AR inspections that change surveying work: new ideas for labor saving and error prevention

Table of contents

• Introduction

• Challenges of conventional surveying and inspection work

• What is AR inspection

• Labor savings enabled by AR inspection

• Error prevention enabled by AR inspection

• Use cases of AR inspection

• Points to keep in mind when introducing AR

• Make AR inspection even easier with simple surveying using LRTK

• Frequently asked questions

Introduction

In construction and civil engineering sites, surveying and inspection tasks have long required significant effort and time. The work of cross-checking design drawings against actual construction conditions to confirm quality requires allocating personnel and careful execution, which imposes a burden on sites. There is also a risk of rework and quality defects caused by misreading complex drawings or communication errors. In recent years, AR (augmented reality) technology has attracted attention as a trump card for solving these issues through labor saving and error prevention. By using AR on smartphones and tablets, new ideas are emerging for surveying and inspection sites.

AR is a technology that overlays digital information such as CG onto real-world scenes viewed through a camera. It used to be an advanced experiment, but with the improved performance of mobile devices, it can now be used easily without special equipment. Modern smartphones are actually equipped with high-performance cameras and sensors (such as LiDAR), and with dedicated AR apps, necessary information can be intuitively confirmed on site. As industry-wide digital transformation (DX) progresses, led by initiatives like the Ministry of Land, Infrastructure, Transport and Tourism’s [i-Construction](https://www.mlit.go.jp/tec/i-construction/), inspection methods using AR are expected to be a groundbreaking solution that simultaneously improves on-site productivity and quality. This article explains how surveying work will change with AR inspection, detailing concrete approaches and benefits. At the end of the article, we also introduce a method using a new technology called LRTK that allows anyone to easily perform high-accuracy surveying.

Challenges of conventional surveying and inspection work

Conventional surveying and construction inspection processes have several inefficiencies and risks. For example, in as-built inspections (confirmation of final shape), it is common to measure points on site with surveying instruments, bring the data back, and compare it with drawings to decide pass or fail. With this method, there is a time lag between measurement on site and discovery of any issues, which tends to cause rework. Accurate judgment also requires experienced surveyors, and many tasks are done in pairs, so this is a burden amid labor shortages and an aging workforce.

Human error during construction is another issue. Tasks such as determining positions or marking while looking at paper drawings can lead to serious mistakes from slight misreads or transcription errors. Communication gaps such as “I wasn’t told” or “I thought I told them” often cause missed checks. Less experienced staff, in particular, tend to find it difficult to envision drawing information on site, making oversights and misunderstandings more likely. As a result, construction can proceed without noticing errors, leading to time-consuming rework later.

Thus, conventional surveying and inspection methods inherently have issues such as being time- and labor-intensive, prone to being person-dependent, and unable to completely eliminate mistakes. A new approach was needed to break these constraints and achieve both site efficiency and safety/quality assurance.

What is AR inspection

AR inspection is a method that incorporates AR technology into surveying and inspection tasks to streamline on-site verification work. Specifically, design data, reference lines, and points to check are overlaid as CG on the screen of a smartphone or tablet, and inspections are performed while comparing with actual structures and terrain. Simply pointing a camera on site makes the information drawn in the design appear over the live image, so the person in charge can intuitively grasp “where to measure and what to check.” What used to be a process of recording numbers with surveying instruments and comparing them to drawings becomes something that can be visually confirmed on the spot with AR inspection.

For example, when checking whether rebar spacing and counts are correct, the previous procedure of holding a rebar placement drawing in one hand and measuring with a tape measure is replaced by checking against a rebar model displayed in AR. By overlaying a 3D model of the completed shape at the site and detecting deviations from the design at a glance, one can immediately determine whether “the construction conforms to the drawings” or whether “the required thickness and slope are secured.” With AR inspection, parts that used to rely on reading drawings and experienced intuition become visualized, enabling everyone to check according to the same standards. This leads not only to immediate on-site corrections and prevention of mistakes, but also to more efficient inspection work itself.

