What Is AR Construction Verification in the Era of 3D Construction? Experience the Future of Site Management with LRTK

Introduction: On-site challenges for construction verification and the shift to the 3D construction era

In construction and civil engineering sites, verification work has traditionally relied heavily on manpower and experience. The conventional approach—repeatedly surveying with drawings in hand and depending on the "intuition" of experienced workers to ensure quality—faces numerous issues such as labor shortages and human error. In fact, Japan's construction industry is confronting a declining workforce due to an aging and shrinking population, as well as the "3K" problem of "difficult, dirty, and dangerous," making productivity improvement a major theme. Against this backdrop, the Ministry of Land, Infrastructure, Transport and Tourism launched i-Construction in 2016, aiming to boost construction site productivity by 20% by fiscal year 2025 through the use of ICT technologies and three-dimensional data.

These policies have also given momentum to the rapid spread of construction methods based on three-dimensional data, also referred to as 3D construction. The practice of consistently using 3D design models typified by BIM/CIM from construction through maintenance has become established, and from fiscal 2023 onward the application of BIM/CIM has been made standard in directly managed projects, ushering in an era in which the use of 3D data is commonplace across all projects. Because designers, contractors, and clients can refer to a common 3D model, misreading drawings and miscommunication of design intent can be prevented, making fast consensus-building possible. The industry is truly undergoing a shift into the "era of 3D construction".

So, in this era of 3D construction, how will the crucial on-site construction verification evolve? New approaches using AR (augmented reality) technology are gaining attention as an alternative to the traditional reliance on 2D drawings and visual estimation. In this article, we explain what AR construction verification is, its core technologies and how it can be applied on-site, the benefits it provides, and the challenges involved in implementation. Let’s take a look at the real picture of the cutting-edge technologies that will support future construction management.

What is AR construction verification? Relationship with 3D construction and basic techniques

AR construction verification is a method used on site in which a smartphone or tablet is held up and 3D design data and construction information are overlaid onto the real-world scene seen through the camera to check construction status. In short, instead of paper drawings or 2D photos, a digital 3D model is projected onto the actual object on site so that you can intuitively understand "what should be built here and how" and "whether the finished work matches the design." This AR-based construction verification serves as a bridge to maximize on-site use of BIM/CIM and other data that have increased in the era of 3D construction.

For example, if you AR-display the finished 3D model of a structure on-site during construction, you can verify construction accuracy by directly comparing the real object with the virtual model. Parts that previously had to be imagined from plans and cross-sections become immediately clear with AR because a three-dimensional design model appears within the real scene. Elements that were difficult to inspect with the naked eye or a tape measure—such as rebar spacing and the location of buried pipes—can be cross-checked against the digital model to prevent oversights.

As the fundamental technologies for realizing AR construction verification, high-precision positioning techniques that accurately determine a device's position and orientation, and alignment techniques that match digital models to the physical space are important. Using the built-in sensors of smartphones and tablets (camera, gyroscope, LiDAR, etc.) and an AR app, it is possible to overlay virtual objects onto the real world itself, but arranging models accurately to centimeter-level precision requires additional measures. Traditionally, cumbersome initial calibration was necessary—placing markers on site for camera recognition or having operators manually position models to match reference points. However, recently systems have emerged that combine RTK-GNSS (high-precision GPS) to measure the device's coordinates with centimeter accuracy and automatically correct model positions. Thanks to these technologies, the digital model can align perfectly with the real object without troublesome on-site alignment work, bringing AR construction verification closer to practical use.

Use Cases of AR Construction Verification on 3D Construction Sites

How is AR construction verification actually being used on real building and civil engineering sites? Here we introduce typical use scenarios at sites where **3D construction** is advancing.

• Civil engineering works (heavy equipment operation and foundation installation): On large-scale land development and road construction sites, heavy equipment operators and construction managers have begun to use AR while holding a tablet. For example, during excavation and embankment work, operators can display the designed final terrain model in AR in front of the machine through the tablet, allowing them to constantly compare the current ground surface with the target height and slope while working. Even less experienced operators can perform excavation according to the design line without relying on intuition, reducing variability in as-built results. In addition, construction managers can visualize layout markings for foundations and the installation positions of structures with AR, enabling accurate positioning and installation even without the intuition of veterans. There have been reported cases in road and bridge construction where overlaying a 3D model on site allowed work to proceed with the accuracy specified in the design drawings.

