The Future of 3D Surveying Pioneered by LRTK: Accelerating Construction DX with High Precision and Labor Savings

Recently, digital transformation (DX) has been rapidly advancing in the construction industry, and “3D surveying” is attracting attention as a core technology. Traditional surveying required skilled technicians and long hours, but new 3D surveying technologies are expected to improve on-site productivity. This article reviews the basics of 3D surveying and the challenges of conventional methods, and introduces how the latest solution, LRTK — which combines smartphones with RTK (real-time kinematic) technology — is changing industry norms, achieving both labor savings and high precision to accelerate construction DX. Please read to the end to help you consider introducing 3D surveying.

What is 3D surveying?

3D surveying is a surveying method that measures an object’s shape and position in three directions—length, width, and height (X, Y, and Z axes)—to obtain three-dimensional data. A key feature is the ability to capture terrain undulation and structural forms in detail, which cannot be obtained with traditional planar surveying. 3D measurement results are expressed as dense sets of points (point cloud data) or 3D models, digitally reproducing the site as it actually is. Because many of these methods can measure remotely and without contact, they are suitable for surveying steep terrain or large structures that are difficult to access. This technology enables consistent, high-precision process management based on accurate data from pre-construction terrain assessment through to post-construction as-built management.

The importance of 3D surveying for construction DX

The construction industry faces severe labor shortages and stagnant productivity, and DX (digital transformation) is being promoted as a key solution. The Ministry of Land, Infrastructure, Transport and Tourism’s i-Construction initiative aims to improve productivity at construction sites by 20% by 2025 through full utilization of ICT. Furthermore, the recently formulated "i-Construction 2.0" aims to reduce the number of on-site workers by 30% by fiscal 2040 (labor-saving), promoting further automation and DX.

3D surveying plays an especially important role in this trend. 3D data obtained on site can be linked to BIM/CIM models at the design stage for construction planning and used for maintenance and management after completion. Issues that are easily overlooked in planar drawings or paper reports can be intuitively understood with three-dimensional data, facilitating smoother communication between clients and contractors. In addition, in 2022 the Ministry of Land, Infrastructure, Transport and Tourism published a revised draft of guidelines for as-built management using 3D surveying technology, and the onsite adoption of 3D surveying has begun to move toward industry standardization.

Also, the ability to digitally record and share the site in real time enables remote progress management and quality checks, significantly transforming work processes. Given this background, the question of “how to efficiently perform high-precision 3D surveying” has become a key to promoting DX.

Conventional surveying methods and challenges of 3D conversion

Traditionally, surveying at construction sites typically used specialized instruments such as total stations and levels (surveying spirit levels), with multiple people measuring coordinates and elevations point by point. Total stations can measure point positions with millimeter-level accuracy, but they require setting up the instrument at each location and sighting and reading each point individually, so measuring large areas or complex structures involves enormous effort and time. Because there is no data between measured points, understanding the shape of the entire site required interpolating between survey points or measuring an extremely large number of points. Surveying tasks typically required a two-person team (instrument operator and staff holding the reflector), increasing labor costs.

In recent years, technologies that can more efficiently acquire 3D data for entire sites have emerged, such as drone (UAV) photogrammetry and 3D laser scanners. Drone photogrammetry creates 3D models of terrain and structures by analyzing many aerial photos, significantly reducing labor compared to conventional methods. However, to ensure accuracy it is necessary to place known ground control points, and it is also subject to weather conditions and flight regulations. Laser scanners can automatically acquire high-density point clouds with high accuracy, but the equipment is large and expensive, and because scanning is done from fixed set-ups on tripods, combining data from multiple scan positions is required for wide areas. Moreover, assembling a suite of purpose-specific equipment such as RTK-GNSS receivers and cameras for photogrammetry increases initial investment, operator training, and data integration workload.

Thus, conventional technologies each have pros and cons, and challenges remain in “easily obtaining high-precision 3D data.” A simpler, all-in-one surveying solution was in demand.

Smartphone + RTK: an evolving 3D surveying solution

Against this backdrop, a new 3D surveying solution combining smartphones with compact RTK positioning devices has recently emerged. By attaching a palm-sized RTK-GNSS receiver to the latest smartphones — which are equipped with high-performance GPS, cameras, and LiDAR sensors — centimeter-level positioning and 3D scanning can be achieved remarkably easily. The receiver is an all-in-one design with built-in antenna and battery, and weighs only around a hundred grams, making it extremely lightweight. It attaches to the device like a phone case and connects wirelessly via Bluetooth, eliminating complicated wiring and large set-ups. RTK surveying, which used to require a fixed base station and heavy tripods, can now be completed within the palm of a hand with a smartphone and a compact device.

In this solution, called LRTK, a dedicated app is launched on the smartphone screen to receive high-precision position data from the GNSS receiver in real time. It supports network RTK methods (such as VRS) that use correction information delivered from base stations and Japan’s GNSS control network (electronic reference points), and positioning can go from device power-up to FIX status determination in just a few seconds. Even if satellites are temporarily obstructed in mountainous areas or near tunnels, high-precision positioning is quickly restored, allowing surveying to continue without stress in sites with frequent movement.

Notably, the smartphone + RTK device combination becomes an all-in-one surveying instrument that performs multiple roles with a single unit. By using the LRTK system, you can instantly realize a variety of on-site functions such as:

• 3D point cloud scanning: With a LiDAR-equipped smartphone, simply walking around the site lets you laser-scan terrain and structures in a short time to obtain high-density point cloud data. Each point is tagged with absolute coordinates (global positioning coordinates) from RTK, so the resulting point cloud can immediately be used as a 3D model aligned to real-world coordinate systems. It digitizes as-built conditions with precision comparable to large laser scanners and can be used directly for earthwork volume calculations and as-built management.

