Thorough Verification of the Effects of Introducing AR Inspection: The Secrets of Labor Saving and Accuracy Improvement

Table of Contents

• What is AR inspection?

• Issues with conventional inspection methods

• Immediate visualization of on-site inspections using AR technology

• Labor savings achieved by introducing AR inspection

• Accuracy improvements achieved by introducing AR inspection

• Other benefits of introduction

• Simple surveying with LRTK

• FAQ

What is AR inspection?

AR (augmented reality) inspection is a method that uses AR technology to overlay digital information such as design drawings and 3D models onto real-world images seen through a smartphone or tablet camera, allowing intuitive on-site confirmation of the finish and quality of structures. On construction sites, it has always been essential after construction to compare completed work against drawings to check “Is it really built as designed?” AR inspection transforms that norm. By simply pointing a smartphone, the completed structure can be displayed in AR on the spot, enabling real-time checks of whether construction matches the design. This dramatically improves the speed and reliability of on-site quality checks and strongly supports the DX (digital transformation) of construction management tasks.

Traditionally, in civil engineering and building works, “as-built inspection” (as-built management) has been a quality assurance process in which the shape and dimensions of completed structures or terrain are measured to confirm they conform to the design, and defects are corrected if found. Typically, heights, thicknesses, and slopes at various locations are measured on site with surveying instruments, and the results are taken back to the office for comparison with drawings to decide pass/fail. However, this method cannot confirm results on site and tends to cause rework, making efficiency a major challenge. AR inspection has attracted attention as the next-generation method to overcome this situation. Driven by initiatives such as the Ministry of Land, Infrastructure, Transport and Tourism’s i-Construction policy and the recent spread of smartphones equipped with high-performance cameras and LiDAR sensors, the environment for using AR in routine construction management is coming together. AR is now proving useful even in inspection work.

Issues with conventional inspection methods

On-site inspection and surveying are indispensable processes for ensuring quality, but conventional methods involved many inefficiencies. The main issues can be summarized as follows.

• Long work times: Because staff measured each inspection location painstakingly with surveying instruments (levels, total stations, etc.), vast amounts of time were required for large sites or many measurement points. It was not uncommon for it to take several days from taking measurements to returning to the office to compare them with drawings and decide pass/fail.

• Dependence on manpower and skilled technicians: Accurate inspection and surveying require experienced technicians, and two-person teams are often necessary. With severe labor shortages and an aging technician workforce, ensuring quality with limited personnel became a heavy burden.

• High equipment costs: To measure with millimeter-level precision, specialized equipment such as total stations or RTK-GNSS receivers is indispensable, and the initial investment often runs into the millions of yen. Costs are also incurred for maintenance and theft prevention, making adoption a high hurdle for small and medium-sized companies.

• Risk of human error: Manual measurement workflows tend to accumulate small errors each time, and transcription mistakes can occur when transferring numbers from field notes to drawings. Later discovery of recording errors can lead to re-measurement and rework.

• Delay in problem detection: Even if construction defects (insufficient thickness, incorrect slope, etc.) exist, conventional methods often cannot detect them on site; problems may only become apparent after data are returned and plotted on drawings—sometimes on the next day or later. Delays in rework can make correction difficult (for example, concrete hardening), leading to extra work and increased costs.

• Burden of report creation: Creating drawings and reports based on field measurements and submitting them was also a major burden. Time spent organizing photos and plotting on drawings meant that the valuable data collected was not always effectively used for quality improvement.

As outlined above, conventional on-site inspection methods suffered from a lack of real-time capability and heavy burdens in terms of personnel and cost. A new inspection method that can capture on-site conditions accurately and in real time was needed.

Immediate visualization of on-site inspections using AR technology

So how does on-site inspection change when using AR technology? By overlaying digital information onto the real world and visualizing as-built confirmations on site—work that used to be performed on drawings—checks can be made immediately. Representative use cases include:

• Overlaying design models in AR: 3D design data for buildings and civil structures (BIM/CIM models, etc.) can be overlaid at full scale onto the site scenery, allowing intuitive confirmation of structure placement and dimensions. You can compare via the camera whether columns or walls under construction are deviating from the design positions. Discrepancies from the intended finished image that are hard to grasp from paper drawings or numerical data can be instantly understood as life-size visuals in AR.

• Heatmap display of as-built deviations: It is becoming common to compare 3D point cloud data of as-built conditions with the design model and display deviations as color-coded heatmaps on site. If a heatmap automatically generated in the cloud is downloaded to a smartphone and overlaid on the camera feed, it becomes immediately obvious which areas are higher or lower than the design. For example, evaluating embankment heights or pavement thickness in area terms and instantly correcting defective sections helps accelerate the PDCA cycle.

