One-person Layout Marking: Improving Work Efficiency with AR Guidance and High-Precision Positioning

Layout marking (setting out), indispensable on construction sites, is the important task of indicating reference lines and positions on site so that structures are built according to the design drawings. However, traditionally this layout marking required multiple people and considerable effort, relied heavily on the intuition and experience of skilled workers, and if mistakes occurred they could affect the entire project. If layout marking could be done accurately and quickly by a single person, productivity could be greatly improved even on sites suffering from labor shortages.

In this article, we introduce how to efficiently carry out layout marking alone by leveraging the latest technologies: high-precision positioning (RTK-GNSS) and AR (augmented reality) guidance. From the challenges of conventional methods, the mechanism of high-precision positioning, the role of AR guidance that supports solo work, concrete on-site use scenarios, to the effects on standardization, labor reduction, and error reduction produced by these technologies, we explain from the perspective of field practitioners.

The importance of layout marking and the challenges of conventional methods

In building and civil engineering work, layout marking is the process of reflecting the positions and shapes of buildings and structures shown on design drawings onto the actual site, and displaying the reference lines and points. Marks made during layout marking—such as lines indicating the edges of foundations, centerlines for columns and beams, and reference heights for finishes—serve directly as construction guides. Naturally, the accuracy of layout marking determines construction quality; even a slight deviation can lead to rework in later stages or distortions of the entire structure. Therefore, experienced surveyors meticulously check their work, but conventional methods had several problems.

The first challenge is that it requires manpower and time. For example, when laying out the building footprint, a surveyor reads offsets from drawings and uses tape measures or a total station to mark the site. This process requires at least two people: an instrument operator and a staff member holding a leveling rod or prism at a distance. Depending on the situation, an assistant to mark the layout points may also be needed, making it a two- to three-person task. Setting up tripods and instruments, repeatedly walking back and forth to confirm positions—these steps are cumbersome, and even marking a single point can be time-consuming. When there are many survey points, it is not uncommon for the work to take an entire day.

The second challenge is the dependence on skilled techniques and the risk of human error. Layout marking involves reading reference dimensions from drawings, measuring dimensions on site, and drawing lines; much of this process relies on the human hand and eye, so less experienced workers are prone to misreading or measurement mistakes. Even a small misread number can shift a reference line and lead to construction errors. In practice, many steps depended on the intuition and experience of veterans and tended to be subjective. Moreover, simply marking points on site does not always allow sufficient cross-checking with the drawings at that moment, and sometimes errors are discovered only after comparing with the plans later, causing rework. Under conventional methods, a single mistake can lead to significant loss, posing concerns for quality control.

The third challenge is chronic labor shortages and reduced work efficiency. The construction and civil engineering industries face aging skilled workers and a shortage of young talent, making it difficult to secure personnel capable of layout marking. Performing multi-person layout marking with limited staff is a heavy burden and constrains the overall site schedule. For example, if a surveyor is assigned to multiple sites, work can be temporarily halted while waiting for “layout marking.” With the need for efficiency, conventional layout marking methods have significant room for improvement in terms of manpower and time.

How high-precision positioning (RTK-GNSS) enables solo work

The key to performing layout marking alone is accurate positioning technology. Conventional GPS produces errors of several meters and is unusable for construction surveying. However, the increasingly common RTK-GNSS (Real-Time Kinematic Global Navigation Satellite System) technology enables high-precision positioning with errors on the order of centimeters. RTK-GNSS uses both a base station installed at a known location and a rover used while moving to receive GNSS satellite signals; the base station captures error information and sends real-time corrections to the rover. As a result, current position can be determined with planar accuracy of about 2–3 cm and vertical accuracy of about 3–4 cm, achieving positioning performance comparable to conventional surveying instruments.

