Visible Surveying with AR-Enabled GNSS Receivers ─ Intuitive High-Precision Position Verification

Introduction: What Surveying Innovation Does the Fusion of AR and GNSS Receivers Bring?

In recent years, the use of AR (augmented reality) technology and smartphones has made surveying work on civil engineering and construction sites remarkably easier. Everyday devices like smartphones can now perform roles that were once the domain of expensive, specialized surveying instruments, bringing an era in which anyone can perform centimeter-level (cm-level, half-inch accuracy) high-precision surveying. From experienced site workers to beginners, this new technology overturns the conventional notion that “surveying = difficult and laborious,” promising major labor savings and improved efficiency. At the core of this is “visible surveying,” which combines AR and high-precision GNSS receivers to overlay surveying data onto real-world scenes seen through a camera, enabling intuitive verification.

This article first explains the basics of achieving centimeter-level high-precision positioning with GNSS receivers, then introduces the appeal of “visible surveying” when combined with AR. We then cover concrete use cases such as stakeout assistance, as-built management, buried utility verification, and inspection support, and consider comparisons with traditional methods and future prospects. Finally, we present a case study of AR surveying using the LRTK Phone (GNSS receiver). We hope this provides tips for surveying companies, local governments, and construction contractors looking to accelerate on-site DX.

Basics of Achieving Centimeter-Level High-Precision Positioning with GNSS Receivers

First, let’s cover the basics of high-precision positioning using GNSS (global navigation satellite systems such as GPS). GNSS calculates positions by receiving signals from multiple positioning satellites, but typical smartphone-built-in GPS can produce errors on the order of several meters. By combining error-correction technologies such as RTK (real-time kinematic), positioning accuracy can be improved to within several centimeters. In RTK-GNSS, the observation data from a base station with a known position and a rover (mobile station) are compared in real time; error information from the base station is applied to the rover’s position calculation, enabling centimeter-level positioning. While ordinary GPS positioning yields errors of several meters both horizontally and vertically, RTK can reduce errors to several centimeters (several in) horizontally and several centimeters (several in) vertically. This technology makes precise vertical measurements possible where they were previously difficult, allowing accurate determination of not only planimetric position but also elevation.

In the past, achieving centimeter-level positioning required expensive Class-1 GNSS receivers for both a base station and a rover, with data communication via radio or the internet. The equipment—tripods, poles, external batteries, and controller terminals—was large-scale, and initial satellite acquisition and stabilization of positioning accuracy could take several minutes, making cost and operation hurdles high. However, advances in technology and cost reduction have led to portable, compact GNSS receivers that, when combined with smartphones or tablets, enable easy high-precision positioning. For example, in Japan the quasi-zenith satellite system “Michibiki” provides a centimeter-level correction service (CLAS), allowing devices in mountainous areas outside mobile communication coverage to obtain correction information directly from satellites and maintain accuracy. Against this backdrop, the adoption of GNSS receivers that can be used on site has accelerated, bringing the benefits of high-precision positioning to a wide range of fields beyond surveying.

The Appeal of “Visible” Surveying Combined with AR (On-Site Visualization and Intuitive Operation)

By combining position information obtained from high-precision GNSS with AR technology, information that was previously only verifiable as numbers or on drawings can now be “visualized.” AR (augmented reality) overlays three-dimensional digital information onto real-world images captured through a camera. In surveying and construction, AR is used to project design models and survey point data onto on-site video, allowing confirmation as if the physical object were actually there. For example, overlaying the completed structure’s image or reference lines from the design drawing onto the actual site scene viewed through a smartphone makes spatial relationships that were hard to grasp from paper drawings immediately and intuitively understandable. AR-based “visible” surveying has dramatically advanced on-site visualization.

This visualization makes on-site verification work far more intuitive. Compared to traditional tasks such as reading numbers from surveying instruments or comparing drawings to the site, workers can progress simply by following guides displayed in AR, enabling even non-experts to perform accurate stakeout and checking by feel. For instance, if virtual stakes or markings displayed in an AR app are used as markers on site, moving to those markers guides the user to the correct survey points, so novice surveyors can mark stake locations without getting lost. Also, AR allows construction personnel and designers to share the same digital model on site, confirming design intent in real time while proceeding with construction. This reduces rework and mistakes caused by misalignment in understanding, and smooths on-site communication.

