Construction Management DX with AR in Construction! RTK-enabled Misalignment-free AR Display and Increased Surveying Accuracy for Significant On-site Efficiency Improvements

Table of Contents

• Challenges of conventional surveying and construction management

• Solutions using AR×RTK technology

• Methods of utilizing LRTK

• Specific implementation effects (reduced manpower, high-precision guidance, no need for layout marking, time savings)

• Future prospects

• FAQ

Challenges of Conventional Surveying and Construction Management

On civil engineering and construction sites, construction management has long been carried out using surveying instruments such as total stations and levels, as well as marking-out (staking-out) work. However, conventional methods have many challenges. For example, manually surveying a large number of points across a wide site requires significant time and effort, and it was not uncommon for as-built inspections to take several days. For marking out pile-driving positions, teams—including experienced personnel—need to proceed while confirming measurement points in multiple stages, and laying out dozens of piles can take a full day. In this way, work that relies on manual labor placed a major burden on efficiency.

Furthermore, accurate surveying and construction management require experienced technicians. However, the construction industry is facing chronic labor shortages and an aging workforce of technicians, and it continues to depend on veteran workers with skills. The burden on skilled workers has become concentrated, making it increasingly difficult to secure sufficient personnel at each site.

There are also challenges in terms of ensuring accuracy. Surveying instruments that achieve millimeter-level (mm, 0.04 in) accuracy are expensive, and initial investments can amount to several million yen; maintenance costs and the risk of theft are also non-negligible for small and medium-sized enterprises. In addition, measurements carried out mainly by hand cannot avoid the possibility of human error such as recording mistakes or misreadings, and if the numbers jotted down on site are transcribed incorrectly into drawings at the office, there have been cases where measurements had to be redone later.

A lack of real-time capability was also a major problem. Traditionally, data collected on site had to be taken back for analysis and drafting, so defects tended to be discovered late. Even when there were construction defects, they often went unnoticed on the spot, and it was not uncommon for problems to be identified the next day or later, resulting in rework. Furthermore, with only plans and numerical data, it is difficult for all stakeholders to visualize the finished result, which can lead to misalignment in understanding between the client and the contractor and increase the risk of adjustments and mistakes.

As described above, conventional surveying and construction management methods lack "immediacy" and "clarity," require a great deal of manpower and time, and still carry a risk of errors. On-site personnel are beginning to feel these limits, and solutions based on new digital technologies are being sought.

Solutions Using AR×RTK Technology

A digital technology that combines AR (augmented reality) and RTK (high-precision positioning) has attracted attention as a trump card for solving these issues. AR technology, which can overlay 3D design data and guidance information onto real scenery through a smartphone or tablet camera, has become a highlight of construction management DX as an intuitive means of information sharing. Because it can display and share a life-size representation of the completed image on site, which previously could only be checked on drawings, it has a major effect in eliminating gaps in understanding with clients and preventing construction errors. However, with standard GPS accuracy, positional errors can be several meters, so even if a design model is overlaid in AR, it will be displaced from the actual position and thus difficult to use in practice.

Thus, an approach has emerged that leverages RTK, a high-precision GNSS positioning technique, to dramatically improve the accuracy of AR displays. RTK (Real Time Kinematic) is a technique that uses correction information from a base station to cancel GNSS positioning errors in real time, achieving positioning accuracy of approximately 1-2 cm (0.4-0.8 in). By combining a smartphone with a compact RTK-capable GNSS receiver, it becomes possible to overlay virtual objects on the camera feed so they precisely align with the physical environment. In other words, you can place virtual models at the exact coordinates measured by GNSS.

This AR×RTK "RTK AR" technology is turning augmented reality—which until now had large errors and was impractical—into a usable tool for surveying and construction management. Because the on-site position and the 3D model are continuously tracked by RTK-GNSS, the model does not shift even when the user moves, and the troublesome initial alignment becomes unnecessary. For example, even in areas with poor visibility due to vegetation, the exact installation position can be pinpointed on the AR, so there is no need to rely on nearby landmarks. Since the AR guides always match the real world, workers are accurately guided to target positions simply by following virtual signs or arrows seen through the camera. This enables high-accuracy construction work even by non-experts and helps reduce human error.

In other words, AR×RTK technology is a solution that brings both "clarity" and "accuracy" to the field. Because it allows sharing completed designs with intuitive 3D displays and visualizing measurement results in real time, early detection of issues and rapid responses become possible. The traditional divide between surveying and construction management is also being lowered, and there will likely be more situations where on-site staff themselves can grasp conditions on the spot and make decisions. Highly compatible with the Ministry of Land, Infrastructure, Transport and Tourism's *i-Construction* initiative promoting construction DX, AR×RTK is attracting strong expectations as the next-generation construction management technology.

