3D Surveying Without Expert Knowledge: Construction DX Starting with LRTK

In the construction industry, DX (digital transformation) through 3D surveying is attracting significant attention. Among construction DX initiatives that leverage ICT and AI, three-dimensional surveying—which accurately digitizes on-site conditions—is a foundational and important technology. While three-dimensional measurement traditionally required expensive surveying equipment and expert knowledge, recent technological innovations are enabling tools that anyone can use even without expert knowledge.

This article explains the basics and benefits of 3D surveying, outlines the challenges of conventional methods, and considers its role in construction DX. It also introduces “LRTK” as an example of a new technology that can be implemented without expert knowledge and describes the transformation it brings to the field.

What is 3D surveying

Three-dimensional surveying (3D surveying) is a method of measuring the position and shape of objects or terrain as three-dimensional coordinate data (length, width, and height). A major feature is its ability to capture three-dimensional shapes that conventional planar (2D) surveying could not. Specifically, sensors such as laser scanners and cameras are used to acquire point cloud data (a collection of many coordinate points) from object surfaces, and 3D models of terrain and structures are generated from those point clouds. There are several 3D surveying methods, including aerial photogrammetry using drones, ground-based 3D laser scanner measurements, and, more recently, scans using smartphone-mounted LiDAR sensors. Because all of these methods acquire the shape of targets as digital three-dimensional data, they are extremely useful for civil engineering construction and infrastructure maintenance management.

Benefits of 3D surveying

3D surveying offers many advantages not found in traditional labor-intensive surveying. First, it enables efficient measurement of large areas in a short time. With drones or laser scanners, large sites can be measured in a short time to collect large amounts of point cloud data, drastically shortening work that used to take days for planar surveying. In fact, there are reports that a survey that previously took two days was completed in half a day using drone surveying:contentReference[oaicite:0]{index=0}. Second, it provides high-accuracy and comprehensive data. Because the entire object is recorded as point cloud data, omissions are reduced compared to measuring points one by one manually, and minute differences on the millimeter scale can be detected:contentReference[oaicite:1]{index=1}. For example, measurements of structures inside deep foundation pits, which were difficult with conventional methods, have been reported to be performed safely and accurately using point cloud measurement. Third, improvements in safety should not be overlooked.

Fourth, there are cost reduction effects from preventing rework. High-precision measurement allows early detection of construction errors and prevents rework, which leads to shorter construction periods and reduced extra costs.

Even in dangerous areas or places where people cannot enter, remote 3D surveying eliminates the need for direct work, contributing to worker safety. The acquired data can also be shared in the cloud as digital records, allowing all stakeholders to view the same three-dimensional information and making information sharing between the site and the office smooth.

Main use cases for 3D surveying:

• Earthwork volume management: calculating the volumes of cut and fill and the amounts of soil transported

• As-built inspection: comparing point cloud data with design models to determine whether measurements are within specified tolerances

• Construction progress management: periodically scanning the site to record construction progress in 3D

• Infrastructure inspection: understanding displacements and damage to bridges, tunnels, etc., with point clouds and analyzing aging-related changes

• Disaster surveys: quickly grasping damage by aerial photography and scanning immediately after a disaster

Challenges of conventional surveying and the barrier of expert knowledge

Conventional surveying methods had several challenges, which contributed to the impression that “you can’t handle it without expert knowledge.” The main issues are listed below.

• Time and labor burden: Manual surveying requires measuring and recording each point with a tape measure or total station, and measuring large areas required enormous time and manpower. On sites with labor shortages, it was sometimes impossible to secure enough measurement points, reducing survey frequency.

• Measurement errors and accuracy limits: Manual work always carries the risk of human error, and there were limits to ensuring accuracy based on experience. The data obtained was also limited, and because structures could only be captured as discrete points, there was a risk of overlooking small deviations in details.

• Inefficient data management: Measurement results were recorded by hand on paper drawings and tables and matched with photo logs, making management cumbersome. Digital data sharing did not progress, and it was not easy to find needed information later.

Thus, conventional human-dependent surveying had the problems of being “time-consuming,” “incomplete,” and “underutilized,” and fundamental improvements were required in modern times that demand higher sophistication and efficiency. Conventionally, performing millimeter-level high-precision positioning on site required dedicated equipment and experienced technicians, and the equipment itself was extremely expensive, costing several million yen:contentReference[oaicite:2]{index=2}. Such high barriers made 3D surveying a high-threshold “expert’s job.”

