Achieving Labor Savings! The Implementation Effects AR Inspection Brings to Surveying Sites

Table of Contents

• What is AR inspection?

• Benefits of introducing AR inspection

• Use cases of AR inspection

• Key points for implementing AR inspection

• Challenges and countermeasures when introducing AR inspection

• Simple surveying with LRTK

• Frequently Asked Questions

What is AR inspection?

On civil engineering and construction sites, inspections and surveying—confirming whether completed structures and construction conditions match the design—are indispensable. Traditionally, survey instruments such as total stations (TS) and levels have been used to measure heights and positions point by point on site, after which workers return to the office to compare measurements with drawings and judge whether the construction is acceptable. However, this method tends to create a time lag between measurement and problem discovery, causing rework to occur in the intervening period. Accurate measurement and judgment also require experienced surveyors, and many tasks are performed in two-person teams, making the process inefficient amid labor shortages and an aging technician population. Sites now demand further labor savings and efficiency, and one trump card attracting attention in recent years is AR (Augmented Reality) technology.

AR technology overlays three-dimensional digital information (such as drawings or 3D models) onto real-world imagery. Once cutting-edge, AR is now usable in everyday construction management thanks to the improved performance of smartphones and tablets. In particular, the latest smartphones and tablets come equipped with high-performance cameras and LiDAR sensors; using dedicated AR apps that leverage these features lets site personnel intuitively check as-built conditions on site. With industry-wide DX initiatives such as the Ministry of Land, Infrastructure, Transport and Tourism–led [i-Construction](https://www.mlit.go.jp/tec/i-construction/), the adoption of AR inspection is increasingly expected as a powerful solution to simultaneously improve on-site work efficiency and quality.

Benefits of introducing AR inspection

Applying AR technology to surveying and as-built inspections yields a variety of benefits not available with conventional methods.

• Real-time problem detection: By using AR, construction defects or deviations from the design can be discovered immediately on the spot, allowing prompt corrective action. For example, areas with insufficient pavement thickness or slope can be color-coded on the AR display immediately after construction, enabling additional placement or trimming the same day. Detecting and addressing issues on site minimizes rework and prevents quality defects from being left unaddressed.

• Reduced work time and labor savings: Traditional inspection work—measuring point by point with surveying equipment while referring to paper drawings—is replaced by an intuitive method of holding a digital model up on site with AR. Because as-built conditions across a wide area can be visualized at once, inspections that used to take several days can be greatly accelerated. Also, since one person can complete measurement and verification, staffing arrangements are simplified, resulting in labor savings.

• Addressing labor shortages: Even without relying on specialized surveyors or veteran technicians, site personnel can evaluate as-built conditions on the spot. AR apps are simple to operate; following on-screen prompts completes measurement and inspection. Because special skills are not required, AR prevents work from becoming person-dependent and allows less-experienced staff to perform high-accuracy inspections.

• Cost reduction: AR using smartphones or tablets eliminates the need to newly purchase expensive total stations or GNSS surveying equipment. Conventional surveying instruments often require initial investments on the order of several million yen, but now a centimeter-level positioning environment (cm level accuracy, half-inch accuracy) can be built at low cost simply by combining existing mobile devices with relatively inexpensive GNSS receivers. Maintenance costs of dedicated equipment and transport expenses to sites can also be reduced.

• Improved measurement accuracy and reliability: AR reduces risks of human measurement errors and recording mistakes. There is no need to handwrite results on site and transcribe them in the office; digital data can be compared directly, eliminating human error. Furthermore, combining AR with high-precision positioning techniques such as RTK-GNSS yields centimeter-level accuracy aligned to public coordinate systems, enabling more reliable as-built verification than before.

• Efficient recording and reporting: AR lets you preserve inspection results as visual data, making report creation easier. For example, including AR screen screenshots or difference heatmap images directly in inspection reports creates far more understandable documentation than listing numbers alone. Ministry of Land, Infrastructure, Transport and Tourism field demonstrations have confirmed that AR can simplify submission documents such as as-built drawings. Because records remain as digital data, later review is easy and reporting burdens are reduced.

