Construction Site DX Starts with AR Inspections: How to Dramatically Streamline As-Built Inspections

Table of Contents

• What is AR inspection (as-built inspection using AR)?

• Challenges of traditional as-built inspections

• On-site use cases of AR inspection: immediate checks through digital visualization

• Benefits of introducing AR inspection

• Key points for introducing AR inspection

• Simple surveying with LRTK

• FAQ

What is AR inspection (as-built inspection using AR)?

On construction sites, checking whether completed structures match the design is a routine task for engineers involved in construction management. Lately, however, this common practice is being transformed by *as-built inspections* that utilize AR (Augmented Reality)—in other words, AR inspection. By overlaying design drawings or 3D models at actual scale through a smartphone or tablet camera, you can intuitively verify on the spot whether the work matches the plan. This dramatically increases the speed and reliability of on-site quality checks and strongly advances the DX (digital transformation) of construction management.

As-built management (as-built inspection) is a quality assurance process in civil and building works that measures and confirms whether completed structures or terrain are finished to the shapes and dimensions specified in the design drawings. During or after construction, measurements such as elevation, thickness, and slope are taken at prescribed survey points and errors from design values are checked to determine pass/fail. Traditionally, elevations and thicknesses were measured using levels or total stations (TS), and the results were taken back to the office to be compared on drawings. This work, which could not be verified on site, was time-consuming and labor-intensive. A next-generation method attracting attention to solve these issues is as-built AR checking. By applying AR technology to as-built management and digitally “visualizing” construction results on site for immediate checking, this method has rapidly moved into practical use in recent years, driven in part by the Ministry of Land, Infrastructure, Transport and Tourism’s *i-Construction* initiative. The spread of modern smartphones equipped with high-performance cameras and LiDAR sensors has created an environment where AR can be used in daily tasks, and AR is now playing a role in as-built management.

Challenges of traditional as-built inspections

As-built management is indispensable for ensuring quality, but traditional methods come with many inefficiencies. Here are the representative challenges.

• Time-consuming work: Staff measured each survey point one by one with levels or total stations, brought the results back, compiled them on drawings, and then judged pass/fail. For large sites or many survey points, this required enormous time. It was not uncommon for several days to pass between measurement and judgment.

• Dependence on manpower and skilled technicians: Accurate measurement and evaluation require experienced surveyors, and two-person crews are often necessary. With severe labor shortages and an aging workforce, maintaining high quality with limited personnel imposed a heavy burden.

• High equipment costs: To measure with millimeter-level precision (around 0.04 in), dedicated equipment such as total stations or RTK-GNSS receivers is indispensable, but these come with very high upfront investments. There are also maintenance costs and theft risks, making adoption difficult for small and medium-sized enterprises.

• Measurement errors and recording mistakes: Manual surveying inevitably accumulates small errors and involves human errors when transcribing numbers noted on site into drawings. There is always the risk of discovering mistakes later and having to re-measure or rework.

• Time-consuming report preparation: Preparing as-built drawings and reports for clients based on measurement results was also a major burden for site personnel. Sorting photos and plotting on drawings took a lot of time, and in some cases the data collected was not fully leveraged for quality analysis.

• Delay in defect detection: Even when construction defects such as insufficient thickness or improper slope existed, they were often not noticed on site and were identified only after returning to the office and plotting data on drawings. By the time problems were discovered, concrete might already have hardened or heavy machinery might have been removed, leading to rework and extra labor and cost.

As described above, traditional as-built inspections lacked immediacy and imposed heavy burdens in terms of personnel and cost. A new method that enables real-time, accurate, and intuitive as-built understanding was needed.

On-site use cases of AR inspection: immediate checks through digital visualization

How can AR technology actually be used on site? By overlaying digital information to visualize as-built data directly on site—a task previously done on drawings—you can perform immediate checks there and then. Typical use cases include:

• AR overlay of design models: 3D design data for buildings or civil structures (BIM/CIM models, etc.) can be overlaid on the site view so the location and dimensions of structures can be intuitively checked on the spot. You can compare via the camera whether columns or walls under construction have shifted from their design positions. Gaps between the planned completion image, which are hard to grasp from paper drawings or numeric data, become instantly obvious as life-size visuals in AR.