• AR “see-through” for buried objects: The positions of underground structures or pipes can be displayed in AR as if viewed through the ground even after backfilling. For instance, by scanning pipes with a smartphone before burial and saving the position-tagged point cloud data to the cloud, anyone can later understand pipe alignment and depth through the screen even after pavement is finished. This allows buried items to be identified on the spot without surface markings or carrying drawings, helping prevent construction mistakes and ensuring safety.

• Other applications: AR can also guide equipment operators by displaying construction extents or elevation criteria, virtually mark concrete placement points in advance, and be used for safety education and training via AR simulations that recreate the site. There are many expanding uses, but in particular AR’s introduction into inspection fields is viewed as a high-potential use case.

Labor savings achieved by introducing AR inspection

How do the above issues get resolved by introducing AR inspection? A major advantage is labor savings and work efficiency on site. Because AR enables confirmation of inspection results on the spot, the time lag from measurement to judgment is eliminated and corrective actions can be taken immediately. If defects are found, rework can be minimized. In practice, dramatic time reductions have been reported, where inspections that used to take half a day were completed in minutes. Real-time results drastically reduce rework and dramatically improve overall work efficiency. Such significant efficiency gains directly contribute to shorter construction schedules and reduced labor costs, improving site-wide cost performance.

Furthermore, AR inspection can be performed by a small number of people and helps alleviate labor shortages. With only a smartphone and an AR app, one person can carry out surveying and inspection, enabling tasks previously requiring two or more people to be done solo. Parts of the work previously dependent on veteran intuition and experience can be supplemented by digital technology, allowing less experienced staff to carry out efficient, high-quality inspections. The ability to achieve both labor reduction and quality assurance on sites suffering from chronic labor shortages is a major strength of AR inspection adoption. Also, because there is no need to purchase expensive specialized instruments, the system can be started with an affordable setup of a smartphone and small devices, yielding advantages in initial costs.

Accuracy improvements achieved by introducing AR inspection

Digital overlay in AR directly contributes to improved inspection accuracy. Because design data can be overlaid on camera footage, subtle finish discrepancies and dimensional shortages or excesses are not overlooked. Even millimeter-level errors that are hard for experienced personnel to notice can be visualized on AR as color-coded heatmaps, allowing intuitive understanding of how many centimeters (in) a given point is higher or lower than the design. For example, if the roadbed height or pavement thickness is scanned with a smartphone to create point cloud data and compared with the design model for color-coded display on the spot, even small unevenness becomes immediately apparent. In this way, anyone can perform reliable inspections without relying on experience, preventing missed quality defects.

Visual inspection via AR also reduces human error. Because it does not rely on reading numbers or handwritten records, transcription mistakes and misreads are less likely. In addition, buried items that become invisible after construction can be accurately located with AR display of pre-acquired 3D data even after backfilling. For example, if a sewer pipe is scanned before burial, its alignment and depth can be checked through a smartphone even after pavement completion, reducing the risk of accidental damage in subsequent processes. By reliably detecting and correcting such small defects, AR inspection greatly contributes to improved construction quality and trouble prevention.

Other benefits of introduction

The benefits of introducing AR inspection extend beyond work efficiency and accuracy improvements. Here are some additional notable advantages.

• Efficient data recording and utilization: Positioning data and site photos are immediately saved and shared to the cloud, eliminating the need to transcribe notes later or recompile reports. Obtained point clouds and coordinate information can be exported in formats that are easy to use in business (CSV, SIMA, LAS, etc.) and smoothly imported into existing CAD and GIS software. Past inspection data can be easily searched and referenced in the cloud, greatly improving the efficiency and accuracy of information management compared with paper records.

• Faster remote sharing and consensus building: AR-visualized inspection results are easy to share with stakeholders who are not on site. By showing and explaining to owners or supervisors on a smartphone or tablet screen, consensus building that used to be done with drawings and reports can be accelerated. It also enables remote presence from afar to grasp the situation and give instructions, advancing DX across the entire inspection process.

• Improved safety: The ability to perform surveying and inspection without entering hazardous areas is another key benefit. For example, the as-built of steep slopes can be checked by viewing heights in AR from below, avoiding the need to approach dangerous areas. Being able to see buried objects through AR also reduces the risk of accidental damage to underground structures during digging. AR inspection contributes to improving on-site safety.

