The New Norm in 3D Surveying: Digital Construction Anyone Can Do with LRTK

Introduction

The construction and civil engineering industries are rapidly pursuing digital transformation (DX) to boost productivity and efficiency. At the same time, challenges such as a shortage of experienced surveyors and an aging workforce are driving the need to reduce labor through digital technologies. Among these, 3D surveying, which acquires and utilizes site information in three dimensions, is gaining attention as a central element of digital construction. Precision surveying that once required specialist surveyors and expensive equipment is being transformed by technological innovation into something accessible to everyone. In this article, we explore the latest trends in 3D surveying and examine the emerging surveying technology LRTK as a means to enable digital construction that anyone can carry out.

How 3D Surveying Advances Digital Construction

Recently, the use of 3D survey data on construction sites has increased dramatically. By capturing terrain and structures as point clouds or 3D models and leveraging them, teams can visualize gaps between design and construction and streamline verification of as-built conditions. The Ministry of Land, Infrastructure, Transport and Tourism’s promotion of ICT construction (the so-called *i-Construction*) also positions data usage from 3D surveying as a key pillar. For example, it is becoming common to acquire detailed point cloud data of existing terrain via drone photogrammetry or laser scanners and apply that data to earthwork volume calculations and construction planning. The adoption of 3D surveying enables intuitive understanding of site conditions that were previously invisible from drawings or numbers alone, making it easier to share a common understanding among stakeholders and leading to improved quality, safety, and shorter schedules. Moreover, 3D survey data is starting to be used for machine guidance (MG) and machine control (MC) of heavy equipment, creating workflows in which as-built data and design models obtained by surveying are directly reflected in construction.

Traditional Surveying Methods and Their Challenges

Despite growing recognition of the value of 3D surveying, traditional methods have faced several hurdles. High-precision surveying has typically required specialized equipment such as total stations or GNSS survey receivers and was usually performed by two-person teams including licensed surveyors. Detailed point cloud measurement with laser scanners and photogrammetry with drones involve high equipment costs, advanced skills, and specialized software. These factors have sometimes prevented small- and mid-sized sites or labor-short situations from fully adopting 3D surveying. Especially with an aging workforce and personnel shortages among surveyors, critics point out the limits of the conventional "people-dependent" surveying model.

In addition, making acquired 3D data usable on site has required expertise in coordinate transformations and data processing, making real-time sharing and utilization challenging. For instance, even if point cloud data were captured, it often required processing on a high-performance PC before it could be used, leaving site personnel to rely on flat drawings. In other words, to fully benefit from 3D surveying in the past required substantial investment and specialized expertise.

How LRTK Opens a New Era in 3D Surveying

In this context, LRTK has emerged as a solution that overturns conventional assumptions. LRTK is a next-generation positioning system that brings RTK-GNSS (real-time kinematic positioning) capabilities to smartphones in an easy-to-use way. By attaching a dedicated ultra-compact GNSS receiver to an iPhone or iPad, the typical meter-level error of smartphone positioning can be improved to centimeter-level accuracy. In general GNSS positioning errors can be several meters, but RTK corrects the rover’s position to centimeter-level accuracy by simultaneously observing satellite signals at a base station (with a known position) and at the rover, canceling out common error factors. Performing this correction in real time enables immediate high-precision coordinates for the point being measured. While traditionally one needed to set up a personal base station or transmit correction data via radio, recent developments—such as network RTK using the Geospatial Information Authority of Japan’s reference station network and the spread of augmentation signals (CLAS) from Japan’s Quasi-Zenith Satellite System, Michibiki—have made centimeter-level positioning achievable without dedicated base stations.

LRTK devices themselves are pocket-sized and lightweight (about 130 g), with built-in batteries and high-performance antennas designed for easy transport on site. Using a smartphone app, users can capture positioning data at the touch of a button and immediately record and share it. Operation is simple and attaching the device is a one-touch process. The user interface is intuitive enough for people without special training to use. In other words, LRTK transforms a smartphone into a "pocket-sized all-purpose surveying device", lowering the bar for precision surveying that previously required experts so that anyone can perform it routinely.

Digitalization of the Site Enabled by LRTK

By using LRTK, the following types of digital construction can be carried out by anyone on site:

• High-precision surveying (acquiring positional coordinates): Simply point a smartphone at the desired spot and press a button to record latitude, longitude, and elevation to centimeter accuracy. Tasks that previously required survey stakes or experienced personnel—such as layout work—can now be completed quickly by a single person. The captured coordinate data are automatically converted to standard coordinate systems (e.g., the plane rectangular coordinate system), making them immediately usable for design checks and as-built management.

• 3D point cloud measurement and earthwork calculation: By combining a smartphone’s camera or LiDAR capabilities with LRTK’s high-precision positioning, you can capture the site’s terrain and structures as 3D point cloud data. The acquired point clouds can be visualized as 3D models in the cloud, and excavation/fill volume calculations can be performed automatically with the push of a button. This allows site personnel to perform 3D as-built measurements that were previously outsourced to specialists.

• AR-assisted construction support: Design 3D models can be overlaid on the site view through a smartphone so the completed image can be shared intuitively. With LRTK’s precise position and orientation tracking, models stay nearly perfectly aligned with reality even when viewing from various angles while walking around. This makes it easy to spot and correct discrepancies between the design model and existing conditions on the spot, or to share the intended finished appearance with clients and workers to align construction expectations. For example, AR has been used to overlay embankment models on site to verify whether construction can proceed according to design.

• Immediate sharing and use of survey data: Positioning data, point clouds, and photos collected via the LRTK app can be uploaded to the cloud on site for sharing within and outside the organization. Office staff can instantly check field survey results remotely, and data from different sites can be compared and reviewed. Using cloud maps and CAD integration, coordinates collected on site can be immediately matched against drawings or BIM/CIM models. Real-time data sharing reduces reporting and review time lags and is expected to accelerate the PDCA cycle for construction management.

