centimeter-level augmentation service (the CLAS signal) provided by Japan’s Quasi-Zenith Satellite System “Michibiki.” With compatible devices, you can continue high-precision positioning via satellite even outside mobile coverage, providing a backup to maintain positional accuracy in disaster zones where terrestrial communication infrastructure is disrupted. In this way, network RTK—combining ground reference station networks and satellite augmentation—serves as a foundational technology for stable centimeter-level surveying across diverse environments.

How Smartphone RTK (LRTK) Changes Field Accuracy, Procedures, and Speed

With high-precision RTK positioning becoming so accessible, a new solution has emerged to fully leverage its benefits: smartphone RTK. Historically, RTK surveying equipment required investments on the order of hundreds of thousands of dollars, with stationary receivers, antennas, and controllers. Recently, however, products combining compact RTK-GNSS receivers that attach to smartphones with dedicated apps have been developed, ushering in an era where a smartphone itself becomes a centimeter-accuracy surveying instrument. A notable example is LRTK, released in 2022 by a startup originating from Tokyo Institute of Technology: by attaching a tiny device weighing only around 100 grams to an iPhone or Android smartphone, positioning comparable to expensive dedicated equipment becomes possible.

Using a smartphone-mounted RTK system like LRTK dramatically changes field surveying workflows. In terms of accuracy, smartphone built-in GPS typically has errors of about 5–10 m, while a dedicated antenna plus RTK corrections can reduce errors to a few centimeters. Horizontal accuracy of around ±2–3 cm and vertical accuracy of a few centimeters are attainable, comparable to conventional surveying instruments. This level of accuracy can meet stringent requirements that are difficult with standalone positioning—for example, as-built inspections that require verification within a few centimeters.

Survey procedures and preparation are also simplified. Smartphone RTK eliminates the need for heavy tripods and stationary equipment. Simply bringing a smartphone and a pocket-sized receiver to the site and turning them on allows positioning to begin immediately. Previously, setup time for assembling equipment and installing reference points was required for each survey; that is no longer necessary. For example, LRTK connects wirelessly to a smartphone via Bluetooth or Wi‑Fi, removing complicated cable routing. The ability to complete surveying and recording with “just a smartphone” brings real ease to the field.

Speed and efficiency have improved dramatically. Previously, survey data often required post-processing back in the office—plotting coordinates on drawings, calculating volumes, etc.—so there was a time lag before results could be used. With smartphone RTK, acquired data can be shared to the cloud in real time from the field, enabling immediate confirmation and follow-up actions. This “measure, then immediately confirm and share” flow has in some cases shortened processes that previously took days to a single day or just a few hours. For example, at a road construction site, tasks that took several days using a total station and laser scanner—establishing control points, point cloud measurement, and as-built inspection—were completed in one day using a single smartphone equipped with LRTK. Field staff can now take measurements and confirm results without waiting for surveying specialists, leading to substantial labor savings and faster project timelines.

Additionally, smartphone RTK systems lower the cost barrier to adoption. Because only a pocket-sized device and a smartphone are required, initial costs can be an order of magnitude lower than conventional equipment. Deploying one device per person becomes realistic, and site supervisors or foremen starting to carry smartphone RTK devices for routine surveying and checks is emerging. The ability to measure immediately when needed and share results to the cloud—preventing construction mistakes before they occur and enabling optimized workflows—allows rapid PDCA cycles that were previously difficult. This democratization of high-precision positioning is what enables these swift improvements in operational efficiency.

UX Design Enabling Solo Surveying (Apps, AR Guidance, Photo Positioning, etc.)

To realize solo surveying, it is not enough to be able to measure precisely; the system must also offer “usability that a single person can master” and “features that let one person measure accurately without confusion.” Smartphone RTK apps are designed with intuitive UX so that people with limited experience with professional equipment can learn the basics quickly. For example, from starting positioning to saving records can be done with a single button press; complex settings and calculations are handled automatically by the app. For each survey point, latitude, longitude, and elevation are automatically recorded, along with the timestamp and measurement status (e.g., whether a fixed solution FIX was obtained). When taking photos, the image is tagged with the capture location and orientation, eliminating the need to later sort “which photo was taken at which point.” This removes the need to copy notes into a paper fieldbook and significantly reduces the risk of human error. The system prevents omissions and transcription mistakes in the field and enables stable data capture by anyone.