Also, 3D surveying using drones or laser scanners required advanced post-processing—such as measuring control points (known reference points) to align the acquired data to an accurate coordinate system and correcting point cloud distortions:contentReference[oaicite:3]{index=3}. These tasks also demanded specialized knowledge and a great deal of time, further raising the barriers to 3D surveying.

3D surveying driven by construction DX

To solve the challenges mentioned above, the construction industry is advancing innovative initiatives through surveying DX (digital transformation) and smart construction. Under the Ministry of Land, Infrastructure, Transport and Tourism’s *i-Construction* (productivity improvement measures using ICT on sites) and initiatives promoting infrastructure DX, the trend to centralize the entire construction production process—from investigation and surveying to design, construction, inspection, and maintenance—into three-dimensional data is accelerating:contentReference[oaicite:4]{index=4}. Specifically, the use of point cloud data obtained by drone aerial photography or ground laser scanners and BIM/CIM models created during design for site management is becoming widespread, dramatically improving construction accuracy and operational efficiency:contentReference[oaicite:5]{index=5}. As mentioned earlier, there are examples where drone surveying greatly shortened work time, and cases where productivity improved by about 30% through automated control of construction machinery and IoT-based real-time visualization:contentReference[oaicite:6]{index=6}. By introducing 3D surveying technology, it has become possible to measure large areas non-contact and at high speed, and software can automatically analyze the detailed data to perform quality checks and quantity calculations. This enables detection of minute displacements difficult to capture with manual surveying, immediate pass/fail judgments, and rapid creation of as-built diagrams and tables. Surveying DX is fundamentally changing construction management.

Emergence of technologies that eliminate the need for expert knowledge

Recently introduced technologies are making “3D surveying without expert knowledge” a reality. A representative example is high-precision surveying devices compatible with smartphones. For example, a combination of a small GNSS receiver that can be attached to a smartphone and a dedicated app now allows anyone to easily perform centimeter accuracy (cm level accuracy (half-inch accuracy)) positioning:contentReference[oaicite:7]{index=7}. Conventionally, centimeter-class RTK-GNSS surveying required expensive equipment and experienced personnel, but with just a smartphone and a palm-sized receiver you can start positioning instantly with the push of a button, with no complex setup required:contentReference[oaicite:8]{index=8}:contentReference[oaicite:9]{index=9}. Acquired positioning data is automatically saved and shared in the cloud, allowing real-time sharing between the site and the office. Recent products even include models compatible with Japan’s satellite positioning augmentation service “Michibiki” CLAS signals, enabling direct reception of correction information from satellites and maintaining accuracy even in mountainous or out-of-coverage disaster areas. With these advanced technologies, an era has arrived where site personnel can perform 3D surveying themselves without surveying expertise or advanced equipment operation.

Intuitive 3D scanning technologies using smartphone cameras and sensors are also advancing. For example, there are solutions that allow you to obtain point clouds by simply “walking with your smartphone in hand” without special training:contentReference[oaicite:10]{index=10}. By moving around the site while pointing the camera, high-accuracy point cloud data with positional coordinates is automatically generated, and measurements of distances, areas, and volumes are completed in the cloud:contentReference[oaicite:11]{index=11}. The previously cumbersome installation of control points is unnecessary, and the acquired point clouds can be used in formats that conform to the Ministry of Land, Infrastructure, Transport and Tourism’s deliverable standards, providing quality suitable for formal as-built documentation:contentReference[oaicite:12]{index=12}. Such “walk-and-scan” capabilities enable site staff to intuitively perform 3D surveying.

Furthermore, various 3D surveying devices tailored to field applications have appeared. For example, some high-precision GNSS devices incorporate a 360° camera, and there are types that allow hands-free positioning by mounting a thin antenna on a helmet or vest:contentReference[oaicite:13]{index=13}. Because workers’ exact positions can be known in real time, the system can trigger alarms if a worker accidentally enters a restricted area, contributing to safety management:contentReference[oaicite:14]{index=14}. These new technologies not only increase surveying efficiency but also contribute to improved on-site safety.

