Secrets to Introducing As-built AR Checks: Practical Tips for Achieving Results on Site

Table of Contents

• What is an as-built AR check?

• Benefits of AR implementation

• Key implementation points to achieve results on site

• Use cases of AR as-built checks

• Challenges and countermeasures to consider when implementing AR

• Simple surveying and AR checks enabled by LRTK

• Frequently Asked Questions

What is an as-built AR check?

"Dekigata kanri" refers to a quality control process in civil and construction works that verifies whether completed structures and terrain have been constructed according to the design drawings. Traditionally, this as-built verification was commonly carried out using surveying instruments such as total stations (TS) and levels: measuring heights and thicknesses at individual points on site, then returning to the office to compare the drawings with the measurements and determine pass/fail. However, this method tended to create a time lag between measuring on site and discovering problems, causing rework: it was prone to a time lag between on-site measurement and problem discovery, which led to rework. Also, because accurate measurement and judgment require skilled surveyors and many tasks are performed by two-person teams, it has become an inefficient process in the face of labor shortages and an aging workforce, and construction sites have been demanding further efficiency.

In recent years, the technology attracting attention as a trump card to solve these challenges has been AR (Augmented Reality) technology. AR is a technology that overlays three-dimensional digital information (models, drawings, etc.) onto real-world imagery; it used to be a cutting-edge experiment, but improvements in the performance of smartphones and tablets have made it an era in which it can be used in everyday construction management. In particular, the latest smartphones and tablets are equipped with high-performance cameras and LiDAR sensors, and by using dedicated AR apps that leverage these, it has become possible to intuitively check as-built conditions on site. With DX being promoted across the industry through initiatives such as the Ministry of Land, Infrastructure, Transport and Tourism–led [i-Construction](https://www.mlit.go.jp/tec/i-construction/) initiative, expectations are growing that the introduction of AR for as-built checks is a powerful solution that simultaneously improves on-site efficiency and quality.

Benefits of Implementing AR

Applying AR technology to as-built verification offers many benefits that traditional methods do not.

• Real-time problem detection: Construction defects and deviations from the design can be identified immediately on-site, enabling prompt corrective action. For example, areas with insufficient pavement thickness or slope can be color-coded in AR right after construction, allowing additional work or trimming to be carried out the same day. PDCA can be executed on-site immediately, thereby minimizing rework and preventing quality defects from being left unaddressed.

• Time savings and labor reduction: Tasks that previously involved measuring each point with paper drawings and surveying instruments are replaced in AR by intuitive checks that simply require holding up a digital model. Because the as-built condition across a wide area can be visualized at once, inspections that previously took several days are greatly sped up. Also, since measurement and verification can be carried out by one person, the effort required to arrange personnel is reduced, contributing to labor savings.

• Addressing labor shortages: Site personnel will be able to evaluate as-built conditions on the spot without relying on specialist surveyors or veteran technicians. The AR app is simple to operate, and inspection tasks can be completed just by following the on-screen instructions. Because it can be used without special skills, it prevents reliance on specific individuals, and even inexperienced workers can perform measurements and checks.

• Cost reduction: If you use AR that leverages smartphones or tablets, there is no need to purchase additional expensive TS or GNSS surveying equipment. Dedicated surveying instruments often require an initial investment on the order of several million yen, but recently it has become possible to build a low-cost measurement environment with centimeter-level accuracy (half-inch accuracy) by combining existing mobile devices with relatively inexpensive GNSS receivers. Equipment maintenance and transport costs to sites can also be reduced.

• Improved measurement accuracy and reliability: Using AR reduces the risk of manual measurement errors and recording mistakes. There is no need to copy numbers written down on site, and because digital data can be compared directly, human error can be eliminated. Furthermore, when combined with high-precision positioning technologies such as RTK-GNSS, measurement results will consistently achieve centimeter-level accuracy (half-inch accuracy) that aligns with public coordinate systems, enabling more reliable as-built verification than before.

• Streamlining recording and reporting: AR allows the results of as-built inspections to be captured as intuitive visuals, making it easier to prepare reporting materials. For example, attaching screenshots of the AR view or difference heatmap images directly to inspection reports produces materials that are easier to understand than traditional reports that contain only numbers. In fact, field demonstrations by the Ministry of Land, Infrastructure, Transport and Tourism confirmed that the use of AR technology can simplify submission documents such as as-built drawings. Because records are stored digitally in this way, follow-up checks are easy, which helps reduce the burden of reporting tasks.