• Positioning & single-point measurement: Point coordinates including latitude, longitude, and elevation can be recorded by pointing the device at the desired location and pressing a button. Measured points are automatically saved with IDs and timestamps, and conversions to plane rectangular coordinate systems and geoid height calculations are performed instantly. There is no need to record in a field notebook and convert coordinates later, and managing many spontaneously recorded points remains uncomplicated.

• Photogrammetric measurement (high-precision geotagged photos): The smartphone can automatically attach high-precision coordinates and camera orientation (azimuth) information to site photos. For example, when inspecting buried assets and taking photos inside a manhole, the photo can be accurately plotted on a map showing the exact location and direction from which it was taken. This eliminates the need to infer photo locations later and streamlines report preparation.

• Stakeout and installation guidance: The system also provides navigation to preset reference points or coordinates on design drawings while viewing the smartphone screen. Arrows and distances are displayed so users can be guided to the target position, allowing stakeout and installations to be performed at specified coordinates even by non-experts. Switching to AR mode overlays target markers onto the real camera view so the target position appears superimposed on reality, enabling intuitive positioning as if a physical marker were present. Traditionally, stakeout required a surveyor operating the instrument and an assistant moving the stake, but with LRTK one person can quickly and accurately establish positions.

• AR visualization: By leveraging LRTK’s high-precision positioning, advanced uses such as AR display of design models or the locations of buried utilities on site are possible. Previously, GPS errors caused misalignment between virtual models and reality, but with centimeter-level RTK accuracy, design lines and predicted completion models can be overlaid exactly on the site. This enables contractors and clients to share the completed vision or to visually confirm underground pipes before excavation, functioning as a DX-era communication tool.

Thus, the linkage of smartphones and LRTK devices has ushered in an era in which surveying, measurement, stakeout, and verification can all be performed with a single device. Compared to specialized equipment, upfront costs are lower, the devices are easy to carry, and they are user-friendly, accelerating their adoption on-site. Because point clouds, photos, and positioning data obtained within the same system are already aligned to a unified coordinate system, there is no later effort required to merge results from different instruments. On-site information can be reflected in CAD drawings and BIM models immediately, dramatically speeding up data utilization.

Effects on the field: achieving both accuracy improvement and labor savings

The benefits of smartphone + RTK 3D surveying solutions are immense. First is the labor-saving aspect of surveying work. There is no need to transport and set up bulky equipment, and a single person can efficiently measure large sites. Terrain surveys that used to take survey teams several days can, in some cases, be completed in a short time with LRTK. In practice, there are reports where roadwork site surveys that once took several days were completed in less than half a day using LRTK 3D scanning, demonstrating significant on-site efficiency gains. Completing surveys in a shorter time not only reduces staffing needs but can also shorten overall construction schedules.

Next is improved data accuracy and reliability. Centimeter-level positioning with RTK matches the precision of total station surveying and fixed laser scanning. Whereas conventional photogrammetry sometimes required post-processing checks for decimeter-level errors, point clouds and coordinates acquired with LRTK are immediately mapped to a high-precision absolute coordinate system. This reduces the risk of rework and backtracking and allows measurement values to be trusted as deliverables in as-built management.

Improved safety and work efficiency are also notable. Surveying dangerous locations such as cliff faces or disaster sites previously involved significant risk, but measurements using compact devices and smartphones allow rapid recording without prolonged presence in hazardous zones. For example, at a large-scale landslide, a 3D scan can be performed from a safe distance to rapidly determine collapse extent and soil volume. Combining the system with drones or telescoping poles enables acquisition of high-precision position data from afar as needed. Shorter work times reduce workers’ exposure to danger.

Furthermore, the expanded range of data utilization is important. Three-dimensional point cloud data and positioning information can be uploaded to the cloud and shared immediately, enabling timely coordination between the site and the office. Remote engineers can readily check on-site 3D data and issue instructions. Accumulated point clouds can be used for volume calculations, displacement detection, progress comparisons, and other tasks that greatly improve construction management precision. Under DX promotion, data-driven decision-making is emphasized, and the frequent availability of high-precision 3D data contributes to rapid, site-led PDCA cycles.

Another benefit is reduced implementation costs. Surveying systems that utilize commercially available smartphones, like LRTK, are far cheaper than dedicated 3D laser scanners or high-precision GNSS equipment. High-precision surveying that once required investments of several million yen can now be started for a fraction of that budget with a smartphone and a compact device, making adoption feasible even for small-to-medium sites. Lower cost barriers make it realistic for each field worker to carry their own LRTK-enabled device as a “one-person, one-unit” portable surveying tool, allowing immediate surveying and recording whenever needed. In this way, LRTK is turning high-precision surveying — once reserved for specialist technicians — into a routine tool that anyone on site can use.

Closing: the future opened by LRTK

The development and spread of 3D surveying technology are now strongly supporting construction industry DX. At the forefront, LRTK solutions are combining the two values of high precision and labor savings to revolutionize on-site surveying practices. It is a groundbreaking change that surveying work, once entrusted to specialists, is becoming something anyone can do with a smartphone in hand. This helps maintain and improve surveying quality on sites even as experienced technicians decline due to generational change. The use of such advanced technologies can also improve the construction industry’s image, encouraging younger workers to enter the field and facilitating the transfer of expertise from veterans.

Finally, for companies and technicians who want to easily introduce high-precision 3D surveying, consider a simple surveying solution using LRTK. Because it can leverage existing smartphones, initial adoption barriers are low, and you can start using it on-site quickly as part of your DX efforts. Forward-thinking construction sites have already begun adopting smartphone-based surveying technologies. Don’t fall behind this trend—embrace evolving technologies and experience on-site the new era of 3D surveying opened by LRTK.