• Improved consensus-building and communication: AR visualization also enhances information sharing and consensus-building both on and off site. Overlaying the completed image on the actual landscape through a tablet makes explanations smoother during client inspections. Presenting as-built conditions and measurement results in AR reduces divergences in understanding with the client and allows immediate agreement on corrective measures. The ministry’s surveys show AR being used not only for construction management but also for pre-construction resident briefings and information sharing with subcontractors. In this way, introducing AR inspection contributes to smoother communication.

Use cases of AR inspection

AR-based inspections are beginning to be used in various ways on actual surveying and construction sites. Here are some representative scenarios.

• Confirmation of rebar and structure positions: AR is useful for rebar inspection before concrete pouring and for checking positional shifts in structures during construction. For example, when checking whether a column’s rebar arrangement is correct, displaying the rebar layout model in AR on the spot to check counts and spacing replaces the traditional practice of measuring with a tape measure. Overlaying the design 3D model onto the real object can detect even small deviations, allowing construction to proceed while ensuring accuracy. There are reported cases where AR onsite checks discovered rebar mistakes early, reducing rework and material waste.

• As-built inspection of pavement thickness and slope: In road paving, combining AR with point-cloud measurement enables areal evaluation of as-built conditions over wide areas. Immediately after paving, scanning the surface with a smartphone’s built-in LiDAR scanner to obtain a high-density point cloud and overlaying the design 3D model allows creation of a color-coded heatmap of elevation differences on site. This makes it possible to determine at a glance whether pavement thickness across the entire work section is within design tolerances, and to detect unevenness (surface bumps) or insufficient thickness without omission. Because longitudinal slope and width can be measured directly on the acquired point cloud, inspections can be completed safely and quickly; some sites have achieved zero later rework.

• Verification of buried utilities and other hidden objects: Buried pipes and cables that become invisible after backfilling can be confirmed with AR as if viewing through the ground. For example, in a sewer pipe project, pipes were 3D-scanned before backfilling and accurate position and depth point-cloud data were stored in the cloud; after burial, anyone could understand the underground pipe routes and depths simply by holding up a smartphone. This eliminated the need to mark the ground immediately after burial and enables safe excavation that avoids buried objects during future maintenance using AR displays. The ability to visualize the invisible is one of AR inspection’s major advantages.

• Use of slope and terrain models: On steep slope works or large-scale earthworks, combining 3D scanning and AR display for as-built management increases safety and efficiency. For instance, scanning a slope before construction to obtain baseline data and rescanning after construction or post-disaster allows immediate calculation of collapsed soil volumes or changes in embankment volume. Tasks that previously took days to compute can be completed in minutes, aiding recovery plans and as-built evaluation. Overlaying the derived terrain point-cloud model on the site via AR lets all workers intuitively share hazardous areas or anchor reinforcement positions. Visualizing terrain and structure 3D data with AR enables safe and reliable as-built management and anomaly detection over wide areas and at heights.

Key points for implementing AR inspection

To effectively embed AR-based inspections on site and maximize implementation benefits, consider the following points in advance. Addressing these will facilitate smooth on-site use.

• Ensure high-precision alignment: Accurate alignment between digital models and real space is crucial to correctly overlay digital models with AR. On large sites or long objects, even slight misalignment can lead to major errors. Use GNSS-based RTK positioning or calibration with known control points to consistently align models and real space to centimeter-level accuracy. Using an RTK-compatible AR system allows projection of models without placing ground reference markers, and provides stable displays that do not drift even when operators move around.

• Prepare 3D design data: AR inspection requires design 3D models (BIM/CIM data) for comparison. If 3D data are not available from the start, you can create simple models from 2D drawings or perform LiDAR scanning of the site to acquire point-cloud data for digital comparison. The ministry’s CIM initiatives will likely increase the number of projects that prepare 3D data from the design stage. It is important to become familiar internally with handling 3D data as early as possible.

