Tips for Introducing AR Inspections Without Failure: Smoothly Digitize As-Built Inspections

Table of Contents

• As-built inspections and the transformation enabled by AR technology

• Benefits of introducing AR inspections

• Key points for successful AR inspection adoption

• Use cases of AR inspections

• Challenges and countermeasures when introducing AR inspections

• AR inspections expanded by simple surveying with LRTK

• Frequently Asked Questions

As-built inspections and the transformation enabled by AR technology

“As-built inspection” is a quality-control process in civil engineering and construction that verifies whether completed structures and terrain have been built according to the design drawings. Traditionally, as-built checks were performed using surveying instruments such as total stations (TS) and levels: technicians measured elevations and thicknesses point by point on site, then returned to the office to compare measurement results with the drawings to judge acceptance. This method tends to create time lags between measurement and problem discovery, which can lead to rework later. Accurate measurement and judgment also require experienced surveyors, often working in pairs, so in an environment of chronic labor shortages and an aging workforce this method is inefficient. Greater efficiency and labor savings have been demanded on site.

Recently, AR (Augmented Reality) technology has attracted attention as a trump card to solve such site management issues. AR overlays three-dimensional digital information (design models, drawings, etc.) onto real-world imagery. Once seen as an experimental cutting-edge technology, the performance improvements of smartphones and tablets have made AR usable in everyday construction management. The latest smartphones and tablets, equipped with high-performance cameras and LiDAR sensors, together with dedicated AR apps, now allow intuitive on-site as-built checks. With DX (digital transformation) progressing across the construction industry—such as the Ministry of Land, Infrastructure, Transport and Tourism’s *i-Construction* initiative—the introduction of AR into as-built inspections is increasingly expected as a powerful solution to simultaneously improve on-site efficiency and quality.

Benefits of introducing AR inspections

Applying AR technology to as-built inspections brings many advantages that were not possible with traditional methods. The main benefits are summarized below.

• Real-time problem detection: You can discover construction defects and deviations from design on the spot, enabling immediate corrective actions. For example, in road paving work, AR can color-code areas with insufficient pavement thickness or slope immediately after construction, allowing additional paving or trimming the same day. Because you can run the PDCA cycle instantly on site, rework is minimized and the risk of leaving quality issues unaddressed for long periods is reduced.

• Reduced work time and labor savings: Tasks that involved measuring individual points with paper drawings and surveying instruments are replaced by intuitive checks that overlay the digital model by pointing a tablet. Because a wide area of as-built conditions can be visualized at once, inspections that used to take several days can be dramatically sped up. Also, more inspections can be completed by a single person, reducing personnel coordination and saving labor.

• Addressing labor shortages: With AR inspections, site personnel can evaluate as-built conditions without relying on specialist surveyors or veteran technicians. Dedicated AR apps are simple to operate—just follow on-screen guidance to complete measurements and checks. Since special skills are not required, work is less person-dependent and inexperienced workers can perform sufficient measurements and inspections. This helps with workforce development and mitigates staffing shortages.

• Cost reduction: AR using smartphones and tablets eliminates the need to purchase expensive total stations or GNSS survey equipment. Historically, introducing precision surveying equipment required initial investments of several million yen, but today a centimeter-level measurement environment (half-inch accuracy) can be built at low cost by combining a mobile device with a relatively inexpensive small GNSS receiver. Reducing the need to transport and maintain heavy equipment on site also cuts costs, yielding significant economic benefits.

• Improved measurement accuracy and reliability: AR reduces human measurement errors and recording mistakes. Because there is no need to write numbers on paper and manually enter them later, digital data can be compared on the spot to eliminate human error. When combined with high-precision GNSS (RTK positioning) and similar technologies, measurements can achieve centimeter-class accuracy (half-inch accuracy) in a public coordinate system, enabling more reliable as-built verification than before. Ensuring measurement accuracy and improving data credibility increase confidence in inspection results.

• Streamlined recordkeeping and reporting: AR allows inspection results to be saved as intuitive visual data, making report creation easier. For example, attaching AR screen screenshots or heatmap images showing differences to inspection reports creates much clearer documentation than traditional number-heavy reports. Ministry of Land, Infrastructure, Transport and Tourism field demonstrations have confirmed that AR can simplify required as-built documents. Digital records make later verification easy and significantly reduce the time and effort spent on reporting.