How to use LRTK

That said, it is also true that realizing RTK AR in the field involves several hurdles, such as preparing high-precision GNSS receivers and dedicated software. The solution developed to make high-precision positioning easier to use on site is LRTK (LRTK). LRTK is an all-in-one surveying system consisting of an ultra-compact RTK-GNSS receiver that can be attached to a smartphone, a dedicated app, and cloud services, designed so that anyone on site can perform centimeter-level positioning with a single touch. A major feature is that, without complex base station installation or specialized setup, you can obtain high-precision global coordinates (WGS84) instantly with just a smartphone.

For example, if you attach an LRTK device to an iPhone and launch the app, you can obtain real-time current position coordinates with centimeter-level accuracy (cm level accuracy, half-inch accuracy). By utilizing that high-precision positioning information, you can not only perform point surveying on maps and record coordinates on photos, but also 3D-scan with the phone’s LiDAR to obtain point cloud data, or display arbitrary target locations in AR to guide users—all completed with just a smartphone. Tasks that traditionally required specialized surveying equipment or multiple-person teams can be easily handled by a single person using LRTK, so on-site workflows are likely to change dramatically. The receiver supports multi-GNSS and multi-band reception, making it robust in satellite environments, and is compatible with Japan’s Quasi-Zenith Satellite System Michibiki’s free centimeter-class (cm, half-inch accuracy) augmentation service (CLAS) as well as existing network RTK services (VRS). Flexible operation is possible—for example, using CLAS signals in mountainous areas without cellular coverage and using internet-based VRS in urban areas—allowing stable high-precision positioning regardless of location. In short, it is a revolutionary tool "a smartphone becomes a high-precision surveying instrument" that, with an intuitive UI requiring no expert knowledge, dramatically improves the efficiency of on-site surveying and stakeout operations.

By leveraging LRTK, the various uses of AR×RTK technology introduced so far can be easily implemented in real-world field settings. Below are examples of key application scenarios.

• AR stake-out navigation (positioning): Displays virtual arrows and pins on a smartphone screen to guide workers to pile/stake positions on the drawings. This enables intuitive and accurate positioning even for those who are not experienced, contributing to improved work efficiency and reduced human error.

• AR overlay of design models: Displays the planned building model in AR on an empty site so the client and construction team can share the completed-image. Because the finished form that was hard to grasp on paper drawings can be experienced at full scale, it prevents misunderstandings like “it looks different from the image” and smooths consensus building. Thanks to precise alignment using RTK, there is almost no discrepancy between the model and the terrain, allowing for highly convincing explanations.

• As-built verification and quality checks: Displays the design 3D data in AR on constructed structures so you can confirm on site whether the finished work fits the drawing’s position and dimensions. Differences between the model and the actual structure become immediately apparent, enabling quick self-checks before detailed measurements and leading to early detection of rework and defects.

• Visualization of buried utilities: If you record the positional information of pipes and cables buried underground, their routes can be displayed in AR even after burying. Being able to identify the location of unseen piping before excavation prevents accidental damage. There is no need for the hassle of marking the site with layout spray paint, and anyone can intuitively grasp the location of buried utilities, providing peace of mind.

In this way, using AR×RTK (LRTK) will greatly transform on-site tasks such as measuring, displaying, and verifying. The traditional separation between surveying and construction management will be reduced, and there will be more situations where field staff themselves can grasp conditions in real time and make decisions.

Specific implementation effects (labor reduction, high-precision guidance, no layout marking required, time savings)

Labor reduction: The introduction of AR×RTK technology enables on-site work to be carried out without relying on experienced surveyors. For example, surveying and stake-out tasks that traditionally required two people working as a pair can be handled by a single person using AR visual guidance. An intuitive tool that anyone can use eliminates reliance on specific individuals and allows work to proceed efficiently even at sites with staffing shortages.

High-precision guidance: Because the AR display is based on position data that RTK continuously corrects to within a few centimeters of error, the positions indicated by the virtual guide align with physical space. Workers are guided to the exact designated locations simply by following the arrows and lines seen through the camera, making it far more accurate than reading numbers on drawings and measuring with a tape as before. As a result, construction mistakes and rework caused by slight positioning errors are reduced, helping to ensure quality.

Eliminating layout marking tasks: Because digital AR displays function as "virtual layout lines," marking work on the ground and on structures can be greatly reduced. For example, in road construction, height and slope information that was traditionally conveyed using batter boards and layout markings can be shown via AR on a tablet in the operator's cab, removing the need to mark the actual site. This reduces the hassle of taking measurements from drawings on site and prevents human errors such as forgetting to erase layout markings or misreading them.