Challenges in solo surveying such as “locating survey points” and “stakeout” are supported by smartphone RTK’s AR (augmented reality) guidance features. Dedicated apps provide a coordinate navigation function that displays guide arrows and bearing on the smartphone screen pointing toward a preconfigured target coordinate. Workers simply follow the on-screen directions to reach target points on the ground that may not be visually obvious. Even when benchmarks are obscured by vegetation or snow, following the device’s indicated direction will lead to the mark. When approaching the target, enabling AR overlay on the camera view will display a virtual stake or marking superimposed at the coordinate, as if a physical stake were present. This AR stake display allows tasks such as layout and staking—which used to require two people—to be performed accurately by one person. There is no need to rely on intuition with drawings in hand; even novices are guided to the intended survey points without hesitation. Field reports indicate that AR-guided layout eliminated the need for traditional batter boards, allowing inexperienced operators to execute accurate construction without relying on veterans; visual guidance has led to significant efficiency gains, demonstrating the strength of AR + RTK.

Furthermore, smartphone RTK enables tasks that were difficult for a single person—such as photo-based positioning and 3D scanning. For instance, capturing multiple photos of an object with a smartphone camera and processing them with photogrammetry software can produce a high-precision 3D model of a small structure. RTK-provided position tags on each photo ensure accurate model scale and orientation without installing numerous control points. On devices equipped with LiDAR scanners (like some iPhones), simply walking while holding the smartphone can scan surrounding terrain and structures to acquire high-precision 3D point cloud data. Since the collected point cloud is already tagged with global coordinates (absolute coordinates), georeferencing when combining or comparing point clouds with other survey data is unnecessary. All these functions can be executed with just a smartphone and one RTK device, allowing a single operator to perform surveying while simultaneously capturing photos and 3D measurements. The smartphone has become a versatile surveying instrument that strongly accelerates field digital transformation (DX).

Compatibility with Point Cloud Scanning, As-Built Management, CAD and Cloud Integration

Positioning data acquired with smartphone RTK is highly compatible with CAD software and cloud systems. Traditionally, points measured in the field were re-plotted into CAD drawings back at the office, and point clouds from laser scanners were post-processed on PCs for as-built inspection. After adopting smartphone RTK, data obtained in the field can be uploaded to the cloud immediately and conveniently utilized for CAD and point cloud processing as needed.

For example, with an LRTK system, coordinates and photo notes measured on the smartphone are automatically plotted on a cloud map. Office staff can access that map in a web browser to view survey point coordinates and photos in real time. Measured results can be downloaded as CSV or PDF, and common civil survey data formats such as SIMA and DXF are supported, enabling smooth import into existing CAD drawings or BIM models. In as-built management, measured 3D point cloud data can be overlaid directly on the design 3D model for comparison. The combination of smartphone RTK and cloud services makes the flow from surveying → drawing creation → inspection seamless, substantially reducing the hassle of data handoffs and format conversions.

Additionally, by issuing a shared URL in the cloud, stakeholders such as clients and subcontractors can view the latest survey data without logging in. Information that used to be exchanged with paper drawings or USB drives can now be shared instantly over the internet. This realizes real-time field visualization, dramatically shortening the time required for post-survey data organization and communication. For example, on large-scale earthworks sites, daily accumulation of survey data to the cloud allows all stakeholders to always access the latest terrain model and as-built progress, aiding adjustments to construction plans and schedule management. Since point cloud data and photos are stored with spatial coordinates, it is clear “where a given point is” and “from where a photo was taken,” which is powerful when preparing reports or performing later verification.

The fit with as-built management is particularly strong. Using 3D data acquired with smartphone RTK, as-built inspections can be performed immediately after construction and results presented to the client via the cloud. At one site, point clouds acquired by smartphone RTK were instantly compared with the design model via AR on site to confirm deviations right away. This eliminated the traditional time lag of “measure, then wait days to issue corrective instructions,” so that fixes could be made on the same day, enabling smooth, rework-free quality control. Cloud integration directly links office and field, synchronizing CAD data and field data in real time and dramatically improving the accuracy and speed of construction management.

