RTK AR turns your smartphone into a surveying tool! Dramatically improving field work efficiency

Table of Contents

• What is RTK AR? A new technology that makes smartphones surveying tools

• Centimeter-level positioning with RTK

• The surveying revolution opened by smartphone + RTK

• Visualizing the site with AR

• Main use cases for RTK AR

• Benefits brought by RTK AR

• Easy high-precision surveying with LRTK

• FAQ

What is RTK AR? A new technology that makes smartphones surveying tools

In recent years, a new technology called RTK AR has been attracting attention in the surveying world. RTK AR is a solution that combines RTK (Real Time Kinematic), a high-precision GNSS positioning technology, with AR (Augmented Reality), which overlays digital information on real-world imagery. Simply put, it equips familiar devices like smartphones and tablets with high-precision positioning capabilities and allows survey data and design information to be overlaid and displayed on their screens at the job site. This makes it possible to achieve both centimeter-level positioning (cm level accuracy (half-inch accuracy)), which previously required dedicated equipment, and intuitive AR visualization on a single smartphone.

For example, standing on site with a smartphone, you can display map or drawing points at their actual locations through the screen, or visualize invisible boundary lines or the positions of underground buried utilities on the imagery. What was difficult with traditional smartphone GPS, which had low positional accuracy, can now be realized by RTK AR as an almost perfect overlay of real scenery and digital information. As smartphones transform into surveying tools, this technological innovation is greatly improving fieldwork efficiency and ushering surveying and construction management into a new era.

Centimeter-level positioning with RTK

So what exactly is RTK? With normal GPS-based positioning, errors of about 5〜10 m (16.4〜32.8 ft) occur due to satellite signal errors and other factors. Built-in smartphone GPS alone can result in position shifts on maps of several meters, making it unsuitable for precise surveying. This is where RTK positioning comes in. The RTK (Real Time Kinematic) method receives signals from GNSS satellites at both a base station with known accurate coordinates and a rover that performs mobile positioning, then sends the error information measured at the base station to the rover in real time to correct it. This differential correction reduces positional errors that were several meters with standalone positioning to within a few centimeters (cm level accuracy (half-inch accuracy)). In other words, using RTK allows you to know your position outdoors anywhere with centimeter accuracy (cm level accuracy (half-inch accuracy)).

In Japan, a network RTK system utilizing the Geospatial Information Authority of Japan’s electronic reference point network (GEONET) has been established, and by using Ntrip services that distribute base station data nationwide via the Internet, correction information can be easily obtained from a smartphone. Additionally, the Cabinet Office–operated Quasi-Zenith Satellite System "Michibiki" provides the CLAS (Centimeter Level Augmentation Service); with compatible receivers, you can receive correction signals directly from satellites and achieve high-precision positioning even in mountainous areas or remote islands without cellular coverage. With these mechanisms, RTK is becoming a familiar technology that can be used without specialized surveyors or large equipment.

The surveying revolution opened by smartphone + RTK

Although centimeter-level positioning with RTK has become possible, it used to require expensive, large GNSS receivers and antennas to be installed. Because surveying methods required equipment to be mounted on tripods and operated by specialists, it was unrealistic for general field staff to use them in daily work. However, recent technological advances have led to the development of ultra-compact RTK-GNSS receivers, and products that can be attached to smartphones have appeared. By attaching a small device weighing a few hundred grams to a smartphone and connecting via Bluetooth or cable, the smartphone quickly becomes a high-precision positioning terminal. This heralds an era in which anyone can easily perform centimeter-level surveying (cm level accuracy (half-inch accuracy)) with a smartphone.

Surveying with smartphone + RTK has the potential to reduce tasks that previously required 2–3 people to a single person. There is no need to carry and set up tripods, and you can record high-precision positions while moving. For example, when you need to measure many points across a large site, you can walk around with a smartphone in hand to measure and record, dramatically shortening work time. Furthermore, the latest smartphones include LiDAR sensors and high-performance cameras, and by combining these with RTK positioning you can scan surrounding terrain and structures in 3D to obtain high-precision point cloud data with location information. With just a palm-sized device and a smartphone, surveying tasks that once required specialized equipment and skilled technicians are becoming accessible to anyone—a true revolution in surveying.

Visualizing the site with AR

Even though RTK enables high-precision positioning, that alone is insufficient for digital transformation (DX) of surveying sites. It is important to share the numeric data and drawing information obtained on site in a way that all stakeholders can intuitively understand. This is where AR (Augmented Reality) technology shines. Using AR to overlay CG models, lines, text, and other information onto the real landscape seen through a smartphone or tablet camera allows you to visually confirm the site situation and plan data simultaneously.

