Innovating As-Built Management! Real-Time 3D Construction Verification Enabled by LRTK

Introduction

In the construction industry, attention is increasingly turning to “3D construction” as a trump card for improving productivity and addressing labor shortages. Construction methods that utilize ICT technologies and digital data are expected to greatly enhance site efficiency and quality. Among these, as-built management—confirming that constructed works are finished according to design—is a crucial pillar of quality assurance. However, traditional as-built management has required significant effort and time, and has been limited in the area it can measure.

This article explains how the latest smart construction technology, LRTK, is revolutionizing as-built management. With LRTK, you can 3D-scan a site and verify as-built conditions in real time, instantly compute volumes from point cloud data, and visualize construction status with AR (augmented reality), enabling unprecedentedly efficient construction management. LRTK’s simple operation makes high-precision 3D construction accessible even to small and medium-sized contractors and surveying professionals—let’s explore its appeal.

What Is As-Built Management? Problems with Conventional Methods

As-built management is the process of verifying that structures, prepared ground, and other works built during construction conform to the specification values defined in the design, thereby ensuring quality. It is one of the key pillars of construction management alongside schedule and quality control, and involves measuring on-site to confirm that the shape and dimensions requested by the client have been achieved. For example, it is necessary to measure and record during construction the thickness of roadway subgrade, slope gradients, or burial depths of pipes—areas that will later be hidden after completion—to provide evidence that the work was performed according to the drawings.

However, several issues have been pointed out with traditional as-built management methods. Typical methods involve site supervisors or surveyors measuring specified positions and elevations point by point using tape measures, levels, and total stations, and recording those values on paper drawings or inspection tables. As-built photos are also taken before and after work. But such records consisting only of points and lines inevitably have limited coverage. Irregularities between measured points or areas that were accidentally not photographed cannot be followed up later, which can lead to later regrets or disputes such as “records are insufficient” or “it might differ from the design but there’s no evidence.”

Moreover, conventional methods require a great deal of labor and time just to measure and record as-built conditions. Manually checking measurement points one by one is extremely time-consuming, and with limited personnel it is difficult to measure large areas in detail. As a result, there is a risk of forgetting to take necessary photos in the busyness of work, or only being able to check a few cross-sections and thus failing to grasp the whole picture. Because gaps and omissions in as-built management affect quality assurance, the field has been seeking more reliable and comprehensive measurement and recording methods.

Real-Time As-Built Verification Enabled by LRTK

An innovative solution that addresses these issues is LRTK. LRTK is a new measurement system that combines high-precision GNSS (global navigation satellite system) RTK positioning with LiDAR scanners built into smartphones and other sensors, enabling anyone to perform 3D measurements on site easily. Measurements that used to take specialized technicians half a day can be completed in just a few minutes with LRTK.

LRTK consolidates the required surveying equipment into a compact device small enough to hold in one hand. On site, you connect an LRTK unit to a smartphone such as an iPhone and simply walk around holding up the camera; the surrounding terrain and structures are scanned in 3D in real time. Just like shooting a video, you can walk the site and acquire high-density point cloud data comprising tens of thousands of points. Because RTK provides absolute coordinates to the acquired point clouds, there is no need for post-measurement coordinate alignment (georeferencing). From the moment scanning finishes, the point cloud data are already positioned in the same coordinate system as the design drawings and can be immediately checked and used via the cloud-based 3D viewer described later.

Real-time as-built verification means being able to check as-built conditions instantly while construction is ongoing. For example, scanning a slope with LRTK lets you immediately view the acquired point cloud as a 3D model on a tablet or smartphone and compare it with the design shape. Judgments that previously required waiting for reports from the survey team—such as “Has the embankment reached the design height?” or “Have we excavated too much?”—can be made on site in real time with LRTK. This prevents rework and allows on-the-spot fine adjustments during construction, reducing quality variability and ensuring the work conforms to design values.

3D Data Acquisition by Point Cloud Scanning and Volume Calculation

One of LRTK’s strengths is the instant calculation of as-built quantities (volume/area) using the acquired point cloud data. Point clouds captured by LRTK faithfully reproduce the site terrain and structures in three dimensions. By analyzing this point cloud data, processes that used to require manual creation of cross-sections and volume calculation reports can be completed in an instant.