• Improved consensus-building and communication: AR visualization is powerful for sharing information both inside and outside the site. For example, presenting a tablet view that overlays the finished image and as-built data onto the real site during an inspection meeting makes explanations much smoother. Having stakeholders directly view the AR-displayed as-built conditions reduces misunderstandings and enables on-the-spot agreement on corrective work. The ministry’s surveys also show AR is beginning to be used not only for construction management but also for pre-construction resident briefings and information-sharing with subcontractors. In this way, AR facilitates communication among stakeholders and helps build trust between the site and the client.

Key points for successful AR inspection adoption

To establish AR-based as-built inspections on site and reliably achieve results, several points must be kept in mind. Being aware of the following at introduction will help you extract benefits smoothly and without failure.

• Ensure high-precision alignment: Accurate overlay of digital information in AR requires extremely precise alignment between the real-world coordinates and the model. Especially on large sites or long structures, even small positional errors can lead to large measurement errors. Use RTK positioning with GNSS or calibration using known control points to maintain centimeter-level alignment between the model and real space. RTK-enabled AR systems can project models without placing physical targets on site, providing stable AR displays that do not drift even when walking across a wide area. Operating with a constant emphasis on high precision forms the foundation for reliable AR inspections.

• Prepare 3D design data: AR-based inspections rely on 3D design models (BIM/CIM models, etc.) as the comparison standard. If 3D data are not available, you can create simple models from 2D drawings or obtain point cloud data by LiDAR scanning the current state to prepare digital comparison materials. With the ministry-led push for CIM (Construction Information Modeling), 3D models are expected to become easier to obtain for many projects. In any case, getting your team accustomed to handling 3D data early is important. Although it may feel laborious at first, once the model is prepared it can be used in subsequent process management and future maintenance, so investing in digital data preparation is an investment for the future.

• Integrate into operational workflows: To prevent AR inspections from ending as one-off demonstrations and to make them standard practice, decide clearly when, who will use, and at what timing AR will be used. For example, include in construction plans or checklists that “AR will be used for rebar inspection before concrete placement” or “use AR to check finish after each embankment completion.” Also determine how to record AR inspection results and reflect them in reports. For instance, using a system that automatically records date/time and location information for AR screenshots and saves them to the cloud makes those images usable as evidence in inspection records. Integrating AR into existing quality-control flows helps it become a routine tool everyone on site uses.

• Train and inform site staff: When introducing new technology, it is essential that site staff understand how to use it and its benefits. Start with an ICT-savvy person leading small-scale AR inspections. The key is to let people experience that “anyone can measure by simply following on-screen instructions.” Modern AR apps are intuitive and can be learned through short training without specialized knowledge. Share procedures through in-house study sessions and on-the-job training (OJT), and show veteran staff concrete examples where they benefit—this helps acceptance without resistance.

• Phased introduction and verification of effects: Rather than introducing AR across all sites and processes at once, begin experimentally at a few sites or in selected processes to verify effects and identify issues—this is the shortcut to success. For example, trial AR measurements alongside traditional methods in a specific section, and present data showing efficiency gains and error reduction compared to previous methods to gain internal and external understanding. Start small to accumulate know-how, and once you find issues (equipment handling, accuracy verification methods, etc.), improve and then roll out company-wide. Preparing internal manuals and checklists based on demonstration results smooths subsequent deployment.

• Use cloud services: When AR apps are linked with cloud services, measurement data, point cloud models, and site photos are automatically saved and shared in the cloud. This enables real-time information sharing between the site and office, allowing managers at remote locations to instantly check the as-built status on the AR screen. Because the whole team can view and comment on the latest data in the cloud, instructions for corrective work and requests for additional investigations can be issued quickly. Data also accumulate as a history in the cloud, useful for future similar projects or as evidence if problems arise. When introducing AR, make maximum use of cloud integration features for centralized data management and smooth information sharing.

Use cases of AR inspections

In real-world sites, AR-based as-built inspections are beginning to prove effective across various applications. Below are some representative use cases.

