RTK AR Success Stories: How High-Precision AR Positioning Has Transformed the Field

Table of Contents

• What is RTK AR?

• Why traditional technologies fall short and why high-precision AR positioning is needed

• Benefits RTK AR brings to the field

• On-site use cases of RTK AR

• Simple surveying with LRTK

• FAQ

What is RTK AR?

In recent years, digitalization of construction sites (so-called construction DX) has accelerated, and there is growing attention on using drawings and 3D models on site. In particular, AR (augmented reality) technology is expected to help share completed images and guide work. However, conventional AR suffered from positioning errors. RTK AR has emerged to address this.

RTK AR combines satellite positioning technology called RTK (Real Time Kinematic) with AR (augmented reality) technology to overlay digital information on the real world with high-precision alignment. RTK, also called real-time kinematic, is a technique that uses signals from GNSS satellites to achieve centimeter-level positioning accuracy. AR overlays CG and other digital information on the real-world view through a camera, but the GPS in a typical smartphone alone has large errors, causing AR objects to be off by several meters. By applying RTK’s high-precision positioning to AR, RTK AR enables virtual objects to be placed in the real world with an accuracy of about several centimeters.

RTK AR uses mobile devices such as smartphones and tablets combined with RTK-capable GNSS receivers. While conventional GPS positioning had errors of roughly 5–10 m (16.4–32.8 ft) and struggled to measure elevation, RTK-GNSS can pinpoint positions with horizontal ±1–2 cm (±0.4–0.8 in) and vertical accuracy of about ±3 cm (±1.2 in). Having this high-precision absolute coordinate makes it possible to align 3D models and guidance markers displayed in AR precisely with the actual construction coordinate system. For example, if a 3D design model has coordinates acquired by surveying attached in advance, when that model is displayed in AR on site it will appear in the exact location as if the real object were there. RTK AR has dramatically improved the alignment between digital data and the real world.

Why traditional technologies fall short and why high-precision AR positioning is needed

Why has high-precision AR positioning like RTK AR become necessary? The background lies in problems that existed with traditional technologies.

First, on construction and surveying sites, specialized equipment such as total stations and GPS surveying instruments have been used for layout and marking. Total stations can survey to millimeter accuracy, but the equipment is large and heavy, requires two or more operators and advanced training, and needs regular calibration and maintenance. On the other hand, general GNSS positioning (so-called GPS) is convenient, but as mentioned earlier has errors of several meters and cannot obtain reliable vertical information. As a result, when transferring planned positions from drawings to the actual site, only rough alignment was possible and fine adjustments still relied on manual work and experienced intuition.

Conventional AR technology also has limitations. AR apps on smartphones alone often show 3D models displaced from real positions due to the accuracy limits of built-in GPS and inertial sensors, leading to situations where “what should be here looks like it’s over there” in AR. There are methods that place markers on the ground and calibrate AR display to those markers, but this requires repeated setup and is impractical for large sites. In short, conventional AR lacked alignment accuracy and was unsuitable for applications requiring the precision demanded on construction sites.

RTK AR emerged to solve these issues. High-precision positioning makes it possible to overlay digital information on the real world without misalignment, greatly improving the quality of many on-site tasks and communication.

The construction industry is also facing future labor shortages and challenges in skills transfer, and there is strong demand for productivity improvements using digital tools that anyone can operate. RTK AR is expected to meet these needs as a practical solution.

Benefits RTK AR brings to the field

Introducing RTK AR brings many benefits to the field, including the following:

• Improved accuracy: AR displays can achieve centimeter-level positioning accuracy, allowing virtual models and guide markers to be placed at their actual positions. Discrepancies between drawings and the site and errors caused by misaligned AR displays can be greatly reduced.

• Increased efficiency: Some traditional surveying and marking tasks performed by heavy equipment or multiple personnel can be digitized, enabling one person to perform layout tasks. For example, when checking many points across a large site, an RTK AR-enabled device can verify positions simply by walking around, reducing work time. Traditionally, surveyors would perform layout and then construction personnel would start work; with RTK AR, workers themselves can instantly identify needed points, reducing waiting time and communication losses.