• Integrate into operational workflows: To prevent AR inspection from becoming a one-off demonstration and instead make it part of standard site operations, decide in advance “when, who, and at which process will it be used.” For example, include procedures such as “use AR for rebar inspection before concrete placement” or “check as-built conditions with AR after each embankment completion” in construction plans and inspection checklists. Also determine rules for how AR-verified content will be recorded and reflected in reports. Automatically attaching date/time and position information to AR screenshots and saving them to the cloud makes them convenient evidence for inspection forms. Incorporating AR into existing quality management flows will make it a familiar tool for everyone on site.

• Training for site staff: To eliminate psychological resistance to new technology, it’s important that site staff understand how to use AR and its benefits. Start with ICT-savvy personnel and trial AR inspections on small tasks. Demonstrating operation and letting staff experience that “anyone can measure by following on-screen prompts” is crucial. Recent AR apps are intuitive and easy to learn with short training sessions. Share operation procedures through in-house training and on-the-job training so veteran staff can also realize the benefits, enabling smooth acceptance.

• Phased introduction and effect verification: Rather than rolling out AR across all sites and processes at once, initially introduce AR inspection experimentally on a subset of sites or specific processes to verify effects and issues. For example, trial AR measurements in parallel with conventional methods on a particular section and show data on efficiency gains and error reductions compared to the traditional approach to obtain internal and external buy-in. Start small to accumulate know-how; if issues (such as equipment handling or accuracy verification) are found, improve them before company-wide rollout. Preparing manuals and checklists based on demonstration results will make subsequent expansion to other sites smoother.

• Use cloud services: Using cloud services linked to AR apps lets you instantly save and share measurement data, point-cloud models, photos, and more. This enables real-time information sharing between site and office and allows people in remote locations to check as-built conditions on AR screens. With team members able to view and comment on the latest data in the cloud, instructions for corrective work or additional investigations can be issued quickly. Data are also accumulated in the cloud as a history, allowing reference for future projects or use as evidence if problems arise. When introducing AR, actively use cloud integration to centralize data management and facilitate smooth information sharing.

Challenges and countermeasures when introducing AR inspection

AR technology brings many benefits, but there are also challenges to consider during introduction and operation. The main concerns and countermeasures are summarized below.

• Concerns about accuracy: A common concern is, “Can AR really measure accurately?” Indeed, decisions cannot be trusted if alignment is off, so accuracy management is important. Countermeasures include using GNSS RTK corrections and strict calibration with known points to eliminate misalignment between the digital model and real space. Integrating GNSS rovers with AR allows precise spatial overlay of design data and actual as-built conditions; when operated properly, checks can be performed at accuracy comparable to traditional surveying (plane and height within a few centimeters (within a few in)). In the early stages of introduction, use conventional measurements at key points in parallel to verify errors and ensure accuracy.

• Effort to prepare digital data: AR requires comparison 3D models or point-cloud data, and preparing these can be time-consuming. While BIM/CIM and 3D data are increasingly common, many small- to medium-scale projects still lack 3D models. In such cases, LiDAR-scanning the site to obtain point-cloud data can produce an impromptu 3D model. There are also apps that can create simple AR models from 2D drawings. The ministry’s guidelines encourage transition to three-dimensional measurement techniques for as-built management, so digital data will become easier to obtain over time. Although preparation may feel burdensome at first, once data are organized they will aid subsequent process management and future maintenance; treat digitalization as an investment.

• Dealing with devices and site environments: Prepare for physical challenges of using smart devices outdoors. For example, screens can be hard to see in direct summer sunlight and batteries can drain quickly in high temperatures. Use tablet sunshades or carry mobile batteries as countermeasures. For rainy conditions, have waterproof cases or water-resistant covers. In dusty environments, clean camera and sensor areas frequently. If holding a tablet for long periods is difficult, consider using a neck-mounted holder. Adopting accessories and operational methods suited to the site environment will make devices easier to use and maximize AR’s benefits.