By using RTK technology, layout marking can be completed by a single person. If a worker holding a receiver can measure their own standing position with high precision, they can go directly to the coordinates on the drawing and indicate the point on site. For example, if the coordinates of column locations or structural reference points are known, a single worker can walk to those coordinates and mark the specified points to complete the layout. There is no need to set up tripods and measure angles each time like with a total station, or call out adjustments to a partner. Even when measuring multiple distant points on a large site, there is no need to repeatedly set up equipment and the worker can simply walk around with the rover, enabling significant efficiency gains in surveying and layout marking. Because RTK can position even in locations that are in the shadow of obstacles as long as radio signals are available, layout marking in previously hard-to-see locations becomes easier.

To achieve high-precision positioning, a good GNSS signal reception environment and a means of receiving correction information from a base station are necessary. In Japan, network RTK services using electronic reference stations and centimeter-level positioning augmentation services (CLAS) provided by the quasi-zenith satellite "Michibiki" are making stable correction information available even in mountainous or previously out-of-coverage areas. By leveraging these services, high-precision positioning based on public coordinate systems can be achieved without installing a dedicated base station on site. In addition, compact RTK-GNSS receivers that can attach to smartphones have recently appeared, enabling centimeter-level positioning with the convenience of carrying a phone. With these advances, layout surveying that once required specialized equipment and experienced operators is becoming a measurement technology that anyone can handle easily.

The role of AR guidance and its impact on work efficiency

Even if each worker can obtain accurate coordinates with high-precision positioning, site work will not be sufficiently efficient without a system that allows those coordinates to be intuitively understood. This is where the power of AR (augmented reality) guidance comes in. When viewing the site through a smartphone or tablet camera, design lines and pile positions can be overlaid on the screen as virtual objects—this is the concept of AR-based work guidance. For example, if a point corresponds to a building corner on the design drawing, a virtual pin or glowing marker will appear at that point on the phone screen. The worker moves their position or changes orientation slightly to find the point where the AR marker overlaps the ground at the intended location, and then marks that spot. Tasks that once relied on guessing by comparing paper drawings and the ground—"this area should be the design position..."—are transformed into actions where accurate position confirmation is done by simply looking at the screen.

AR guidance leads to major efficiency improvements and error reduction in layout marking. Because workers can visually align positions intuitively, measurement mistakes and misreads leading to rework are reduced. Even beginners can accurately mark points by following instructions on the phone screen without needing advanced surveying knowledge. AR apps track and display positions in real time, so a lone worker can proceed from one target point to the next without getting lost. Tasks that conventionally required two workers to call out "move a bit more that way" or "mark that spot" can be carried out by following the on-screen guide. Moreover, because the design lines and virtual stakes displayed in AR are always based on accurate coordinates, work can progress without physically stretching string lines or chalk lines. If needed, workers can leave physical marks only at key points and continue with the work while relying on the on-screen lines. Using AR guidance enables solo layout marking that is fast and reliable. Additionally, because design information and site conditions can be constantly cross-checked on the screen, discrepancies with the design can be detected and corrected on site immediately, helping to prevent rework.

Practical on-site use scenarios

Below are concrete examples of how site work changes when AR guidance and high-precision positioning are combined.

• Pile-driving tasks: For marking baseline lines and pile-driving locations, craftsmen traditionally walked the site and coordinated with surveyors, marking the ground with wooden stakes or chalk. With RTK×AR technology, simply pointing a device at the location corresponding to a pile on the design drawing displays a virtual pile or marker on the screen. Using that as a reference, actual piles can be driven in place; even when physical piles cannot be driven due to rock or steep slopes, the exact position can be indicated virtually. When there are multiple pile points, the worker’s device will display the next design location as they move, allowing a single person to sequentially indicate pile positions.

• Foundation layout: AR guidance is also powerful for marking the building outline and foundation positions. Normally, measurements from drawings are used to chalk lines or stretch string to show the foundation shape, but this method risks measurement errors and resulting deviations. By loading a building’s design data (plan lines) into an AR-capable device, the foundation outline can be virtually displayed on the ground simply by pointing the camera. The worker then marks key points along that line to complete accurate layout marking. A single person can thus lay out the precise exterior line of a building, preventing rework due to foundation misalignment and enabling smooth start of later tasks.

