The buzz about impressive implementation effects! 5 benefits AR inspection brings to the field

Table of contents

• What is AR inspection?

• Challenges of conventional on-site inspections

• Benefit 1: Dramatic improvement in work efficiency and labor saving

• Benefit 2: Quality improvement through high-precision checks

• Benefit 3: Reduced rework through real-time correction

• Benefit 4: Smooth communication through intuitive visualization

• Benefit 5: DX promotion through digitization and sharing of data

• How to easily introduce AR inspection

• FAQ

What is AR inspection?

In recent years, introducing AR (augmented reality) technology into construction and infrastructure on-site inspections has been creating a lot of buzz for its impressive effects. But what exactly is "AR inspection"?

AR inspection is a method of performing inspections on-site by holding up a smartphone or tablet to overlay and display digital information such as drawings and 3D models onto the real scene. With AR (short for Augmented Reality), for example, projecting design lines or models in real time over an existing structure allows you to intuitively confirm whether the finished work matches the plan. By overlaying digital information on camera footage to "visualize" it, differences between the actual object and the design become immediately obvious. Inspection tasks that used to require comparing drawings and measurement values are increasingly able to be carried out easily on the spot by anyone through the use of AR.

This AR-based on-site inspection method is attracting attention as a next-generation technology that significantly contributes to labor saving and quality improvement. The push for digitalization in the construction industry through initiatives like *i-Construction* promoted by the Ministry of Land, Infrastructure, Transport and Tourism has also helped, and AR inspection has rapidly reached a practical stage. The spread of the latest smartphones and tablets equipped with high-performance cameras and LiDAR means the environment for using AR in routine inspection work is becoming available. As a true "smart on-site inspection you can do with a smartphone," AR inspection is expected to become even more widespread.

Challenges of conventional on-site inspections

To understand the benefits of AR inspection, let’s first summarize the issues with traditional methods. Conventional on-site inspections (such as as-built management) have required a lot of effort, time, and personnel, and the following problems have been pointed out.

• Time-consuming and labor-intensive work: Measurements and recording were done manually using surveying instruments and tape measures, measuring and recording each dimension point by point. On large sites or where there are many measurement points, it is not uncommon for inspections to take a full day or more. Measurement work usually required teams of two or more people, and securing personnel was a major burden.

• Risk of oversights and errors: Manual work limits the number of points that can physically be measured, so only a subset of representative points can be checked. As a result, there is a risk of overlooking locations that differ from the design. Also, transcription errors (mistakes in writing or omitted records) often occur when transferring values noted on-site to drawings later, creating the risk of re-measurement or corrective work due to mistakes being discovered.

• Delay in defect detection: Traditionally, measurement results were taken back to the office and summarized on drawings or tables before pass/fail judgments were made, so problems tended to be discovered days after construction. For example, even if there is a construction defect such as insufficient concrete thickness, it is often not noticed on-site and is only identified in later inspections. By the time the problem is noticed, the structure may already be completed, causing additional costs and schedule extensions due to rework.

• Administrative burden such as report preparation: Creating drawings and reports to submit to clients based on measurement results also required significant time and effort. Even though data were collected on-site, there were cases where they could not be fully utilized because staff were overwhelmed preparing paper documents.

Thus, conventional on-site inspection methods had many problems such as inefficiency, labor shortages, and quality risks due to errors. AR inspection is expected to be a new approach to solve these problems and enable more efficient and reliable on-site inspections. Next, let’s look at the specific benefits of introducing AR inspection.

Benefit 1: Dramatic improvement in work efficiency and labor saving

The most immediate benefit of introducing AR inspection is a dramatic improvement in on-site work efficiency. By using AR technology, surveying and inspection tasks that used to require two people can be completed by a single person with just a smartphone. For example, where one worker had to measure and another had to record, AR inspection automatically displays measured values and pass/fail results on the device screen, allowing a large reduction in manpower. This is a major advantage for sites chronically short of personnel, enabling labor saving while maintaining quality.

AR also dramatically speeds up the measurement process itself. Because you can perform wide-area 3D scans or continuously acquire data, tasks that previously required painstaking point-by-point measurements become highly efficient. In practice, there are dramatic time savings reported—for example, an investigation that used to take half a day was completed in 5 minutes of actual work. Situations where work halts while waiting for surveying are reduced, and the ability to inspect whenever needed helps keep projects moving smoothly.