• Consensus building and communication improvement: The "visualization" provided by AR is also effective for sharing information with on-site personnel and clients. If you hold a tablet at the construction site and overlay the finished image onto the actual object, explanations become smoother during client inspection attendance. For example, by showing the as-built condition on AR, misunderstandings with the client are reduced and agreement on corrective locations can be reached on the spot. A survey by the Ministry of Land, Infrastructure, Transport and Tourism also reports that AR has begun to be used not only for construction management but also for pre-construction briefings to residents and information sharing with subcontractors. In this way, AR contributes to smoothing communication both inside and outside the site.

Key implementation points for achieving results on-site

There are several key points for effectively establishing AR-based as-built inspections on-site. By addressing the following points during implementation, you can achieve smooth, successful results.

• High-precision alignment: To correctly overlay digital information in AR, accurate registration with real-world coordinates is essential. Especially on large sites or with long objects, even slight positional offsets can lead to significant errors, so leverage GNSS RTK positioning and calibration using known control points to always perform alignment with centimeter-level accuracy (half-inch accuracy). Using RTK-enabled AR systems allows you to project models without the hassle of placing markers on site and provides a stable AR display that won’t drift as you walk around.

• Preparation of 3D design data: AR as-built checks rely on a 3D model of the design drawings (such as BIM/CIM data). If you do not yet have 3D data, prepare comparison data by creating a simple model from 2D drawings or by digitizing the current conditions via point-cloud scanning. Because the CIM initiatives promoted by the Ministry of Land, Infrastructure, Transport and Tourism are driving the production of 3D data from the design stage, models should become easier to obtain for any project in the future. It is important to become familiar with handling 3D data in-house as early as possible.

• Embedding into the operational flow: To make AR checks part of standard on-site operations rather than a one-off demonstration, clearly define when, who, and at what timing it will be used. For example, incorporate procedures such as “use AR for rebar inspection before concrete pouring” or “use AR to verify finishes after each embankment completion” in advance into construction plans and checklists. Also, decide in advance how the results confirmed by AR will be recorded and reflected in reports. If you use a system that automatically adds date/time and location information to screenshots and saves them to the cloud, they can be used directly as evidence in inspection forms, which is convenient. By integrating AR into existing quality management flows, it will become established as a tool that everyone on site uses routinely.

• Training for on-site staff: To eliminate resistance to new technology, it is important for on-site staff to understand how to use AR and the benefits it brings. At first, a tech-savvy person should take the lead and trial AR checks on small-scale tasks. Demonstrating it in practice and letting them experience that "anyone can take measurements simply by following the on-screen prompts" is essential. Recent AR apps are intuitive and easy to use and can be learned with a short training even without specialized knowledge. By sharing operating procedures through in-house training and on-site OJT and showing concrete examples so that veteran staff also see the benefits, smooth adoption becomes possible.

• Phased implementation and validation: Rather than introducing AR checks across all sites and all processes at once, first trial them on a limited number of sites or processes and verify their effects and issues. For example, try using AR measurement alongside conventional methods in a specific construction section and show the degree of efficiency improvement and error reduction compared with the previous approach with data—this will make it easier to gain understanding both internally and externally. Start small to accumulate know-how, and if problems are found (such as how to handle equipment or methods for validating accuracy), improve them before rolling out company-wide to ensure confidence. Based on the validation results, prepare internal manuals and checklists so that subsequent deployments to other sites proceed smoothly.

• Utilizing cloud services: By using cloud services linked to AR apps, measurement data, point-cloud models, site photos, and so on can be automatically saved to and shared on the cloud. This enables real-time sharing of information between the field and the office, allowing the as-built status to be checked on the AR screen even from remote locations. Because the entire team can view and comment on the latest data in the cloud, instructions for corrective actions and requests for additional inspections can be made quickly. Furthermore, data are stored on the cloud as a history, so they can be referenced for future projects or used as evidence if a problem arises. When introducing AR, enable cloud-integration features as much as possible to achieve centralized data management and smooth information sharing.

Use Cases for AR As-Built Checks

On actual job sites, AR-based as-built verification is beginning to be used in a variety of ways. Here are some representative use cases.

• Verification of rebar and structure positions: AR is effective for inspecting rebar layouts before concrete placement and for checking positional deviations of structures during construction. For example, when confirming whether there is any misalignment in column reinforcement positions, if you display the rebar layout in AR on site and check the number of bars and spacing, tasks that were traditionally measured with a tape measure can be completed at a glance. By overlaying the design 3D model on the actual object to detect minute errors, construction can proceed while ensuring accuracy. There have even been cases reported where AR site matching enabled early correction of defects, reducing rework and material waste.

