How Finished-Shape AR Checks Work: Real-Time On-Site Verification Enabled by AR×GNSS

目次

• [出来形 AR チェックとは何か](#出来形-ar-チェックとは何か)

• [従来の出来形管理手法とその課題](#従来の出来形管理手法とその課題)

• [AR×GNSSが可能にするリアルタイム出来形検証の仕組み](#ar×gnssが可能にするリアルタイム出来形検証の仕組み)

• [現場での具体的なワークフロー例](#現場での具体的なワークフロー例)

• [国交省の出来形管理要領とi-Constructionの動向](#国交省の出来形管理要領とi-constructionの動向)

• [AR出来形チェックがもたらすメリット](#ar出来形チェックがもたらすメリット)

• [おわりに：AR出来形チェックを手軽に始めるには](#おわりにar出来形チェックを手軽に始めるには)

• [FAQ](#faq)

出来形 AR チェックとは何か

“Finished-shape management” is an essential process in civil engineering and construction for confirming and recording whether completed structures and developed land have been finished to the design’s intended shapes and dimensions. In public works, the results of finished-shape management are often conditions for inspection approval and handover, making it a cornerstone of quality assurance. Traditionally, finished-shape checks relied on direct measurements using tape measures, staffs (level rods), and levels, combined with photography; measured results were compiled into tables and photo albums for reporting. However, manual finished-shape verification requires significant labor and time, and measurement points are limited, so the risk of omissions cannot be ignored.

Against this backdrop, a new on-site verification method attracting attention in recent years is the “Finished-Shape AR Check.” This approach combines AR (Augmented Reality) technology with GNSS positioning to enable real-time finished-shape verification on site. Through a smartphone or tablet camera, design drawings or 3D model information are overlaid and displayed on the actual construction site, allowing intuitive recognition of discrepancies between as-built conditions and design. For example, projecting design lines or shapes in AR onto the constructed terrain or structures makes it immediately obvious whether the finish meets standards. What makes this possible are high-precision GNSS (Global Navigation Satellite System) position information and smartphone sensor technology. The combination of AR×GNSS is driving the digital evolution of finished-shape management.

従来の出来形管理手法とその課題

First, let us review the traditional approach to finished-shape management and its challenges. Under conventional methods, manual measurements are taken at key points of completed structures, and deviations from design values are checked and recorded. For example, in road works, the thickness, width, and height of subbase and pavement are measured for certain segments; for slope works, gradients and lengths are measured and organized into finished-shape management tables (measurement result lists). However, this approach has long attracted criticisms from the field.

• Labor- and time-intensive: Dimensional measurements usually require a team of multiple people, and large sites with many measurement points can take a full day. Securing skilled surveyors is difficult, and in the face of labor shortages, it is hard to proceed efficiently within deadlines.

• Lack of comprehensiveness and risk of omissions: Manual work limits the number of physical points that can be measured, making it impossible to cover the entire construction area. Measuring only a limited set of representative points risks overlooking areas that differ from the design. The larger the structure, the more difficult it is to grasp subtle unevenness and variations, sometimes resulting in hurried rework after inspection identifies discrepancies with the drawings.

• Risk of human error: Busy sites are prone to human mistakes such as forgotten photos or recording errors. For example, if photos are not taken before backfilling buried utilities, it may become impossible to prove the construction condition after completion. Mistakes in note-taking or transcribing measurement values have led to quality problems, placing a heavy burden and anxiety on site personnel.

Because of these issues, a more efficient and reliable method of finished-shape management has long been sought. Especially recently, with labor shortages and work-style reforms, the use of new technologies is strongly expected from the perspectives of labor savings and productivity improvement.

AR×GNSSが可能にするリアルタイム出来形検証の仕組み

A key solution to these challenges is the fusion of AR technology and high-precision GNSS positioning. By using a small RTK-GNSS receiver that attaches to a smartphone and a dedicated app, anyone can now easily obtain centimeter-level position accuracy (cm level accuracy, half-inch accuracy) with their phone. RTK (Real Time Kinematic) GNSS combines satellite positioning with correction information from a base station to reduce position errors to within a few centimeters. What once required expensive surveying equipment can now be obtained on a smartphone in real time.

With high-precision self-positioning, spatial matching with design data becomes possible. By loading BIM/CIM models or drawing data into a dedicated app and aligning them to the field coordinate system, those models can be overlaid and displayed in the smartphone camera view at accurate positions. For example, pointing a smartphone at a scene can AR-display the completed shapes or reference lines from the design drawing. Because GNSS aligns positions to global coordinates, the virtual model does not drift from reality as the user moves, which is a major advantage. This allows one-to-one comparison between real structures and digital design information and enables finished-shape verification on site.

Moreover, using built-in smartphone LiDAR scanners or high-resolution cameras, on-site 3D measurement can be performed simultaneously. For example, scanning the area to be verified with a smartphone to obtain point cloud data and comparing it to the design’s 3D model in the cloud can generate a difference heatmap. If the heatmap data indicating deviations is downloaded to the smartphone, it can be overlaid in AR on the real scene. Because the error distribution is projected onto the actual view, it is immediately clear which areas are higher or lower than the design, allowing instant corrective actions such as adding fill or excavation. Traditionally, after point cloud processing, a color-coded map (heatmap) would be created on a plan and submitted, and then staff would locate the corresponding points on site; with AR, you can “see it directly on site.”

