Challenges and Solutions for Introducing AR As-Built Inspections: For Smooth Operation

Table of Contents

• What is AR as-built inspection?

• Issues with traditional as-built management

• Benefits of introducing AR as-built inspection

• Challenges of introducing AR as-built inspection

• Solutions for successful AR as-built inspection implementation

• Simple surveying realized with LRTK

• FAQ

What is AR as-built inspection?

On construction sites, confirming whether a completed structure matches the design is a task that construction managers perform routinely. Traditionally, staff used paper drawings and surveying instruments to measure heights and thicknesses at each point on site, then brought the results back to the office to compare them against drawings. Recently, however, this convention has been changing thanks to AR (Augmented Reality) technology. By simply pointing a smartphone or tablet, design drawings and 3D models can be overlaid on the real scene, allowing intuitive, on-the-spot checks of whether the work matches the plan. This dramatically improves the speed and reliability of on-site quality checks and strongly accelerates the DX (digital transformation) of construction management tasks.

As-built management (as-built inspection) itself is a quality assurance process in civil engineering and building works that measures and verifies whether completed structures and terrain conform to the shape and dimensions specified in the design drawings. Heights, thicknesses, slopes, and other parameters are measured at prescribed survey points during and after construction, and differences from the design values are used to judge pass/fail. However, traditional methods could not deliver immediate results on site and required considerable time and effort. AR as-built inspection (as-built AR check), which applies AR technology to as-built management and digitally “visualizes” construction results on site for immediate inspection, has attracted attention as a next-generation solution to these problems. Driven in part by the Ministry of Land, Infrastructure, Transport and Tourism’s *i-Construction* initiative, this approach has rapidly entered 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 operations, and AR is now playing an active role in as-built management.

Issues with traditional as-built management

As-built inspection is indispensable for quality assurance, but traditional methods involve many inefficiencies and problems. The representative issues are summarized below.

• Time-consuming work: Staff must painstakingly measure each survey point using levels or total stations, so large sites or many survey points require enormous time. It was not uncommon for measurement results to be taken back to the office, compiled into drawings, and judged over the course of several days.

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

• High equipment costs: High-precision measurements down to the millimeter require specialized equipment such as total stations and RTK-GNSS receivers, which entail initial investments on the order of several million yen. Maintenance costs and theft risks also exist, making adoption difficult for small and medium-sized enterprises.

• Measurement errors and recording mistakes: Manual surveying inevitably accumulates small errors each time, and human error can occur when transcribing field notes to drawings. Discovering such mistakes later can lead to re-measurement and rework.

• Time-consuming report preparation: Preparing as-built drawings and reports based on measurement results is a significant burden for field personnel. Sorting photos and plotting points on drawings takes time, and sometimes on-site data cannot be fully utilized for quality improvements.

• Delayed detection of defects: Construction defects such as insufficient thickness or improper slopes are not always noticed on site and often become apparent only after drawing up the results—frequently the next day or later. By the time problems are found, concrete may have hardened or heavy equipment withdrawn, resulting in additional labor and cost for rework.

As described above, traditional as-built management methods suffer from a lack of real-time capability and heavy burdens in terms of personnel and cost. It goes without saying that a new method that allows immediate and accurate grasp of as-built conditions on site was needed.

Benefits of introducing AR as-built inspection

So how do the above issues get resolved when AR as-built inspection is introduced? The main benefits are listed below.

• Real-time checks and rapid corrective action: Because as-built conditions can be checked immediately on site, there is no time lag between measurement and judgment. If a defect is found, corrective measures can be taken on the spot, minimizing rework. There are dramatic time-saving reports where inspections that used to take half a day are completed in a matter of minutes. Eliminating carryover of issues to the next day or later significantly speeds up the construction PDCA cycle.

• Labor saving and efficiency improvement: With AR displays on smartphones and tablets, measurement and inspection can be performed by a single person, dramatically improving team efficiency. Tasks that previously relied on veteran experience and intuition can be replaced by technology, enabling anyone to perform efficient, high-quality construction management. This ability to reduce manpower while maintaining quality is a major advantage amid chronic labor shortages.

• Cost reduction: There is no need to acquire expensive dedicated equipment; AR can be implemented with a modest initial investment by combining existing smartphones or tablets with small devices. Furthermore, reductions in rework lead to shorter schedules and lower labor costs. In many cases, equipping each worker with a smartphone surveying system still costs less than traditional equipment, making AR a highly cost-effective solution.

• Improved accuracy and reliability: Centimeter-level positioning using RTK-GNSS and high-resolution point cloud measurements using LiDAR dramatically increase the accuracy and reliability of as-built data. Measurement data can be automatically saved to the cloud and output as reports and drawings in formats compliant with the Ministry of Land, Infrastructure, Transport and Tourism’s as-built management guidelines. As AR use has begun to gain official recognition, its reliability as inspection records is increasingly assured.

