AR出来形検査で実現する省人化：一人でもできる現場検査

目次

• AR出来形検査とは？

• 従来の出来形検査の課題

• AR技術の現場活用：即時チェックの実現

• AR出来形検査のメリット

• 導入にあたってのポイント

• LRTKで実現する簡易測量

• FAQ

AR出来形検査とは？

Construction site engineers routinely verify whether as-built structures conform to the design drawings. Recently, however, this convention is being transformed by AR (Augmented Reality) technology. By simply pointing a smartphone or tablet, design drawings and 3D models can be overlaid onto the real-world view at actual scale, allowing intuitive on-the-spot checks of whether the construction matches the plan. This dramatically improves the speed and reliability of on-site quality checks and strongly supports the DX (digital transformation) of construction management tasks.

First, as-built control (出来形管理) is the quality assurance process in civil engineering and building works that measures and confirms whether completed structures or shaped terrain match the shape and dimensions specified in the design drawings. During or after construction, heights, thicknesses, slopes, and other parameters are measured at designated points, and deviations from design values are assessed for pass/fail. Traditionally, levels and total stations have been used to measure heights and thicknesses, and the data were taken back to the office for comparison on drawings. It was not possible to determine pass/fail on the spot, making the process time-consuming and labor-intensive. As a next-generation solution to these issues, AR as-built inspection has attracted attention. Applying AR technology to as-built control to digitally "visualize" construction results on-site and check as-built conditions instantly has rapidly reached practical use, aided by the Ministry of Land, Infrastructure, Transport and Tourism’s push for ICT construction / i-Construction. 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 an active role in as-built control.

従来の出来形検査の課題

As-built inspection (as-built control) is essential for quality assurance, but traditional methods came with many inefficiencies. Here are the main issues.

• Time-consuming work: Because staff measured each survey point one by one using levels or total stations, large sites or many measurement points required enormous time. It was not uncommon for compiling results on drawings and making pass/fail judgments to take several days.

• Dependence on manpower and skilled technicians: Accurate measurement and evaluation required experienced surveyors, and two-person teams were often needed. With severe labor shortages and an aging workforce, ensuring quality with limited personnel became a major burden.

• High equipment costs: Millimeter-level high-precision measurement requires dedicated instruments such as total stations (TS) or RTK-GNSS receivers, and acquiring them requires an initial investment on the order of millions of yen. There are also maintenance costs and theft risks, making adoption a very high hurdle for small and medium-sized companies.

• Measurement errors and recording mistakes: Manual surveying can accumulate small errors each time, and there is a risk of human error when transcribing field notes into office drawings. Discovering recording mistakes later can lead to re-measurement and rework.

• Effort required for report creation: Creating as-built drawings and reports from measurement results and submitting them to clients is a significant burden for site personnel. Organizing photos and plotting them on drawings takes time, and sometimes field data cannot be fully leveraged for quality analysis.

• Delayed detection of defects: Even if there are construction defects such as insufficient thickness or incorrect slope, traditional methods often mean these are not immediately noticed on-site and only discovered after returning data to the office and producing drawings, sometimes the next day or later. By the time the problem is noticed, concrete may have hardened or heavy equipment may have been removed, causing extra labor and cost due to rework.

As described above, traditional as-built inspection methods faced problems such as a lack of real-time capability and heavy burdens in terms of personnel and cost. It goes without saying that a new method enabling accurate, intuitive, real-time on-site as-built assessment was urgently needed.

AR技術の現場活用：即時チェックの実現

So how can AR technology be used on actual sites? By overlaying digital information to visualize as-built conditions directly on-site—a task previously done in the office with drawings—you can check on the spot instantly. Examples of use cases include:

• AR overlay of design models: 3D design data (BIM/CIM models, etc.) of buildings and civil structures can be overlaid onto the site view, allowing intuitive on-site confirmation of placement and dimensions. You can compare whether columns or walls under construction are out of position relative to the design through the camera. Discrepancies between the finished image and what paper drawings or numeric data make hard to grasp can be immediately understood as life-size visuals in AR.

• Heatmap display of as-built deviations: It is increasingly possible to compare 3D as-built data (point clouds, etc.) with design data and display deviations as a color-coded heatmap on-site. A heatmap automatically generated in the cloud by comparing design models with as-built point clouds can be downloaded to a smartphone and overlaid on the camera view, making it immediately clear which areas are higher or lower than the design. For example, this helps evaluate the finished surface or pavement thickness across an area and quickly correct defects, speeding up the PDCA cycle.

• AR visualization of buried objects: The positions of buried structures and pipes can be displayed as if seen through the ground even after backfilling. For example, in sewer pipe works, scanning pipes with a smartphone before backfilling and saving point cloud data with position information to the cloud allows anyone to see the pipe alignment and depth through the smartphone after backfilling. This makes it possible to identify buried items on the spot without marking the surface or carrying drawings, helping prevent construction mistakes and ensuring safety.

• Other applications: Beyond the above, AR can guide work during heavy equipment operation by displaying construction ranges and height references, virtually mark concrete pour locations in advance, and more. In education and training, AR recreations of actual sites are gaining attention as tools for safety training and procedural practice. While applications continue to expand year by year, as-built control × AR is among the use cases where immediate benefits are often realized right after introduction, earning high expectations from the field.

AR出来形検査のメリット

How do the problems described earlier get resolved by introducing AR as-built inspection? Here are the main advantages.

• Real-time confirmation and rapid correction: Since as-built conditions can be checked on-site immediately, the time lag from measurement to pass/fail judgment is eliminated. If a defect is found, corrective action can be taken on the spot, minimizing rework. There are dramatic time-saving cases reported where surveys that used to take half a day were completed in just 5 minutes of actual work.