• Resistance from site staff: Psychological barriers to new technology are real. Veteran workers may say they feel safer relying on traditional manual methods. The most effective remedy is letting them experience AR and see its benefits firsthand. Share specific results such as “measurements that used to take half a day were completed in 30 minutes” or “a previously missed rebar error was discovered on the spot.” Tools like LRTK that enable “anyone to perform surveying alone” can turn two-person operations into single-person tasks and are often welcomed on site. Start with younger employees, let them use the tools, and spread the convenience across the site to gradually reduce resistance.

• Introduction cost and ROI: New equipment and software entail costs, but AR can leverage existing smartphones and tablets, significantly lowering the initial investment barrier. As noted above, you can start with costs for GNSS receivers and software subscriptions rather than purchasing expensive dedicated surveying equipment. Considering reductions in rework and labor costs, payback on investment can be expected relatively early. For those concerned about cost-effectiveness, begin with limited introduction and demonstrate visible results (e.g., percentage reduction in work time, decrease in number of defect reports) to stakeholders. Calculating ROI based on actual outcomes will help persuade management and clients and support further investment decisions.

• Application to official inspections: Currently, as-built management guidelines may still require conventional measurements and drawing creation to be performed in parallel. Some inspectors may be reluctant to accept inspection approval solely based on AR displays on a tablet. However, the ministry has already confirmed the effectiveness of AR-assisted on-site as-built inspections through field demonstrations, and AR-based labor-saving methods are expected to be incorporated into official guidelines going forward. Even now, using software that automatically generates as-built documents from AR-acquired point clouds and photos can effectively allow inspection completion with AR measurements alone. The key is to appropriately explain AR inspection results to clients and inspectors to gain their understanding. For example, showing an as-built heatmap on a tablet during inspection can demonstrate quality more persuasively than paper drawings. With growing public–private understanding of AR, early adopters who accumulate know-how will gain future advantages.

Simple surveying with LRTK

A solution gaining attention for making AR-based inspections easier and more accurate is “LRTK.” LRTK is a modern tool comprising a small GNSS receiver that attaches to a smartphone and a dedicated app, enabling centimeter-level high-precision positioning (cm level accuracy, half-inch accuracy) via RTK positioning with minimal effort. It is a next-generation system that allows surveying tasks—previously requiring expensive specialized equipment and skilled operators—to be completed by a single person. It supports CLAS corrections from the Japanese quasi-zenith satellite “Michibiki” and network-type RTK, maintaining stable high accuracy even in mountainous areas lacking communication coverage. In short, a major strength is that, even without a veteran surveyor, you can perform everything from control point measurement to as-built inspection with just a smartphone.

LRTK also integrates seamlessly with AR functionality. Using precise position information from high-accuracy GNSS, 2D and 3D design data can be overlaid exactly onto the local scene, eliminating the tedious alignment work and removing concerns about objects drifting on the screen. For example, simply walking around the site with a tablet can accurately display the virtual stake positions from the design model on the actual ground, allowing target coordinates to be visually identified at distant points in a single glance. It is also possible to automatically overlay acquired point-clouds of current conditions and the design model in the LRTK cloud for difference comparisons, enabling instant checks on whether construction is proceeding according to plan.

LRTK provides a cloud platform where measured and scanned data sync in real time. Team members can immediately view the latest 3D point clouds and measurement point information acquired on site from office PCs, enabling collaborative verification among stakeholders. The cloud supports distance, area, and volume measurements and one-click listing of photos linked with positional information. This enables collaboration that transcends the site–office boundary and dramatically improves the efficiency of as-built inspections.

Additionally, LRTK offers a variety of features beyond as-built management, such as a “coordinate navigation” function that guides stake positions so one person can perform staking, functions to compute embankment volumes from LiDAR-acquired point clouds, and sharing of high-precision geotagged photos via the cloud. In other words, LRTK is designed so that surveying, measurement, recording, and as-built inspection—previously performed with multiple devices—can be completed with a single iPhone. Data acquired 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 firms are adopting LRTK to realize both labor savings and quality improvements.