• Efficient data use and recordkeeping: Since measurement data and on-site photos are saved and shared to the cloud on the spot, the time-consuming office task of transcribing data to drawings can be eliminated. Acquired point cloud and coordinate data can be output in common formats such as CSV, SIMA, and LAS, which are easily imported into existing CAD and GIS systems. Past as-built data can be quickly searched and referenced in the cloud, greatly improving recordkeeping efficiency and accuracy compared to paper field notebooks.

• Improved safety: Non-contact measurements that avoid entering hazardous areas contribute to worker safety. For example, slope measurements can be checked from below via AR to reduce risk. AR can also visualize the locations of buried pipes and cables, reducing the risk of damaging buried utilities during excavation. Thus, AR brings significant benefits not only to efficiency but also to on-site safety.

With these benefits, AR as-built inspection greatly contributes to achieving both productivity improvements and quality assurance on site. Next, let us examine the challenges of introducing this new technology.

Challenges of introducing AR as-built inspection

Although AR as-built inspection is innovative, several hurdles must be overcome to implement it on site. The main challenges include the following.

• High-precision alignment: General smartphone AR functions can suffer from drift over time, causing display positions to shift. If positions drift by several meters on a wide outdoor site, AR is useless for civil engineering purposes. To ensure the accuracy required for as-built inspection, high-precision alignment methods that precisely match the virtual model to real-world coordinates are indispensable.

• Operational proficiency and in-house training: Although AR surveying and inspection are intuitive, staff may initially be confused by new devices and software. Veterans may be resistant to “surveying with a smartphone.” Additionally, without prior organization of data handling and operational rules, confusion can occur on site. Preparing in-house training and rules for personnel development is a key challenge at the time of introduction.

• Preparation of digital data: AR as-built inspection requires design drawings and measurement results to be digitized. Without 3D design models (BIM/CIM data) or existing point cloud data, AR overlays will lack necessary reference information. If only paper drawings are available, time is needed to digitize and 3D-ize the drawings in advance.

• Equipment and app preparation: Using AR and high-precision positioning requires compatible devices and applications. Older devices may not support AR display or 3D scanning or may be slow. If additional devices such as GNSS receivers are used, connectivity environments (Bluetooth and internet) must also be arranged. Equipment preparation is thus a challenge for smooth operation.

• Consistency with existing workflows: Even after introducing AR-based inspection, consideration is needed on how to integrate it with existing construction management workflows and other surveying instruments. Initially, distrust in AR measurements may lead to dual management with traditional methods. Data integration—whether AR-acquired data can be converted into established CAD formats and report templates—is also an issue. Adjustments are needed so that field personnel and clients accept the new operation and recognize AR results as official inspection records.

• Regulatory concerns: Despite being groundbreaking, there may be concerns about whether AR methods are officially accepted as inspection means. Questions about compliance with national or local inspection standards and required submission documents can be barriers. If AR inspections still require separate preparation of traditional reports, the effort becomes counterproductive. Clear agreements and guideline development on these points are also necessary.

Solutions for successful AR as-built inspection implementation

Below are key points to address the above challenges and enable smooth on-site operation of AR as-built inspection. Consider the following when introducing the technology.

• Use of high-precision positioning: To eliminate AR display drift and ensure accuracy, combine AR with high-precision positioning technologies such as RTK-GNSS. Connecting an RTK-capable GNSS antenna to a smartphone can correct satellite positioning errors to the centimeter level, allowing the virtual model to be accurately aligned with the site coordinate system. For example, by using known coordinates of control points to correct the smartphone’s position, design data and real objects can be precisely overlaid on wide sites. When operating for the first time, verify error tendencies by comparing AR display results with values measured using existing total stations.

• Phased introduction and training: Although AR surveying and inspection are intuitive, conducting basic operation training and establishing data-sharing rules in-house at the early stage facilitates smooth rollout. Predefining file naming conventions and cloud-sharing procedures helps prevent operational confusion. Begin with a small pilot team to verify accuracy and effectiveness, then gradually expand company-wide. Provide support so field staff become comfortable with devices.

• Coexistence with existing methods and data integration: Initially, operate AR alongside traditional surveying equipment and compare results to understand precision and variance trends, which reassures field teams. For instance, compare coordinates obtained by an AR system (such as LRTK) with total station measurements and move to full operation after confirming acceptable agreement. Also test beforehand whether measurement data exported from the cloud can be imported into existing CAD and drawing tools. Choosing tools that support industry-standard formats (SIMA, LandXML, etc.) improves compatibility with existing workflows. Preparing internal operation flows in advance allows field teams to use AR inspection without confusion.

• Preparing a digital data environment: To maximize AR as-built inspection, prepare 3D design models and point cloud data. BIM/CIM models provided in contract documents are ideal, but if only 2D drawings exist, consider creating simplified 3D models for key elements or acquiring point clouds after construction using drones or smartphone LiDAR. The effectiveness of on-site comparison depends on matching design models with as-built measurement data, so give attention to prearranging data. Digitizing and sharing design drawings and as-built management items will fully unlock the benefits of AR introduction.