• Infrastructure maintenance and management (inspection and repair): AR is being used in inspection work for infrastructure facilities such as railways, highways, and bridges. Even in maintenance sites where workers traditionally had to search for the actual object while holding drawings and past records, AR can overlay design drawings and inspection information onto the structure in front of them. For example, in bridge inspections, AR can superimpose bridge drawings and repair histories onto the real structure so that workers can instantly identify areas that require repair. If previously repaired crack locations are marked in AR, during the next inspection it becomes immediately clear "whether it is the same spot as before", helping prevent oversights. Moreover, displaying warning signs and procedural instructions in the worker’s field of view via AR helps prevent entry into hazardous areas and reduces human error. Thus, the use of AR in infrastructure maintenance significantly contributes to both streamlining inspections and improving safety.

• Surveying and pre-construction checks (stake setting / as-built verification): AR is a powerful tool even in the world of surveying technicians. For example, traditionally positioning structures required measuring reference points with a total station and driving stakes to mark the site, but with AR you can display virtual stakes and batter lines on site without surveying instruments. A person holding a tablet can walk the site and place AR markers at any chosen point indicating “drive a stake here,” dramatically reducing labor. Even on slopes or where obstacles exist, you can project virtual stakes to targeted points from a distance, so you can accurately position hazardous locations that cannot be physically accessed. Furthermore, you can overlay point cloud data of the existing terrain (3D-scanned survey data) with the design 3D model in AR to pre-verify whether the planned structure will fit the actual site topography. For example, some cloud services automatically align the existing point cloud and design data and provide a system that allows designers to easily check “can this be constructed as imagined?” By leveraging AR plus survey data in this way, improvements in construction planning accuracy and prevention of rework can be expected.

As described above, in the era of 3D construction, AR construction verification is beginning to be used in a variety of on-site situations. Its applications range widely, from large-scale projects by general contractors to municipal infrastructure maintenance and surveyors’ as-built inspections. In fact, there have been reports that Fukui City in Fukui Prefecture introduced a smartphone AR system for on-site surveying in disaster recovery, achieving early surveying of damaged areas and shortening recovery timelines, and it can be said that momentum for AR adoption is rising across the industry.

Benefits of AR Construction Verification: Labor Reduction, Error Prevention, Client Explanations, etc.

The reason AR construction verification is becoming more widespread is that it brings significant benefits to job sites. Here, we summarize the main advantages.

• Improving operational efficiency and addressing labor shortages: By utilizing AR, it becomes possible to achieve labor savings in construction verification and surveying. Positioning tasks that previously required multiple people can be checked by a single person holding a tablet, leading to reduced staffing. If sites can be inspected and instructed remotely via AR, the number of business trips can be reduced, and travel time can be cut. In fact, there have been reports that visualizing progress in real time with AR enabled early detection of schedule delays and optimization of personnel allocation. On sites facing severe labor shortages, AR is a valuable asset and is helping to usher in an era where, with "one smartphone per person," anyone can become a surveyor or supervisor.

• Error prevention and quality improvement: By carrying out construction while cross-checking against a digital design model, there is an effect of preventing human error before it occurs. Comparing the 3D model in AR with the actual object makes it easy to detect slight misalignments or omissions that would previously have been overlooked. For example, in rebar placement checks, you can immediately determine on site whether the number and spacing are correct, and if defects are found they can be corrected before concrete is poured. At one site, overlaying the drawing model during construction enabled early correction of construction defects, which was reported to have led to a significant reduction in rework and material waste. In this way, AR greatly contributes to streamlining quality inspections and preventing rework, and as a result improves productivity across the entire project.

• Easier explanation for clients and stakeholders: AR construction verification is also a powerful communication tool. Because all stakeholders—from clients and designers to site workers and nearby residents—can share the same vision of the finished result, it becomes easier to eliminate misunderstandings. For example, if you display a pre-completion structural model on-site in AR, clients and local residents can intuitively understand the finished appearance within the actual landscape, preventing mismatches like "this isn't what I expected." In on-site meetings using AR, a client can make concrete proposals on the spot—such as "could we make this a bit lower?"—and the construction team can immediately adjust the model, enabling two-way interaction. This shortens the time needed to reach agreement and reduces rework. Information that is hard to convey with drawings or text can be understood at a glance with full-scale AR visuals, which also reduces the burden of explanatory work.