Simple surveying with LRTK

One solution gaining attention for enabling easy on-site AR inspection is LRTK. LRTK is a next-generation surveying system consisting of an ultra-compact RTK-GNSS antenna that attaches to a smartphone and a dedicated app, turning a smartphone into a centimeter-level accuracy (half-inch accuracy) surveying instrument. Real-time kinematic (RTK) satellite positioning corrections reduce GPS errors to within a few centimeters (within a few inches), allowing anyone to perform high-precision positioning and AR display with palm-sized equipment. Combined with the latest smartphone-built-in LiDAR and high-performance cameras, the surroundings can be scanned to obtain 3D point cloud data, and volume calculations, embankment quantity measurements, and buried-pipe depth checks can be completed on site. Acquired point clouds and photos are automatically shared to the cloud, allowing the office to grasp site conditions in real time. No specialized equipment or complex initial setup is required; simply attach the device to the smartphone and launch the app to start high-precision positioning, a convenience that is highly valued on site.

The LRTK series is designed to meet construction and civil engineering site needs, offering strong positioning performance and durability in harsh environments. It supports iOS devices such as iPhone and iPad and is noted as a next-generation solution that meets the requirements promoted by the Ministry of Land, Infrastructure, Transport and Tourism’s i-Construction initiative.

This “one-device-per-person versatile surveying instrument” approach using LRTK for simple surveying is already being introduced at construction sites nationwide, dramatically shortening the time required for surveying and as-built confirmation while being easy enough for non-specialist staff to use. A reasonable price point supports adoption, and it has quietly become a new tool supporting on-site DX. If you have not yet experienced high-precision AR inspection, why not consider introducing LRTK now? Once you experience the labor savings and accuracy improvements, you may find you cannot return to previous methods. The DX of construction management starting with a smartphone will continue to improve on-site productivity and quality assurance.

For product details and consultation on introduction, please see the product information pages and case studies on the [LRTK official site](https://www.lrtk.lefixea.com). Inquiries are accepted at any time, so please feel free to contact us. Let LRTK’s simple surveying evolve your sites toward next-generation construction management.

FAQ

Q: What is AR inspection? A: It is an inspection method that overlays drawings and design data onto site images using AR so you can confirm on the spot whether completed structures are as planned. By visualizing inspections that used to be done with paper drawings and surveying instruments on a smartphone or similar device, it enables real-time, intuitive quality confirmation.

Q: What equipment and preparations are required for introduction? A: Basically, a smartphone or tablet capable of AR display and high-precision positioning, a corresponding high-precision GNSS receiver, and a dedicated AR app are required. For example, attaching an RTK-GNSS device like LRTK to the latest iPhone or iPad enables inspections that combine centimeter-level positioning (half-inch accuracy) with AR functionality. In addition, digital design data such as drawings or BIM/CIM models must be prepared.

Q: Can inspection accuracy be adequately ensured? A: Yes; under appropriate conditions, RTK-GNSS positioning can achieve high accuracy within several centimeters (within a few inches). This allows the measurement precision required for inspections to be met. A GNSS receiver attached to the smartphone receives correction information and overlays 3D models or point cloud data accurately in site coordinates. Demonstrations compliant with the Ministry of Land, Infrastructure, Transport and Tourism’s guidelines have also confirmed the effectiveness of AR-based inspection methods.

Q: How much does introduction cost? A: It is considerably lower than conventional surveying equipment. By leveraging commercial smartphones and adding a small GNSS device, initial costs are roughly equivalent to one high-precision GNSS unit and are very reasonable. Subscription-based usage plans are also available, allowing low-cost operation for only the needed period. Even adopting one device per person can be expected to offer good cost-effectiveness.

Q: Does it comply with Ministry of Land, Infrastructure, Transport and Tourism standards? A: Yes; acquired point cloud data and inspection results can be output and submitted in formats aligned with the ministry’s as-built management procedures. The guidelines actually state that “if as-built measurement results projected on site via AR are used for pass/fail judgment, traditional form submission may not be required,” and AR-based inspection methods are gaining official recognition. Thus, introducing AR inspection on site can be integrated into conventional inspection workflows without issue.

Q: What kinds of sites can it be used at? A: It is used in a wide range of civil and building construction situations. Examples include as-built surveying and earthwork quantity calculations at development sites, pile position setting and batter board verification in roadworks, as-built inspection of structures in bridge and tunnel construction, and 3D recording of disaster-affected areas—essentially any scene requiring high-precision position information. Tasks that used to be outsourced to specialists can now be carried out quickly on site by staff, contributing to shorter schedules and improved quality. Going forward, AR inspection and surveying techniques using smartphones will increasingly become standard tools across diverse sites.