• Pavement thickness and slope as-built inspection: In road pavement works, combining AR and point cloud surveying enables area-based evaluation of as-built conditions over wide areas. Immediately after paving, scan the road surface with a LiDAR-equipped smartphone to obtain a high-density pavement point cloud. By overlaying the design 3D model on this, an as-built heat map with elevation differences color-coded can be generated on the spot. You can instantly determine whether the pavement thickness across the entire section is within the design range, and unevenness or insufficient thickness can be detected without omission. Because longitudinal gradient and width can also be measured directly on the point cloud data, inspections can be completed safely and quickly, and some sites have achieved zero rework afterward.

• Checking buried pipes and other hidden objects: Objects buried underground, such as pipes and cables that can no longer be directly seen after installation, can be "seen through" and inspected with AR. For example, in sewer pipeline projects, pipes are 3D-scanned before burial and the point cloud data of their exact position and depth is stored in the cloud; after backfilling, there are cases where simply holding up a smartphone makes it possible for anyone to grasp the route and depth of the underground pipes. This can eliminate the marking work immediately after burial and make it easy to excavate while avoiding buried items during future maintenance using AR displays. The ability to visualize things that cannot be seen is also a major advantage of AR as-built checks.

• Use of slope and terrain models: On steep-slope construction and large-scale earthworks, combining 3D scanning and AR for as-built management can improve safety and efficiency. For example, by scanning the slope once before construction to acquire baseline data, and re-scanning after construction or following a disaster and comparing the results, you can instantly calculate the extent of collapse and changes in fill volume. Earthwork volume calculations that previously took several days now complete in minutes, and can be used for recovery planning and as-built evaluation. Furthermore, if you overlay the resulting slope point-cloud model onto the real-world site view with AR, danger zones and reinforcement anchor locations can be intuitively shared among all workers. In this way, by combining 3D data of terrain and structures with AR visualization, as-built management and damage/deformation detection over wide areas and at heights that were previously difficult can be carried out safely and reliably.

Challenges and Countermeasures to Consider When Introducing AR

As-built verification using AR offers many benefits, but there are also several points to keep in mind when implementing and operating it. Below we summarize the main challenges and their countermeasures.

• Concern about accuracy: The worry "Can AR really measure accurately?" is often heard. Indeed, if alignment is incorrect you cannot make correct judgments, so managing accuracy is important. As countermeasures, eliminating discrepancies between the digital model and the real world by RTK corrections using GNSS and precise calibration at known points can be cited. If you integrate a GNSS rover with AR, you can spatially overlay the design data and the as-built in front of you exactly, and it has been demonstrated that, with proper operation, checks can be carried out at a level of accuracy equivalent to conventional surveying (both horizontally and vertically within several centimeters (within a few in)). In initial stages, be careful to ensure accuracy by, for example, combining conventional measurements at key points to verify errors.

• Digital data preparation burden: While AR use requires digital 3D models or point cloud data, there are concerns that preparing them is time-consuming. Although BIM/CIM design data are gradually becoming more widespread, some small- to medium-sized projects still lack 3D data. Even in such cases, performing a LiDAR scan of the site to obtain as-built point clouds allows use as an improvised 3D model. There are also apps that can display simplified models of reference lines and surfaces in AR for projects that only have 2D drawings. The Ministry of Land, Infrastructure, Transport and Tourism’s guidelines are also advancing the transition to as-built management using 3D measurement technologies, and digital data will become increasingly easier to obtain. It may seem like extra work at first, but once the data are prepared they will aid subsequent process management and future maintenance, so it is important to approach this as an investment in digitalization.

• Device and on-site environment considerations: It is necessary to take into account the physical challenges of using smart devices on site. For example, under direct midsummer sunlight a screen can become hard to see and battery consumption can increase dramatically. Outdoors, these issues can be addressed by using a sun hood for the tablet or carrying a portable battery. Also, for use in rainy conditions, prepare a waterproof case or a splash-proof cover for the tablet. On dusty sites, it is important to frequently clean the camera and sensor areas. Furthermore, if it is difficult to work for long periods holding a tablet in one hand, solutions such as using a neck-mounted holder can be effective. By incorporating accessories and operational methods suited to the site environment and creating conditions in which devices can operate easily you can maximize the effectiveness of AR.

• Resistance from on-site staff: The psychological hurdle toward new technologies cannot be ignored. Particularly among veteran workers, you sometimes hear comments like "I feel safer with the traditional manual methods." The best solution to this issue is to actually demonstrate AR and let people experience its effects. For example, sharing concrete results—such as inspections that used to take half a day now finishing in 30 minutes, or previously overlooked rebar errors being discovered on the spot—can significantly change attitudes. Also, tools like LRTK that "allow anyone to easily survey alone" are often welcomed on site because tasks that used to require two people can be handled by a single person.

