3D Scanning Enabled by the Latest Positioning Technologies: Streamlining Construction Site Execution Management

What is 3D scanning? Three-dimensional measurement on site made possible by the latest technologies

In construction and civil engineering, 3D scanning (point cloud measurement) for three-dimensional measurement is becoming the “new normal” in execution management. 3D scanning is a technique that records site topography and structures as a multitude of points (point cloud data) using laser light or photogrammetry. Each point contains X, Y, and Z coordinate values (positions), and some methods also capture information such as color or reflectivity. By plotting the collection of points in three-dimensional space, a precise digital 3D model that faithfully reproduces the actual terrain or structure is obtained. The higher the density of the point cloud data, the more lifelike the shape becomes, enabling reproduction of features to the millimeter level.

Such high-precision 3D scanning technology has begun to spread rapidly on sites, supported by initiatives like the Ministry of Land, Infrastructure, Transport and Tourism’s i-Construction promotion. Its use is expanding in many fields, such as infrastructure inspection and diagnosis of aging structures. In execution management as well, high-precision point cloud measurement combined with the latest positioning technologies is attracting attention, and an era is approaching in which “anyone can easily,” “use precise 3D data,” and “apply it immediately on site.” The latest positioning technologies make 3D scanning possible and have begun to make a major contribution to improving on-site productivity and enhancing quality control.

Differences from conventional surveying and benefits of introducing 3D scanning

Conventional surveying typically uses instruments such as total stations (TS) and levels, with two-person teams measuring target points like prisms one point at a time. A TS can measure a specific point with very high accuracy, but the information acquired at one time is only the coordinates of a “point.” In contrast, 3D scanning (point cloud measurement) can obtain millions to tens of millions of measurement points in a single scan, enabling fast area- and volume-based surveying. In other words, while conventional surveying measures by “points,” point cloud surveying measures by “surfaces.” With a laser scanner, broad areas can be measured non-contact from a distance in a short time, and complex terrain and large structures can be recorded safely. Steep slopes, cliffs, and elevated structures that are difficult to measure manually can be captured remotely simply by directing a laser at them, reducing the risk of exposing workers to danger. Because broad areas can be measured comprehensively, subtle irregularities and changes that were previously overlooked can now be identified.

A major benefit of introducing 3D scanning is the dramatic improvement in work efficiency. In one case, measuring an earthwork site of several hectares took about three days with traditional TS surveying; using a ground-based 3D laser scanner it was completed in about two days, and photogrammetry with a drone finished in roughly half a day. In another experiment, surveying with a drone-mounted laser scanner completed wide-area data acquisition in about one-sixth the time of traditional methods, and the overall number of working days was reduced to less than half. By leveraging point clouds in this way, surveying productivity improves dramatically, directly resulting in shorter construction schedules and reduced labor costs.

Ensuring high accuracy is another important advantage. Using the latest laser scanners and photogrammetric analysis, the error in obtained point cloud data can be kept to on the order of a few centimeters to a few millimeters. With appropriate corrections using control points, point cloud measurement can secure accuracy comparable to conventional detailed surveying. Comparative verifications have shown that as-built quantities calculated from 3D scans (volumes derived from post-construction shapes, etc.) had errors within about 1% compared to results from conventional manual surveys. In short, 3D scanning is a technology that achieves both dramatic efficiency gains and sufficient measurement accuracy.

Against this backdrop, the Ministry of Land, Infrastructure, Transport and Tourism is promoting the principle application of CIM (Construction Information Modeling) to directly managed projects, accelerating DX (digital transformation) in the construction industry. From the perspectives of chronic labor shortages and work-style reform, labor-saving and quality improvement through digital technology are urgent issues. Point cloud data obtained by 3D scanning is expected to be a key tool that simultaneously improves accuracy in execution management and reduces labor. Next, let’s look at specific examples of using 3D scanning in execution management tasks.

