AR As-Built Inspection Anyone Can Do: Accurate Checks Even With Zero Specialized Knowledge

Table of contents

• What is AR as-built inspection?

• Challenges of conventional as-built control

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

• Benefits of introducing AR as-built inspection

• Points to consider when introducing

• Simple surveying realized with LRTK

• FAQ

What is AR as-built inspection?

On construction sites, comparing completed structures to drawings to check “are they really built according to the design?” is a routine task for engineers involved in construction management. In recent years, this routine has been changing thanks to AR (Augmented Reality) technology. By simply pointing a smartphone or tablet, you can overlay design drawings or 3D models at actual scale on the real scene, allowing anyone to intuitively verify on the spot whether the construction matches the plan. This mechanism dramatically improves the speed and reliability of on-site quality checks and powerfully promotes the DX (digital transformation) of construction management. In addition, it is easy for staff with little field experience to use, making accurate as-built checks possible even with zero specialized knowledge — a major advantage.

As-built control is, fundamentally, a quality assurance process in civil engineering and building works that measures and confirms whether completed structures or terrain have been finished in the shapes and dimensions specified by the design drawings. During or after construction, heights, thicknesses, slopes, etc., are measured at specified survey points and the deviations from design values are examined to determine pass/fail. Traditionally, heights and thicknesses were measured using leveling instruments or total stations, and the recorded values were brought back to the office to be checked against drawings. Because results could not be confirmed on site, the work was time-consuming and laborious. As a next-generation method that addresses these issues, AR as-built inspection is attracting attention. By applying AR technology to as-built verification and digitally “visualizing” construction results on site for immediate checks, this method has rapidly entered practical use, supported in part by the Ministry of Land, Infrastructure, Transport and Tourism’s *i-Construction* initiative. The spread of modern smartphones and tablets equipped with high-performance cameras and LiDAR sensors has created an environment where AR can be used in daily operations, and AR is now proving useful in as-built control.

Challenges of conventional as-built control

As-built control is essential for ensuring quality, but conventional methods involved many inefficiencies. Key challenges are summarized below.

• Long work times: Because staff measured each survey point painstakingly with leveling instruments or total stations, vast amounts of time were required when sites were large or survey points were numerous. It was not uncommon for the process of bringing measurement results back and compiling them on drawings to determine pass/fail to take several days.

• Dependence on manpower and skilled technicians: Accurate measurement and judgment require experienced surveyors and other skilled technicians, and two-person teams are frequently needed. With severe staff shortages and an aging workforce, ensuring quality with limited personnel became a major burden.

• High equipment costs: Millimeter-level high-precision measurement requires specialized instruments such as total stations (TS) or RTK-GNSS receivers, which need an initial investment on the order of several million yen. There are also maintenance costs and theft risks, making adoption difficult for small and medium-sized enterprises.

• Measurement errors and recording mistakes: Manual surveying can accumulate small errors or introduce human mistakes when transcribing field notes into drawings. Discovering recording errors at a later date can necessitate re-measurement or remediation.

• Time-consuming report preparation: Creating as-built drawings and reports based on measurements and submitting them to clients is a significant burden for on-site staff. Time spent organizing photos and plotting data on drawings can mean that valuable field data are not fully utilized for quality analysis.

• Delayed discovery of defects: Even if there are construction defects such as insufficient thickness or incorrect slope, they are often not identified immediately and may only become apparent when data are mapped onto drawings the following day or later. By the time a problem is noticed, concrete may have hardened or heavy equipment may have been removed, leading to additional rework and cost.

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

So how can AR technology be used in the field? By overlaying digital information to “visualize” as-builts directly on site instead of checking them on paper drawings, immediate on-site checks become possible. Typical use cases include the following.

• AR overlay of design models: 3D design data (BIM/CIM models, etc.) of buildings and civil structures can be overlaid on the site view, allowing intuitive on-the-spot confirmation of structure placement and dimensions. You can compare through the camera whether columns or walls under construction are offset from their design positions. Misalignments with the completed image that are hard to grasp from paper drawings or numerical data are immediately apparent as life-size visuals in AR.

