Frontline AR Inspections on Site: Labor Savings and Accuracy Improvements Achieved by Adoption

Table of Contents

• What is AR inspection?

• Challenges of traditional on-site inspections

• On-site use of AR technology: immediate checks through visualization

• Benefits of introducing AR inspection

• Points to consider when introducing AR

• Simple surveying realized with LRTK

• FAQ

What is AR inspection?

On construction sites, confirming whether completed structures are “really built according to the design” is a routine task for engineers involved in construction management. In recent years, however, this common practice has been changing thanks to AR (Augmented Reality) technology. By overlaying design drawings or 3D models through a smartphone or tablet camera, it has become possible to directly compare physical objects and digital information on the spot. Because you can intuitively check whether the constructed element matches the plan, the speed and reliability of on-site quality verification have improved dramatically, strongly promoting the DX (digital transformation) of construction management.

As-built management on site is a quality assurance process in civil engineering and building works that measures and verifies whether completed structures and terrain conform to the shapes and dimensions specified in design drawings. Height, thickness, slope, and other parameters are measured at specified survey points during or after construction, and the deviations from design values are checked to judge pass/fail. Traditionally, measurements were taken with surveying instruments such as levels or total stations, and the data were brought back to the office for comparison on drawings. AR-based on-site inspection (so-called as-built AR checks) is attracting attention as a next-generation method that solves the problems of conventional approaches, which cannot be checked on-site and are time-consuming. Driven in part by the Ministry of Land, Infrastructure, Transport and Tourism-led i-Construction initiative, this method has rapidly reached practical use in recent years. The spread of modern smartphones equipped with high-performance cameras and LiDAR sensors has created an environment where AR can be used in daily work, and now the era in which AR inspections play an active role on site has arrived.

Challenges of traditional on-site inspections

On-site inspections (as-built management) are essential for ensuring quality, but conventional methods have been accompanied by many inefficiencies. Here are the typical challenges.

• Long working hours: Because staff measured each survey point painstakingly using levels or total stations, a large site or many survey points required enormous amounts of time. It was not uncommon for it to take several days to bring measurement results back and determine pass/fail on drawings.

• Dependence on manpower and skilled technicians: Accurate measurement and evaluation require experienced surveyors, and two-person teams are often necessary. With severe labor shortages and an aging workforce, ensuring quality with limited personnel has become a major burden.

• High equipment costs: Achieving high precision at the millimeter level requires specialized instruments such as total stations or RTK-GNSS receivers, which require an initial investment on the order of several million yen. Maintenance costs and theft risk are also non-negligible, making adoption very difficult for small and medium-sized enterprises.

• Measurement errors and record mistakes: Manual surveying can accumulate small cumulative errors each time, and there is a risk of human error when transcribing memoed numbers into drawings. Discovering such mistakes later can lead to re-measurement and rework.

• Laborious report creation: Creating as-built drawings and reports based on measurement results and submitting them to clients was also a significant burden for site staff. Time spent organizing photos and plotting on drawings sometimes prevents site-acquired data from being fully utilized for quality analysis.

• Delayed discovery of defects: Even when construction problems exist, such as insufficient concrete thickness or incorrect slopes, they are often not noticed on-site and are discovered after returning with the data, sometimes the next day or later. By the time the problem is noticed, the structure may have hardened or heavy machinery may have been removed, resulting in extra rework and costs.

As described above, conventional on-site inspection methods suffer from a lack of immediacy and heavy burdens in terms of personnel and cost. There was a clear need for a new method that enables real-time, accurate, and intuitive grasp of as-built conditions.

On-site use of AR technology: immediate checks through visualization

So how can AR technology actually be used on site? By overlaying digital information on the real scene and directly “visualizing” inspection and measurement confirmation tasks that used to be done on paper drawings, immediate checks become possible. Examples of use cases include the following.

• AR overlay of design models: Display 3D design data (BIM/CIM models, etc.) of buildings and civil structures over the on-site scenery to intuitively confirm structure placement and dimensions. It is possible to compare through a smartphone camera whether columns or walls under construction have shifted from their design positions. Discrepancies with the envisioned completed image that are hard to grasp with paper drawings or numerical data can be instantly perceived as life-size visuals in AR.