• Preparing high-performance devices: To smoothly run AR apps and point cloud functions, provide high-performance smart devices. The latest-generation iPhones and iPads or high-end Android devices are generally recommended; older models may not support AR display or LiDAR scanning or may be slow. Large-screen tablets are useful for detailed point cloud inspection and should be used according to the application. Also, because outdoor use drains batteries quickly, carrying mobile battery packs and other basic preparations are important.

• Building stakeholder understanding and consensus: Explain the benefits and procedures of AR as-built inspection in advance to stakeholders involved in inspection, such as clients and inspectors, and obtain their understanding. To have AR accepted as an official inspection method, agree on operational methods in pre-construction consultations. Fortunately, the Ministry of Land, Infrastructure, Transport and Tourism promotes 3D measurement and AR use, and AR-based inspection methods are gradually being accepted. As discussed below, the latest standards clarify the treatment of AR in as-built management. Gain stakeholder cooperation to embed the new technology on site.

If you prepare with the above points in mind, you should be able to introduce AR as-built inspection smoothly and enjoy its benefits to the fullest. Finally, as a concrete example of combining AR technology with high-precision positioning, we introduce simple surveying using LRTK.

Simple surveying realized with LRTK

A noteworthy solution for easily implementing AR as-built inspection is LRTK (pronounced 'Eru Aru Tī Kē'). LRTK is an innovative system that transforms a handheld smartphone into a centimeter-accuracy surveying device by attaching a small, high-precision RTK-GNSS receiver to the phone. Real-time kinematic (RTK) satellite positioning corrections cancel out GPS positioning errors that typically span several meters to within several centimeters (within several in), enabling high-precision surveying with palm-sized equipment.

Moreover, when combined with the latest smartphones’ built-in LiDAR scanners and high-performance cameras, simply scanning the surroundings captures 3D point cloud data, enabling on-the-spot volume calculations, as-built earthwork volume and excavation calculations, and checks of buried pipe depths. Acquired point cloud data and photos are automatically shared to the cloud, allowing remote offices to monitor as-built conditions in real time. No specialized heavy equipment or complex setup is required—just attach the device to a smartphone and launch the app to start positioning, which is a major advantage.

This simple surveying with LRTK is rapidly spreading across many domestic sites. It aims to be a “one-device-per-person universal surveying tool,” and its affordable pricing has quietly created a boom on sites. If you have not yet tried high-precision GNSS positioning or AR as-built checks, now may be a good opportunity to adopt LRTK. Once you experience the labor- and efficiency-saving benefits, you may find it hard to return to previous methods. Starting as-built management DX from a smartphone will further improve on-site productivity and quality assurance.

For product details or questions about implementation, please feel free to contact us. Advance your site to next-generation construction management with the simple surveying of LRTK.

FAQ

Q: What is AR as-built inspection? A: It is an as-built management method in which drawings and design data are overlaid onto the real site view using AR to check on the spot whether a completed structure matches the plan. Traditional as-built inspection performed with paper drawings and surveying equipment is replaced by digital visualization on smartphones and other tools, enabling real-time and intuitive quality checks.

Q: What equipment and preparations are required for introduction? A: Basically, a smartphone or tablet capable of AR display and high-precision positioning, a GNSS receiver that can achieve centimeter-level positioning, and a compatible app are required. For example, attaching an RTK-GNSS receiver such as LRTK to a modern iPhone or Android device allows reception of satellite correction information and high-precision alignment on the smartphone, enabling AR-based as-built inspections. It is also essential to have digitized design information such as drawings or BIM/CIM models for overlay. In some cases, 3D scanners or drones are used to acquire point clouds to verify current conditions.

Q: Is measurement accuracy sufficient? A: Yes. Using high-precision positioning with RTK-GNSS provides positioning accuracy within several centimeters (within several in). This achieves the accuracy required for as-built management. A GNSS receiver attached to the smartphone applies real-time corrections based on control points to align 3D models and point clouds accurately to site coordinates. Validation in accordance with the Ministry of Land, Infrastructure, Transport and Tourism’s guidelines has also confirmed the effectiveness of AR-based as-built inspection methods.

Q: How much does implementation cost? A: It is considerably lower cost compared with conventional surveying equipment. By leveraging commercial smartphones and adding small GNSS devices, the initial cost is roughly equivalent to that of a single high-precision GPS receiver and is very affordable. Subscription-based plans are also available to use the system only for necessary periods, enabling efficient operation. Specific costs vary by configuration and number of units, but equipping each person with a device can often pay for itself.

Q: Does it comply with the Ministry of Land, Infrastructure, Transport and Tourism’s standards? A: Yes. Acquired point cloud data and differences from design can be output and submitted in formats consistent with the Ministry’s “As-Built Management Guidelines (draft).” In fact, the guidelines include wording that “when as-built confirmation is performed directly on site using AR technology, submission of traditional as-built management drawings may be unnecessary,” and AR-based as-built management methods are increasingly being recognized officially. Thus, introducing AR as-built inspection on site can be operated without issues in supervision and inspection.