Have younger employees start using it first and roll it out in a way that spreads its convenience throughout the whole site, and the resistance will gradually fade.

• Implementation cost and ROI: Introducing new equipment and software involves costs, but in the case of AR, because existing smartphones and tablets can be reused, the initial investment hurdle is greatly reduced. As noted above, since you do not need to purchase expensive dedicated surveying instruments, you can get started with costs on the order of GNSS receivers and software licensing fees. In addition, considering quantifiable effects such as reduced rework and labor savings, a relatively quick return on investment can be expected. For those concerned about cost-effectiveness, it is effective to introduce the technology on a limited basis first and demonstrate visible results (e.g., 〇% reduction in man-hours, a △-case decrease in defect corrections, etc.) within the company. Calculating ROI based on actual performance data will provide material for explaining the case to management and clients, making it easier to secure further investment decisions.

• Application to formal inspections: Under current as-built management procedures, traditional measurements and drawing preparation may still be required to be carried out in parallel. Some supervisors (inspectors) may be cautious about accepting work based solely on checks on a digital device. However, the Ministry of Land, Infrastructure, Transport and Tourism has confirmed the effectiveness of on-site as-built inspections using AR and similar technologies, and AR-based labor-saving methods are expected to be incorporated into guidelines going forward. Even now, using software that automatically generates as-built documents from point clouds and photos acquired with AR can produce deliverables equivalent to manual work, so in practice AR measurement alone can complete the process. What is important is appropriately explaining AR results to the client and supervisors and obtaining their understanding. For example, during an inspection, directly showing an as-built heat map on a tablet screen can demonstrate quality more convincingly than paper drawings. As both the public and private sectors are gradually gaining a deeper understanding of AR utilization, early adoption and accumulation of know-how will lead to a future competitive advantage.

Simplified surveying and AR checks enabled by LRTK

One solution attracting attention for enabling such AR as-built checks more easily and more accurately is "LRTK". LRTK is a cutting-edge tool that, simply by attaching a compact GNSS receiver to a smartphone, enables RTK positioning for centimeter-class high-precision positioning (cm level accuracy (half-inch accuracy)), and is a next-generation system that allows surveying work that previously required specialized equipment and skilled operators to be completed by a single person. It supports CLAS corrections from Japan's GPS "Michibiki" and network RTK, maintaining stable high accuracy even in mountainous areas outside communication coverage. In other words, its major strength is that even without a veteran surveyor you can handle everything from control point surveying to as-built inspection with just a smartphone.

Furthermore, LRTK integrates seamlessly with AR functionality. Based on high-precision GNSS positional data, it can perfectly overlay 2D/3D design data on-site, so the cumbersome alignment work is unnecessary and there is no worry about objects shifting. For example, simply walking the site with a tablet lets you accurately indicate a virtual pile-driving position from the design model on the actual ground, and you can visually confirm target coordinates at distant points in an instant. It is also possible to automatically overlay the acquired current point cloud data with the design model on the LRTK cloud for difference comparisons, enabling you to instantly check whether construction is proceeding according to plan.

LRTK also provides a cloud platform, and data measured and scanned on-site are synchronized to the cloud immediately. Team members can view the on-site 3D point clouds and survey point information in real time from office PCs, and proceed with verification while sharing data among stakeholders. It is also possible with one click to perform distance, area, and volume measurements on the cloud, or to link location information to photos and display them in a list. This enables collaboration that transcends the boundaries between site and office, dramatically improving the efficiency of as-built inspections.

Additionally, LRTK offers a variety of features beyond as-built management, such as a "Coordinate Navi" function that can guide a single person to pile-driving positions, a function to calculate embankment volumes from point clouds acquired by a LiDAR scanner, and a cloud-sharing function for high-precision positioning photos. In other words, it is designed so that from surveying to verification, recording, and as-built inspection — processes that previously required multiple devices — can be completed with a single iPhone. The data obtained on site can also be used and delivered in formats compliant with the Ministry of Land, Infrastructure, Transport and Tourism's as-built management guidelines, and in fact many construction companies have begun adopting LRTK to achieve both labor savings and improved quality.