Real-Time Office–Field Integration (Cloud Maps, Shared Survey Points, Coordinate Navigation)

As described above, smartphone RTK brings the office and field together so that the distance between them becomes zero in terms of data. Survey points plotted on a cloud map are reflected on the office PC screen the moment they are measured in the field. This allows field staff and office engineers to communicate while sharing identical, real-time information.

Specifically, coordinates, photos, and notes acquired on the field smartphone can be sent to the cloud with a single button, and the office can view the latest data on a web map. For example, during layout work, an office supervisor can immediately check whether the placed points match the drawings, and if issues are found can provide feedback to the field by phone or chat. Conversely, if the office wants to add survey points or design lines, the coordinate list can be sent via the cloud to field smartphones, and workers can locate those positions using the coordinate navigation function and mark them—the result is true two-way collaboration.

This real-time integration is especially powerful when managing multiple distant sites or providing urgent survey support. Even if only one person is on site, headquarters or senior staff can monitor the situation via the cloud and provide instructions, effectively enabling remotely assisted solo surveying. In situations requiring complex decisions, instant sharing of measured data allows consultation with experts for peace of mind. The cloud map also stores history, so it keeps track of when and where measurements were taken and how often they were re-measured. Because stakeholders can always confirm the “latest truth” by looking at the cloud data, misunderstandings and transmission errors are less likely.

Moreover, leveraging smartphone RTK’s coordinate navigation and AR guidance allows design drawings produced in the office to be accurately realized in the field. For example, if CAD data of a planned excavation area is preloaded into the app, the smartphone’s AR view can project a virtual excavation guideline onto the ground. Excavator operators can follow the on-screen line and achieve the designed shape and slope. This is another example of the fusion of office design data and field execution. The combination of real-time information sharing and immediate feedback on site has significantly changed surveying and construction workflows.

Time Savings, Removal of Skill Dependency, Improved Safety, and Applications to Disaster Response

Summarizing the benefits of single-person surveying using smartphone RTK, they center on dramatically increased productivity and stabilized work quality. Because sufficient surveying data can be obtained with fewer people and in less time, staffing burdens and on-site waiting times decrease and total work time is greatly reduced. If surveying that used to require two or three people a full day can be done by one person in half a day or less, the economic effects—such as reduced labor costs and redeployment of resources to other tasks—are significant. Immediate sharing of survey results to inform construction reduces overall schedule time and rework.

Reducing dependency on particular experts is another major benefit. Previously, advanced surveying relied heavily on the experience of veteran technicians, and work could stall if such specialists were unavailable. Smartphone RTK integrates surveying know-how and calculation procedures into apps so operations are completed by tapping buttons and following on-screen instructions. New staff or non-survey specialists can capture data with consistent accuracy, reducing delays caused by “waiting for surveying” and standardizing and leveling the quality of work across sites. This democratization of high-precision positioning represents a key element of DX and work-style reform in an industry facing severe labor shortages. Smartphone RTK can serve as a new resource by enabling less experienced personnel to perform tasks that were once expert-only.

Improved safety is also noteworthy. Fewer personnel and shorter task durations mean reduced exposure to hazardous environments. Solo surveying reduces the need for flaggers on busy roads and minimizes long-duration work near operating heavy machinery. AR guidance allows stakeout from a distance without approaching dangerous locations, and features for measuring from a safe vantage point (for example, high places or restricted areas) exist. Small, lightweight equipment is easier to carry into steep mountain sites or debris-strewn disaster zones, reducing operator physical burden. Rugged devices with dust and water resistance allow surveying in places where deploying large equipment would be difficult, enabling safe and rapid situational assessment.

Smartphone RTK also has great utility in disaster response. Immediately after a major disaster, rapid measurement and recording of damage is essential. A device like LRTK that can operate outside mobile coverage and use Michibiki’s CLAS corrections enables high-precision positioning without setting up base stations, allowing immediate surveying on arrival at the site. For example, during the 2023 Noto Peninsula earthquake, LRTK was used in damaged areas with communication outages. Operators recorded conditions with pocket-sized devices and uploaded high-precision location data derived from satellite corrections to the cloud for sharing with relevant agencies. Where previously damage might be noted roughly (e.g., “a crack near point X, approximately Y meters”), smartphone RTK lets you record latitude, longitude, and elevation precisely—greatly aiding recovery planning and long-term monitoring.