• Heatmap display of as-built deviations: There is growing use of comparing post-construction 3D as-built data (point clouds, etc.) with design data and viewing deviations as color-coded heatmaps on-site. If a heatmap automatically generated by comparing design models and as-built point clouds in the cloud is downloaded to a smartphone and overlaid on the camera view, it becomes obvious at a glance which areas are higher or lower than the design. For example, this helps speed up the PDCA cycle by evaluating embankment or paving thickness over areas and immediately correcting defective locations.

• AR visualization of buried objects: The positions of structures or pipes buried underground can be displayed as if “see-through” with AR even after backfilling. For example, in sewer pipe work, scanning pipes with a smartphone before burial and storing point cloud data with location information in the cloud allows anyone to understand pipe alignment and depth through a smartphone screen even after backfilling. Because you can identify buried objects immediately on-site without marking the surface or carrying drawings as before, this helps prevent construction mistakes and ensures safety.

• Other applications: AR can also guide operations by displaying construction ranges or elevation criteria during heavy equipment operation or virtually mark concrete pour locations in advance. In building services work, attempts have emerged to streamline sleeve location checks by integrating AR technology with the cloud, enabling efficient completion with just a tablet. For training, AR-based safety drills and task familiarization tools that recreate site conditions are attracting attention. Uses are steadily expanding, and in particular the combination of as-built management and AR is gaining high expectations from sites as a use case that can deliver results immediately after introduction.

Benefits of introducing AR inspection

If you introduce as-built checks using AR (AR inspection) on site, how will the issues described above be resolved? Here are the main benefits.

• Real-time verification and rapid rework: Because you can check as-built conditions immediately on site, the time lag from measurement to pass/fail determination is eliminated. If a defect is found, corrective action can be taken immediately, minimizing rework. There are reported cases of dramatic time reduction, such as investigations that used to take half a day being completed in an actual working time of 5 minutes.

• Increased efficiency and reduced manpower: With just a smartphone and AR, one person can perform surveying and inspection, dramatically improving team efficiency. Tasks that relied on veteran experience and intuition can be replaced by technology, enabling anyone to efficiently perform high-quality construction management. This ability to achieve both labor savings and quality assurance amid chronic labor shortages is a major advantage.

• Cost reduction: You do not have to purchase a full set of expensive surveying equipment; the ability to introduce the system with an affordable initial investment consisting of smartphones and small devices is attractive. Further benefits are expected from shortened schedules and reduced labor costs due to fewer reworks. In many cases, equipping one person with one smartphone AR system fits within the budget, making this a highly cost-effective solution.

• Improved accuracy and reliability: Centimeter-level accuracy achieved by RTK-GNSS positioning and high-resolution point cloud measurements dramatically increases the reliability of as-built data collected. Measurement values are automatically saved in the cloud and can be output and used in formats compliant with the Ministry of Land, Infrastructure, Transport and Tourism’s as-built management guidelines. AR use has begun to be officially recognized in recent years, and the reliability of inspection documents based on digital data can be sufficiently assured.

• Data utilization and streamlined recordkeeping: Measurement data and site photos are saved and shared to the cloud on-site, eliminating the need to transcribe data into drawings later. Point cloud and coordinate data can be output in commonly used formats such as CSV, SIMA, and LAS, and smoothly imported into existing CAD software and GIS systems. Past data can be easily searched and referenced in the cloud, greatly improving recordkeeping efficiency and accuracy compared with paper field notebooks.

• Improved safety: Since measurements can be taken remotely without entering hazardous areas, AR contributes to safety assurance. For example, surveying steep slopes can be done by confirming heights with AR from below, reducing the risk of going to high places. AR visualization of buried objects also reduces the risk of accidentally damaging pipes or cables during excavation. Thus, AR use delivers major benefits not only in operational efficiency but also in site safety.

Points to consider when introducing

When newly introducing AR inspection (as-built AR checks), consider the following points to maximize effectiveness.

• Phased introduction and internal training: Although AR-based surveying and checks are intuitive to operate, it is smoothest to conduct basic operation training and establish usage rules within the company during the initial introduction. For example, deciding on file naming conventions and sharing procedures for acquired data in advance prevents operational confusion. Start with a small pilot group to verify accuracy and effectiveness, and then roll out company-wide in stages—the key to success. When using the system for the first time, it is also effective to deepen understanding of the equipment by verifying errors at known control points.

