Improving Construction Layout Efficiency with RTK AR: Dramatic On-Site Productivity Gains

Table of Contents

• Challenges in Traditional Construction Layout

• What Is RTK AR? Overview of the New Technology

• Benefits of Introducing RTK AR for Construction Layout Efficiency

• On-Site Use Cases of RTK AR

• Conclusion: Towards a Smarter Site with Simplified Surveying

• FAQ

Challenges in Traditional Construction Layout

In recent years, the construction industry has promoted the use of ICT and construction DX (digital transformation); however, surveying work and construction layout on site still require substantial time and effort. With an aging workforce and growing labor shortages, maintaining and improving productivity with limited personnel has become a major challenge.

Surveying technology itself has also evolved. Whereas total stations and standalone GPS positioning were once mainstream, high-precision positioning with RTK-GNSS and drone surveying have been spreading on sites in recent years. Among these, RTK-GNSS, which can provide centimeter-level (cm level accuracy (half-inch accuracy)) precision, is becoming an indispensable foundational technology for civil engineering construction management and as-built measurement. Recently, a new approach called "RTK AR," which fuses RTK and AR technologies, has emerged, ushering in an era in which high-precision surveying and intuitive AR visualization are possible with a single smartphone. By combining high-precision GNSS with site staff devices, surveying and design-verification tasks that previously required specialized equipment and advanced skills can be dramatically simplified.

In traditional construction layout work, skilled surveyors operated optical instruments such as total stations and, typically with multiple personnel, set up batter boards and scribed marks (reference marks) using wooden stakes. Because latitude/longitude and elevation at each point had to be observed one by one, the work required many people and much time, and the overall construction schedule often stalled while waiting for surveying due to weather or terrain conditions.

Furthermore, converting on-site survey results into drawings or compiling reports was an analog, manual process that was very labor-intensive. Construction personnel had to imagine the finished form from 2D drawings, which risked mistakes and rework due to misalignment in understanding. To eliminate these inefficiencies and enable smooth construction with limited personnel, a fundamental improvement in the efficiency of layout work is required.

What Is RTK AR? Overview of the New Technology

RTK AR is a new method that combines high-precision GNSS positioning "RTK (Real Time Kinematic)" and "AR (augmented reality)" to greatly improve construction management efficiency on site. This section explains the basics of RTK and AR and the effects created by merging the two.

RTK positioning (Real Time Kinematic): A technique that corrects GNSS satellite positioning errors in real time to determine positions with centimeter-level (cm level accuracy (half-inch accuracy)) precision. A base station (a receiver installed at a known point) and a rover (a receiver on site) observe satellite signals simultaneously; the error information obtained at the base station is sent to the rover sequentially, reducing typical meter-level positioning errors to around a few centimeters (a few in). Reports from national mapping agencies also show that RTK-GNSS dramatically improves accuracy compared to standalone positioning, and it is becoming a foundational technology essential for infrastructure surveying and machine control in civil engineering. Network RTK methods that obtain correction information via the internet (such as VRS) and CLAS (centimeter-class augmentation service) provided by Japan’s Quasi-Zenith Satellite System "Michibiki" make it increasingly possible to perform centimeter-level (cm level accuracy (half-inch accuracy)) positioning without installing a local base station. In recent years, the appearance of high-performance GNSS chips in smartphones and compact receivers with integrated antennas has made RTK positioning possible with palm-sized devices rather than dedicated equipment.

AR (Augmented Reality): A technology that overlays CG models, text, and other information on real-world imagery captured by a camera. Using a smartphone or tablet, you can synthesize 3D design models and instruction information into the view of the actual site, virtually extending the real space. AR use has begun in the construction field—for example, overlaying a 3D model of a planned building on site for stakeholder sharing, or displaying pipe routes behind walls on drawings to check for clashes during construction. Previously, site personnel had to infer the finished form from paper drawings, which could cause mistakes and rework due to differing interpretations; AR enables everyone to intuitively share the completed image, greatly improving communication efficiency and preventing errors.

New possibilities enabled by RTK × AR: By combining RTK’s high-precision positioning with AR’s visualization, site work gains advantages never before possible. The key point is that it enables stable AR displays based on absolute coordinates. Conventional smartphone AR required initial calibration (marker placement or plane recognition) to correctly align the real view and CG, and models would gradually drift due to camera tracking errors as the user moved. However, if AR is displayed while continuously obtaining centimeter-level positioning from RTK-GNSS, virtual models can be placed directly in a geodetic coordinate system, so they won’t shift relative to the real world when the user moves. This eliminates tedious alignment work: simply selecting the design data in the app immediately displays the model in its correct on-site position. For example, even for a structure placed within dense vegetation with poor visibility, RTK AR can pinpoint and visualize the installation location so that the exact stake placement is clear at a glance. RTK also allows high-precision correction of the device’s orientation, so the model’s position and orientation remain stable and accurate even when the user walks around and views it from various angles.