Thus, solo surveying enabled by smartphone RTK supports a wide range of field activities—from routine construction management to emergency disaster surveying. The Ministry of Land, Infrastructure, Transport and Tourism’s “i-Construction” initiative emphasizes labor saving and productivity improvement through ICT and DX, and smartphone RTK is precisely a solution that addresses these themes. By allowing site personnel to capture and share data that formerly required survey specialists, smartphone RTK can drive transformational changes in business processes. Faced with shortages of experienced personnel, smartphone RTK provides a new workforce capability. The trend of solo surveying, which overturns traditional expectations, is already producing concrete results across fields and is expected to see further application.

Natural Introduction and Guidance for Introducing Simple Surveying with LRTK

As described above, the combination of network RTK and smartphone RTK provides substantial benefits to surveying and construction sites. Now that “centimeter-accuracy solo surveying” is a reality, there is no reason not to adopt it. Fortunately, smartphone RTK systems like LRTK are very simple to introduce and operate. The basic components are just “a smartphone,” “a small RTK receiver,” and “a connection to a correction data service.” Attach the dedicated device to your smartphone, launch the app, and the smartphone functions as a surveying instrument. At a target point, raise the phone and tap a button to record high-precision coordinates along with timestamp and notes, which are then synced to the cloud. Complex setup is unnecessary, and initial configuration can be completed in a few minutes by following on-screen guides.

After introduction, surveying specialists are not the only ones who can perform measurements—site supervisors and technicians can routinely perform positional checks and inspections. For example, during breaks in construction they can measure a questionable elevation and confirm it immediately, or scan the ground to estimate soil volumes before work begins. Tasks once outsourced to specialists can be handled in-house, improving on-site capabilities. Cloud sharing also smooths reporting to superiors and communication with clients. Although advanced technology might sound intimidating, smartphone app operations are similar to map apps or camera use that people are already familiar with. Intuitive UI and robust support make it easy for those less comfortable with machines to start using the tools confidently.

Across the construction industry, the adoption of simple surveying tools like smartphone RTK is advancing as part of DX initiatives. Early adopters report benefits such as “we no longer have to allocate staff for surveying and can focus on other tasks,” “construction mistakes have decreased and quality control has improved,” and “records are fully digitized, reducing reporting workload.” Smartphone RTK is not limited to specialized sites; it becomes an immediate asset in ordinary civil engineering and surveying tasks. If you face challenges such as “not enough staff to keep up with surveying” or “uncertainty about where to start with field DX,” trying a pilot introduction of smartphone RTK is a good option. Begin with small sites and gradually expand usage to experience its convenience and benefits. We encourage your company or organization to try this new standard of centimeter-accuracy solo surveying and use it to improve operations and safety.

FAQ (Frequently Asked Questions)

Q1. What do I need to use smartphone RTK? A1. Basically, you need a smartphone (iOS or Android) and an RTK-capable small GNSS receiver that can be attached to the phone. In addition, a connection to a correction data service is required to achieve centimeter-level positioning. Specifically, you register with a network RTK service (VRS, etc.) provided by government or private entities and configure login settings for that service in the smartphone RTK app. A surveying pole (monopod or telescopic staff) is helpful for accurately measuring ground points (the smartphone and receiver are mounted at the pole tip). With the required equipment, start the app and receive correction data to begin centimeter-accuracy surveying.

Q2. Is smartphone RTK really centimeter-level accurate? A2. Yes—under appropriate conditions, horizontal accuracy within a few centimeters and vertical accuracy of a few centimeters can be achieved. Many smartphone-mounted GNSS receivers support dual-frequency or higher and compute positions using RTK correction data, providing accuracy comparable to conventional survey GNSS equipment. Field results show that single-point real-time positioning typically exhibits about 1–2 cm standard deviation, and averaging many measurements can yield sub-centimeter accuracy in some cases. However, to realize this accuracy you need a clear sky view and a sufficient number of satellites. In urban canyons surrounded by tall buildings or inside dense forest, satellite signals can be blocked and errors increase; in such environments positioning may become unstable or produce deviations on the order of tens of centimeters. Choosing appropriate measurement environments and, where necessary, increasing measurement duration and averaging can help obtain stable high accuracy.