• Rebar and structure position confirmation: AR is effective for rebar inspection before concrete placement and for checking whether structures under construction have shifted from their design positions. For example, when checking if rebar positions for a column are misaligned, a task that used to require tape measures can be made obvious by displaying a 3D model of the rebar arrangement in AR to confirm counts and spacing. Overlaying a design model on the actual object makes even small deviations of a few centimeters (a few inches) detectable, allowing construction to proceed with accuracy. There are reported cases where early correction by AR site verification reduced rework and material loss.

• Pavement thickness and slope as-built inspections: In road paving, combining AR with point cloud measurement enables area-based evaluation of as-built conditions over a wide range. Use a smartphone with LiDAR to scan the road surface immediately after paving to obtain high-density point cloud data. Overlaying the design 3D model produces an as-built heatmap color-coded by elevation differences on the spot. This makes it possible to judge at a glance whether pavement thickness across the entire road segment is within design tolerances and to detect unevenness or insufficient thickness. On the acquired point cloud you can also directly measure longitudinal slope and road width, allowing safe and rapid completion of inspections. One site reported zero rework after paving using this method.

• Confirming buried objects such as pipes: AR can “see through” to confirm objects buried underground, such as pipes and cables that are no longer visible after installation. For instance, in a sewer pipe project, the pipe can be 3D-scanned before burial and accurate position and depth point cloud data saved to the cloud; after backfilling, simply pointing a smartphone at the surface allows anyone to see the underground pipe alignment and depth. This eliminates the previous practice of marking the ground immediately after burial and enables safe excavation for future maintenance by checking buried object positions with AR. Visualizing structures invisible to the naked eye is one of AR inspection’s major advantages.

• Using slope and terrain models: For steep slope engineering or large-scale land development, combining 3D scanning and AR improves safety and efficiency in as-built management. For example, scanning a slope before construction to obtain baseline data and rescanning after construction (or after a disaster) allows immediate calculation of collapse areas and changes in fill volume. Earthwork volume calculations that used to take days can be completed on site in minutes, aiding rapid recovery planning and as-built assessment. Overlaying the slope point cloud model in AR on the actual landscape lets workers intuitively share dangerous areas and the locations of reinforcement anchors. Combining 3D data with AR allows safe and reliable management and anomaly detection over wide or high-altitude areas that were previously difficult to handle.

Challenges and countermeasures when introducing AR inspections

While AR brings many benefits to as-built inspections, there are also challenges to consider during introduction and operation. Below are common concerns and countermeasures.

• Concerns about accuracy: People often ask, “Can AR really measure correctly?” Indeed, without accurate alignment, correct judgments are impossible, so accuracy management is a key issue. Countermeasures include using GNSS-based RTK corrections and rigorous calibration with known points to eliminate discrepancies between the digital model and the actual structure. Linking GNSS rover equipment with AR enables precise spatial overlay of design data and the actual as-built. Properly operated, AR checks can achieve accuracy comparable to traditional surveying—errors on the order of several centimeters (a few inches) in horizontal and vertical dimensions have been demonstrated. During initial introduction, combine AR with spot checks using conventional methods to verify errors and ensure confidence.

• Effort to prepare digital data: Using AR requires digital 3D models or point cloud data, and some worry about the preparation effort. While BIM/CIM use of 3D design data is gradually spreading, many small- and medium-scale projects still lack 3D models. In such cases, LiDAR scanning the site to obtain as-built point clouds provides an ad-hoc 3D model. Some AR apps can also create simple models from 2D drawings by selecting baseline lines or surfaces. The ministry’s as-built management guidelines are being revised to incorporate 3D measurement technologies, so design data digitization will progress further. Although preparation may feel burdensome initially, once data are organized they are valuable for subsequent process management and future maintenance. Use AR adoption as an opportunity to pursue long-term digitalization of site information.

• Dealing with devices and site environments: Using smart devices outdoors introduces physical challenges. For example, screens can be hard to see under hot sunlight and batteries drain quickly; using tablet sunshades and carrying mobile batteries mitigates these issues. For rainy conditions, waterproof cases or splash covers are advisable. Dusty sites can soil cameras and sensors, so frequent cleaning is necessary. If holding a tablet for long periods is burdensome, neck straps or harnesses reduce fatigue. By adopting site-appropriate accessories and operational measures to ensure devices perform adequately, you can maximize AR effectiveness.