• Safety and risk reduction: AR also contributes to on-site safety management. By highlighting hazardous areas in the camera view and displaying guided work procedures, it helps with raising awareness and preventing human error. In addition, if the positions of buried pipes and cables are displayed in AR before construction, the risk of accidental damage during excavation can be reduced. Because anyone can accurately know “what is buried where” for future works, this contributes to preventing unforeseen accidents and improving safety. As a result, AR plays a role in realizing a secure and safe working environment.

As described above, AR construction verification can be said to be "the trump card for on-site DX" that elevates every aspect of construction management. Because it offers multifaceted benefits—addressing labor shortages, ensuring quality, streamlining communication, and enhancing safety—its adoption is likely to accelerate going forward.

Challenges and Countermeasures for AR Adoption in 3D Construction

AR-based construction verification offers many benefits, but there are several challenges when it comes to actual implementation and operation. Here we explain the potential challenges and practical countermeasures.

• ① Accuracy and alignment challenges: To perform accurate construction verification with AR, the alignment accuracy between the digital model and the real site is critically important. With typical smartphone AR, GPS errors and sensor drift can cause the model to shift. To address this issue, the use of high‑precision positioning technologies (such as RTK‑GNSS) is effective. By using recently introduced L1/L5‑capable GNSS receivers and augmentation signals from quasi‑zenith satellites, centimeter‑level positioning becomes possible even on smartphones, allowing the model to consistently match the coordinates of the physical world. In practice, systems have been commercialized that combine a dedicated RTK device with a smartphone so that the design model snaps perfectly onto the actual terrain as soon as the app is launched. Using such technologies enables stable AR projections without positional offsets or drifting, greatly alleviating concerns about accuracy.

• ② Implementation costs and equipment challenges: When people think of using AR, they may imagine expensive AR glasses or specialized equipment. However, today it’s possible to carry out AR construction verification using just smartphones or tablets. The latest iPhone/iPad models are equipped with high-performance cameras and LiDAR and have sufficient processing power, making them fully practical as on-site AR platforms. In addition, various companies offer solutions that combine compact GNSS antennas with dedicated apps, allowing you to introduce AR on-site with an investment of around several hundred thousand yen. Compared to traditional surveying instruments, 3D scanners, or AR glasses, this is significantly lower-cost and more versatile. Because many site staff can use the smartphones they are already familiar with, training and education costs can also be kept down. In short, you can start AR construction verification simply by "smartly using the smartphones you already have".

• ③ Data preparation and operational challenges: As a prerequisite for AR construction verification, it is necessary to organize digital information such as 3D design data and point cloud data. On small- and medium-sized sites, there may be cases where “there is no 3D model to begin with.” In this regard, national policies promoting BIM/CIM have led to environments in which 3D models are becoming available for major infrastructure projects. Also, even for existing structures, it has become possible to easily obtain 3D point clouds using iPhone LiDAR or drone surveys. For example, using LRTK you can record point clouds with global coordinates simply by walking around a site with an iPhone, and you can then compare them with design models in the cloud. On the data management side, systems that integrate with cloud services are increasing, enabling workflows such as automatically uploading point clouds and photos captured on site and sharing them with the office. This is gradually reducing barriers such as “data is difficult to handle” and “sharing is a hassle.”