Using RTK AR makes it possible to seamlessly link design data and on-site surveying information. Because the coordinates on drawings or CAD (e.g., public coordinate system XYH) match the on-site coordinates obtained by RTK AR, you can accurately overlay digital design models onto the real space without complex coordinate transformations or on-site calibration. With consistent data from surveying through design and construction, on-site inspections and instruction become dramatically more efficient.

Benefits of Introducing RTK AR for Construction Layout Efficiency

Using RTK AR not only dramatically streamlines traditional time-consuming construction layout work but also brings multiple benefits such as enhanced safety and cost savings. The main points are summarized below.

• Labor reduction and improved work efficiency: By introducing RTK AR, surveying and positioning tasks that traditionally required multiple people can be done by a single person. The combination of high-precision positioning and AR reduces rework and simplifies setup, dramatically cutting the man-hours required for surveying and construction management. Interruptions to construction caused by waiting for surveying are also reduced, allowing smoother overall site progress. Even sites with few personnel can more easily maintain productivity, contributing to work-style reform.

• Intuitive, simple operation: Operations that were once difficult with surveying equipment can now be performed intuitively via a smartphone app. Visual guidance through AR allows accurate position checks and measurements even by non-experts. Reducing dependence on veteran staff makes it manageable for younger workers, easing the burden on technicians and aiding skill transfer.

• Real-time on-site verification: Because design models and measurement data can be displayed in AR immediately on site, rapid verification and decision-making can occur on the spot. Small deviations in as-built conditions discovered during construction can be corrected immediately, and progress can be shared among stakeholders in real time. Data can be synchronized between the field and the office via the cloud, enabling remote monitoring and instruction and smoothing communication.

• Cost reduction: You do not need to invest in expensive dedicated surveying equipment; a smartphone combined with a compact GNSS receiver suffices, significantly reducing equipment costs. Paper drawings and forms can be digitized and reduced, and a single device can serve as an all-purpose surveying tool, lowering rental and outsourced surveying costs.

• Improved safety: AR enables non-contact surveying and instruction, reducing risks in hazardous locations such as heights and slopes. For example, coordinates of a slope can be obtained by pointing a camera from a safe distance, reducing the number of workers required and lowering the risk of collisions with heavy machinery.

• Data utilization and promotion of construction DX: Position data and photos obtained with RTK AR can all be saved and shared as digital data and used directly for comparison with 3D design models or for creating as-built documentation. This reduces transcription to paper drawings and reports and allows centralized information management, greatly advancing on-site digitalization (construction DX). It also aligns with the Ministry of Land, Infrastructure, Transport and Tourism’s *i-Construction* initiative and may qualify for subsidy projects in some cases.

On-Site Use Cases of RTK AR

Streamlining stake-driving and scribing tasks: RTK AR greatly simplifies layout tasks such as stake-driving and scribing during construction. Because design positions on drawings can be displayed directly over the site camera feed in AR, workers can accurately set stakes or draw lines by following virtual markers shown on the smartphone screen. This eliminates the time-consuming setup of batter boards and string lines and enables intuitive, unambiguous instructions without relying on experience. Displaying virtual batter boards or string-line planes (reference elevation planes) in AR makes height references—which previously required reading numbers—immediately apparent. For example, if an AR virtual plane shows the designed excavation bottom elevation before digging, the operator can intuitively understand how far to excavate. Eliminating the need for physical stakes or strings reduces labor and speeds up the work.

Use in as-built management (quality inspection): RTK AR is also effective for as-built management after construction. Traditionally, a survey team measured the site after construction and compared elevation data to drawings, but RTK AR allows immediate on-site verification. For instance, after paving or embankment work, you can use a smartphone’s 3D scanning or surveying functions to capture surface shape data and automatically generate a heat map that color-codes deviations when compared with the design model in the cloud. Displaying that heat map in AR on site makes it easy to see where the surface is higher or lower than designed. What used to require searching through paper drawings and numbers to find defects can now be identified instantly by viewing colored visual information in AR, enabling immediate corrective cutting or filling. Visualizing quality on site while inspecting saves considerable time and effort in confirming as-built conditions.

