How to Use RTK AR: Streamlining Construction and Surveying Sites with High-Precision AR

Surveying technology in the construction industry has changed dramatically in recent years. Traditionally, transit instruments, total stations, or standalone GPS were commonly used, but with the move toward ICT and DX, new high-precision and efficient technologies such as RTK-GNSS and drone surveying have begun to permeate job sites. In particular, the use of Real-Time Kinematic (RTK) positioning has attracted attention, and there are increasing cases of construction management and as-built inspections being performed with centimeter-level accuracy (inch-level accuracy). Against this background, a next-generation approach that combines high-precision positioning via RTK with AR technology—enabling surveying through construction management using just a smartphone—has emerged: RTK AR.

This article explains the basics of RTK AR, its application scenarios, and the benefits of adoption in detail, and at the end introduces a solution to easily realize high-precision AR. Let’s look concretely at what RTK AR is and how it can be useful on site.

Table of Contents

• What is RTK AR?

• Examples of RTK AR use on construction sites

• RTK AR application scenes in surveying

• Benefits of RTK AR

• Simple surveying with LRTK

• FAQ

What is RTK AR?

Recently, a new technology called RTK AR has been attracting attention on construction and civil engineering sites. RTK AR combines “RTK (Real-Time Kinematic) high-precision positioning” with “AR (Augmented Reality).” This makes it possible to overlay digital information onto the real world with centimeter-level accuracy (inch-level accuracy). First, let’s briefly look at each technology.

AR (Augmented Reality) is a technology that overlays digital information such as CG models or text onto live images of the real world captured by cameras on smartphones, tablets, or smart glasses. For example, you can overlay a model of a planned building onto the site’s scenery, or project piping routes from drawings onto actual structures to check alignment. By visualizing information that cannot be seen with the naked eye, AR dramatically improves image sharing and instruction-giving on construction sites. In practice, major general contractors have been overlaying BIM data onto real images to check piping that will be hidden before finishing or to share plans for the next work step on site (e.g., Shimizu Corporation’s “Shimz AR Eye”). Such efforts have demonstrated that AR technology greatly helps prevent construction mistakes and facilitates smooth information sharing.

On the other hand, RTK positioning is a high-precision surveying technique that corrects errors in GNSS (Global Navigation Satellite Systems) such as GPS in real time to determine the current position within an error range of several centimeters (several inches). A base station placed at a known reference point and a rover station that moves while positioning both receive satellite data simultaneously; the base station sends error information obtained back to the rover via communication to correct it, reducing typical positioning errors of about 5–10 m (16.4–32.8 ft) down to about 1–2 cm (0.4–0.8 in). By using network RTK (VRS method) or the CLAS (centimeter-class positioning augmentation service) provided by Japan’s quasi-zenith satellite system “Michibiki,” centimeter-level positioning is possible over wide areas without setting up a dedicated base station. In Japan, by using Michibiki’s CLAS you can achieve centimeter-level augmentation even at sites out of mobile communication range, enabling high-precision positioning without an internet connection. Also, by using private Ntrip-type network RTK services, you can obtain real-time data from nationwide reference stations, yielding stable accuracy even in urban areas. In this way, RTK technology is creating an environment where even non-experts can obtain high-accuracy position information on site.

So what can be achieved by combining RTK and AR? The greatest feature of RTK AR is that it enables “AR displays tied to absolute coordinates without drift.” Traditional AR apps required initial alignment with markers or plane recognition, and CG would drift relative to reality as the user moved. However, by using the high-precision current position data from RTK-GNSS, 3D models and other elements on AR can be placed directly in a global coordinate system. Even if users walk around the site, the models do not shift and remain stably displayed in the correct positions. In other words, it realizes “high-precision AR without initial alignment.” For example, even in low-visibility locations you can pinpoint installation positions in AR, overlaying virtual models on real objects with errors of only a few centimeters (a few inches). RTK also captures user movement paths and orientation with high precision, so virtual objects maintain correct position and orientation from any viewing angle.

Examples of RTK AR use on construction sites

RTK AR technology can be applied in various situations on construction and execution sites. Below are the main expected use cases on construction sites.

• Streamlining piling and layout marking work: For locating buildings and structures, survey instruments and manual marking were previously necessary. With RTK AR, design piling positions and reference lines can be displayed directly on the ground in AR. Workers can determine positions more quickly and accurately by viewing virtual piles or lines standing on the ground through a smartphone or tablet screen. This reduces the need for multiple people and repeated re-measurements, shortening work time and reducing labor.