However, conventional smartphone AR apps suffered from misalignment between virtual models and reality due to GPS and electronic compass errors. As users moved, the display would gradually drift, making precise alignment difficult. RTK AR solves this issue. Because RTK provides centimeter accuracy (cm level accuracy (half-inch accuracy)) for the smartphone’s own position at all times, if digital information is pre-positioned at specific coordinates in a geodetic coordinate (surveying coordinate) system, the AR display on the screen will almost perfectly coincide with the real-world positions. Virtual objects won’t drift away from reality as users move, maintaining stable AR displays at all times. There is no need for complicated marker placement or manual alignment; simply select the data you want to display in the app and virtual models or lines will appear on site instantly.

For example, projecting normally invisible land boundaries onto the ground with AR lets all stakeholders see them at a glance. Even those who cannot read drawings will intuitively understand “where the property starts and ends,” making boundary inspections smoother. Also, displaying the routes of buried pipes and cables on AR can visualize “no-dig areas” on the spot and reduce the risk of accidental damage to piping. In this way, AR visualization of the site smooths communication and greatly contributes to improved safety.

Main use cases for RTK AR

RTK AR technology is expected to be used in a variety of field operations. Here are some representative scenarios.

• Boundary confirmation and stake restoration: RTK AR is powerful for boundary meetings and restoring lost boundary stakes. If coordinates of boundary points obtained beforehand are registered in a smartphone app, simply pointing the smartphone on site will display invisible boundary lines in AR. Compared to traditional methods where surveyors indicate points with temporary stakes or chalk, everyone present can visually share the same positions, helping prevent disputes caused by differences in boundary recognition. Even when boundary markers are missing, the app can navigate precisely to boundary points with centimeter accuracy (cm level accuracy (half-inch accuracy)), allowing location identification before re-staking.

• Temporary stake placement and construction layout: Before construction begins, AR is very useful for placing temporary stakes along property boundaries or planning fence lines. By loading boundary lines and building layout data in advance, the smartphone screen can display virtual stake position markers or lines on site. Using these markers as guides, stakes can be driven at precise points, reducing the need for transit instruments or surveying equipment. Wide-area staking can be performed by one person confirming points sequentially, enabling significant labor savings and time reduction.

• Guidance and checks during construction: RTK AR is also promising during site construction. For example, displaying the as-built model of a structure in AR on site can guide heavy equipment operators and workers to correct installation positions. Even in poor visibility or night work, following AR guides enables low-error positioning. In addition, measuring as-built shapes with a smartphone’s LiDAR to capture point clouds and overlaying them with the design model in AR allows instant visual identification of excesses or shortages in fill or excavation by color-coding. Sharing those results in the cloud for quality inspection is also easy.

• Safety management and visualization of unseen hazards: Continuously displaying boundary lines or no-entry areas in AR on a construction site also enhances safety management. If a “do not enter beyond this point” zone is digitally shown, machine operators and workers can recognize hazardous areas at a glance. Tasks that previously required ropes or personnel to guide and warn can be replaced by AR displays, reducing human error and workload. For example, point-cloud scans of underground utility lines can be recorded in advance and projected in AR during subsequent work to indicate “locations that must not be excavated.” In this way, RTK AR contributes to safe and efficient construction management.

Benefits brought by RTK AR

As described above, the use of RTK AR technology brings numerous benefits to field work. Here are the main advantages.

• Improved work efficiency and labor savings: With smartphone + RTK, surveying, recording, and verification can be done quickly by a single person, greatly streamlining tasks that previously required multiple personnel. There is no need to transport or set up heavy equipment, reducing preparation time. Being able to measure many points in a short time leads to overall productivity improvement. Even in difficult terrain, minimum personnel can respond, contributing to improved safety.

• Smoother consensus building and communication: Because AR can “visualize” boundary lines and installation positions on site, it allows owners and workers without specialized knowledge to be explained intuitively. Information that was difficult to convey with drawings alone becomes immediately obvious when virtual models or lines are viewed together on the smartphone screen. This makes it easier to resolve misunderstandings on the spot and smoothes consensus building during inspections and construction meetings, ultimately helping to prevent disputes and mistakes.

• Improved data recording and reproducibility: Coordinate data, point clouds, photos, and other data obtained with smartphone surveying apps can be saved to the cloud in real time. Accurate positions and shapes measured on site can be stored directly, eliminating the need to transcribe handwritten notes later. Once stored in the cloud, data can be reused in the future; when revisiting a site years later, past surveying results can be recalled to pinpoint the same locations accurately. Data handover across personnel changes enhances long-term record reliability.