The on-site application of this AR technology can fundamentally transform conventional surveying and inspection work. Replacing analog work with paper and tools with digital workflows can be expected to achieve dramatic labor savings and higher precision. We are now in an era where the smartphone everyone carries can serve as a surveying tool, and AR inspection is gaining attention as a key solution for on-site DX.

Labor savings enabled by AR inspection

One of the biggest benefits of introducing AR inspection is on-site labor saving. Below are the main labor-saving points achievable through AR.

• Reduced work time: Because wide areas of inspection can be visualized at once, measurements and checks that used to take days can be greatly sped up. For example, when inspecting pavement height or slope, conventional methods required level measurements at multiple points and time-consuming data organization, but with AR inspection you can point a tablet and grasp bumps and hollows across the whole site at a glance. By efficiently correcting only the problem areas, work can proceed without waste.

• Enabling small teams or single-worker operations: Using AR increases the number of situations where surveying and inspection that used to require two people can be completed by one person. Since necessary information is displayed on the screen, there is no need to have an assistant call out numbers or a recorder take notes. This reduces personnel coordination burdens and enables smooth quality control even at sites with labor shortages.

• Ease of use for non-experts: Even without specialized surveyors or veteran technicians, inspections can be performed by following intuitive AR displays. No difficult calculations or advanced skills are required—just point the device’s camera and follow the instructions—so inexperienced staff can become productive. Preventing person-dependence and enabling the whole team to share tasks addresses the issue of veteran shortages.

• Simplified heavy equipment and cost reduction: AR inspection using handheld devices like smartphones and tablets can in some cases eliminate the need to purchase expensive surveying equipment. Previously, confirming millimeter-level precision required dedicated instruments costing several million yen, but recently solutions have emerged that enable inexpensive centimeter-level accuracy (half-inch accuracy) positioning by using affordable GNSS receivers that attach to handheld devices. The effort of transporting and setting up equipment is also reduced, making operations more cost-effective overall.

Thus, introducing AR inspection significantly reduces on-site workload and creates an environment where limited personnel can quickly and accurately perform quality checks.

Error prevention enabled by AR inspection

Another major advantage of AR inspection is the prevention of construction errors and improvement of quality. By using digital technology to make the invisible visible, AR reduces human error and supports safer, more reliable construction.

• Real-time defect detection: Overlay displays with AR allow slight misalignments or deficiencies during construction to be discovered on the spot. For example, if areas where pavement thickness or slope do not meet specifications are highlighted in color, problems can be identified immediately after construction and repaired right away. This reduces cases where defects are discovered later and prevents larger mistakes through early correction.

• Reduction of human error: Risks such as misreading drawings or transcription errors can be minimized with AR inspection. Records that relied on visual checks and manual entry can be directly compared as digital data, eliminating errors like “measured incorrectly” or “wrote it down wrong.” Continuous checks against design data prevent oversights and reduce variation in quality.

• Unified understanding through information sharing: Inspection information displayed in AR can be shared on the same screen by everyone present. Points of caution that existed only in experienced workers’ heads become visible on AR, so even newcomers see them. This reduces misunderstandings like “I didn’t hear that” or “I didn’t know,” making it easier for the team to align on preventing mistakes. Because the screen can be shown to clients or other departments on site, discrepancies in understanding that lead to rework can also be suppressed.

• Enhanced safety management: AR can indicate potential hazards in advance, helping to prevent safety-related mistakes. For example, if the positions of buried pipes or cables are shown in AR, machine operators can avoid damaging lifelines during excavation. In Japan, more than 100 accidents involving damage to underground utilities are reported annually, and AR visualization is effective in preventing such incidents. By adopting AR inspection, sites can improve not only quality but also safety.

Use cases of AR inspection

AR inspection is being applied across a variety of on-site scenarios. Here are some main use cases.

