Construction Management Transformed! Overlay 3D Drawings on Site with Absolute-Coordinate AR

As digital technologies are increasingly used on construction sites, techniques that overlay 3D drawings onto the site using AR (augmented reality) are attracting attention. In addition, tailwinds for construction DX such as i-Construction promoted by the Ministry of Land, Infrastructure, Transport and Tourism are further raising expectations for on-site digitalization. By using AR, a three-dimensional model representing the finished image can be projected on site, which is expected to reduce construction errors and improve progress-management efficiency.

However, conventional AR usage had several challenges. It is difficult to imagine the finished form from paper drawings alone, and on site there were many occasions that relied on the intuition of experienced personnel.

• Manual alignment (calibration) was required for initial setup

• The model's displayed position drifts over time and with movement

• It cannot adequately meet the accuracy required on civil engineering and construction sites

The key to solving these problems is absolute-coordinate AR that leverages high-precision positioning technology RTK (Real-Time Kinematic). Because RTK enables displaying 3D models while correcting the device's position to centimeter-level accuracy (half-inch accuracy), the model can be anchored at an accurate position without prior reference alignment. Even when users move around the site, the model continues to be displayed without shifting, enabling a stable AR overlay that supports construction management.

This article explains the transformation that overlaying 3D drawings using absolute-coordinate AR brings to construction management, and introduces practical use cases and key points for implementation.

⒈ What does overlaying 3D drawings with absolute-coordinate AR mean? ⒉ Overview and benefits of 3D drawing overlay achieved with absolute-coordinate AR ⒊ Use cases for 3D drawing AR overlay ⒋ Challenges and countermeasures in implementation ⒌ The future of AR use in construction sites ⒍ Summary ⒎ FAQ

What does it mean to overlay a 3D drawing using absolute-coordinate AR?

With conventional AR technology, markers had to be placed or manual alignment (reference alignment) performed each time in order to overlay drawings or models on-site. This approach caused problems such as 3D models drifting over time and the alignment process being time-consuming.

On the other hand, absolute-coordinate AR is a method of rendering AR based on a pre-defined coordinate system (for example, a public coordinate system used in surveying). By improving GNSS (satellite positioning) accuracy with RTK—ordinary GPS typically has errors of several meters (several ft), but RTK can reduce them to a few centimeters (a few in)—and by determining the device's position to the centimeter level (cm (in)), a digital 3D model can be fixed at the correct position in physical space. As a result, without performing calibration, the model is always displayed at the position that matches the real object and remains fixed in place even when the user moves. Absolute-coordinate AR has made it possible to overlay 3D drawings on site without error.

Benefits of Absolute Coordinate AR for Construction Management

Absolute-coordinate AR brings the following benefits to construction site management.

• Reduction of construction errors: By projecting drawing data onto the actual site for verification, dimensional errors and positional misalignments can be detected and prevented in advance. This reduces rework and quality defects, preventing redo work and additional costs.

• Improved efficiency in progress and quality management: By comparing the as-built condition of structures on site with 3D models, progress and finishing accuracy can be understood immediately. Because it allows intuitive on-site verification and correction—not just records from surveys or photos—process management becomes smoother. It also reduces the need for supervisors to run around for sequential checks, easing the burden of management tasks.

• Smoother consensus-building: AR visualization is also effective for communication with clients and on-site staff. Because it enables sharing the finished image and showing design intent on the spot, explanations and meetings become faster and misunderstandings that lead to trouble are reduced. For example, during site walkthroughs the client (owner) can confirm while viewing the actual work, which helps provide reassurance.

• Enhanced safety management: Because AR can visualize unseen hazards and construction risks in advance, it contributes to accident prevention. For example, knowing the location of buried pipes reduces the risk of accidental damage, demonstrating effectiveness for safety.

• Labor savings in surveying and marking tasks: Because baseline lines and design models can be displayed in AR, the effort for marking and positioning traditionally performed by skilled surveyors can be reduced. Working according to a digital guide shortens task time and reduces personnel burden. As a result, it also reduces surveyors' workload and labor costs.

Use Cases for AR Overlay of 3D Drawings

So, in what specific situations can AR overlay of 3D drawings be utilized? Below are the main use cases.

• Pre-construction design check: Before starting construction, display the 3D design model on-site in AR to confirm whether construction can proceed as designed. For example, you can verify in advance whether the building’s placement and height match the surroundings, and if issues are found, revise the plan before construction begins. This allows potential construction errors to be nipped in the bud.

• Accuracy verification during construction: At intermediate stages of construction, check in real time whether the structure under construction matches the design data. Compare the positions of formwork and the installation status of steel frames with the AR model, and correct any discrepancies immediately. For example, before concrete placement, you can compare the design model with the on-site formwork and correct position or height deviations on the spot. Because corrections can be made immediately, rework is minimized.