• Heatmap display of as-built deviations: Work is also beginning in which 3D as-built data (point clouds, etc.) obtained after construction are compared with design data and displayed on site as a color-coded heatmap of deviations. If an automatically generated heatmap—created by comparing the design model and as-built point cloud in the cloud—is downloaded to a smartphone and overlaid on the camera view, it becomes immediately clear which areas are higher or lower than designed. For example, this helps evaluate the finishing of embankments or pavement thicknesses in a surface-based manner and enables immediate correction of defects, speeding up the PDCA cycle.

• Visualization of buried objects in AR: The positions of underground structures or pipes can be displayed in AR for verification even after backfilling. For example, in sewer pipe work, scanning the pipe with a smartphone before burial and saving position-attached point cloud data to the cloud allows anyone to view the pipe’s alignment and depth through the smartphone screen even after backfilling. This makes it possible to identify buried objects on the spot without marking the ground or carrying drawings, contributing to error prevention and safety.

• Other applications: Beyond the above, AR can guide operators with AR displays of work areas or elevation criteria during heavy equipment operation, or virtually mark concrete pouring locations in advance. In training, AR recreations of sites are attracting attention as tools for safety drills and procedure familiarization. While use cases will continue to expand, as-built management × AR is particularly expected by the field as a use case that delivers visible benefits immediately after introduction.

Benefits of introducing AR inspection

How do AR as-built checks alleviate the challenges described earlier? Here are the main benefits.

• Real-time verification and rapid rework: Since as-built conditions can be checked on site immediately, there is no time lag from measurement to judgment. If defects are found, corrective actions can be taken at once, minimizing rework. There are reported cases of dramatic time savings where investigations that used to take half a day are completed in 5 minutes of actual work.

• Improved efficiency and reduced manpower: With a smartphone and AR, surveying and inspection can be performed by a single person, dramatically improving overall team efficiency. Tasks that once relied on veteran intuition and experience can be replaced by technology, enabling anyone to perform efficient, high-quality construction management. This is a major advantage in maintaining quality while reducing manpower amid chronic labor shortages.

• Cost reduction: There is no need to acquire expensive surveying instruments; introduction is possible with a modest upfront investment in smartphones and small devices. Further savings can be expected from reduced rework, shorter schedules, and lower labor costs. Equipping one device per person often fits within budgets, making this a highly cost-effective solution.

• Improved accuracy and reliability: Centimeter-level positioning (half-inch accuracy) provided by RTK-GNSS and high-resolution point cloud measurements dramatically increase the reliability of as-built data. Measured values are automatically saved to 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. As AR use has begun to be officially recognized, the reliability of AR-based inspection documents has also been sufficiently secured.

• Efficient data utilization and recordkeeping: Measurement data and site photos are saved and shared to the cloud on the spot, eliminating the need to transcribe into drawings later. Point clouds and coordinate data can be exported in common, 업무-friendly formats such as CSV, SIMA, and LAS for smooth import into existing CAD or GIS systems. Past data are easily searchable and referenceable in the cloud, greatly improving the efficiency and accuracy of recordkeeping compared to paper field books.

• Improved safety: Because measurements can be taken remotely without entering hazardous areas, AR contributes to safety. For example, measurements on steep slopes can be checked from below using AR, reducing risk. Displaying buried objects in AR also reduces the risk of accidentally damaging pipes or cables during excavation. AR delivers major benefits not only in efficiency but also in on-site safety.

Key points for introducing AR inspection

When newly introducing as-built AR checking, consider the following to maximize effectiveness.

• Phased introduction and internal training: While AR-based surveying and checking are intuitive to operate, it is smoothest to conduct basic operation training and establish usage rules internally during the initial introduction. Defining file naming conventions for acquired data and sharing procedures in advance prevents confusion during operation. Start with a small pilot to verify accuracy and effectiveness, then roll out company-wide in stages—this is a recipe for success. For first-time use, it is also effective to verify errors at known points to deepen understanding of the equipment.

• Combining with existing methods and data integration: At the start of introduction, it is reassuring to use traditional surveying equipment and methods in parallel and compare measurements obtained with LRTK and total station 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 prevent confusion on site.

• Provide appropriate devices: To run AR apps and point cloud measurement comfortably, provide as high-performance devices as possible. In general, the latest iPhone or iPad and high-end Android devices are recommended. Older models may not support AR processing or LiDAR scanning, or may operate slowly. Large-screen tablets are suitable for checking point cloud details, so use them according to the application.