In short, the AR×GNSS mechanism is transforming the traditional workflow of measuring, then checking and reporting in the office into real-time on-site verification. Surveying, finished-shape checks, and photographic records can be completed with a single smartphone, and necessary data is immediately shared to the cloud so stakeholders can confirm and decide on next steps on the spot. This technological innovation can dramatically improve site productivity and quality control.

現場での具体的なワークフロー例

How is a finished-shape AR check actually performed on site? Below is an example workflow for civil engineering works that uses AR×GNSS for finished-shape verification.

• 事前準備（設計データの用意）: First, prepare the design drawings and 3D model data of the work in digital format. BIM/CIM models or CAD data contain the completed shape and reference lines and surfaces. Load these into the dedicated app and align them with the site coordinate system (survey coordinates). For public works, BIM/CIM adoption has been made more standard from fiscal 2023, so digital design data is often available.

• 機器のセットアップ: Attach an RTK-GNSS receiver to a smartphone or tablet and set it up to receive GNSS correction information on site. In Japan, centimeter-level positioning augmentation services such as CLAS using the QZSS “Michibiki” or network RTK over the internet make high-precision positioning easy to obtain. Once positioning stabilizes, start AR display mode in the app and, if necessary, calibrate the compass orientation.

• 出来形の確認作業: For example, to check the finished height of a development area, display a virtual horizontal plane representing the design elevation in AR. The smartphone screen will show a translucent “design height plane” over the site image, allowing the operator to walk around and check whether the actual ground is above or below the virtual plane. Where the virtual plane appears to float above the ground indicates insufficient fill; where it appears sunk into the ground indicates excess fill. Similarly, for road works you can project the vertical and cross-sectional design lines in AR to verify pavement thickness and gradients on the spot.

• リアルタイムの指示と修正: If AR reveals discrepancies, share them immediately with workers and perform prompt corrections. For example, if you see “this point is 5 cm (2.0 in) lower than the design,” additional fill can be placed right away. Numeric guidance displayed in AR (e.g., “add +5 cm”) and color-coded indications are intuitive for workers and convey instructions more clearly than words alone. This minimizes rework while allowing construction to proceed.

• データの記録と報告: After verification, save the check results as data. Geotagged photos taken with the smartphone are uploaded to the cloud with location and orientation, allowing later office review. If a point cloud scan was performed, some systems can generate finished-shape heatmaps and management tables with one click. These digital data can be organized and submitted as reporting materials to the client.

Through such a flow, AR×GNSS finished-shape checks enable on-site verification and correction in real time and carry recording of final outcomes through in a fully digital process. Compared to the era of paper field notebooks and tape measures, the workflow is dramatically more efficient.

国交省の出来形管理要領とi-Constructionの動向

Even though it is cutting-edge, “Finished-Shape AR Check” is not an eccentric method deviating from existing standards. In fact, the Ministry of Land, Infrastructure, Transport and Tourism (MLIT) is actively promoting ICT utilization in construction management and officially supporting digitization of finished-shape management.

As part of the *i-Construction* initiative, MLIT has promoted the introduction of BIM/CIM and 3D measurement technologies. In particular, it has formulated the “Guidelines for Finished-Shape Management Using 3D Measurement Technologies (draft)” and has developed methods for finished-shape measurement using drone photogrammetry and terrestrial laser scanners. Furthermore, in 2022 the finished-shape management guidelines were revised, and the use of simple mobile devices such as smartphones for finished-shape measurement in public works was officially permitted. This means that even small- to medium-scale sites can potentially perform 3D finished-shape management using smartphones without expensive dedicated equipment.

Moreover, in 2024 MLIT issued notices for trials of supervision and inspection leveraging digital data on MLIT-direct projects, indicating a new approach of “projecting 3D models created during construction on site using AR technology and conducting finished-shape measurements there.” The idea is to streamline the traditional process—creating heatmaps from point clouds and submitting them, then re-measuring on site during inspection—by performing on-site confirmation with AR. Thus, both public and private sectors are advancing digital transformation (DX) on sites, and AR×GNSS finished-shape checks align with this trend.

From fiscal 2023, the principle application of BIM/CIM began for all MLIT-direct projects except small-scale ones. As a result, 3D design data will be prepared in many projects, dramatically increasing the digital information available for AR. The automation of data linkage is truly taking hold in the construction industry, and smart construction that does not depend on paper and manual work is beginning to permeate finished-shape management.

AR出来形チェックがもたらすメリット

The AR×GNSS finished-shape check method offers substantial benefits on site. The main advantages are summarized below.

• 大幅な効率化と省人化: Surveying and inspection tasks that used to require two or more people can be completed by a single person, increasing flexibility in staffing. Enabling one-person surveying helps address chronic labor shortages while raising overall site productivity. Interruptions due to waiting for surveys are reduced, and measurements and checks can be performed whenever needed, smoothing project progress.