• Coexistence with existing methods and data linkage: In the initial phase, it is reassuring to use conventional surveying equipment and methods in parallel and cross-check measurements obtained with LRTK against those from total stations to understand error trends. It is also important to test in advance whether data exported from the cloud can be smoothly imported into existing CAD software. LRTK supports industry-standard data formats and has high compatibility with existing workflows, but preparing operational flows in advance helps avoid confusion on site.

• Provision of compatible devices: To run AR apps and point cloud measurements comfortably, prepare as high-performance devices as possible. Generally, the latest iPhone or iPad and high-end Android devices are recommended. Older models may not support AR processing or LiDAR scanning or may run slowly. Large-screen tablets are suitable for detailed point cloud inspection, so use them as appropriate for your purposes.

Simple surveying realized with LRTK

One solution attracting attention for easily implementing as-built AR checks (AR inspection) is LRTK. LRTK is an innovative technology that transforms your smartphone into a centimeter-level accuracy surveying instrument by attaching a compact high-precision RTK-GNSS antenna to the phone. Real-time kinematic (RTK) satellite positioning corrections reduce typical smartphone GPS errors of several meters (several ft) down to a few centimeters (a few inches), allowing anyone to perform high-precision surveying with palm-sized equipment. Combine this with the LiDAR scanner and high-performance cameras built into the latest smartphones, and you can obtain 3D point cloud data simply by walking around the site and complete tasks on the spot such as volume calculations and as-built measurements like embankment quantity measurements and buried pipe depth checks. Acquired point cloud data and photos are automatically shared to the cloud, enabling real-time confirmation of on-site as-built conditions from the office. No specialized equipment or complicated setup is required—just attach the device to your smartphone and launch the app to start positioning immediately.

LRTK-based simple surveying is gradually spreading across many sites. Aiming for a “universal surveying instrument, one per person,” this system, combined with its reasonable pricing, has already sparked a quiet boom at many sites. If you have not yet tried high-precision positioning or AR checks, why not introduce LRTK now? Once you experience the labor savings and efficiency gains, you may find it hard to return to previous methods. By starting as-built management DX with a smartphone, site productivity and quality assurance will continue to improve.

For product details or inquiries about introduction, please feel free to [contact us](https://www.lrtk.lefixea.com/contactlrtk). Advance your site to next-generation construction management with LRTK’s simple surveying.

FAQ

Q: What is an as-built AR check? A: It is an as-built management method that AR-displays drawings and design data on the real site scenery to confirm on the spot whether constructed structures comply with the plans. By digitally visualizing on-site as-built inspection—previously done with paper drawings and surveying equipment—via smartphones and the like, real-time and intuitive quality verification becomes possible.

Q: What equipment and preparations are required to introduce as-built AR checks? A: Essentially, you need a smartphone or tablet capable of AR display and positioning, a high-precision positioning device, and a compatible application. For example, attaching an RTK-GNSS receiver like LRTK to a recent iPhone or Android device allows you to combine centimeter-precision location information with AR functionality for as-built checks. In addition, having design data digitized—such as drawings or BIM/CIM models—is indispensable.

Q: Can measurement accuracy be sufficiently ensured? A: Yes. RTK-GNSS positioning provides accuracy within a few centimeters (within a few inches), meeting the measurement accuracy required for as-built management. A GNSS receiver attached to a smartphone receives correction information based on control points to accurately align 3D models and point clouds with site coordinates. Validations conforming to the Ministry of Land, Infrastructure, Transport and Tourism’s guidelines have been conducted, confirming the effectiveness of AR-based as-built inspection methods.

Q: How much does it cost to introduce? A: Introduction costs are significantly lower than those for conventional surveying equipment. By leveraging a commercially available recent smartphone and adding a compact GNSS device, initial costs are roughly equivalent to a single high-precision GPS receiver and are very reasonable. Subscription-based usage plans are also available, allowing low-cost operation for only the periods needed. Exact pricing depends on feature configuration, but equipping each person with one device generally offers good cost-effectiveness.

Q: Does it comply with Ministry of Land, Infrastructure, Transport and Tourism standards? A: Yes. Acquired point cloud data and the results of comparisons with drawings can be output and submitted in formats that conform to the ministry’s as-built management guidelines. The ministry’s guidelines even include wording to the effect that when as-built measurement results are projected on-site by AR for pass/fail determination, submission of traditional as-built management forms may not be required, and AR-based as-built management methods are being officially recognized. Given this background, introducing AR checks on site can be operated without problems in inspection workflows.