Simple surveying with LRTK

A solution attracting attention to easily realize as-built AR checks is LRTK. LRTK is an innovative technology that turns a smartphone into a surveying instrument with centimeter-level accuracy (half-inch accuracy) by attaching a small high-precision RTK-GNSS antenna to the phone. By applying real-time kinematic (RTK) satellite positioning corrections, it reduces GPS errors that are typically several meters (several ft) down to several centimeters (several in), enabling high-precision surveying with palm-sized equipment. Combined with the LiDAR scanner and high-performance cameras built into modern smartphones, you can obtain 3D point cloud data simply by scanning the surroundings and complete volume calculations, embankment quantity measurements, and buried pipe depth checks on site. Acquired point clouds and photos are automatically shared to the cloud, allowing real-time verification of as-built conditions from the office. No specialized equipment or complex setup is required—just attach the device to a smartphone and launch the app to start positioning, which is one of its attractive features.

LRTK-based simple surveying is currently spreading across many sites. Aiming to be the “one surveying device per person,” this system, together with its reasonable pricing, has quietly become popular at many sites. If you have not yet tried high-precision positioning and AR checks, consider introducing LRTK now. Once you experience the labor- and efficiency-saving benefits, you may not want to return to the old way. By starting as-built management DX with a smartphone, field productivity and quality assurance are set to improve even further.

For product details or questions about introduction, please feel free to contact us. With LRTK’s simple surveying, your site can move forward to next-generation construction management.

FAQ

Q: What is AR inspection? A: It is an as-built management method that displays drawings or design data in AR over the actual site view to verify on the spot whether completed structures match the plan. By digitally visualizing what used to be done with paper drawings and surveying instruments on devices like smartphones, real-time and intuitive quality checks are made possible.

Q: What equipment and preparations are required to introduce AR inspection? A: Basically, you need smartphones or tablets capable of AR display and high-precision positioning, a high-precision GNSS receiver, and a compatible application. For example, attaching an RTK-GNSS receiver such as LRTK to a modern smartphone allows you to combine centimeter-accuracy positioning with AR functions for as-built checks. In addition, digitized design data such as drawings or BIM/CIM models are essential.

Q: Can measurement accuracy be sufficiently ensured? A: Yes. High-precision GPS (RTK-GNSS) positioning can achieve errors within several centimeters (several in), meeting the measurement precision required for as-built management. The GNSS receiver attached to the smartphone receives correction information based on control points and overlays 3D models or point clouds accurately to site coordinates. Verifications compliant with 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 introduction cost? A: Introduction costs are significantly lower than those of traditional surveying equipment. By utilizing commercial smartphones and adding a small GNSS device, initial expenses are roughly comparable to a single high-precision GPS receiver, making it very affordable. There are also subscription-based plans rather than purchase, allowing low-cost operation only for necessary periods. Specific pricing depends on feature configuration, but it is generally a level where equipping one device per person still yields good cost-effectiveness.

Q: Is it compliant with the Ministry of Land, Infrastructure, Transport and Tourism’s standards? A: Yes. Acquired point cloud data and the results of comparisons with drawings can be output and submitted in formats that follow the ministry’s as-built management guidelines. The guidelines explicitly state that “if as-built measurement results are projected on site with AR for pass/fail determination, submission of traditional as-built management forms may not be required,” and AR-based as-built management methods are increasingly being officially recognized. Thus, introducing AR checks on site can be operated without issues in inspections.

Q: For what kinds of construction or sites is AR inspection effective? A: It is effective wherever you want to verify on-site deviations between design and construction results, whether civil or building works. For instance, in large-scale road or land development works, AR heatmaps are powerful for managing extensive as-built elevations. For structures like tunnels or dams, 3D model comparisons make it easier to inspect thicknesses and shapes. In building works, uses include comparing column and wall positions in structural work with BIM models and checking for interference in piping and ductwork during equipment installation. In short, AR inspection is effective on any site where you want to verify construction results on the spot, and it is especially advantageous where re-measurement and rework costs are high.

Q: Is operating AR inspection difficult? A: Operation is intuitive and even digitally inexperienced young staff can learn it with short training. Measurement and AR display can be performed with a smartphone app as easily as taking a photo, and no special surveying skills are required. The site data used are pre-prepared design models and drawings, so you just select the file in the app and follow the instructions. Tools with thoughtfully designed UIs like LRTK guide users on-screen so anyone can perform accurate as-built checks. Results are shown visually and are easy to understand, making information sharing within the team simple and allowing young engineers to adopt the technology without resistance.