Easy high-precision surveying with LRTK

As a solution that combines the latest smartphones and RTK technology to achieve high-precision surveying, there is LRTK. LRTK is a system developed by a startup originating from Tokyo Institute of Technology and is an all-in-one surveying platform consisting of a small RTK-GNSS receiver that attaches to a smartphone, a dedicated app, and cloud services. By attaching the compact receiver (the LRTK Phone device) that fits in your pocket to your smartphone, the smartphone transforms into a centimeter-level surveying instrument (cm level accuracy (half-inch accuracy)). Communication with the smartphone is via Bluetooth or cable, and by receiving network RTK (Ntrip) or Michibiki CLAS signals as described above, real-time high-precision positioning is possible anywhere in Japan. The device is dustproof and waterproof, has a built-in battery, and can be used reliably in harsh outdoor sites.

With the dedicated LRTK app, you can easily perform all tasks on your smartphone from starting positioning to data storage and AR-guided navigation. For example, you can switch from single-point measurement to continuous area surveying with one tap, and acquired points are plotted on a map in real time and synchronized to the cloud. On the cloud, you can review acquired data in a 3D viewer or export it for CAD software. It also includes data-sharing functions that connect the field and the office, making it a next-generation tool that seamlessly links surveying with design and construction management.

With LRTK, you can easily realize the RTK AR surveying world described above with just a smartphone. Initial setup and operation are intuitive, and people without surveying expertise can start using it after a short training session. Users on sites that have adopted it praise the mobility that allows surveying and verification “anytime, anywhere, immediately.” The lower introduction cost compared to dedicated equipment is also attractive, enabling small companies and sites to start high-precision surveying easily. By leveraging such smartphone + RTK solutions, surveying work that used to require time and manpower can be dramatically streamlined. Try incorporating LRTK for simple surveying and experience the convenience of RTK AR and centimeter-level positioning (cm level accuracy (half-inch accuracy)) on site.

FAQ

Q: Can smartphone-based RTK positioning really achieve centimeter accuracy? A: Yes, it is possible under favorable conditions. By using a smartphone receiver that supports high-precision GNSS (for example, devices like LRTK) and appropriate correction information, a smartphone can achieve horizontal accuracy of ±1～2 cm (±0.4～0.8 in) and vertical accuracy on the order of several centimeters (cm level accuracy (half-inch accuracy)). Considering that typical smartphone GPS has errors of several meters, this represents a dramatic improvement. In practice, the positioning accuracy obtained with RTK-capable equipment reaches levels comparable to traditional surveying instruments.

Q: What equipment and preparations are required to use RTK AR on site? A: Basically, you need a small receiver that supports high-precision GNSS and a way to receive correction information. Prepare an RTK receiver that attaches to a smartphone (e.g., an LRTK device) and connect it to a service that provides the correction data it receives. Correction information can be obtained via network RTK (Ntrip) services using cellular networks or via Japan’s Michibiki CLAS signals. For AR display, it is also advisable to prepare control points and design data coordinates in advance and load them into the app. No special large equipment or surveying specialists are required; as long as you have a smartphone + a small receiver + the data, you can start immediately.

Q: Can high-precision positioning and AR display be achieved in places without Internet, such as mountainous areas? A: Yes. By using CLAS as mentioned above, you can obtain centimeter-level accuracy in real time without Internet even in mountainous areas or remote islands where cellular coverage is unavailable. Alternatively, by setting up your own base station (reference receiver) and distributing correction information via radio to create a local RTK environment, you can achieve high-precision positioning offline. In other words, even on sites with limited network connectivity, high-precision smartphone positioning and AR display can be realized via satellite augmentation signals or by operating your own base station.

Q: Will smartphone RTK surveying completely replace conventional surveying equipment? A: Smartphone + RTK surveying is powerful in many situations, but it does not completely replace conventional instruments. Smartphone RTK excels in mobility and efficiency for large-area terrain surveys, sequential point recording, and point cloud acquisition. However, for precision measurements requiring millimeter-level accuracy or cases that require indoor or underground positioning, traditional surveying instruments such as total stations remain important. It is desirable to use each tool according to site requirements; smartphone RTK should be regarded as a new option that complements and streamlines traditional methods.

Q: I’m worried adoption will be difficult because operation seems complicated. Can beginners handle it? A: The operation is simple and designed to be user-friendly for beginners. Products like LRTK feature intuitive user interfaces that make everything from starting positioning to saving points and toggling AR displays smooth. Even those unfamiliar with smartphones can get the hang of it quickly by following on-screen guidance. In addition, training and robust support systems are provided at introduction, so you can continue operation with confidence if questions arise after starting. The ease of use that anyone can handle is a major reason smartphone surveying is spreading on sites.