Consensus-building through AR visualization of design data: AR is powerful as a communication tool on site. Projecting a design model at 1:1 scale on the actual site via a smartphone or tablet helps stakeholders intuitively grasp spatial relationships that are difficult to understand from drawings alone. For example, overlaying models of building columns, beams, or installed equipment on site allows prechecking of temporary enclosures and interactions with existing structures. During erection planning, you can check crane swing ranges and potential interference with material storage areas in AR. If construction staff and designers view the same AR model on site during meetings, it becomes easier to share design intent that is hard to convey on drawings, preventing mistakes and misunderstandings that lead to rework.

Other applications: RTK AR can also be applied to tasks such as confirming parcel boundaries for land surveys and locating underground buried objects. If known boundary point coordinates are pre-registered, the boundary line can be displayed in AR as a virtual fence on site, allowing all participants in a site meeting to instantly share “where the property begins and ends.” Displaying the routes of buried pipes and cables in AR helps intuitively identify obstacles before excavation, supporting safer and more efficient construction planning. In these and many other scenarios, RTK AR is expected to improve both productivity and safety on site.

There are real examples where RTK AR introduction has led to smoother consensus-building. For instance, one municipality used RTK AR during land acquisition explanation meetings. The official loaded planned boundary line coordinates into a tablet and displayed them to landowners on site in AR; as a result, attendees could immediately understand “how far the road will extend,” and consensus was reached more smoothly than when using stakes and drawings alone. The AR visualization increased stakeholder understanding and enabled quicker agreement—an exemplary case.

Conclusion: Towards a Smarter Site with Simplified Surveying

RTK AR is an innovative technology that can dramatically improve productivity for on-site tasks, including construction layout. By bringing high-precision positioning and visual information sharing to the field, it addresses challenges such as labor shortages and inefficiencies, contributing to both quality assurance and shorter schedules. It is also expected to serve as a trump card in realizing on-site digital transformation (DX).

Today, solutions that enable anyone to easily implement RTK AR using a smartphone are available. One such solution is our own LRTK. By introducing LRTK, your smartphone can become a surveying device with centimeter-level (cm level accuracy (half-inch accuracy)) precision, and AR-based intuitive visualization makes positioning and as-built verification simple. Please visit the [LRTK official site](https://www.lrtk.lefixea.com/) for details and consider incorporating simplified surveying with cutting-edge RTK AR technology on your sites. You should be able to achieve smart site operations that balance accuracy and efficiency.

FAQ

Q: What is RTK AR? A: It is a technology that combines centimeter-level (cm level accuracy (half-inch accuracy)) positioning via RTK-GNSS with AR (augmented reality) display to accurately overlay design data on the real site. By using high-precision position information to project lines and models from drawings onto the real space, it streamlines traditional surveying and scribing tasks and enables intuitive construction management.

Q: What is required to introduce RTK AR? A: Basically, a smartphone or tablet, a compact RTK receiver that supports high-precision GNSS, and a dedicated app to link them are required. An internet connection to obtain correction data for the receiver (or use of augmentation signals from the Quasi-Zenith Satellite System) is also needed. With this setup, anyone can use RTK AR with their own device.

Q: How accurate is the positioning? A: With RTK-GNSS, errors can be reduced to a few centimeters (a few in). While standard GPS positioning can have meter-level errors, RTK’s corrections from a base station achieve accuracy suitable for civil engineering construction. In appropriate conditions, positioning can match the accuracy of conventional optical surveying equipment.

Q: Can it be used in mountainous areas without network coverage? A: Network RTK requires communication, but even in areas with poor connectivity, devices that support satellite augmentation signals like CLAS from Michibiki can achieve centimeter-level (cm level accuracy (half-inch accuracy)) positioning without internet connectivity. Alternatively, a local RTK setup using a pre-installed base station (base & rover) enables RTK AR operation in areas where communication is unavailable.

Q: How much efficiency improvement can be expected on site? A: It depends on the site and tasks, but there are cases where time spent on scribing has been reduced to less than half of previous durations. Reports indicate reduced schedule loss from waiting for surveys and drastically fewer reworks, so overall surveying and as-built verification man-hours can be greatly reduced. Effects on safety and quality assurance are also significant, leading to improved overall on-site productivity.

Q: Are professional surveying qualifications or long-term training required? A: Operating RTK AR itself does not require special national certifications. Basic equipment operation is straightforward, and with simple pre-training, site staff can handle it. However, when submitting public surveying results as official deliverables, traditional qualified surveyors must oversee the work as before. RTK AR is a tool to support everyday construction management and enables non-experts to participate in surveying and inspection tasks, contributing to overall site productivity.