• Heatmap display of as-built deviations: 3D as-built data obtained after construction (such as point clouds) can be compared with design data and displayed on site as color-coded heatmaps indicating deviations. By downloading a heatmap automatically generated in the cloud that compares the design model and as-built point cloud and overlaying it on the camera view, you can instantly see which areas are higher or lower than the design. This helps speed up PDCA cycles, for example by enabling planar evaluation of embankment or pavement thickness and immediate correction of defects.

• AR visualization of buried objects: The positions of buried structures and pipes can be displayed in AR and checked even after backfilling. For example, in sewer pipe work, scanning the pipe with a smartphone before burial and saving the point cloud with position information to the cloud allows anyone to view the pipe alignment and depth through a smartphone screen even after backfilling. This immediate identification of buried objects without marking the surface or carrying drawings helps prevent construction errors and enhances safety.

• Other applications: Beyond the above, AR can guide heavy equipment operators by displaying construction areas and height standards, pre-mark concrete placement locations virtually, and more. For training, AR reproductions of sites are gaining attention as tools for safety drills and procedural familiarization. Applications are expected to expand, and the combination of as-built management × AR is attracting particular interest as a use case that delivers benefits immediately after introduction.

Benefits of introducing AR as-built inspection

How do the previously mentioned challenges get resolved by introducing AR as-built inspection? Main benefits include:

• Real-time confirmation and rapid remediation: Because as-builts can be checked immediately on site, there is no time lag between measurement and pass/fail judgment. If defects are found, corrective measures can be taken instantly, minimizing rework. Dramatic time reductions have been reported, such as investigations that used to take half a day being completed in about 5 minutes of actual work.

• Improved efficiency and labor savings: With just a smartphone and AR, one person can perform surveying and inspection, greatly improving team productivity. Tasks that relied on veteran experience and intuition can be replaced with technology, enabling anyone to perform efficient, high-quality construction management. This combination of labor savings and quality assurance is a major advantage amid chronic labor shortages.

• Cost reduction: There is no need to purchase expensive surveying equipment; adoption can be achieved with a reasonably priced initial investment such as a smartphone and a compact GNSS device. Further benefits include reduced rework leading to shorter schedules and lower personnel costs. Supplying one device per person often fits within budget, making this a cost-effective solution.

• Improved accuracy and reliability: Centimeter-class positioning (cm level accuracy (half-inch accuracy)) using RTK-GNSS and high-resolution point cloud measurement dramatically increases the reliability of as-built data. Measurement 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 control guidelines. As AR use has begun to be officially recognized, the credibility of inspection documents is increasingly assured.

• Efficient data use and recordkeeping: Measurement data and site photos are saved and shared to the cloud on the spot, eliminating the need to transcribe them into drawings later. Point cloud data and coordinates can be exported in versatile formats such as CSV, SIMA, and LAS, which are easily used in existing CAD software and GIS systems. Past as-built data are easily searchable and accessible in the cloud, greatly improving the efficiency and accuracy of record management compared to paper field books.

• Improved safety: Because measurements can be taken remotely without entering hazardous areas, AR contributes to safety. For example, surveying steep slopes while viewing heights via AR from below reduces risk. AR display of buried objects also lowers the risk of accidentally damaging pipes or cables during excavation. Thus, AR use brings significant benefits not only to work efficiency but also to on-site safety.

Points to consider when introducing

When introducing AR as-built inspection, keep the following points in mind to maximize its effectiveness.

• Phased introduction and internal training: While surveying and checking with AR are intuitive, it is advisable to conduct basic operational training internally during the early stages of introduction and establish usage rules (file naming conventions, sharing procedures, etc.). Start with a small pilot group to verify accuracy and effectiveness before rolling out company-wide. When using for the first time, verifying errors against known control points and deepening understanding of the equipment is effective.

• Combination with existing methods and data linkage: In the early stages, it is reassuring to use AR alongside traditional surveying instruments and methods, comparing measurements obtained with LRTK and those from total stations to understand error tendencies. 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 procedures in advance will help avoid confusion on site.

• Provision of compatible devices: Prepare as high-performance devices as possible to run AR apps and point cloud measurements smoothly. In general, the latest iPhones and iPads and high-end Android devices are recommended, because older models may not support AR processing or LiDAR scanning or may run slowly. Large-screen tablets are suitable for detailed inspection of point cloud data, so consider devices according to use cases.