Q3. Can network RTK be used anywhere? What about places without radio coverage? A3. Network RTK can be used almost anywhere nationwide so long as network (communication) is available. If mobile phone coverage exists, a smartphone can connect to a correction service and receive virtual reference station data. However, if you are outside coverage or the signal is poor, you cannot obtain correction data and conventional network RTK becomes difficult. As a countermeasure, using a receiver that supports CLAS corrections from Michibiki allows centimeter-level positioning via satellite even when mobile coverage is absent. CLAS-compatible smartphone RTK equipment can continue centimeter-level positioning outside mobile coverage. In some situations, operators may set up a simple local base station to transmit corrections to the smartphone (offline RTK). In most cases, network RTK covers the needs except in special environments such as deep mountains, remote islands, or tunnels; in those cases satellite augmentation or a local base station should be considered.

Q4. Can I really survey alone? Aren’t there tasks that traditionally required two people? A4. The advent of smartphone RTK means that most surveying work that previously required two or more people can now be done by one person. For example, total station surveys typically required one person to operate the instrument and another to hold the prism, but GNSS surveying requires no fixed instrument; a single person carrying the rover can acquire points by walking. Because line-of-sight is not required, no assistant is necessary. Stakeout and layout tasks can also be done solo using AR coordinate guidance. Attaching the smartphone to a pole allows familiar positioning and marking postures, so one person can hold the pole, view the screen, and mark points as before. Of course, there are situations where having additional people for safety is recommended, but the surveying tasks themselves can generally be completed solo. Many sites that adopted smartphone RTK have reduced surveying personnel and reassigned freed-up staff to other construction management tasks. When surveying alone, be sure to pay extra attention to safety and work within reasonable limits.

Q5. What are the running costs of smartphone RTK? A5. The primary running cost to consider is the subscription fee for the correction data service. Some network RTK correction services are offered free by governments or municipalities, but many services involve monthly fees or usage charges (varying by provider and guaranteed accuracy level). These costs are generally modest compared to maintenance contracts for conventional surveying equipment, and short-term subscriptions are often possible. Communication costs are typically covered by normal mobile service plans when using phone data (correction data volumes are minimal, since large video transfers are not involved). Device upkeep is limited to battery charging and occasional consumables; there are no calibration or installation costs like those for large instruments. Overall, operating costs for smartphone RTK are often considerably lower than those for conventional surveying equipment. Investigate correction service plans before adoption and choose a contract that matches your usage. Discounts for bulk device deployments may also be available.

Q6. Is it acceptable to use smartphone RTK data as official survey results? A6. For typical construction surveying, as-built management, and design/construction workflows, survey data obtained with smartphone RTK can generally be used without issue. The Ministry of Land, Infrastructure, Transport and Tourism’s i-Construction guidelines and various standards include GNSS-based surveying and as-built management methods. However, for legally strict surveys such as “public surveying” or “cadastral surveying,” it is necessary to perform control surveys under a licensed surveyor’s supervision and adhere to prescribed accuracy management and procedures. In those cases, smartphone RTK data can be used as auxiliary data or to increase efficiency—for example, using smartphone RTK-derived points as provisional references for detailed surveys. Whether the final deliverable will be used as an official survey record affects the required handling. For routine construction management and private surveys, smartphone RTK accuracy is usually sufficient, but when submitting drawings to public agencies it’s prudent to verify measurements against known control points.

Q7. Can smartphone RTK be used in rain or at night? A7. GNSS surveying can generally operate in rain without issue. Many LRTK-type devices are water-resistant, and light rain typically does not impede work (in heavy rain take care not to wet devices directly). GNSS positioning works day or night, and in some cases ionospheric disturbances are lower at night, improving stability. Considerations for night work include ensuring good lighting for foot and site safety and that AR displays may be harder to see because the camera view is dark; using strong illumination or relying on navigation-only displays can help. Also, smartphone screens and UI may be harder to read at night, so headlamps and other lighting are recommended. The flexibility to operate regardless of weather or time is an advantage of solo surveying; for instance, night shoulder surveys that avoid traffic closures are a practical application.

That concludes the overview of new surveying methods enabled by smartphone RTK and network RTK. The innovation of centimeter-accuracy solo surveying holds great promise for surveyors and construction managers. With technological advances making it possible for “anyone, anywhere, immediately, and accurately” to measure, we encourage you to experience the benefits on your sites. We hope smartphone RTK—an innovation that overturns conventional wisdom—helps you improve workflow efficiency, quality, and safety on the job.