• Easier consensus building: Because completed images and installation locations can be shared on the spot, aligning understanding with clients and stakeholders becomes smoother. Showing the completed appearance overlaid on the actual scenery in AR conveys what drawings alone could not, enabling immediate shared understanding. This can reduce rework.

• Improved safety: If locations of underground utilities or hazardous areas obtained in advance are visualized in AR, workers can intuitively recognize hidden dangers on site. This prevents accidents such as accidentally hitting buried pipes or entering prohibited areas.

• Cost reduction: Expanding the scope of work that in-house staff can handle without relying on high-precision equipment or external surveying teams reduces rental costs for surveying equipment and labor costs. The reduction in mistakes and rework also cuts unnecessary reconstruction expenses.

• Faster information sharing: Positioning data and AR screen captures obtained digitally can be uploaded to the cloud on the spot and immediately shared with remote office personnel and stakeholders. This speeds up on-site reporting, inspection, and approval processes, improving overall efficiency.

On-site use cases of RTK AR

Here are some innovative examples of how RTK AR has been used on site.

Consensus building by displaying design models in AR

On a civil engineering site, a completed structural model (BIM/CIM model) was projected on site using RTK AR and used in meetings with the client. Viewing the completed image overlaid on the actual landscape through a tablet helps everyone intuitively understand the final appearance that drawings alone could not convey. For example, by showing the finished height and shape of a riverbank protection structure on site, the client can confirm the completed appearance in advance and share additional requests or concerns early. For contractors, reducing misunderstandings before starting work means fewer rework instances during construction. Sharing accurate completed models via RTK AR has greatly facilitated consensus building among stakeholders.

Safety management innovation by visualizing buried utilities

In another case, before road construction, underground pipes and cables were visualized with RTK AR to inform work planning. Position information of buried utilities obtained through test excavations or surveys was digitized and displayed in AR on site, allowing workers to know in real time what is buried under the ground and where. For example, if data of pipelines installed in past work are acquired by Lidar scanning, their routes can be visualized with RTK AR from above the pavement. This reduces the risk of damaging pipes during excavation and is an effective safety measure. Site supervisors can also confirm buried utilities just by holding up a tablet, enabling accurate decisions such as marking hazardous points or implementing detours. Once stored in the cloud, the location data of buried utilities can serve as accurate information for future works, contributing to long-term safety management.

Improved efficiency and accuracy in piling and layout marking

RTK AR has also transformed piling and layout marking tasks on building sites. Traditionally, surveyors derived positions from drawing coordinates on site and marked them with piles or chalk, which was time-consuming and labor-intensive for large sites with many points. With RTK AR, markers and guides appear in AR at pre-set installation positions, so workers can drive piles or draw lines directly while viewing them. For example, when installing a foundation for a signal pole, the correct position is shown on the screen, allowing precise equipment placement even by non-surveying specialists. In one case, an RTK AR-enabled device guided a single worker to mark all piling positions in a short time. RTK AR makes layout tasks faster and more accurate, reducing human measurement errors.

Application to as-built verification

RTK AR is powerful for as-built verification after construction completion. Traditionally, verifying as-built conditions required measuring dimensions with tapes or survey instruments and visually comparing the completed site to the as-built drawings. With RTK AR, design data can be overlaid directly on the finished structure to confirm the state of the work. For example, during road embankment work, AR can check whether the finished height matches the design, and if any area appears to protrude from the design model, additional grading can be decided on the spot. Photos can be taken to keep records of before-and-after comparisons using AR overlays. RTK AR reduces the effort of cross-checking with drawings and enhances the efficiency and reliability of on-site inspections.

Simple surveying with LRTK

One solution gaining attention for easily enjoying the benefits of RTK AR is LRTK. It has already begun to be adopted by some local governments and construction companies and, because of its ease of use, is becoming a new standard tool on sites. LRTK is a simple surveying system consisting of a small RTK-GNSS receiver that attaches to a smartphone and a dedicated app, enabling anyone to easily achieve centimeter-level positioning and AR display.