Use in surveying tasks: rapidly obtaining detailed as-built conditions

First, the use of 3D scanning in site surveying (as-built surveys). Grasping the as-built topography before construction, which forms the basis of civil engineering works and construction planning, is a critical process that affects the accuracy of construction planning and design. Traditionally, surveying staff set control points on site and measured key terrain points one by one with total stations or GPS surveying instruments. This method requires considerable time and effort to capture detailed topography over wide areas and depends on experienced personnel.

Using 3D scanning dramatically increases surveying productivity. For example, if a drone photographs a site from above and a point cloud model is generated from those images, a detailed topographic model can be obtained in a short time even for large-scale earthwork sites in mountainous areas. In some cases, surveying work that would take days manually can be completed in half a day or less. The high-density point cloud data captures all surface undulations without omission, improving the accuracy of contour maps and longitudinal/cross-sectional drawings derived from it. Earthwork quantity calculations and construction planning at the design stage can be prepared based on more accurate as-built data.

Moreover, once point cloud data has been acquired, arbitrary cross-sections can be generated later as needed. With conventional methods, if something was missed in measurement, additional field surveying was required, but with point cloud data, additional sections can be cut at the desk later, reducing redundant on-site work. Even in complex terrain, efficient remote measurement of steep slopes where people cannot enter or areas with dense vegetation is possible. Accurate topography can be obtained in a short time even by non-expert surveyors, and the resulting 3D models can be immediately shared with designers and clients for rapid feedback.

Note that using 3D scanning does not make conventional surveying instruments entirely unnecessary. Total stations (TS) are still effective for highly accurate control point surveying over small areas and for precisely locating buried objects—measurements that require pinpoint accuracy. In practice, hybrid operations where known points obtained with a TS are used to georeference point clouds are becoming common. This combination enables high-precision 3D measurement even in environments where satellite positioning cannot be used, such as inside tunnels. In other words, point cloud scanning is responsible for broad-area, high-density measurement, while TS complements the assurance of accuracy at specific points. By leveraging the strengths of both, as-built surveying can become more efficient and more accurate than before.

Use in as-built management: advanced, labor-saving quality inspection

Next is the use of 3D scanning in as-built management during and after construction. As-built management refers to the process of verifying that the shape and dimensions of completed structures conform to design drawings to ensure quality. Many measurements can only be taken at specific construction stages—immediately after concrete placement or before backfilling, for example—so it is important to record as-built dimensions at each stage to prevent mistakes that cannot be corrected later. Traditionally, as-built measurements were recorded manually by site staff using tape measures or laser distance meters, with results logged on check sheets or photos. Manual inspection is time-consuming and limited in the number of measurable points, making it difficult to capture the entire shape of a structure.

Point cloud data obtained by 3D scanning has recently gained attention for as-built management. Introducing 3D scanning into as-built management offers the following benefits:

• Precise inspection: Point clouds obtained by 3D laser scanners or photogrammetry are extremely detailed, and with proper procedures, as-built conditions can be captured with millimeter-level accuracy. Differences from design values can be detected down to details that manual surveys cannot measure, revealing slight irregularities or dimensional excesses/deficits. Strict quality inspection becomes possible, reducing the risk of rework or repairs.

• Improved work efficiency: Point cloud measurement enables acquisition of vast as-built data in a single scan, greatly simplifying inspection tasks. Because broad areas can be measured non-contact in a short time, point acquisition that previously required many personnel and effort can be completed in one operation. After acquisition, specialized software can automatically check differences from the design model and determine pass/fail, reducing manual calculations and time spent comparing drawings. As a result, inspection time is shortened, easing the burden on inspectors and directly improving productivity.

• Digital records and reuse: Point cloud data can be stored and shared digitally in the cloud, becoming a valuable record asset over time. The acquired 3D data can be viewed from arbitrary viewpoints on a PC or tablet, and additional sections can be cut or measurements rechecked later as needed. Information that could only be preserved in 2D photo logs on paper can now be stored as three-dimensional evidence in point clouds. For example, saving point cloud data at the completion of a bridge allows comparison with point clouds acquired during later periodic inspections to detect minute displacements or deterioration, supporting maintenance applications. There is also a trend toward integrating acquired as-built point clouds with 3D design data to create CIM models for use in as-built inspection discussions with clients. As such, point clouds as digital records are useful for aftercare and consensus-building among stakeholders after handover.

