Surveying with a Smartphone! The On-site DX Revolution Brought by i-Construction

In the construction industry, leveraging digital technology to improve on-site productivity has become an urgent priority. In this context, the Ministry of Land, Infrastructure, Transport and Tourism’s [i-Construction](https://www.mlit.go.jp/tec/i-construction/) initiative has attracted attention as a drive to achieve on-site DX (digital transformation) across surveying, construction, and management. Especially in the field of surveying, there is a movement to innovate work that once relied on manual labor and specialized instruments by using smartphones combined with high-precision positioning technologies. The era when you can survey with just a smartphone has arrived, and a true on-site DX revolution is underway.

This article, titled "Surveying with a Smartphone! The On-site DX Revolution Brought by i-Construction," explains in detail the overview and background of i-Construction in surveying, the challenges of conventional methods, and cutting-edge surveying techniques using smartphones × RTK (real-time kinematic). It also introduces the diverse features enabled by smartphone surveying—such as point cloud scanning, AR functions, and cloud sharing—and the operational transformation and benefits these bring. Finally, we touch on the advantages of easy surveying using a solution called LRTK that enables smartphone surveying, offering tips for taking the first step toward on-site DX.

Overview and Background of i-Construction (Focused on Surveying)

Overview of i-Construction: i-Construction is a productivity improvement project for construction sites launched by the Ministry of Land, Infrastructure, Transport and Tourism in 2016. It refers to efforts to enhance efficiency and sophistication across the entire construction process—from surveying and design to construction, inspection, and maintenance—through the full-scale use of ICT (information and communication technologies). The initiative responds to chronic labor shortages in the construction industry and difficult working conditions often described as the "3Ks" (kitsui — tough, kitanai — dirty, kiken — dangerous). In fact, the number of people employed in construction has declined from a peak of about 6.85 million in the late 1990s to about 4.79 million in 2022. An aging workforce and a shortage of younger workers are becoming severe. The government has set a target under i-Construction to raise on-site productivity by 20% by fiscal 2025, and has been promoting measures such as ICT adoption, standardization of 3D data, and leveling of construction schedules.

The beginning of surveying DX: i-Construction has brought particularly significant change to the field of "surveying." Traditional terrain surveys that relied on total stations and levels operated manually have begun to give way to drone aerial surveying and point cloud measurement via 3D laser scanners thanks to i-Construction’s promotion. The adoption of 3D surveying, which can measure wide areas in a short time, has enabled workflows that capture terrain and structures as high-density point cloud data for use in design and construction. For instance, flying a drone over an earthwork site in a mountainous area can quickly capture detailed terrain data for the entire site, after which heights and distances at arbitrary locations can be measured. Introducing ICT-based surveying has greatly improved efficiency and accuracy in surveying work and served as a first step toward on-site DX.

Conventional Surveying Methods and Their Limits (Labor, Accuracy, Schedule, Safety)

• Dependence on manpower and specialized skills: Conventional surveying has relied on professional surveyors and technicians, with the accuracy often depending on the experience and intuition of veterans. Multiple people are required to operate equipment, and with staff shortages, it can be difficult to carry out surveying operations at all.

• Limits on time and efficiency: Because survey points have historically been measured one by one, vast sites or highly uneven terrain require enormous amounts of time. Work can be interrupted by weather, and the longer surveying takes, the more it impacts the overall project schedule.

• Challenges in accuracy and coverage: Although modern total stations and other instruments are highly accurate, the number of points they can measure is limited, making it difficult to fully capture complex terrain or structures. Two-dimensional drawings represented by points and lines may overlook small irregularities, and errors due to missed measurements or recording mistakes cannot be eliminated entirely.

• Safety risks: Surveying along roadsides or on steep slopes always carries the risk of accidents or injuries. Carrying heavy equipment in extreme heat or cold places a large burden on workers, and harsh working conditions have contributed to people leaving the industry.

As described above, conventional methods impose many constraints on efficiency and safety, presenting challenges to productivity improvement in the construction industry.