• 高密度な測定で品質向上: Point cloud scanning and continuous measurement enable high-density measurement over wide areas, allowing finished-shapes to be understood as surfaces. This makes it harder to overlook slight unevenness or dimensional variation and reduces variability in construction quality. The ability to cover the whole site with data provides peace of mind for both owners and contractors from a quality management perspective.

• リアルタイムの是正と手戻り削減: Because verification can be done immediately after construction on site, nonconformities that would otherwise be discovered only at later inspections can be prevented. “Check on site, correct on site” becomes possible, and early detection and instant response to errors reduce rework and schedule extension risks, thereby suppressing unnecessary costs.

• 直感的で分かりやすいコミュニケーション: Information visualized in AR is more intuitive than text- or number-only reports. When everyone on site sees the same AR view on a smartphone, it is immediately clear which locations need what degree of correction. This reduces reliance on experienced practitioners’ intuition and facilitates shared understanding and agreement among workers and supervisors.

• データ記録と継承の容易さ: Because measurement data and photos are all stored and shared digitally, the effort of creating forms and reports is reduced. Finished-shape data centrally managed in the cloud can be used for future maintenance and renovation works. Also, the skills and site knowledge of experienced personnel remain as data, supporting knowledge transfer without reliance on individuals.

• 安全性の向上: Remote measurement via AR reduces the need to enter hazardous areas. For slopes and high locations, AR markers can be set and used to guide measurements from safe distances, reducing the need for workers to adopt risky postures for surveying. Pointing out measurement points around heavy machinery via AR guidance can also reduce collision risk. Consequently, site safety levels improve.

As described, finished-shape AR checks are more than a novelty; they provide practical benefits that directly address site issues. With aging and labor shortages advancing in the construction industry, this technology is expected to spread widely as a trump card for achieving both efficiency and quality.

おわりに：AR出来形チェックを手軽に始めるには

AR×GNSS-based finished-shape checks were once a frontier requiring specialized equipment. However, easy solutions that combine smartphones and compact GNSS receivers are emerging. For example, the Tokyo Institute of Technology-originated venture developed LRTK, a system composed of a pocket-sized RTK-GNSS device that can attach to an iPhone and a dedicated app, transforming the field so that “surveying and inspection can be completed with just a smartphone.” Even general engineers without special training can operate it intuitively and immediately use high-precision positioning, point cloud scanning, and AR-based finished-shape verification with its simple surveying functions.

Using tools like these makes AR finished-shape checks accessible for everyday operations, lowering the previous barriers to adoption. With a single smartphone you can measure, record, compare, and share seamlessly, enabling digital construction management even on small sites or with limited personnel. The most important thing is to actually try it on site. You may be surprised how easily tasks that relied on paper drawings and tape measures can be digitized. AR×GNSS finished-shape checks are not a special future technology but a familiar tool already usable on site. Why not start simple smart construction at your site?

FAQ

Q: If AR is used for finished-shape management, is the accuracy reliable? A: When AR is combined with high-precision GNSS (RTK-GNSS), positional accuracy can be secured to within a few centimeters. Ordinary smartphone GPS has errors on the order of meters, but RTK corrections enable self-positioning at levels comparable to surveying reference points, so AR overlays align with minimal offset. In addition, proper calibration of the smartphone’s gyroscope and compass keeps directional accuracy within practical limits.

Q: What preparations and equipment are required to display AR on site? A: Basically, a smartphone/tablet + RTK-capable GNSS receiver + dedicated app are sufficient. Prepare the design data (3D models or digital drawing data) in advance and load them into the app. GNSS receivers that can receive correction data via the internet are convenient. Outdoors with radio connectivity, you can use correction services without preparing your own base station.

Q: What about environments where GNSS cannot be received, such as inside tunnels or indoors? A: Pure GNSS positioning cannot be used where there is no sky view. In such cases, place known points (reference markers) as AR markers or perform alignment using predetermined reference coordinates. For example, inside a tunnel you could use coordinates measured near the entrance by GNSS and then perform relative alignment to known points inside the tunnel to enable AR display. Indoors, QR codes or feature-point markers are sometimes used for AR alignment.

Q: Isn’t there a cost to introducing AR finished-shape checks? A: It is considerably lower cost than purchasing large dedicated equipment. Many people already have smartphones, and compact GNSS receivers are more affordable than traditional surveying instruments. Software is often provided as cloud services, allowing flexible licensing for only the required period. More importantly, time savings and personnel reduction bring significant cost benefits, so overall the investment can be offset by its effects.

Q: Can anyone quickly become proficient with AR? Are special skills unnecessary? A: Basic operations are not difficult if you follow the app’s guidance. For example, with systems like LRTK, simply pointing an antenna-equipped phone at the point to be measured and pressing a button records coordinates, and AR overlays are applied by selecting model data from the menu. However, you will need to get used to handling equipment and calibration procedures, so brief training beforehand is recommended. You will gain a feel for it by using it repeatedly on site.