• Improved safety: With 3D scanning, hazardous locations can be measured remotely and non-contact, improving safety during inspections. High or confined areas where people cannot enter, or zones around operating heavy machinery, can have as-built data captured from a distance by directing a laser at them. Compared to conventional methods requiring scaffolding or aerial work platforms, the risk to workers is reduced, contributing to safety. Point cloud measurement is particularly advantageous for quick inspections during limited nighttime work windows or as-built inspections on highways under traffic restrictions, as it can be completed in a short time with safety benefits for the surroundings.

As described above, as-built management using point cloud data outperforms conventional methods in accuracy, efficiency, and safety. In fact, there are voices saying that “adopting three-dimensional as-built surveying is becoming the new normal,” and it is expected to become an increasingly standard approach.

Use in earthwork quantity calculation: rapid and accurate volume calculation

Finally, the use of 3D scanning in earthwork quantity calculation (calculating achieved quantities) in earthworks. In road construction, land development, and similar projects, accurately grasping the volume of excavation and fill is crucial for construction planning and progress management. Traditionally, quantity calculation was generally performed using the average cross-section method based on sectional drawings on plans. Benchmarking (level surveying) or TS was used to record ground elevations at regular intervals, multiple cross-sections were created, and volumes were calculated from average cross-sectional areas. However, this method required considerable time and effort for field surveying, drafting, and calculation, and because points between measurements are interpolated linearly, fine undulations were not reflected.

High-precision earthwork calculation unique to point clouds solves these problems. Using 3D scanning, the ground surface before and after construction can each be acquired as point cloud data, and excavation and fill volumes can be automatically calculated from their differences. Because detailed data measuring the entire ground surface is compared, high-precision volume calculation that reflects subtle terrain undulations is achieved. Once point clouds are acquired, calculating volumes for different compartments or elevation references later is easy. For example, if a portion of the terrain changes due to heavy rain, one can extract the necessary area from previously acquired point clouds and recompute volumes without additional field surveying. The ability to handle various quantity calculations without extra on-site measurement is another advantage of point cloud data.

This drastically shortens the time required for field surveying and quantity calculation, enabling rapid progress tracking, which is a major benefit. As an example of dramatic efficiency gains, at one major construction company’s earthwork site, a quantity measurement and calculation task that previously took 4 people × 7 days (28 person-days total) was switched to drone photogrammetry (generating point clouds from aerial images), and was completed by 2 people × 1 day (2 person-days). This represents a reduction to about 1/14 (around 7%) in personnel and days. Nonetheless, the calculated earthwork volumes were comparable to conventional methods, with errors within about 1%, as verified. This is a prime example of achieving dramatic efficiency and high accuracy simultaneously. In another project, the time required for testing as-built earthwork quantities was reduced to 1/6, and the overall schedule was shortened to less than half. Thus, volume calculation by 3D scanning is an innovative method directly linked to improving construction site productivity.

Notably, in recent years such point cloud measurement has become possible not only with drones and expensive dedicated equipment but also with smartphones and tablets. For example, using LiDAR-equipped iPhones or iPad Pros with dedicated apps, you can scan embankments or spoil piles on site and obtain point clouds and volumes within minutes. With the ease of walking around the object with a smartphone in hand, systems that automatically calculate fill volumes immediately after scanning have emerged. In practice, site supervisors have started to quickly scan small spoil volumes themselves to arrange dump trucks immediately, or to grasp daily progress volumes in real time and adjust heavy equipment operation plans. Tasks that used to require waiting for specialized survey staff or office-based analysis are increasingly completed on site.