• ④ 現場への浸透・人材育成の課題：新しいデジタル技術を導入する際には、現場スタッフの抵抗感や習熟度も課題になります。特に年配の技術者ほど最初は戸惑うかもしれません。しかし、スマホやタブレットという馴染みあるデバイスで動作し、直感的な操作で使えるARアプリであれば受け入れられやすい傾向にあります。実際に一度AR施工確認を現場で試してみると、その分かりやすさから「これなら使える」「もっと現場に取り入れたい」と感じる方も多いようです。若手にとってはゲーム感覚で3Dモデルを扱えることもあり、新人の戦力化・デジタル人材育成にもつながるでしょう。さらに、AR活用によってベテランの勘や経験に頼らない標準化施工が可能となれば、属人的なノウハウを組織全体で共有しやすくなります。暗黙知だった職人技をデータやARマニュアルの形で蓄積すれば、世代交代が進む中でも技術継承がスムーズになります。導入初期は小規模な実証から始め、成功体験を現場にフィードバックすることで、徐々に現場全体へ浸透させていくのが現実的な対処法と言えます

Despite these challenges, advances in technology and growing on-site needs mean that solutions are becoming clearer. In particular, the combination of high-precision GNSS and smartphones has made AR construction verification something anyone can use by balancing accuracy and ease of use. The important thing is to start small, confirm the benefits, and scale up while gaining understanding both inside and outside the company. On-site DX won’t happen overnight, but since it clearly delivers value to the field, it can be regarded as a challenge that can be steadily overcome.

Summary: The future of construction management realized by 3D construction is here

From an era that relied on drawings and intuition to an era that leverages data and technology — construction management in the era of 3D construction is steadily evolving. A hallmark of this shift is the new method introduced in this article: AR construction verification. By using AR, on-site information can be "visualized" in real time and shared in a form that anyone can intuitively understand. This is a boon for construction sites struggling with labor shortages and dependence on skilled workers, and it will be the key to achieving quality assurance, efficiency, and safety all at once.

The important point is that this kind of future construction management is already right in front of us. AR construction verification is by no means science fiction; it is already being introduced at sites across the country. In the Ministry of Land, Infrastructure, Transport and Tourism’s i-Construction initiative, the technology of projecting 3D models and as-built data created during the construction phase onto the actual site via AR and using them to make pass/fail judgments is listed as a key focus for fiscal 2025. In other words, AR-based construction management is highly likely to become the new norm in the construction industry. Incorporating AR construction verification on-site at this time will also help strengthen competitiveness for the future.

In conclusion: With LRTK, AR construction verification and surveying can be completed on a smartphone

We have outlined the future vision of AR construction verification, and as a concrete solution to make that future a reality, we introduce LRTK. LRTK is a positioning device and cloud service developed by Reflexia, a venture company spun out of Tokyo Institute of Technology, which is used by attaching a compact RTK-GNSS antenna to a smartphone. When combined with the latest iPhone, a palm-sized smartphone transforms into an "all-purpose surveying instrument" capable of centimeter-level positioning and 3D scanning. By leveraging LRTK, precise surveying and point cloud acquisition—tasks that previously required expensive, specialized equipment—become accessible to anyone, and the captured data can be uploaded to the cloud and shared instantly.

What makes LRTK especially effective for AR construction verification is its ability to simply achieve the aforementioned "high-precision alignment." Because LRTK continuously and accurately tracks a smartphone's position and orientation, launching the app alone causes the 3D design model to align perfectly with the actual terrain. Even when users walk around the site, the model neither shifts nor floats, remaining stably displayed as if the structure were truly standing right before their eyes—a breathtaking sight. Enabling "AR projection without positional drift" without cumbersome initial calibration can be considered a revolutionary advance for using AR on-site.

Furthermore, LRTK offers an all-in-one suite of versatile functions that leverage high-precision positioning, ranging from point-cloud scans of the existing terrain and AR display of as-built heatmaps to overlaying design CAD drawings, coordinate-based stake-positioning/navigation, indoor positioning, and recording movement trajectories. All 11 of these functions can be completed with just an iPhone and LRTK, with no special equipment or large-scale systems required. As a solution that truly enables “both AR construction verification and surveying to be completed on a smartphone,” it powerfully supports the digital transformation of worksites.

LRTK has already begun to be adopted at many civil engineering construction sites, and its ease of use—"anyone can handle everything from surveying to AR verification with one smartphone per person"—has won support. As a cutting-edge i-Construction–compatible technology, it has been gaining visibility, drawing attention at Ministry of Land, Infrastructure, Transport and Tourism–hosted exhibitions and technical proposals. If you're interested in AR construction verification or smartphone surveying, please take a look at LRTK's official website and materials. The future of construction management is already in your hands. Why not use LRTK and your smartphone to take a new step on site starting tomorrow?