• Overlaying 3D design models: Use of 3D design models (BIM/CIM) at construction sites is increasing. With RTK AR, these 3D design models can be overlaid on the actual site with perfect alignment. For example, displaying a finished building model in AR on an earthwork site helps intuitively share the final image. Displaying buried piping or cable locations in AR beforehand helps prevent near-miss incidents during excavation and avoids construction mistakes. Because you can visualize the finished form on site instead of relying only on drawings or mental models, communication among stakeholders becomes smoother and rework decreases.

• On-site as-built verification (quality checks): “As-built” refers to the actual shapes and dimensions after construction. RTK AR can be used to compare as-built results with design data on site and visualize deviations. Specifically, 3D point cloud data of the as-built, acquired with smartphone-mounted LiDAR scanners, can be overlaid with the design model. If displayed as a color-coded heat map indicating areas that are short in elevation or overfilled, the quality of the finish can be assessed at a glance. High-precision AR displays allow immediate detection of differences between drawings and reality on site, enabling on-the-spot decisions for corrections and directly contributing to quality control and schedule reduction. Additionally, automatically calculating cut-and-fill volumes from the acquired point cloud lets you quantify excesses or shortages and achieve efficient work.

RTK AR application scenes in surveying

RTK AR is also revolutionizing field surveying. Tasks that used to require a team can now often be completed with a single smartphone. Here are the main use cases.

• Use in boundary surveying: RTK AR can be used to identify boundary points of land and place temporary stakes. Preload known boundary coordinate data into a dedicated app, and simply point a smartphone camera on site to reveal normally invisible boundary lines or markers in AR. Even if boundary markers are hidden by vegetation, virtual markers can indicate the boundary, making it easier to share positions with landowners or neighbors. This smooths boundary meetings and negotiations and helps prevent disputes caused by differing boundary recognition.

• Surveying and recording at disaster sites: RTK AR is powerful at disaster sites such as landslides or flooding. If pre-collapse terrain data or buried object locations are displayed in AR at the site, recovery planning and damage assessment can proceed quickly. Being able to view conditions from a safe distance reduces the risk of secondary disasters.

• Topographic surveying and cloud sharing: Detailed point cloud data acquired with RTK-capable smartphones can be uploaded to the cloud and shared in real time with office PCs. With site and office able to view and share surveying data simultaneously, there is no time loss from waiting for instructions or data handover. By “measuring alone and simply uploading to the cloud,” you can share results with distant supervisors or colleagues, speeding decision-making and improving overall site efficiency.

Moreover, reference point surveys and as-built inspections that were previously outsourced to specialized surveying contractors can be handled immediately by site staff, reducing outsourcing costs and scheduling burdens.

Benefits of RTK AR

As seen above, adopting RTK AR brings significant benefits to construction and surveying sites. The main effects are summarized below.

• Shorter work time and improved efficiency: High-precision AR accelerates layout and inspection tasks, enabling surveying and checks that used to take half a day to be completed quickly. Real-time measurement and verification on site reduce rework and duplication, contributing to overall schedule shortening.

• Labor reduction and one-person operation: Because surveying can be completed with a smartphone and a small GNSS receiver, there is no need to transport and set up bulky equipment or deploy assistants. AR displays enable accurate piling and other tasks to be performed by a single person, making sites with labor shortages more manageable. The ability for one person to perform tasks that previously required multiple people improves productivity and reduces labor costs.

• Error prevention and quality improvement: Centimeter-level accuracy (inch-level accuracy) allows major reductions in mistakes from misreading or mismeasuring positions. Construction can be carried out at the designed locations and deviations in as-built results can be detected immediately, directly ensuring construction quality. Sharing the completed image in AR beforehand prevents recognition mismatches and rework, resulting in improved quality and safety.

• Smooth communication: Visualizing information in AR allows everyone from site workers to clients and designers to discuss while viewing the same “real-world image.” It enables intuitive explanations even to non-specialists and smooth consensus building. For boundary checks or as-built inspections, sharing life-size AR displays on site helps people understand the situation at a glance, reducing the time and effort required for explanations and discussions.

• Reduced introduction costs and mobility: Because a smartphone plus a small device can substitute for dedicated precision surveying equipment, initial investment and equipment maintenance costs can be greatly reduced. The compactness of the equipment makes it easy to carry and lightweight to perform surveying while moving across wide sites. The convenience of quickly pulling it out and using it on demand greatly improves on-site agility.