Acquired point cloud data can be centrally managed in the cloud, making it easy to track terrain changes and volume increases/decreases over time. During construction, periodic 3D scans can visualize work progress, and after construction, completed point clouds can serve as a baseline for monitoring long-term changes in maintenance. In the event of a disaster, comparing pre- and post-event terrain point clouds can help estimate the volume of washed-away soil. As cloud-based data sharing progresses, everyone from site personnel to clients and managers can check the same latest status, making reporting and coordination smoother. Thus, point cloud data obtained by 3D scanning is not limited to volume calculation; it can serve as an advanced construction history record and potentially contribute to building a future digital twin (a virtual spatial reproduction of the site).

The latest positioning technologies enabling “anyone can do it” 3D scanning

What supports the 3D scanning use cases described above is the recent development of positioning technologies. Previously, precise three-dimensional surveying required expensive equipment and specialist technicians. Today, however, the spread of real-time correction technologies using GNSS (Global Navigation Satellite Systems) such as RTK positioning and centimeter-class positioning services (CLAS) provided by Japan’s quasi-zenith satellite system “Michibiki” means that anyone can easily obtain centimeter-level high-accuracy positioning information (cm level accuracy (half-inch accuracy)). For example, the advent of small, high-precision GNSS receivers that can be paired with smartphones allows field technicians themselves to measure control point coordinates at the push of a button and immediately assign accurate coordinates to the point clouds acquired with a smartphone.

LRTK is one solution that leverages such latest technologies. It consists of an antenna-type device attachable to a smartphone and a dedicated app, enabling anyone to perform centimeter-level positioning easily. Even without an expensive 3D laser scanner, your smartphone transforms into a “high-precision 3D scanner.” The advantages of smartphone-based point cloud surveying like LRTK are clear. Ground-based laser scanners (TLS) remain highly accurate as stationary precision instruments, but they are costly and require specialized operation. Drone photogrammetry covers wide areas efficiently but can be limited by flight regulations and weather. In contrast, handheld smartphone + LRTK scanning is overwhelmingly easy and versatile, allowing use in narrow indoor spaces, underground locations, or nighttime work—places and times where other methods may struggle. The low initial cost and the ability to deploy it whenever needed are advantages no other method can match.

Furthermore, LRTK supports Japan’s satellite positioning service “Michibiki” CLAS, enabling direct reception of high-precision correction information from satellites even at sites out of communication range such as mountainous areas or offshore. This makes it possible to stably perform centimeter-class (half-inch) accuracy 3D measurements even in environments where network connectivity is difficult. It is truly a technological innovation to realize “anyone, anywhere, anytime” high-precision 3D scanning. With the dramatic expansion of applicable sites, the scope of point cloud data utilization is rapidly widening. In promoting DX on construction sites, accessible solutions like LRTK are becoming indispensable.

Conclusion: Accelerating construction DX through 3D scanning and LRTK

3D scanning technology is literally revolutionizing core execution management tasks such as surveying, as-built management, and earthwork quantity calculation. With the ability for anyone to easily acquire millimeter-precision 3D data, an era in which “managing the entire site digitally” becomes commonplace is within reach. Going forward, smart construction practices such as “calculating as-built quantities from point cloud data” and “constantly sharing 3D scans to the cloud on site and obtaining instant AI analysis feedback” are becoming realistic.

Advancing digital workflows not only promises dramatic improvements in quality and productivity but also significant effects in terms of work-style reform and safety management. 3D scanning is not merely a high-tech upgrade of surveying tasks; it is a foundational technology for construction site DX. For construction companies aiming to survive and thrive, adapting to these latest technologies is no longer optional.

Fortunately, the advent of accessible solutions like LRTK has greatly lowered the barriers to point cloud utilization. If your company or site has not yet adopted these technologies, now is a good time to consider streamlining execution management with 3D scanning. In this unprecedented era where “anyone can easily, with high accuracy, and immediately on site” handle data, a step beyond conventional thinking will open the future for your site.

*For more details, please refer to the official LRTK website. It provides case studies and product information as an easy-to-start high-precision 3D measurement tool. Make use of 3D scanning realized by cutting-edge positioning technologies to achieve DX in execution management at your site.*