Traditionally, achieving centimeter-level positioning required expensive GNSS equipment or large apparatus. With LRTK, attaching a pocket-sized receiver weighing only a few hundred grams to a smartphone or tablet instantly turns it into a full-fledged surveying instrument. Without specialized training, site personnel can carry the device and perform surveying and position checks by themselves. Coordinates of collected points are automatically tagged with latitude, longitude, and elevation, and plotted on a map in real time within the app. With one tap, data can be shared to the cloud, making it easy to immediately share on-site collected information with teams in the office.

LRTK also has AR functionality: simply open pre-uploaded design 3D data on site and it projects without the hassle of alignment. This makes RTK AR methodologies easily accessible, allowing anyone on site to intuitively handle digital information. For example, confirming the placement of complex structures becomes instantly clear through LRTK’s display. It is also possible to scan the existing condition using point-cloud scan functions and compare before-and-after conditions in AR based on that data. LRTK’s simple surveying provides high-precision positioning and AR display in an all-in-one package, strongly supporting DX (digital transformation) on site.

By using LRTK, surveying and layout tasks that were previously entrusted to specialists can be easily carried out by in-house staff. This will contribute significantly to on-site productivity improvement and cost reduction. High-precision AR positioning technology is expected to become the new norm on construction sites, and further advances in high-precision AR will continue to evolve work styles in construction.

FAQ

Q. What is the difference between regular smartphone AR and RTK AR? A. AR using only a typical smartphone often suffers from GPS errors (on the order of several meters) and sensor drift, causing AR objects to be displaced from their real-world positions. RTK AR, on the other hand, uses high-precision RTK-GNSS positioning to reduce errors to about a few centimeters, enabling practical AR use in applications that require accurate positioning such as construction and surveying.

Q. What equipment and preparations are required to use RTK AR? A. Basically, you need an RTK-compatible GNSS receiver, a smartphone or tablet that can connect to it, and a dedicated application. The GNSS receiver should be able to receive satellite correction information (for example, correction radio from a base station or correction data via the internet). Recently, products that combine small receivers attachable to smart devices and easy-to-use apps (such as solutions like LRTK) have appeared, making it easy to introduce RTK AR without specialized knowledge.

Q. What level of positioning accuracy can RTK AR achieve? A. Depending on the environment, you can generally expect about ±1–2 cm (±0.4–0.8 in) horizontally and about ±3 cm (±1.2 in) vertically. If the device is stationary and positional values are averaged over a certain period, errors can fall below 1 cm (0.4 in). This is vastly more accurate than standalone GPS and enables AR displays with nearly indistinguishable positional accuracy from reality.

Q. Can RTK AR be used indoors or in areas where satellite signals are blocked? A. RTK AR fundamentally relies on signals from GNSS satellites, so it cannot demonstrate its full accuracy in environments where satellites cannot be received, such as indoors or inside tunnels. When using AR in such places, it is necessary to set reference points on site in advance and perform AR display based on relative positions, for example. However, in fully indoor environments, high-precision positioning via RTK is difficult, so RTK AR is primarily used in open outdoor locations.

Q. Is operating or configuring the equipment difficult? A. No. RTK AR systems are designed to be easy for non-specialists to use on site. For example, with LRTK, attaching the receiver to a smartphone and pressing a button is enough to record points and display AR, and the app automatically handles complex coordinate calculations. Even first-time users can start using it on site after simple training or following a manual.

Q. Is an internet connection required to receive RTK correction information? A. RTK requires real-time reception of correction data from a reference station to achieve high-precision positioning. In many cases, these correction data are obtained over the internet using mobile data. Alternatively, you can set up your own portable reference station (GNSS base station) and exchange correction data via radio communication. In Japan, services that provide satellite-based centimeter-level augmentation signals (for example, signals derived from quasi-zenith satellite systems) are also available. Depending on the site environment, combining internet, dedicated radio, or satellite communications enables stable RTK AR operation.

Q. What kinds of sites and fields can RTK AR be applied to? A. RTK AR is especially effective in outdoor surveying, construction, and civil engineering sites. Examples include site planning confirmation for earthworks and road construction in civil engineering, foundation position checks and equipment layout verification in building construction, locating buried utilities for infrastructure maintenance, and recording damage conditions at disaster recovery sites. RTK AR is useful in a wide range of scenarios where accurate spatial positioning information is required. Because it can be applied across operations involving terrain and structures, its use is expected to expand into increasingly diverse fields.