What Surveying DX Is (Definition and the Relationship with i-Construction)

Surveying DX (digital transformation) means introducing digital technologies into surveying operations to fundamentally change work processes. It is not just digitizing surveying instruments; it involves leveraging 3D measurement technologies, mobile apps, and cloud services to innovate how surveying is performed, how accurate it is, and how data is utilized. The ICT-driven construction sites envisioned by i-Construction are built on this foundation of surveying DX.

Specifically, examples such as automatically processing point cloud data obtained from drone photogrammetry or laser scanners with software to quickly generate terrain models have become widespread. Terrain surveys that used to take experienced personnel days to complete can now be finished in hours under DX, and the results can be recorded and shared as detailed 3D data. Furthermore, data measured on-site is recorded not in paper fieldbooks but on tablets or in the cloud, enabling immediate sharing with the office for analysis and drawing creation. Through surveying DX, surveying itself is sped up and labor is reduced, and the collected data can be used seamlessly in subsequent design and construction processes, directly contributing to productivity improvements across construction projects.

Technical Overview and Accuracy of Surveying with Smartphones × RTK

The recently emerged smartphone × RTK surveying technology has made it possible to use smartphones as high-precision surveying instruments. RTK (real-time kinematic) is a technique that applies correction information from a base station to GNSS (satellite positioning) data to greatly reduce positioning errors. While the GPS built into typical smartphones has errors on the order of meters, using RTK reduces errors to on the order of centimeters. Centimeter-level accuracy that once required professional GPS survey equipment can now be achieved with a smartphone.

Concretely, a small RTK-GNSS receiver attached to a smartphone and a dedicated app are used to receive real-time correction data from base stations (Ntrip) or augmentation signals from satellites over a network. In Japan, devices that use the QZSS (Michibiki) CLAS signals have appeared, enabling positioning even where network coverage is limited. With apps on the smartphone, high-precision positioning becomes possible within just a few tens of seconds after starting, enabling not only single-point coordinate measurement but also guidance to arbitrary coordinates (stakeout work). The accuracy in immediate measurement can be roughly 1–3 cm horizontally and vertically, and averaging measurements can achieve errors under 1 cm. Achieving that level of accuracy from a device that fits in your pocket is a major breakthrough in surveying technology.

Smartphone Surveying Features: Point Cloud Scanning, AR, and Report Output

• Point cloud scanning: Using a smartphone camera or LiDAR, you can scan the surrounding environment and record it as a collection of countless points (a point cloud). With RTK-enabled smartphone surveying, it is easy to obtain absolute-coordinate 3D point clouds where each point is assigned global coordinates (latitude, longitude, elevation). Complex terrain and structures can be turned into high-precision 3D data simply by walking around while holding a smartphone, and you can later measure distances, areas, and volumes at arbitrary spots or compare and analyze them against drawings. (LiDAR-only smartphone scanning can suffer distortions when moving, but RTK continually corrects the device’s position to produce more accurate point clouds.)

• AR display and stakeout guidance: You can overlay design drawings or 3D models on the smartphone screen to visualize the completed form on-site as AR (augmented reality). This lets you instantly verify whether construction is proceeding according to plans and easily share the completion image with clients. Smartphones can also provide position guidance based on the device’s measured location to navigate to specified coordinates (assisting stakeout work). Because the phone guides you to points on the drawing, even non-experts can perform accurate layout and marking. Additionally, by scanning and recording the positions of buried utilities as a point cloud in advance, you can project those locations in AR during future excavations to avoid pipes and ensure safe construction.

• Automatic calculations and report output: Smartphone surveying apps automatically calculate and organize the necessary information from the collected data. For example, they can instantly compute cut-and-fill volumes from numerous measured points or display the differences between current point cloud data and design data as a color-coded heat map. Results required for quality control can be generated on the spot, and standard reports and drawings (such as cross-sections) can be automatically produced and exported. This greatly reduces tedious manual calculations and CAD drafting.

Changing Sites with Accessible UX, Automation, and Cloud Sharing

A major advantage of smartphone surveying systems is that their usability and automation make them accessible to anyone. Traditional surveying instruments required specialized knowledge to operate, but smartphone apps enable intuitive measurement and data processing through user-friendly UIs. You can record survey points by tapping on a map, or have coordinate transformations and calculations done with a single button—the app handles complex tasks in the background. This makes it easier for site supervisors and younger staff who are not surveying specialists to acquire and use data, reducing the burden on experienced personnel.