By addressing these points, AR as-built inspection can be smoothly embedded in site operations. To maximize the benefits of new technology, focus on preparation and the establishment of operating rules.

Simple surveying realized with LRTK

One solution gaining attention for easily implementing AR as-built inspection is LRTK. LRTK is an innovative technology that turns a smartphone into a centimeter-accurate surveying instrument by attaching a compact high-precision RTK-GNSS receiver (antenna) to the phone. Using Real-Time Kinematic (RTK) satellite positioning corrections, it cancels out GPS positioning errors that are normally on the order of several meters (m (ft)) down to a few centimeters (cm (in)), allowing anyone to perform high-precision positioning with palm-sized equipment. Combined with the LiDAR scanner and high-performance cameras built into the latest smartphones, simply scanning the surroundings yields 3D point cloud data, enabling on-site volume calculations, embankment quantity measurements, and buried-pipe depth checks. Obtained point clouds and photo data are instantly shared to the cloud, allowing office staff to grasp site as-builts in real time. No specialized equipment or complicated settings are required — just attach the device to a smartphone and launch the app to start positioning immediately.

LRTK series also supports the Ministry of Land, Infrastructure, Transport and Tourism’s i-Construction initiative, making it an ideal next-generation solution for the digitalization of the construction industry.

LRTK-based simple surveying is penetrating many sites today. Aiming to be the “one-device-per-person versatile surveying instrument,” this system, together with its reasonable price, is already creating a quiet boom. If you have not yet tried high-precision positioning or AR as-built inspection, consider introducing LRTK now. Once you experience labor and efficiency savings, you may never return to previous methods. With as-built management DX starting from 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). Let LRTK’s simple surveying move your site forward into next-generation construction management.

FAQ

Q: What is AR as-built inspection? A: It is an as-built control method that displays drawings and design data as AR in the actual site view so you can verify on the spot whether completed structures match the plan. By digitally visualizing as-built inspection that used to be done with paper drawings and surveying instruments on smartphones, it enables real-time, intuitive quality checks.

Q: What equipment and preparations are required for introduction? A: Essentially, you need a smartphone or tablet capable of AR display and high-precision positioning, a high-precision GNSS receiver, and a compatible application. For example, attaching an RTK-GNSS receiver like LRTK to a modern iPhone or Android device enables as-built inspection by combining centimeter accuracy (cm level accuracy (half-inch accuracy)) position information with AR functionality. In addition, having digitized design data such as drawings or BIM/CIM models is indispensable.

Q: What types of construction and sites can it be used for? A: It can be used across a wide range of civil and building works. For example, in earthworks such as roads and land development it is useful for checking pavement thickness and slope; in concrete structure works it helps verify formwork and embedded component positions; in buried pipe works it checks excavation depths and pipe alignments. AR as-built inspection is useful wherever on-site confirmation of shape or position is needed. Especially in projects with complex shapes or strict precision requirements, AR visualization helps detect problem areas early and delivers significant benefits. Basically, any site with measurement-and-verification tasks can benefit from AR as-built inspection.

Q: Is measurement accuracy sufficient? A: Yes. Positioning using high-precision GPS (RTK-GNSS) keeps errors within a few centimeters, meeting the measurement accuracy required for as-built control. The GNSS receiver attached to the smartphone receives correction information based on control points and accurately overlays 3D models and point clouds to the site coordinates. Validations 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: What should be noted when introducing it? A: Before starting full operation, conduct basic operational training and pilot introductions with a small group to verify equipment accuracy and effectiveness, and then roll out in stages. It is also essential to check errors by comparing with conventional surveying results and to prepare high-performance compatible devices. Furthermore, confirm in advance that the design data to be displayed in AR has appropriate coordinate information and aligns with the site coordinate system. Preparing these elements will help ensure smooth introduction and maximize the benefits of AR as-built inspection.

Q: How much does introduction cost? A: Compared with traditional surveying equipment, the initial cost is considerably lower. Since commercially available smartphones can be used and only a compact GNSS device needs to be added, the initial investment is roughly equivalent to a single high-precision GPS receiver and is very affordable. Subscription plans are also available instead of purchase, allowing low-cost operation for only the required period. Specific pricing depends on feature configuration, but the cost-effectiveness is generally high even when equipping one device per person.