In this way, LRTK enables a seamless workflow not only to "measure and record" but also to immediately "show," "compare," and "use" the measured data on site. It is a powerful tool for accelerating site digitalization.

For example, on a road construction project, LRTK was used to 3D-scan existing terrain before construction, overlay it with the design model, and verify during the planning stage that there were no issues. During construction, excavation depths were measured on demand with LRTK, and automatically calculated earthwork volumes in the cloud were shared instantly to prevent over-excavation or under-excavation. Processes that used to require separate specialist teams or later analysis were completed by a single technician in the field, improving efficiency and accuracy across the whole project.

Furthermore, during the 2023 Noto Peninsula earthquake, LRTK was used for rapid 3D documentation of affected sites. High-precision data collected on site was shared immediately and helped with damage assessment and restoration planning. Achievements like these are contributing to the growing presence of mobile surveying technologies like LRTK in civil engineering and construction.

Comparison with Other Surveying Technologies

• Total station (electro-optical surveying): Total stations offer millimeter-level accuracy by measuring distance and angles from a reference point to a prism. However, they require line of sight and are typically operated by two-person teams. They measure one point at a time, making wide-area surveys time-consuming. Also, to obtain accurate coordinates with a total station you need to set up the instrument based on known points; by contrast, LRTK can obtain global coordinates directly without such initial setup thanks to satellite positioning. Because LRTK uses satellite positioning, it is less constrained by line-of-sight and enables a single operator to survey wide areas quickly.

• Conventional RTK-GNSS survey equipment: High-precision GNSS surveying equipment has long existed, but typically requires large, fixed receivers and dedicated controllers, and is expensive. LRTK delivers comparable positioning accuracy in a pocket-sized device and dramatically improves usability by leveraging smartphones. In addition, functions such as point cloud capture and AR display give LRTK an integrated capability that conventional GNSS equipment often lacks.

• 3D laser scanners: 3D laser scanners can rapidly acquire enormous point clouds and are suitable for millimeter-precision detailed shape measurement. However, they are costly and cumbersome to transport, and aligning acquired data to map coordinates may require target placement or post-processing. For wide-area detailed surveys, laser scanners may need multiple setups, whereas LRTK operators can walk around to continuously capture data from various angles. For cases that do not require ultra-high-density measurements, LRTK’s easy 3D capture provides sufficient results for many needs, enabling immediate use in known coordinate systems.

• Drone photogrammetry: UAV-based photogrammetry can quickly generate 3D models of large areas, but it involves flight permissions, weather constraints, and processing time. Generating point clouds or models from aerial images requires processing in dedicated software, whereas LRTK’s immediacy—allowing data to be used right after measurement—is an attractive advantage. Site personnel can immediately start ground-based surveying, and LRTK is flexible for narrow areas, indoors, or under structures where drones cannot reach. For routine progress surveys and detailed local measurements, LRTK is nimble, and when combined with drone surveys the two methods can complement each other’s limitations.

Benefits of Introducing LRTK

Implementing LRTK on site yields many benefits:

• Simplicity: As a smartphone-based tool, operation is intuitive and staff without specialized training can quickly become proficient. Site workers themselves can collect necessary data without relying on a surveying department, reducing downtime. The familiar smartphone interface makes adoption easy, especially for younger staff.

• Labor savings and efficiency gains: With single-person surveying possible, even labor-short sites can progress surveying tasks efficiently. Layout work and as-built measurements that formerly required two or more people can be completed quickly by one person. Automated data processing and transfer to drawings reduce the time from measurement to reporting.

• Lower cost: With only an LRTK device and a smartphone, there is no need to purchase expensive dedicated surveying equipment, reducing initial investment. Maintenance and outsourcing costs are also reduced, and deploying multiple units as needed becomes realistic. The affordability and ease of deployment make it possible to equip many site personnel and achieve measurement democratization.

• Improved accuracy and reliability: Centimeter-level positioning dramatically increases the reliability of as-built accuracy and survey results. Compared with common GPS positioning (errors of several meters), the improved accuracy reduces rework and mistakes due to misplacement, directly raising quality control. Measurement records also automatically include timestamps and positioning status, ensuring the data’s reliability as evidence.

• Real-time decision making: Because measurement data are shared to the cloud immediately, stakeholders on site can grasp conditions and make decisions on the spot. Responsible managers remotely can check the latest information and give instructions without visiting the site. This shortens the time lag from "measure, report, and wait for instructions," enabling faster on-site decisions. Construction management based on real-time 3D information is likely to become the standard for future project operations.

• Future readiness: The precise 3D data captured with LRTK is directly useful for increasingly demanded BIM/CIM and digital twin workflows. It also makes it easier to comply with new standards and guidelines, such as the Ministry of Land, Infrastructure, Transport and Tourism’s 3D as-built management procedures, allowing smoother adoption of contemporary construction practices.

Conclusion: Toward Digital Construction Anyone Can Do

3D surveying is no longer a specialized skill reserved for a few experts; it is becoming a new norm that anyone on site can utilize. LRTK, the technology leading this change, dramatically lowers the barriers to digital construction and transforms the process beyond merely "measuring" to include immediate utilization of the measured data. Even inexperienced workers can perform high-precision surveys with a smartphone in hand, visualize results intuitively through AR, and share data instantly to drive the next action. The day when such scenes are commonplace is not far off.

We invite you to experience this revolutionary technology that overturns conventional norms at your own sites. By adopting LRTK, "3D surveying anyone can do" becomes a reality, and your site can step into a new stage of digital construction.