Moreover, AR surveying systems make cloud-synchronized data sharing easy. Positioning data and photos acquired on site can be uploaded to the cloud in real time and instantly shared with office staff. This enables remote personnel to grasp site conditions and give instructions or verify survey results. By combining AR-based on-site visualization with cloud synchronization, the field and the office are seamlessly connected, improving efficiency in construction management and overall surveying work.

Concrete Use Cases on Surveying Sites (Stakeout Guidance, As-Built Management, Buried Utility Verification, Inspection Support)

• Stakeout Support: AR is effective for stakeout work that indicates structure positions at construction sites. Traditionally, surveyors used total stations (TS) to measure coordinates and, together with assistants, installed stakes; but with AR stakeout systems, accurate positioning can be done solo. The smartphone screen displays the point “install stake here,” and the user simply moves according to that guidance to be led to the designated location. This enables inexperienced workers to mark stake locations without hesitation, reducing manpower for stakeout and improving accuracy.

• As-Built Management: AR is also powerful for checking the shapes of completed structures and developed land to confirm whether construction was carried out according to design. Traditionally, heights and thicknesses at each point were measured and then compared to drawings back at the office, but with AR you can overlay the design model on the as-built condition on site. By comparing the completed 3D model or reference surfaces to the actual object through the smartphone screen, you can instantly see which parts match the design and where errors exist. For example, when checking pavement as-built conditions, displaying a heat map on AR that color-codes thickness excesses and shortages allows immediate on-site quality judgment. Also, modern smartphones equipped with LiDAR scanners can scan the site to obtain point cloud data, making full 3D measurement of as-built conditions easy. Advanced as-built management methods are emerging that analyze differences between acquired point clouds and design data in the cloud and visualize deviations in AR, contributing to more efficient inspections and higher quality.

• Buried Utility Verification: AR is effective for verifying the positions of buried infrastructure such as underground pipes and cables. For sewer pipe work, positions of piping are surveyed and recorded after burial, and AR allows these buried locations to be confirmed as if seeing through pavement even after surfacing. Pointing a smartphone at the ground displays the routes and depths of buried pipes on the screen, allowing intuitive understanding as if looking beneath the surface. Since high-precision GNSS can align virtual pipe models precisely with actual buried positions, it becomes possible to know on site “what is buried here and at what depth” with errors of only a few centimeters (a few inches). This greatly reduces the risk of accidentally damaging existing buried utilities during excavation, and aids in inspection, maintenance, and renovation planning for buried pipes.

• Inspection Support: The combination of AR and GNSS is also applied to routine inspections of infrastructure and structures. For bridge and tunnel inspections, AR can reproduce records of past cracks and deterioration on site so they are not overlooked. For example, if the location of a crack found in a previous inspection is digitally recorded, AR tags or markers can be displayed at that same location during the next inspection so the inspector can accurately examine the identical spot. Displaying inspection items and procedures in AR also helps prevent missed steps and improve efficiency. Remote inspections are possible too, where distant experts share on-site AR video and give instructions, making it feasible to leverage the knowledge of skilled technicians remotely in the future.

Comparison with Traditional Methods (TS, Manual Drawing Verification, etc.)

What advantages does the new surveying method combining AR and GNSS offer compared with traditional approaches? Below are points that stand out when comparing with total station (TS) surveying and manual methods.

• Equipment and personnel burden: Traditionally, TS and dedicated surveying equipment had to be transported, tripods set up, and heights adjusted, which was time-consuming. TS surveys commonly required at least two people—a surveyor and an assistant—making manpower procurement a challenge.

• Work time and efficiency: Preparation, measurement, and packing up all took time, and even small-scale surveys required substantial effort. Especially when additional points needed to be measured, the entire setup sequence had to be repeated, which was inefficient.

• Lack of real-time feedback: Data measured on site had to be brought back to the office and compared with drawings or CAD data, so results could not be confirmed immediately. Errors or design deviations were sometimes discovered later, leading to rework.