• Infrastructure inspection and maintenance: For completed bridges, roads, and the like, overlay past inspection data and 3D models on-site to visually grasp deterioration and displacement. You can compare aging changes at a glance, which helps in planning repairs and in safety management. Tasks that previously required comparing drawings and photos become immediately clear with AR.

• Underground buried asset location confirmation: Visualize the positions of underground pipes and cables in AR to prevent accidental damage during excavation. By projecting the position data of buried objects obtained from exploratory digging and the pipeline routes from drawings onto the site, workers can accurately identify unseen obstacles. Excavation can proceed with greater confidence, improving safety.

• Sharing the finished image: Present exterior landscaping or post-renovation images to clients and stakeholders using AR. By overlaying a predicted 3D model of the finished product onto the actual site or interior, people can realistically experience the completed image, increasing the persuasiveness of proposals and meetings. Consensus building becomes smoother, and proposing plan changes becomes easier.

Implementation Challenges and Countermeasures

When introducing AR overlay, several challenges can be anticipated. However, they can be overcome with appropriate measures.

• Preparation for high-precision positioning: An RTK positioning environment is indispensable for absolute-coordinate AR. However, high-precision GNSS receivers that can be attached to smartphones have become widespread, making it easy to achieve centimeter-level accuracy (half-inch accuracy) even without dedicated equipment.

• Preparation of 3D design data: AR displays require 3D models or digitized drawing data. In recent years, the use of BIM/CIM has advanced, and three-dimensional data have been prepared in many projects. Even when only 2D drawings are available, creating a simple 3D model or scaling on site can in some cases address the issue. Note that the coordinate system of the design model needs to be aligned with the field surveying coordinates, but modern CAD/BIM software can handle that easily.

• Familiarization of field staff: Staff may feel confused by new technology, but if they are accustomed to using smartphones it is not difficult. Intuitive UIs are designed so that anyone can master them after a short training session. In fact, there have been comments that "it was easier than traditional surveying instruments," and adoption on site is proceeding smoothly.

• Concerns about implementation costs: You may worry that cutting-edge systems are expensive. However, if AR overlay is implemented on a smartphone basis, it can be introduced relatively inexpensively compared to traditional surveying instruments. Above all, considering the reduction in rework due to fewer construction errors, benefits that exceed the cost can be expected.

The Future of AR Use on Construction Sites

The use of AR in the construction industry is expected to expand further in the future. Currently, use is centered on tablets and smartphones, but workers may eventually wear dust- and water-resistant AR glasses (eyewear-type devices) and be able to check AR information hands-free while working. The information displayed in AR will not be limited to design models; a variety of data such as measured data from sensors and AI-driven automatic detection results will likely be provided in real time. For example, AI could check the placement of rebar from camera footage and highlight on the spot areas that differ from the design. A future in which the site's entire "digital twin" is shared in real time can also be envisioned.

Also, in the construction industry, where chronic labor shortages and responses to work-style reforms are ongoing challenges, AR can become a trump card for labor-saving and skill transfer. Because drawing information packed with veterans' know-how can be shared on-site by anyone, even less experienced workers will be able to proceed without errors. Active use of such digital technologies contributes to improved productivity and is also expected as a countermeasure to the so-called "2024 problem." In the near future, on-site overlaying of 3D drawings with AR may cease to be a special cutting-edge case and become an everyday sight.

That said, even without waiting for that future, solutions already usable in the field have emerged. The LRTK introduced next is one of the tools that quickly realizes the advantages of such absolute-coordinate AR.

Easy AR overlay using simple surveying with LRTK

A solution that makes such absolute-coordinate AR easy to realize on-site is LRTK. LRTK consists of a high-precision RTK-GNSS receiver and an AR app for smartphones, and by simply attaching a dedicated device to a smartphone, anyone can achieve centimeter-level positioning and AR display (cm level accuracy, half-inch accuracy). Also, if design data is pre-registered to the LRTK Cloud, it can be immediately retrieved from the on-site app and displayed in AR. Unlike other AR systems, there is no need to place markers or perform complex initial calibration; you can bring it to the site and instantly project 3D drawings.

LRTK is a rare, domestically available smartphone-compatible absolute-coordinate AR tool designed so that people without surveying expertise can use it. The compact, lightweight device can be carried in a pouch and operated intuitively with one hand, dramatically streamlining on-site surveying and verification work. Of course, it employs the latest technology compatible with i-Construction (ICT construction) promoted by the Ministry of Land, Infrastructure, Transport and Tourism, and deployment has already begun at various civil engineering and construction sites.