• Visualization and inspection of underground buried utilities: Prior to excavation work, the positions of buried pipes and cables can be visualized with AR. By displaying pre-identified location data of buried objects on site, construction mistakes such as “accidentally breaking a buried pipe” can be prevented. Post-construction maintenance is also more efficient when the locations of buried infrastructure can be confirmed with AR during inspections. This method of making invisible underground information visible is attracting attention from the perspectives of safety management and error prevention.

• AR for rebar and formwork inspection: AR is used to inspect rebar placement and confirm formwork positions before concrete pouring. A 3D model of the design is overlaid on the rebar and formwork in progress to check whether positions and dimensions are correct. Tasks that used to require measuring each piece with a tape or surveying instrument can be visually verified on site with AR for misalignments or missing elements. Because you can immediately notice issues like “insufficient number” or “misplaced position,” corrections can be made before concrete is poured, preventing serious structural errors.

• As-built inspection (confirmation of finished shape): AR is also effective in as-built inspection to confirm whether structures or developed ground have been completed according to design. By overlaying 3D design data onto completed terrain or structures, you can compare the finished shape at a glance, eliminating the need to set many measurement points and measure heights. For example, when inspecting road embankment height or slope, the traditional method involved checking heights for each cross-section, but AR can color-code differences between the design model and actual ground surface to confirm a wide area at once. Because you can immediately extract failing areas on site, backfilling or grading adjustments can often be completed the same day.

• AR guidance for piling and layout work: AR is applied to piling and layout tasks that place buildings or structures at their design positions. Normally a surveyor sets batter boards or chalk lines based on drawings to indicate positions, but with AR, a tablet can display centerlines and outlines according to the design. Workers can perform piling or equipment installation along virtual position lines, improving efficiency and reducing positioning errors. Complex alignments can be handled intuitively by following on-screen instructions.

As these examples show, AR inspection can be used at all stages—before, during, and after construction. It supports the aspects that relied on the experience and intuition of veterans with technology, contributing to a site environment where anyone can work with high precision.

Points to keep in mind when introducing AR

While AR inspection offers great benefits, there are some points to consider when introducing it on site. To maximize the value of new technology, keep the following in mind.

• Prepare accurate data: Design data and pre-measurement data used for AR display should be as up-to-date and high-precision as possible. If they are based on old drawings or uncertain information, AR inspection will not lead to correct decisions. For inspections of existing structures, obtain the latest drawings from relevant agencies in advance and, if necessary, correct data through field surveys or additional measurements.

• Ensure positioning accuracy: When using AR outdoors on large sites, device position and orientation accuracy directly affect results. While smartphones alone can determine position with GPS and sensors, if centimeter-level accuracy (half-inch accuracy) is required, it is advisable to use a GNSS receiver in combination. Perform calibration (position alignment) at known points as needed and align the digital model with actual coordinates before starting inspections.

• Familiarize site staff: To effectively use AR inspection, it is ideal that all site staff understand the procedures and significance. Even if the operation is simple, some people may be confused at first. Reduce resistance by conducting simple training or demos in advance and letting staff experience it. It is especially important to share AR benefits with veteran workers and gain their cooperation. If they understand that “our experience + AR technology” leads to better quality control, adoption will go smoothly.

• Phased introduction: Rather than applying AR to all processes from the start, consider a trial introduction in areas where the effects are easier to see. For example, try AR for part of as-built inspections to confirm usefulness before expanding its scope to avoid on-site confusion. Accumulating small successes increases staff trust and accelerates overall DX at the site.

By paying attention to these points, AR technology can be integrated into the site and its benefits maximized. With appropriate preparation and operation, AR inspection is likely to become the new on-site standard.

Make AR inspection even easier with simple surveying using LRTK

Finally, we introduce LRTK (Lightweight RTK) as a new technology that makes AR inspection even easier. LRTK is a pocket-sized surveying device consisting of a small high-precision GNSS receiver that can be attached to a smartphone and a dedicated app. Its key feature is that anyone on site can perform centimeter-level accuracy (half-inch accuracy) positioning alone without specialized training or large-scale equipment.