Moreover, the use of AR (augmented reality) technology to overlay acquired 3D data onto the real world is advancing. By displaying 3D design models on a smartphone or tablet screen and overlaying them onto the actual site footage, differences between design drawings and the current situation can be intuitively confirmed. For example, if the positions of underground buried objects previously scanned are displayed in AR, anyone can easily perform excavation work that avoids them:contentReference[oaicite:15]{index=15}. AR functions are also useful for sharing the completed image between clients and contractors, reducing communication loss.

Construction DX starting with LRTK

:contentReference[oaicite:16]{index=16} *A small LRTK positioning device (LRTK Phone 4C) attached to an iPhone. Palm-sized, it can turn a smartphone into a high-precision surveying instrument.*

Among the many new technologies, LRTK was developed specifically for practical use on construction sites. LRTK is a solution consisting of a smartphone-mountable RTK-GNSS receiver device and cloud service developed by a startup from Tokyo Institute of Technology that makes it possible to turn a smartphone into a “one-person, one-device surveying instrument”:contentReference[oaicite:17]{index=17}:contentReference[oaicite:18]{index=18}. By attaching a compact receiver weighing about 125 g to an iPhone or iPad and launching a dedicated app, real-time positioning begins without complex setup, receiving correction information from base stations and calculating the device’s position on the smartphone to centimeter accuracy (cm level accuracy (half-inch accuracy)):contentReference[oaicite:19]{index=19}. Centimeter-accuracy positioning, which previously required total stations or expensive GNSS equipment, has been transformed by LRTK into work that anyone can perform:contentReference[oaicite:20]{index=20}. The ease with which site supervisors and construction managers can perform surveying with just a smartphone is truly a “DX tool that everyone on site can use.”

The effects of introducing LRTK are also significant. For example, taking a photo with a smartphone automatically records latitude, longitude, elevation, and camera orientation, allowing a geotagged photo log to be created with one tap:contentReference[oaicite:21]{index=21}. In earthworks, volumes of fills and excavations can be instantly calculated from acquired point cloud data, and differences from the design model can be color-coded to detect as-built deviations at a glance. Moreover, because the obtained 3D data is managed and shared in the cloud, information measured on site can be immediately shared with the office and clients, enabling rapid decision-making. Even in mountainous areas without network coverage, models compatible with CLAS satellite signals can perform standalone positioning, making LRTK terminals capable of high-precision surveying and information sharing in post-disaster surveys and similar situations:contentReference[oaicite:22]{index=22}. In terms of price, LRTK is much more affordable than traditional equipment, making one-device-per-person deployment realistic:contentReference[oaicite:23]{index=23}. Rather than expensive equipment being used only by limited specialized departments, an era is beginning where each worker can take an LRTK from their pocket and perform surveying when needed.

In practice, high-precision positioning technologies including LRTK are being used across a wide range of fields—construction consultants, surveying companies, construction firms, infrastructure-related businesses, and local governments—and their small size, high accuracy, and affordability are driving wider adoption:contentReference[oaicite:24]{index=24}. These innovative solutions are expected to make major contributions to the advancement of i-Construction and DX in the construction sector promoted by the Ministry of Land, Infrastructure, Transport and Tourism:contentReference[oaicite:25]{index=25}.

As described above, 3D surveying is no longer just for licensed surveyors. Fueled by DX, three-dimensional surveying without expert knowledge is dramatically improving on-site productivity and quality. It will also greatly assist in addressing the “2024 problem” (work-hour caps) and chronic labor shortages facing the construction industry by improving efficiency with smart surveying technologies.

Of course, introducing digital technologies requires human resource development and a review of existing work processes. However, if site engineers become proficient with these ICT tools and can fully utilize the data, the effects of DX will be maximized. If you are considering introducing 3D surveying, you might first consider a solution like LRTK that is easy to start with. By taking the first step into construction DX with LRTK, you can bring the power of digital surveying—usable by anyone—onto the site and raise construction efficiency and accuracy to the next level.

Use advanced technologies to your advantage and create a wave of digital transformation on site with 3D surveying. The sooner you act, the greater the results and competitive advantage are likely to be.

The wave of digitization is already upon us. Without falling behind, proactively incorporate technology into your sites.