• AR display with centimeter-level accuracy (half-inch accuracy) using RTK positioning

• No cumbersome on-site alignment required

• Supports a wide range of applications such as construction management, surveying, and inspections

• Cloud integration enables smooth data sharing

With these features, LRTK brings a major advancement in on-site management, which has traditionally depended on experience and intuition, moving it toward data-driven "visualization".

For example, in revetment construction, overlaying the design model on the embankment under construction to check the as-built (final shape) contributed to speeding up as-built management and preventing rework. In road construction, displaying the planned road geometry on site with AR and confirming the finish in advance leads to more efficient final inspections.

Furthermore, the high-precision data obtained through simplified surveying using LRTK can be shared internally or used for electronic delivery as-is. By directly linking digital systems with on-site operations, the quality and speed of construction management will improve dramatically. Please take advantage of cutting-edge AR technology to help boost productivity on site.

Summary

The technology that overlays 3D drawings onto job sites using AR is poised to bring a major transformation to construction management. High-precision model display through absolute-coordinate AR is already helping reduce mistakes and improve operational efficiency, and some sites have reported improved safety and productivity compared with traditional methods. A future in which AR technology becomes commonplace is just around the corner. As adoption continues to accelerate, adopting these technologies early will directly contribute to increased competitiveness. Be sure to leverage easy solutions like LRTK and experience cutting-edge AR construction management on your own sites. Take the step you can now toward the construction sites of the future.

FAQ

Q: What is absolute coordinate AR?

A: Absolute-coordinate AR is an AR technology that displays virtual models based on a shared reference coordinate system. While typical AR places objects relative to the camera image, absolute-coordinate AR aligns 3D models by linking them to real-world latitude, longitude, and height. A key feature is that once a model is set, it remains at its actual position without shifting due to user movement or the passage of time.

Q: What is needed to overlay 3D drawings in AR?

A: Basically, you need a device such as a smartphone or tablet combined with a high-performance GNSS receiver (RTK-capable) and 3D design data for overlay display. Specifically, prepare a GNSS terminal (or a correction information service) capable of centimeter-level positioning (cm level accuracy; half-inch accuracy), a smartphone that runs the AR app, and the design’s 3D model data (or CAD drawing data). With these in place, you can achieve AR displays on-site that faithfully reproduce the design model.

Q: How accurate is AR overlay?

When using RTK positioning, errors are generally limited to the order of a few centimeters (a few in). Under favorable conditions, horizontal positions can achieve 2–3 cm (0.8–1.2 in) accuracy, and vertical accuracy can be below 5 cm (below 2.0 in), which sets it apart from typical standalone positioning (errors of several meters (several ft)). However, it should be noted that GNSS signal reception can be affected by the surrounding environment, but the accuracy is sufficient for general construction quality control.

Q: Is any specialized knowledge or technical skill required?

A: No. The AR overlay system is intuitively designed so that anyone on site can use it. If you can perform basic smartphone or tablet operations, you only need to follow the on‑screen prompts to display the model. It can be mastered with a short training session, and complex surveying calculations or programming knowledge are not required. Because it is far easier to understand than traditional drawing checks, on‑site adoption should be straightforward.

Q: Can it be used indoors or in tunnels where GNSS does not reach?

A: Because satellite signals cannot be received indoors or inside tunnels, absolute-coordinate AR using RTK is difficult to use as-is. However, techniques are also being researched that achieve similarly high-precision alignment by placing AR markers (printed markers) corresponding to reference points that were surveyed in advance and having the camera recognize them. Currently, use is mainly outdoors, but in the future AR overlays should be usable in all kinds of environments.

Q: Do the benefits justify the implementation cost?

A: Introducing absolute-coordinate AR brings benefits such as reduced construction errors and improved work efficiency. In particular, a method that combines a smartphone and a compact GNSS receiver keeps initial investment low and is less expensive than conventional large surveying instruments. Considering the costs saved by preventing rework and shortening construction time, it can be said to be a sufficiently cost-effective technology.

Q: Can it be used without 3D model design data?

A: Yes — you can make limited use of AR overlaying even without a 3D model. For example, LRTK can project 2D CAD drawings (plan views) directly onto the site. However, to review things in three dimensions it is desirable to prepare a 3D model, even a simple one, and, as needed, methods such as converting existing drawings into 3D or acquiring point clouds of the current conditions via photogrammetry or laser scanning and modeling from them are also used.

Q: Can it be used at sites without an internet connection?

RTK positioning requires receiving correction information, and in many cases connects to a network RTK service via mobile (cellular) communications. Therefore, an environment where the site can connect to the Internet (cellular communication) is generally required. However, in out-of-coverage mountainous areas, it is possible to achieve high-precision positioning even without network coverage by installing your own base station in advance and transmitting correction data by radio.