Thus, AR inspection simultaneously reduces work time and labor. If the time saved by increased efficiency is applied to other important tasks, overall site productivity can improve. Also, because measurements can be taken from a safe, remote location, the need for personnel to enter dangerous high or confined spaces is reduced, contributing to improved safety. Introducing AR inspection greatly contributes to realizing "smart construction" that allows limited personnel to operate the site safely and reliably.

Benefit 2: Quality improvement through high-precision checks

By using AR inspection, you also gain the benefit of dramatically improved inspection accuracy and strengthened quality control. By checking while viewing design data overlaid on camera footage, subtle differences in height or insufficient thickness that are easy to miss with the naked eye are immediately visualized. Millimeter-level (0.04 in) errors can be displayed on the screen, so even fine defects that experienced craftsmen might miss can be reliably detected and addressed early.

Also, by using high-density point cloud data from LiDAR scanners or photogrammetry, you can measure wide areas in a surface-based manner and check every corner. Areas that could previously only be checked by limited sample points can be covered across the entire site with data, reducing variation in quality. For example, when inspecting pavement flatness, scanning the entire surface and displaying elevation differences as a color map (heat map) lets you see at a glance which points are off from the design by how many cm (in). Visualized data prevent inspection omissions and help standardize construction quality—this is a major strength of AR inspection.

Because full-count checks with digital data become possible, clients and supervisors also gain peace of mind. Inspection result reliability improves and can be shared as solid evidence, helping reduce unnecessary quality disputes. AR inspection thus raises the precision and trustworthiness of quality control and contributes to higher satisfaction with on-site workmanship.

Benefit 3: Reduced rework through real-time correction

Another major advantage of AR inspection is that because results can be checked immediately on-site, rework can be greatly reduced. Traditionally, measurements taken on-site would sometimes only reveal defects after being taken back to the office, requiring rework later. With AR technology, you can confirm the finished work on the spot immediately after construction, making "check on site, correct on site" possible.

For example, immediately after concrete placement you can check thickness with AR; if parts are found to be below the required thickness, additional placement or repair can be done on the spot. This prevents situations where defects are discovered the next day after the concrete has hardened. Eliminating problems on the same day avoids large-scale rework later and reduces the risk of schedule delays.

Being able to inspect and correct in real time means early detection and early response to quality issues. As a result, unnecessary cost increases are also curtailed. When a system is in place that always allows pass/fail confirmation on the spot, site personnel can proceed with work with confidence. AR inspection enhances on-site responsiveness and prevents rework, contributing to smoother project progress and cost reduction.

Benefit 4: Smooth communication through intuitive visualization

Visual inspection information provided by AR also facilitates smoother on-site communication. Compared to reports consisting only of numbers and text, colorful AR overlays on video are intuitively easy for anyone to understand. If all stakeholders gather around a smartphone or tablet screen on-site and view the same AR footage, it becomes immediately clear "which parts and to what extent need to be corrected."

This reduces mismatches in recognition among craftsmen, site supervisors, and workers—or even between contractors and clients—allowing quick consensus building. Without relying on veteran intuition or experience, anyone can make objective judgments based on data, making explanations easier. If constructors and inspectors discuss while viewing the AR screen on-site, sharing of issues progresses smoothly.

Moreover, because data can be shared via the cloud, managers or clients in remote locations can be shown the on-site situation. As described later, uploading photos or point cloud data to the cloud allows visual information to be shared with stakeholders in distant locations. Situations that were difficult to convey by words alone can be shared as the same "visible information" using AR, leading to smoother communication.

Benefit 5: DX promotion through digitization and sharing of data

Introducing AR inspection directly supports digital transformation (DX) of on-site operations. In AR inspection, measurement results and check items are all saved as digital data and can be shared and centrally managed in real time in the cloud. This greatly reduces the burden of record-keeping tasks such as organizing photo ledgers and preparing reports that have long troubled site staff.

As-built data and point cloud models accumulated in the cloud can be easily searched and reused later. Easier reuse of past data that was difficult with paper documents makes it possible to use the data for future maintenance planning or renewal work. Also, the know-how of skilled technicians and on-site insights can be preserved as data, turning person-dependent information into shared assets and aiding skill transfer to the next generation.

Digital data also excels at internal and external information sharing. For example, sharing inspection data in the cloud with clients allows you to explain quality with evidence, helping build trust. If headquarters or supervisors in remote locations can review and provide guidance on as-built data in the cloud without visiting the site, the benefits are significant from the perspectives of work-style reform and promoting telework. AR inspection promotes on-site data utilization and can be a powerful tool to accelerate DX across the construction industry.