Traditionally, accurate positioning of structures required full-scale surveying with a total station (TS) or similar equipment. However, with LRTK you can simply point a smartphone and press a button to measure and record the coordinates of an object on the spot. For example, if you measure several points immediately after burying a pipe with LRTK, you can digitalize the pipe route with high accuracy. The acquired data can be shared to the cloud instantly and imported into AR apps, allowing pipes and structures to be displayed in AR at accurate positions immediately after construction. By lowering the barrier to surveying work, LRTK dramatically streamlines the data preparation required for AR inspection.

LRTK also envisions integration with AR beyond position measurement. If virtual objects (models or markings) are placed at coordinates obtained by LRTK in an AR app on a smartphone, applications such as visualizing piling positions or buried routes on site are possible. In short, LRTK is the bridge that connects “measuring (reality)” and “showing (virtual).”

By utilizing such simple surveying tools, the acquisition of high-precision data that used to rely on surveying experts can be done by site personnel. As a result, digital construction including AR inspection will become increasingly accessible. LRTK is a reliable ally supporting construction innovation through AR. Let’s skillfully adopt advanced technologies to achieve safer and more efficient sites.

Frequently asked questions

Q: What do I need to start AR inspection? A: Basically you need a smartphone or tablet capable of AR display and a corresponding AR application. Modern iOS/Android devices come with high-performance cameras and sensors, so you can use AR effectively without special AR-dedicated hardware. It is also important to prepare digital data such as the design data and dimensional information of the inspection target. If high positioning accuracy is required, combining a GNSS receiver that can be attached to a smartphone makes centimeter-level accuracy (half-inch accuracy) alignment possible. Operation itself is intuitive—just point the camera—so advanced expertise is not required. With simple prior training, site staff can handle it well.

Q: How should I prepare data for AR inspection? A: For new construction, creating 3D design data such as BIM/CIM at the design stage makes AR use smoother. For inspections of existing infrastructure or structures, obtain the latest drawings and rebar plans from relevant agencies first. Because old drawings often differ from actual conditions, update the data by conducting additional on-site surveying or scanning as needed. For underground buried objects, confirm accurate positions through ground-penetrating radar or trial excavations and reflect them in the data. Using a simple surveying system like LRTK allows you to quickly acquire high-accuracy data on site and digitalize it. Once digitized, manage position information in the cloud or GIS and keep it up to date.

Q: How much does it cost to introduce AR? A: Costs vary depending on scale and method, but it is much more affordable to start now than before. AR glasses and other dedicated equipment used to be expensive, but you can now use commercial smartphones and tablets to greatly reduce hardware costs. Even when adding GNSS receivers, more affordable products have appeared compared to traditional surveying instruments. Software is also often offered as subscription services, reducing initial costs. Considering costs saved by avoiding rework and reducing accidents, AR introduction generally offers a favorable return on investment.

Q: How reliable is the accuracy of AR inspection? A: The accuracy of AR inspection can be raised to levels comparable to conventional surveying depending on the devices and data used. Positioning with a typical smartphone has errors on the order of meters, but AR apps use image recognition and sensor fusion to adjust to actual objects, so relative accuracy at close range becomes very high. Combining GNSS corrections can improve absolute accuracy on large sites to centimeter-level accuracy (half-inch accuracy). In practice, AR inspections combined with RTK-GNSS technology have reported as-built confirmations with precision comparable to traditional total station surveying. However, to fully trust results, it is advisable to use double checks at critical points and perform equipment calibration and other basic precautions.

Q: What is LRTK? A: LRTK is the name of a GNSS solution that transforms a smartphone into a high-precision surveying instrument. It consists of a palm-sized device and a dedicated app, enabling anyone to easily obtain position information with centimeter-level accuracy (half-inch accuracy). It is an easier-to-use iteration of traditional RTK-GNSS technology, allowing not only on-site surveying but also cloud sharing of acquired data and use in AR displays. As a tool supporting labor-saving and sophistication of surveying tasks such as piling and as-built management, it is attracting attention.