• Dependence on skilled technicians: Operating surveying equipment and interpreting drawings required experience, forcing reliance on experienced personnel. With labor shortages and an aging workforce, this reliance hindered efficiency.

The AR + GNSS approach brings significant innovation against these issues. Equipment is reduced to a smartphone and a GNSS receiver, which are lightweight and compact and easy to carry to sites. Setup is simple and positioning can start with one touch, enabling measurements whenever needed. Tasks can basically be completed by a single person, facilitating adoption even at sites with workforce shortages. Also, since positioning results and design models can be checked and shared on the spot, quality can be checked in real time and corrections made immediately. Even without skills in reading paper drawings or advanced equipment operation, following AR guidance enables high-accuracy surveying work, aiding skill transfer. Of course, for benchmark surveys requiring millimeter-level strict accuracy, traditional TS and similar equipment remain necessary in some situations; however, for general construction management, as-built verification, and quantity surveying, AR surveying achieves sufficient accuracy and dramatic efficiency gains, emerging as a new standard that can replace traditional methods.

Future Prospects and Potential for Widespread Adoption

The surveying method combining AR and GNSS is expected to become increasingly widespread. Government initiatives like i-Construction and the broader trend of construction DX promoted by the Ministry of Land, Infrastructure, Transport and Tourism are tailwinds, and the movement to adopt digital technologies on sites is gaining momentum across the industry. Some municipalities have already begun using smartphone-mounted GNSS receivers and AR for damage assessments in disaster recovery, creating practical case studies. As these success stories are shared, understanding of AR surveying’s usefulness will deepen from surveying companies to construction sites, accelerating adoption.

On the technology side, higher performance and lower costs for devices will further encourage adoption. GNSS receiver–integrated devices are expected to become smaller and cheaper, making them tools that everyone can easily obtain. Deploying one smartphone surveying device per worker is becoming realistic, creating environments where each worker can perform positioning and measurement instantly when needed. AR display devices are also diversifying, and in the future wearable devices like smart glasses may allow hands-free viewing of AR displays while working. As a technology that supports spatial awareness on site, AR will continue to evolve and become a routine tool.

Furthermore, as BIM/CIM penetration and cloud technologies advance, standardized use of digital data from design through construction and maintenance will broaden the scope for AR surveying. For example, machine operators could confirm work areas and buried utility locations in AR while operating equipment, and remote managers could watch AR video of the site in real time to give instructions. In training, young workers could become proficient faster by using intuitive digital tools to compensate for lack of experience. Overall, “visible” surveying using AR × GNSS is expected to become a standard method in the construction and surveying industries, contributing significantly to improved productivity and safety on site.

Case Study of AR × Surveying with LRTK Phone and Natural Guidance

Finally, as an example of AR × GNSS surveying implemented in the field, we introduce the [LRTK Phone](https://www.lrtk.lefixea.com/lrtk-phone). LRTK Phone is an ultra-compact RTK-GNSS receiver that attaches to a smartphone, turning the phone into a centimeter-level surveying device. By integrating with a dedicated app and cloud service, this single device performs positioning, stakeout guidance, stakeout, point cloud measurement, photo records, and AR display. Acquired data is stored and shared to the cloud on site and can be synchronized with the office immediately. Because of its ease of use and practicality, it has quietly gained popularity among site managers and workers, and is highly regarded as a “one-per-worker site surveying tool” that fits in a pocket and is ready to use when needed.

For example, Fukui City was an early adopter of LRTK Phone, combining it with iPhones to rapidly measure disaster site damage and share data via the cloud, achieving early recovery and major cost reductions. Another construction company reported that stakeout work that previously required two people could be completed by one person after adopting LRTK Phone, substantially shortening work time. In these ways, LRTK Phone offers accuracy comparable to expensive Class-1 surveying instruments while remaining easy to use, contributing to DX promotion across many sites.

Visible surveying created by the fusion of AR technology and GNSS receivers is already available in a familiar form. By using solutions like LRTK Phone, anyone can start intuitive high-precision surveying with just a smartphone, even without specialized instruments. If you are looking to improve the efficiency of surveying work or construction management, consider adopting these latest technologies.