How to easily introduce AR inspection

As seen above, AR inspection offers many benefits. So how can you easily start AR inspection on-site? The key is to use tools that can easily acquire high-precision positioning information.

Recently, systems have appeared that allow centimeter-level positioning in the palm of your hand by attaching a small RTK-GNSS receiver (antenna) to a smartphone. For example, LRTK, a venture from Tokyo Institute of Technology, is a solution consisting of a pocket-size GNSS device that can be attached to an iPhone and a dedicated app. Using this, high-precision positioning and point cloud scanning—which previously required specialized equipment—as well as AR-based as-built checks can all be completed with a single smartphone. There is no need for complex equipment operation or settings; just attach the device to the terminal and start the app to begin measurement immediately, which is very convenient.

By using such smartphone-compatible simplified surveying tools, the barrier to introducing AR inspection is drastically lowered. These tools are intuitive enough for technicians without special skills to use, so even small sites and small teams can incorporate AR inspection into daily operations. In fact, lightweight surveying systems like LRTK are spreading through many sites as a "one-device-per-person universal surveying instrument." Because measuring, recording, comparing, and sharing can be done seamlessly with just a smartphone, many users report they cannot go back to the old ways after experiencing the efficiency gains. AR inspection is no longer a special future technology but a familiar tool already usable on-site. Why not take this opportunity to evolve your site to the next stage with smartphone-based AR inspection?

FAQ

Q: If we perform AR inspection, can we trust the positioning accuracy? A: In short, with proper equipment you can obtain sufficiently reliable accuracy. Standard smartphone GPS alone has errors on the order of several meters (several ft), but combining it with RTK-GNSS can improve accuracy to the centimeter level (0.4 in). When displaying AR on-site, measuring the device position with high-precision GNSS and properly calibrating the smartphone's gyro sensors and compass makes it possible to overlay digital information on the real object with minimal offset. In practice, accuracy sufficient for as-built management compliant with standards set by the Ministry of Land, Infrastructure, Transport and Tourism has been achieved.

Q: What preparations and equipment are needed to start AR inspection on-site? A: The basic set is a smartphone (or tablet) + an RTK-capable GNSS receiver + an AR-enabled dedicated app. Prepare the data to be checked—design drawings, BIM/CIM models, etc.—in digital format in advance and load them into the app. GNSS receivers that can receive correction data (base station data) over the internet—network-type receivers—are convenient. If you are outdoors and within a communication area, you can use correction services without setting up your own base station. Once prepared, simply hold the device over the point you want to measure and press a button to record the measurement and perform an AR-based inspection on the spot.

Q: Is AR inspection impossible in places where GNSS cannot be received, such as tunnels or indoors? A: Unfortunately, RTK high-precision positioning cannot be used in environments where GNSS satellites cannot be received directly. However, there are several ways to perform AR inspection even in such environments. One method is to use known points (control points) as AR markers. By adjusting the AR display position according to control points surveyed outdoors in advance, you can achieve relatively high-accuracy overlays even inside tunnels. For indoor use, you can also place markers (QR codes or feature markers) on floors or walls and align the camera footage with them. With some ingenuity, AR inspection can be utilized even in GNSS-denied environments.

Q: I'm worried about the cost of introducing AR inspection. Is a large investment required? A: It is considerably lower cost than purchasing a set of dedicated large surveying instruments. Many sites already own smartphones or tablets, so the main new equipment to procure is often just a small GNSS receiver. This is relatively affordable compared to traditional surveying instruments. Software is also often provided as cloud services that can be subscribed to for needed periods, allowing a small-start approach with low initial investment. Above all, the cost savings from reduced work time and manpower are significant, so the total benefits are expected to outweigh the investment.

Q: If introduced, will site staff be able to use AR inspection right away? Is any special skill required? A: Basic operation is not difficult—just follow the app instructions. For example, in systems like LRTK you simply hold the antenna-equipped smartphone over the point to be measured and press a button to record coordinates, and select the model data from the menu to overlay it for AR checks. However, when first using the system, users need a bit of experience handling the equipment and going through calibration procedures, so a short training session beforehand is recommended. After repeated use on-site, users will pick up the nuances, and without special skills, anyone should be able to use AR inspection in daily operations.