• Resistance from site staff: Psychological barriers to new technology should not be ignored. Some veteran technicians may say, “The old way is more reliable.” The best remedy is to demonstrate AR’s effectiveness in practice. Sharing concrete results—e.g., inspections that used to take half a day now finished in 30 minutes, or rebar errors detected on the spot—can change attitudes. Tools like LRTK that enable “anyone to survey easily alone” are often welcomed because tasks previously requiring two people can be done solo. Start by having younger staff use the tools and let their positive experiences spread, which tends to reduce veteran resistance over time.

• Introduction cost and ROI: New equipment and software require investment, but AR typically leverages existing smartphones and tablets, so initial hardware costs are relatively low. As mentioned, you can start with small GNSS receivers and software subscriptions instead of purchasing high-priced dedicated survey instruments. Considering quantifiable benefits such as reduced rework and labor savings, ROI can be expected relatively quickly. If cautious voices exist internally, begin with limited deployment and present visible results (e.g., percent reduction in man-hours, number of defect corrections reduced) to make the case. Calculating ROI from field demonstration data helps persuade management and clients and supports further investment.

• Application to official inspections: At present, as-built management guidelines often still require traditional measurements and drawing creation in parallel. Some inspectors (client-side supervisors) may be cautious about accepting digital checks on a tablet alone. However, the ministry’s FY2023 field demonstrations confirmed that AR and related technologies can enable simplification or omission of as-built documentation, and AR-based labor-saving methods are likely to be incorporated into official guidelines going forward. Even now, software that automatically creates as-built drawings from AR-captured point clouds and photos can produce deliverables equivalent to manual outputs (drawings and reports). In practice, AR-only completion is possible. The important point is to properly explain AR measurement results to clients and inspectors to gain their understanding. Showing an AR heatmap on a tablet during an inspection can demonstrate quality more convincingly than paper drawings. As public and private understanding of AR grows, adopting it early and accumulating know-how will provide future advantages.

AR inspections expanded by simple surveying with LRTK

As described above, AR-based as-built inspections bring large benefits to the field, and LRTK (Lightweight RTK) has recently attracted attention as a solution that makes this both easier and higher-precision. By attaching a small high-precision GNSS receiver to a smartphone, LRTK enables RTK positioning with centimeter-level positioning (half-inch accuracy), allowing surveying tasks that traditionally required specialized equipment and skilled operators to be completed by a single person. It supports CLAS corrections provided by Japan’s satellite positioning system “Michibiki” and network-type RTK methods, maintaining stable high-precision positioning even in mountainous areas with poor cellular coverage. In short, even without a veteran surveyor on site, a single smartphone can handle everything from control point surveying to as-built checks—a major strength.

LRTK also integrates seamlessly with AR functions. Based on high-precision GNSS positioning, design drawings and 3D models can be precisely overlaid on site, eliminating troublesome alignment work and minimizing model drift. For example, simply walking around with a tablet can accurately display virtual stake positions from the design model on the actual ground. You can confirm the position of target coordinates at a glance even when they are far away, enabling stake-setting (layout) intuitively without specialized surveying knowledge. It is also possible to automatically overlay acquired as-built point cloud data with the design model in LRTK’s cloud and compare differences. This allows immediate on-site checks of whether construction is proceeding as planned.

LRTK provides a cloud platform as well, enabling real-time cloud synchronization of measured and scanned on-site data. Team members can view the latest 3D point cloud data and measurement point information obtained on site from office PCs and collaborate on verification across remote locations. The cloud also allows one-click measurement of distances, areas, and volumes, and linkage of positioning information to photos for list displays. In this way, collaboration that transcends the boundary between site and office is realized, and as-built inspection efficiency improves dramatically.

Additionally, LRTK offers a variety of functions beyond as-built management. These include a “coordinate navigation” feature that guides a single person to stake positions, a function to calculate fill volumes from point clouds captured by an iPhone LiDAR scanner, and cloud sharing of geotagged high-precision photos—handy tools that support site work. In other words, surveying, measurement, recording, and inspection of as-built conditions—processes that previously required multiple instruments and personnel—are designed to be completed with a single smartphone. Data obtained on site can be used and delivered in formats that comply with the Ministry of Land, Infrastructure, Transport and Tourism’s as-built management guidelines, and many construction companies have begun adopting LRTK to achieve both labor savings and quality improvement.