• Improved efficiency and labor savings: 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 even less experienced personnel to manage construction quality efficiently. This capacity to achieve labor savings while maintaining quality is a major advantage amid chronic labor shortages.

• Cost reduction: There is no need to acquire an expensive full set of surveying instruments; it can be implemented with a relatively modest initial investment in smartphones and small devices. Additional benefits include shortened schedules and reduced labor costs from fewer reworks. Deploying one smartphone + AR device per person often fits within budget, making this a highly cost-effective solution.

• Improved accuracy and reliability: Centimeter-level accuracy (half-inch accuracy) positioning via RTK-GNSS and high-resolution point cloud measurements dramatically increase the reliability of as-built data. Measurements 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 gains official recognition, the reliability of submitting such digital measurement data as inspection documentation is also sufficiently ensured.

• Data utilization and streamlined recordkeeping: Measurement data and site photos are saved and shared to the cloud on the spot, eliminating post-field transcription to drawings. Collected point clouds and coordinate information can be exported in common formats such as CSV, SIMA, and LAS, and easily imported into existing CAD software and GIS systems. Past as-built data can be readily searched and referenced in the cloud, greatly improving the efficiency and accuracy of record management compared to paper field notebooks.

• Improved safety: Because measurements can be taken remotely without entering hazardous areas, safety is enhanced. For example, in steep terrain surveys you can confirm heights using AR from a distant position downhill, reducing the risk of surveyors leaning onto slopes. Displaying buried objects in AR also lowers the risk of damaging underground pipes or cables during excavation. Thus, AR use brings significant benefits not only to work efficiency but also to on-site safety.

導入にあたってのポイント

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

• Phased introduction and in-house training: While AR surveying and checks are intuitive to operate, during initial implementation it is advisable to conduct basic operation training and establish utilization rules internally. For example, deciding file naming conventions and sharing procedures for acquired data in advance can prevent confusion during operation. Start with trial implementation on a small project to verify accuracy and effectiveness, then roll out company-wide in stages. When first using the system, it is also effective to deepen understanding of the equipment by, for example, verifying positioning errors using known control points.

• Combining with existing methods and data linkage: At the start, it is reassuring to use traditional surveying instruments alongside AR and compare LRTK-obtained measurements with total station measurements to understand error trends. It is also important to test in advance whether cloud-exported data can be smoothly imported into existing CAD software. LRTK supports industry-standard data formats and is highly compatible with existing workflows, but establishing operational flows beforehand will help avoid confusion on-site.

• Provision of compatible devices: To run AR apps and point cloud measurement functions smoothly, prepare the highest-performance devices possible. Generally, the latest iPhone or iPad, or 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 review, so use them according to site needs.

LRTKで実現する簡易測量

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-level accuracy (half-inch accuracy) surveying instrument by attaching a small high-precision RTK-GNSS antenna to the phone. Using Real-Time Kinematic (RTK) correction technology for satellite positioning, GPS errors that are normally several meters (several ft) can be reduced 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, simply scanning the surroundings captures 3D point cloud data, allowing on-site completion of volume calculations, embankment quantity measurements, and checks of buried pipe depth. Acquired point clouds and photos are automatically shared to the cloud, enabling remote offices to check as-built conditions in real time. No specialized equipment or complicated settings are required—just attach the device to your smartphone and launch the app to start positioning immediately.

This LRTK-based simple surveying is steadily spreading across many sites. Developed with the goal of a “one-person, one-universal surveying device,” this system, together with its affordable pricing, has already sparked a quiet boom at many sites. If you have not yet tried high-precision positioning or AR as-built checks, this may be a good opportunity to adopt LRTK. Once you experience the labor and efficiency benefits, 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 implementation, please feel free to contact us at [お問い合わせ](https://www.lrtk.lefixea.com/contactlrtk). Advance your site to next-generation construction management with LRTK’s simple surveying.

FAQ

Q: AR出来形検査とは何ですか？ A: It is an as-built control method that displays drawings and design data as AR on the actual site view so you can confirm on the spot whether constructed structures are as planned. By visualizing as-built inspections digitally with smartphones instead of using paper drawings and surveying instruments, real-time and intuitive quality checks become possible.

Q: AR出来形検査の導入に必要な機材・準備は何ですか？ A: Basically, you need a smartphone or tablet capable of AR display and high-precision 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 as-built checks by combining centimeter-level position information with AR functions. In addition, it is essential to have digitalized design data such as drawings or BIM/CIM models.

Q: 測定の精度は十分確保できるのでしょうか？ A: Yes. Positioning with RTK-GNSS, a high-precision GPS, provides accuracy within a few centimeters (within a few in), 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 cloud data 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: 導入コストはどのくらいかかりますか？ A: Implementation costs are significantly lower than traditional surveying instruments. By leveraging commercially available modern smartphones and adding a small GNSS device, initial costs are roughly equivalent to the price of one high-precision GPS receiver and are very affordable. Subscription-based plans are also available, allowing low-cost operation for only the required period. Specific pricing depends on selected feature sets, but even equipping one device per person often delivers strong cost-effectiveness.

Q: 国土交通省の規格に対応していますか？ A: Yes. Acquired point cloud data and comparison results with design drawings can be output and submitted in formats aligned with the Ministry of Land, Infrastructure, Transport and Tourism’s as-built control guidelines. The ministry’s guidelines even include a sentence stating that “when as-built measurement results are projected on-site using AR and pass/fail judgments are performed, submission of traditional as-built control forms may be unnecessary,” indicating official acceptance of AR-based as-built control methods. Thus, environments are being established where on-site AR checks can be used without issue in inspections.