By using a smartphone surveying + AR system like LRTK, anyone can easily perform high-accuracy as-built checks, breaking through many of the constraints related to surveying and inspection. Even on sites struggling with labor shortages, deploying a "one device per person" smart surveying tool and leveraging AR can shorten work time, reduce human errors, and improve communication. These technological innovations are powerfully supporting the digital transformation (DX) of construction sites and are fundamentally changing how as-built management is handled. The secret to successfully implementing AR-based as-built checks lies in effectively adopting these advanced tools and using them to improve productivity across the entire site. Be sure to harness the latest technologies and let "As-Built AR Checks" demonstrate their true value on your sites.

Frequently Asked Questions

Q: What do you need to start an as-built AR check? A: Basically, you need a smartphone or tablet capable of AR display, a GNSS receiver to improve measurement accuracy, and an AR surveying app that supports them. The latest iOS/Android devices have well-equipped cameras and sensors, making them suitable for AR use. If centimeter accuracy (cm level accuracy (half-inch accuracy)) is required, combine a small Bluetooth-connected GNSS rover to perform RTK positioning (for example, there are LRTK devices that can be attached to a smartphone). In addition, prepare digital data for comparison such as the design 3D model data or point clouds. Once these are set up, you can immediately try an as-built AR check on site.

Q: Can the accuracy of as-built checks using AR be trusted? A: Yes — if operated properly, high reliability can be ensured. Systems using GNSS RTK corrections can achieve positioning accuracy on the order of several centimeters (a few in) in both horizontal and vertical. This falls within the accuracy ranges typically required for as-built inspections. Also, when confirming differences in AR, you can obtain quantitative information — for example, which point is how many centimeters (how many in) higher or lower — through heatmap displays and similar tools. The important points are to align with site control points beforehand and to perform verification with conventional methods at key locations as needed. If you do so, you can trust AR check results with sufficient justification.

Q: Can AR be used on sites that don't have 3D design models? A: AR can still be used with some ingenuity even when there is no 3D model. For example, some applications can overlay 2D drawing data (DXF, etc.) onto the AR space, allowing key lines and positions to be visualized on site. Also, if the final form is not complex, a simple method is to mark major dimensions on site before construction and superimpose those marks onto images captured with AR. However, AR truly shows its value when a 3D model is available. Recently, the creation of CIM models has become more common, especially for public works, so consider asking the client to provide 3D data or creating a simple model in-house. On the other hand, if the purpose is to compare as-built measured data (point clouds) against design drawings, you can use point cloud processing software to detect differences instead of relying on AR. The main goal is to intuitively verify on site, so choose the best approach depending on whether a model exists.

Q: Can the results of an AR check be used in official inspections? A: Currently, operations that use AR as the sole basis for official inspections are only just getting started, but its use is gradually being accepted. The Ministry of Land, Infrastructure, Transport and Tourism conducted field demonstrations in fiscal year 2023 (Reiwa 5) and confirmed that it is possible to omit as-built documentation using AR technology. At present, records using conventional methods (survey drawings and photo logs) are often still required in parallel, but submitting AR-based confirmations as supplementary materials has the advantage of making it easier for inspectors to understand. For example, during an inspection, displaying information such as "this location is ◯ cm (◯ in) higher/lower than the design" on an AR heat map conveys the information more intuitively than a conventional numerical table. In the future, the likelihood that AR data itself will be recognized as an official deliverable is increasing, but at this stage it is safest to regard it as "used as supporting evidence" and to combine it with traditional measurements as needed.

Q: I'm worried that not everyone on site will be able to master this technology. A: AR construction support tools have become more user-friendly year by year, and the basic operations are not difficult. In fact, at many companies that have adopted them, people from young workers to veterans are able to use them after a short training period. If you still feel uneasy, it is a good idea to start by having a staff member who is familiar with the operation demonstrate it on site while the other staff watch. People tend to engage more positively once they see the benefits with their own eyes. If they feel "it's certainly faster" or "easy to understand," resistance will diminish. In addition, recent AR apps support Japanese displays and have solid support systems in place, making it easy and reassuring to seek help when needed. The use of ICT on site is becoming increasingly essential, so take your time and proceed step by step to build an environment where everyone can use it.

Q: Do I need dedicated AR glasses? A: At present, in most cases smartphones and tablets are more than sufficient for practical use. AR-capable smart glasses (see-through goggles) have appeared, but they are very expensive and have issues such as being difficult to use with safety helmets. In that respect, smartphones and tablets can be used easily on site in dust- and water-resistant cases, and operation is simple by touching the screen. As resolution and processing power improve year by year, both visibility and performance are fine for business use on mobile devices. In the future, if glasses become lightweight and inexpensive, their use may spread, but at present, using handheld devices for AR is the most realistic and cost-effective. It's recommended to start with familiar smartphone AR and consider future device deployments as needed.