Reduction of work time: The use of AR×RTK enables speed-ups in various tasks. For example, a report from a major construction company says that AR surveying using a smartphone reduced the time required for earthwork volume measurement by about 90% compared with conventional methods. A single person can acquire the necessary data in a short time, and there is no need to stop heavy machinery or allocate many personnel for surveying, which leads to shorter overall construction schedules and reduced labor costs. Furthermore, because measurement results and predicted completion can be displayed on site, the time spent bringing data back to the office for analysis and review is reduced, and decision-making speed is improved. Overall, AR×RTK technology delivers time-saving effects that dramatically boost on-site productivity.

Future Possibilities

The DX of construction management using AR×RTK is expected to expand more widely in the future. Overseas, companies have launched products that integrate cameras and IMUs into GNSS receivers to provide AR-based guidance and measurement, and RTK AR is gaining attention as a next-generation technology in the surveying and construction fields. AR surveying instruments have also begun to appear in Japan, and new applications such as the fusion of point cloud measurement and AR display are becoming active. In the future, smart-glass-type devices may become widespread, allowing workers to constantly check AR guidance while keeping both hands free. Remote assistance, where experienced personnel in distant locations give real-time instructions through AR, and applications that automatically check construction status in collaboration with AI, can also be envisioned.

Even now, AR×RTK technology functions fully as a practical solution to improve productivity and safety on construction sites. In particular, by leveraging solutions such as LRTK, high-precision AR can be introduced easily, enabling small and medium-sized companies and sites that until now have found large equipment investments and securing specialized skills difficult to promote digital transformation. In fact, the LRTK series is a next-generation solution compatible with the Ministry of Land, Infrastructure, Transport and Tourism’s *i-Construction*, strongly supporting the digitalization of the construction industry. By adopting the ever-evolving AR construction technologies early, sites can increase their competitiveness and gain a significant advantage in resolving the challenge of balancing productivity improvement and quality assurance. Why not take this opportunity to consider the benefits of introducing simplified surveying with LRTK?

FAQ

Q1. What is AR architecture? A. In the construction industry, AR architecture refers to the practice of incorporating AR (Augmented Reality) technology on site to digitize construction management and surveying. When a smartphone or tablet is held up, 3D design models and instruction information are overlaid on the camera view. Because it enables intuitive information sharing that drawings and photos cannot provide, it is widely used for a range of purposes, from sharing the completed-image to improving the efficiency of surveying work.

Q2. Why is RTK necessary? A. High-precision positioning from RTK is essential to make accurate use of AR. Ordinary GPS can have errors of several meters (several ft), which prevents virtual models from being perfectly overlaid on actual positions. By using RTK, errors can be reduced to a few centimeters (a few in), enabling accurate AR alignment even on construction sites. In other words, only with RTK can AR achieve the accuracy needed to be used as a practical tool for construction management and surveying.

Q3. What is needed to use RTK×AR? A. Basically, the following items are required: ① An RTK-capable GNSS receiver capable of centimeter-level positioning (cm level accuracy, half-inch accuracy) (a high-precision GPS antenna), ② Correction information for GNSS positioning (radio signals from a dedicated base station, network-distributed VRS services, or in Japan, reception of the Michibiki CLAS signal), ③ A smart device capable of AR display (a smartphone or tablet with a camera and sensors), ④ Specialized apps or software that can reflect GNSS position data in AR content. If you are outdoors in an environment where satellite signals can be received, anyone can experience RTK AR by combining these components.

Q4. Can it be used by non-specialist technicians? A. Yes. Smartphone RTK systems like LRTK are designed to be operated intuitively and can be used without specialized knowledge. Simply attach the device to your smartphone and launch the app; high-precision positioning begins automatically, and you just follow the on-screen instructions. The UI is simple and easy to understand, so it can be immediately useful on site even for non-veterans. You can learn as you go, so the barrier to training and deployment is low.

Q5. Specifically, in what situations is it effective? A. It is effective in various construction scenarios. For example, in pile-driving operations AR can guide pile positions, shortening layout time and reducing mistakes. In as-built management, it allows on-site comparison with design data to check for discrepancies, helping to prevent rework. In buried-pipe construction, the positions of installed pipes can be visualized later with AR, enabling safe excavation. In addition, you can display terrain point-cloud data on-site with AR to instantly grasp cut-and-fill volumes, providing a wide range of benefits from shortened schedules to improved quality and enhanced safety measures.