Thus, RTK AR can be a trump card for dramatically improving productivity and precision control on site as part of construction DX (digital transformation). It also aligns with the Ministry of Land, Infrastructure, Transport and Tourism’s promotion of *i-Construction*, and broader adoption is expected going forward.

Simple surveying with LRTK

One solution to easily realize RTK AR on site is LRTK. LRTK is a next-generation surveying system composed of an ultra-compact RTK-GNSS receiver that attaches to a smartphone and a dedicated app. By attaching the pocket-sized compact device to your phone and launching the app, anyone can immediately start centimeter-level positioning and AR displays. Reported comparisons show that the accuracy is comparable to dedicated equipment: when measuring the same point as a grade-1 GNSS receiver used for national reference point surveying, the difference was only on the order of a few millimeters (a few hundredths of an inch).

With LRTK, tasks that previously required expensive surveying equipment or skilled personnel can be completed with a single smartphone. For example, even without installing reference points on site, you can immediately achieve high-precision positioning by using satellite augmentation signals (such as Michibiki’s CLAS) or VRS data. Acquired positioning data are automatically synced to the cloud, enabling progress checks and analysis from the office. Advanced functions such as scanning the surroundings with a smartphone LiDAR to obtain a 3D point cloud and displaying as-built vs. design differences as an AR heat map can be done by a single operator.

The LRTK series is designed for construction and civil engineering sites and offers excellent positioning performance and durability under adverse conditions. It supports iOS devices such as iPhone and iPad and is attracting attention as a solution that meets Japan’s i-Construction requirements. In fact, LRTK has already been introduced at construction sites nationwide, dramatically shortening the time required for surveying and as-built verification while being highly praised for its ease of use by non-specialist site staff.

If you want to try simple surveying using high-precision AR, please consider LRTK. For product information and case studies, see the [LRTK official site](https://www.lrtk.lefixea.com). We accept inquiries and consultations about implementation at any time. Take your site to the next stage with cutting-edge RTK AR technology.

FAQ

Q: What is RTK AR? A: It is a technology that combines RTK high-precision positioning with AR (Augmented Reality) to overlay 3D models and information onto the real world with centimeter-level accuracy (inch-level accuracy). Its notable feature is the ability to display virtual objects accurately in place without the need for initial alignment.

Q: What do I need to introduce RTK AR? A: Basically, you need an RTK-capable GNSS receiver, a smartphone that can connect to it (e.g., iPhone or iPad), and a dedicated AR-capable app. Attach the receiver to your smartphone and prepare an environment to receive GNSS correction information over the network (VRS or Michibiki’s CLAS, etc.) and you can start high-precision AR immediately. Supported devices and apps vary by product, but many recent solutions target iOS devices.

Q: Can you really achieve about 1–2 cm accuracy, and can one person do surveying? A: Yes. Under appropriate conditions, RTK AR can provide horizontal accuracy of about ±1–2 cm (±0.4–0.8 in) and vertical accuracy within a few centimeters (a few inches). Reports show positioning results comparable to dedicated high-precision GNSS equipment. AR guidance functions also allow a single person to perform piling and measurement tasks. The ability for one person to manage precision control on sites with labor shortages is a major strength.

Q: Can someone without specialist knowledge use it? A: Yes. Dedicated apps that are intuitive to operate make it relatively easy even for those who are not comfortable with machinery. Positioning results and AR guidance are clearly displayed on the smartphone screen, so with a little practice, even those without extensive specialist knowledge can utilize high-precision positioning on site. While basic surveying knowledge is helpful, advanced qualifications or long-term training are not required to start using RTK AR.

Q: What happens where satellites cannot be received? A: In places where satellite signals are severely blocked, such as between tall buildings or inside forests, RTK AR will unfortunately struggle to obtain positioning. In such cases, you will still need to use terrestrial surveying instruments like total stations. However, multi-GNSS support and use of quasi-zenith satellites have improved satellite acquisition performance compared with conventional devices. In many cases you can position in places with a bit of open sky, and there are cases where RTK-capable smartphones have successfully measured in mountainous areas that previously produced meter-level errors.

Q: What kinds of sites and applications can it be used for? A: It is used across a wide range of civil and building construction scenarios: as-built surveying and earthwork volume calculations at development sites, piling and batter board (layout) placement for roadworks, as-built checks for bridges and tunnels, recording disaster site damage, and any scene where high-precision position information is required. Tasks that used to require specialized contractors can now be performed quickly by site personnel, contributing greatly to schedule shortening and quality assurance. Going forward, smartphone-based RTK AR surveying is likely to become a commonplace tool across diverse sites.