Using systems like LRTK that combine smartphone surveying and AR enables anyone to easily perform high-precision AR inspections and break various constraints related to surveying and inspection work. Even on sites suffering from labor shortages, a “one-device-per-person” smart surveying tool plus AR can simultaneously shorten working time, suppress human error, and improve communication among stakeholders. These technological innovations strongly support DX in construction and are fundamentally changing as-built management. The key to successful AR inspections is to incorporate such advanced tools effectively and link them to overall productivity improvements on site. Please take advantage of the latest technologies and let “AR as-built inspections” demonstrate their true value at your sites.

Frequently Asked Questions

Q: What do I need to start AR inspections? A: Basically, you need a smartphone or tablet that supports AR display, a GNSS receiver to improve measurement accuracy, and an AR surveying app compatible with that device. The latest iPhones and Android tablets have high-performance cameras and sensors suitable for AR. If centimeter-level accuracy is required, combine the device with a Bluetooth-connected small GNSS rover to perform RTK positioning (LRTK devices that attach to smartphones are available). Also prepare digital comparison data in advance, such as 3D design models or as-built point cloud data. With these set up, you can start trying AR inspections on site immediately.

Q: Can the accuracy of AR-based as-built inspections be trusted? A: Yes. With proper operation, high accuracy and reliability can be achieved. Systems using GNSS RTK corrections can realize positioning accuracy on the order of several centimeters (a few inches) in horizontal and vertical dimensions, which is within the accuracy range typically required for as-built checks. When confirming differences on AR, heatmap displays and similar tools provide quantitative on-the-spot information such as “how many centimeters high/low a point is.” The important points are to align site control points and coordinates beforehand and to perform spot checks with conventional methods as needed. With these measures, AR inspection results can be trusted on a sound basis.

Q: Can AR be used on sites without 3D design models? A: Yes, with some ingenuity. If there is no 3D model, some apps can overlay 2D drawing data (CAD drawings) in AR to visualize major lines and positions on site. For relatively simple completed shapes, you can also mark key dimensions on site before construction and use AR to overlay those markings on captured images for a simple check. However, AR inspections are most effective when 3D models are available. The creation of CIM models (3D design data) is increasingly common in public works, so consider requesting 3D data from the client or creating simple models in-house. If the goal is to compare measured as-built data (point clouds) with drawings, desktop point cloud processing software can detect differences without AR. The main objective is to “enable intuitive on-site confirmation,” so choose the method that best fits whether a model exists.

Q: Can AR inspection results be used for official inspections? A: Currently, using AR as the sole evidence in official inspections is still emerging, but acceptance is gradually increasing. The ministry’s FY2023 field demonstrations confirmed that AR can enable simplification or omission of as-built documentation. At present, traditional records (survey drawings, photo logs, etc.) are often still required in parallel, but submitting AR-visualized data as supplementary materials makes it easier for inspectors to understand. For example, an AR heatmap showing “this location is ◯ cm higher (lower) than design” communicates more intuitively than a table of numbers. In the future, AR-acquired data itself may be recognized as official deliverables, but for now it is safer to use AR as corroborating evidence and retain conventional measurements as necessary.

Q: I’m worried not everyone on site will be able to use this technology. A: AR construction support tools have become increasingly user-friendly, and basic operations are not difficult. Many adopting companies report that staff from young to veteran can use them after short training. If concerns remain, start with an experienced operator demonstrating on site while others learn by watching. People are more willing to adopt new tools when they see benefits firsthand. When staff experience “it’s faster” and “it’s easier than expected,” resistance diminishes. Recent AR apps support Japanese interfaces and a solid support system is often available, making it easy to get help when needed. ICT use in construction will only increase, so gradually build an environment where everyone can use the tools.

Q: Do I need dedicated AR glasses or goggles? A: At present, smartphones and tablets are sufficient for most practical uses. Transparent AR smart glasses have appeared, but they are often very expensive and can be difficult to use with safety helmets. Smartphones and tablets can be used on site with dustproof and waterproof cases and are simple to operate via touch. Device screen resolutions and processing performance continue to improve, so handheld devices are adequate for visibility and performance in professional use. If glass-type devices become lighter and less expensive in the future, their use may expand, but for now adopting AR on familiar mobile devices is the most realistic and cost-effective approach. Start with smartphone-based AR and consider future device expansion as needed.