By using an LRTK smartphone surveying + AR system, anyone can readily perform high-precision AR inspections and break through various constraints related to surveying and inspection. Even on sites suffering from labor shortages, combining personal smart surveying tools and AR technology enables shortened work times, reduced human error, and smoother information sharing. These technological innovations strongly support DX in construction sites and are fundamentally changing how as-built management is conducted. The key to succeeding with AR inspection is to incorporate these advanced tools effectively and boost productivity across the entire site. Embrace the latest technologies and let “AR inspection” demonstrate its true value on your sites.

Frequently Asked Questions

Q: What do I need to start AR inspection? A: Basically, you need a smartphone or tablet capable of AR display, a GNSS receiver to improve positioning accuracy, and an AR surveying app compatible with the device. Modern iOS/Android devices have high-performance cameras and sensors suitable for AR. If centimeter-level accuracy is required, combine the device with a small Bluetooth GNSS rover for RTK positioning (there are LRTK devices that attach to smartphones). Also prepare digital data for comparison, such as 3D models created from drawings or point-cloud data obtained by scanning the site. With this setup, you can start trying AR inspection on site immediately.

Q: Can I trust the accuracy of AR inspection? A: Yes—when operated properly, AR can deliver high accuracy and reliability. Systems that use GNSS RTK corrections can achieve positioning accuracy on the order of a few centimeters in both plane and height, which falls within the precision typically required for as-built inspection. Even when confirming differences in AR, heatmap displays provide quantitative information such as “which point is X centimeters higher/lower.” The important points are aligning site control points with the AR space in advance and performing spot checks with traditional methods as needed. Doing so provides sufficient basis to trust AR inspection results.

Q: Is AR inspection possible on sites without 3D design models? A: Yes—with some creativity. There are apps that overlay 2D drawing data (CAD data, etc.) in AR to visualize key lines and positions on site. For relatively simple finished shapes, you can mark key dimensions on site before construction and overlay those markings on AR images as a simple method. However, AR inspection performs best when 3D models are available. Increasingly, CIM models (3D design data) are being created for 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 design drawings, you can also perform difference detection in point-cloud processing software rather than forcing AR—choose the method that best meets the site’s objective of intuitive on-site confirmation.

Q: Can AR inspection results be used for official inspections? A: Currently, using AR as the sole basis for official inspection is still emerging, but AR is increasingly recognized for such use. The ministry conducted field demonstrations in FY2023 and confirmed that AR can allow omission of certain as-built documents. At present, submission of records using conventional methods (drawings and photo logs) is often still required in parallel, but providing AR-derived confirmation as supplementary material helps inspectors understand the results. For example, presenting an AR heatmap that shows “this location is X cm higher/lower than the design” communicates more intuitively than a numerical table. In the future, AR-acquired data itself may be accepted as official deliverables, but for now it is prudent to use AR as supporting evidence while using conventional measurements as needed.

Q: I’m worried whether all site personnel can master this technology. A: AR construction support tools are becoming increasingly user-friendly, and basic operations are not difficult. Many adopting companies report that from young to veteran staff, people can use the tools after short training. If concerns remain, start by having an experienced operator demonstrate on site while others observe and learn. People are more likely to adopt technology once they see the benefits firsthand—“it’s faster” and “it’s easy to understand.” Recent AR apps support Japanese and offer robust support, making it easy to seek help when needed. ICT use on sites is an unavoidable trend, so proceed steadily and create an environment where everyone can use the tools gradually.

Q: Do I need dedicated AR glasses? A: At present, smartphones and tablets are adequate for most practical cases. AR-capable smart glasses (transparent goggles) are emerging but are very expensive and have challenges such as compatibility with safety helmets. Smartphones and tablets, by contrast, can be used on site in dustproof/waterproof cases and are operated easily by screen touch. Device resolution and processing performance continue to improve, and current handheld devices are suitable for business use. If glasses become lightweight and affordable in the future, adoption may expand, but for now, AR with familiar mobile devices is the most practical and cost-effective approach. Start with smartphone-based AR and consider future device expansion as needed.