• Setting property boundaries: Before starting work, it is necessary to clearly show site boundaries, but when existing boundary stakes are unclear, surveying takes time. If boundary point coordinates obtained with RTK-GNSS are imported into an AR app, cadastral boundary lines can be virtually displayed on site. The boundary appears as a glowing line on the phone screen, making it immediately clear "where the site begins and ends." Workers can mark required points along the on-screen line, greatly reducing the effort of stretching ropes. When confirming boundary positions with surrounding stakeholders, overlaying the line on the actual landscape helps avoid misunderstandings and smooths consensus building.

Contributions to standardization, labor reduction, and error reduction in layout marking

By incorporating high-precision positioning and AR guidance, the following effects can be expected for layout marking tasks:

• Standardization: With digital design data and positioning systems, everyone can perform layout marking using the same procedures, enabling leveling of work quality. Results are less likely to vary between veterans and newcomers, transforming subjective tasks into highly repeatable processes. Because reliance on paper-drawing-reading skills and experience is reduced, site-to-site variability decreases and consistent accuracy is maintained. In addition, coordinates and records of layout points are stored as data, making it easy for third parties to verify or for other workers to take over. This promotes standardization and information sharing in layout marking and improves the reliability of construction management.

• Labor reduction: If layout marking can be completed by one person, the assistants formerly required can be redeployed to other tasks. In extreme cases, with one device per person, each worker can autonomously perform layout marking, eliminating wasted time spent waiting for someone to be available. Even on sites where survey queues used to form due to staff shortages, marking can be done immediately when needed, improving overall efficiency. There are cases where layout marking that used to take three people 20 minutes was completed by one person in 10 minutes; individual work capability has led to significant labor-hour reductions, shorter schedules, and cost savings. Labor reduction contributes not only to lower personnel costs but also to creating flexible site operations that can run with fewer people.

• Error reduction: With fewer human-involved operations such as reading survey values or marking, human error decreases. AR enables immediate detection of deviations from the design on site, preventing rework and corrections. Traditionally, marks made on site were checked against drawings back at the office, and if discrepancies were found, the site had to be revisited for corrections. AR guidance greatly increases the likelihood of correct placement on the first try. Reducing errors improves quality and shortens schedules, and also reduces site stress and waste.

Recommendation for simplified surveying with LRTK

Finally, as an example of a concrete solution that enables solo surveying and layout marking introduced above, we present LRTK. LRTK is an all-in-one surveying system consisting of a compact RTK-GNSS receiver that can be attached to a smartphone and a dedicated app. With a receiver weighing only about 125 g attached to a smartphone, centimeter-level positioning, point recording, layout marking, and even point cloud measurement and AR-based overlay of completed images are covered—providing nearly all the surveying and measurement functions needed on site. No specialized operation is required: tap a button on the smartphone screen at the point you want to measure to instantly record coordinates, and follow the displayed AR guide to reach pile-driving or as-built verification points without getting lost. Measurement data can be shared with stakeholders via the cloud, smoothing coordination between the site and the office.

LRTK’s concept is to make it “measurable by anyone, anywhere, immediately,” aiming to simplify surveying and layout marking as routine tasks. For example, not only veteran technicians but also young site managers or heavy equipment operators can take a device from their pocket and measure necessary dimensions or check reference lines on the spot. In sites where LRTK has been introduced, there are reports such as, "Work that used to stop while waiting for the survey team can now be measured on the spot by a single person, leading to significant time savings." Utilizing such simplified surveying tools that combine high-precision GNSS and AR changes the conventional ways of layout marking and directly leads to productivity improvements and labor savings on site. As a new option to respond to an era of labor shortage, it is well worth considering introduction to your site.