Moreover, cloud integration enables real-time sharing of surveying data. With one tap, data from a smartphone can be uploaded to the cloud and immediately shared with office staff or clients. Point clouds and photos measured on-site can be reviewed with supervisors or partner companies in real time, enabling speedy decision-making without rework. Because data accumulates in the cloud, it can be used as organizational knowledge even after a project ends. Eliminating the need to hand off information via paper or USB removes geographic constraints and allows site and office to operate as one—an important DX-driven operational transformation. Furthermore, remote supervisors or engineers can check cloud-stored data and provide advice without visiting the site, changing how people work.

Benefits of Adoption for Municipalities, Site Managers, and Surveyors

• Municipalities (public clients): For municipalities that commission construction, the spread of smartphone surveying offers benefits in both quality and efficiency. If contractors submit high-precision 3D surveying data as-built, the burden of inspection and on-site attendance is reduced. During construction, municipalities can monitor measurement status via the cloud and issue early instructions as needed. The 3D point cloud data also remains as an asset after completion, usable for maintenance and future planning. Adopting the latest technologies can bring both efficiency and transparency to operations, making smartphone surveying an attractive solution for public clients.

• Site managers (construction supervisors): For on-site supervisors, smartphone surveying can transform daily operations. Without relying on a specialist surveying team, they can measure and verify conditions themselves immediately, eliminating delays caused by "waiting for surveying." For example, scanning the current volume of embankment on the spot lets you quickly determine shortages or excesses and take immediate corrective actions. Differences between drawings and field conditions can be checked with AR, helping prevent rework. Automated report and document generation reduces tedious administrative tasks, allowing supervisors to focus on core construction management. The result is shortened schedules, improved quality, and increased trust from clients.

• Surveyors (surveying professionals): For professional surveyors, the rise of smartphone surveying is not a threat but a helpful aid. Introducing tools that can be used without deep specialized know-how allows assistants and younger team members to handle a range of surveying tasks. With fewer personnel, teams can cover more sites, making it easier to manage workloads amid chronic labor shortages. Automated data processing reduces recording errors and streamlines the creation of inspection and delivery drawings, freeing surveyors to focus on quality control and analysis. Exposure to advanced measurement technologies also contributes to skill development, making surveying itself a more digitally attractive profession. Surveyors who proactively adopt cutting-edge technologies can play leading roles in the ongoing infrastructure DX.

LRTK That Enables Smartphone Surveying and the First Step Toward On-site DX

Finally, a practical way to realize smartphone surveying on-site is by using LRTK. LRTK is a solution consisting of an ultra-compact RTK-compatible device that attaches to a smartphone and a corresponding app, turning an ordinary smartphone into a centimeter-accurate surveying instrument. There is no need to acquire dedicated equipment: with just a smartphone and LRTK, you can immediately start simple surveying, which is a major advantage. The compact design—battery built-in and antenna attached—makes it easy to carry, and devices that can use satellite augmentation signals enable high-precision positioning even where network connectivity is poor, delivering strong performance anywhere.

In practice, companies that have introduced LRTK and implemented a one-person-per-phone smartphone surveying system are already seeing productivity gains. By adopting smartphone surveying with LRTK, you can instantly enjoy the benefits described throughout this article. A smartphone in each worker’s pocket becomes a versatile surveying instrument, providing an all-in-one solution from point cloud scanning to stakeout guidance and cloud sharing. It is lower-cost and easier to adopt than specialized equipment, and the output data conforms to the Ministry of Land, Infrastructure, Transport and Tourism’s standards, so it can be confidently used as official survey results. You can start using it the same day you bring it to the site and feel the effects in a short time. It truly is an ideal first step toward on-site DX.

Why not introduce smartphone surveying—now becoming a new standard in the i-Construction era—on your sites? Start the productivity revolution on your sites with easy surveying DX using LRTK.