For example, volume calculations for embankments or excavated material can be performed immediately on site with LRTK. If you upload the acquired point cloud data to LRTK’s cloud service, you can measure the volume of a specified area with a single click in the browser. Even the amount of soil piled across a large site can be surveyed by simply walking—without using drones or heavy machinery. In practice, LRTK can acquire data from embankments exceeding 200 cubic meters in a single scan and compute accurate volumes in the cloud. You can also measure the distance between any two points in the acquired point cloud and the area of any selected region with the press of a button. Measurements that are difficult with conventional methods—such as the length at the top of a slope or the area of a complex-shaped base—can be obtained in seconds when measured on the point cloud.

What’s more, LRTK excels at quantifying as-built quantities by comparing them with design data. In the LRTK cloud, you can overlay the uploaded as-built point cloud with the design 3D model (or design surface data) and automatically calculate the volume differences between them. This makes it immediately clear how much more soil needs to be added or removed to meet the design. Differences are visualized with a heatmap-style color display, making it intuitive to see where the work is higher than the design or where it has been over-excavated, so corrective locations can be quickly identified. In this way, LRTK dramatically streamlines the quantity calculation needed for as-built management and supports construction decisions based on objective data rather than experience.

Visualizing As-Built Management with AR

Another innovative feature LRTK brings is visualization of as-built management using AR (augmented reality). With AR, digital design and measurement data can be overlaid on the real-world view, allowing on-site visual confirmation of the “final appearance” and any “deviations from the as-built.”

Specifically, you load design drawings or a 3D design model into the LRTK app and perform AR display on site. Thanks to precise alignment enabled by RTK, the model is projected onto the real world without offsets or distortion, accurately matching the design shape to the site. For example, on earthwork sites you can AR-display the design embankment model, and an operator can compare the virtual model with the actual soil heap to intuitively judge how much more soil to place. Once the design model is covered by the actual soil, no further filling is needed—so you can work toward the finished form while viewing it. This AR-assisted construction support is intuitive even for non-experts and is innovative in its ease of ensuring quality.

In addition, LRTK’s AR can overlay a heatmap processed from the aforementioned point cloud data onto the site. If you project a color-coded heatmap of as-built vs. design differences onto the ground—red where the site is higher than the design and blue where it is lower—you can instantly see the areas that require correction. Deviations that used to be checked numerically on drawings can be confirmed visually on the actual site with AR, allowing the owner and contractor to share the same image during inspection and rework.

AR also helps site communication beyond as-built management. Because the final image can be visualized on the spot, explanations to owners and information sharing among site staff become smoother. For instance, on a roadworks site, if the planned pavement lines and heights are AR-displayed, inspectors can make pass/fail judgments by “seeing the actual object on site rather than only the drawing.” This prevents rework due to misunderstandings and ensures all stakeholders share the same finished vision.

Compliance with MLIT Standards and Reliability

Even with the latest technology, a common concern is “Can this really be used for official inspections?” Rest assured: LRTK’s measurements follow the official procedures consistent with the Ministry of Land, Infrastructure, Transport and Tourism’s (MLIT) guidelines for as-built management (draft). MLIT has been promoting ICT construction and has developed the “Guidelines for As-Built Management Using 3D Measurement Technologies (draft),” introducing as-built management using drones, terrestrial laser scanners, photogrammetry, and other methods into public works. Point cloud scanning with LRTK conforms to these guidelines and is recognized as an official as-built management method for earthworks, slopes, paving, riverworks, and more.

On sites that have adopted LRTK, high-precision point cloud data have been used in as-built inspection documentation. Necessary cross-sections can be extracted from the acquired point cloud and compiled into prescribed formats, and DXF drawings can be exported from the LRTK cloud for deliverables. Because these data are acquired in global positioning coordinates, the need for establishing reference points and coordinate transformations—previously required—can be reduced. Additionally, support is provided to client companies for preparing materials to submit to MLIT, so even those trying 3D as-built management for the first time can proceed with confidence.

Adoption results are also steadily increasing. While specific company names are withheld, LRTK is already active at various job sites nationwide. At one riverbank protection project, overlaying the point cloud and design model in AR allowed quick checking of the finish position of revetment blocks. As a result, as-built reporting to the owner went smoothly and the inspection passed at once. In a roadworks example, finished pavement heights and slopes were AR-verified on site, achieving zero rework afterward. In this way, LRTK’s reliability under MLIT standards and its practical usefulness on-site are recognized, and adoption is spreading.

Voices from the Field and Benefits of Adoption

Many positive comments have come from sites that have actually used LRTK. Here are some examples:

• Dramatic reduction in work time: “Measurements that used to take 2–3 people half a day can now be finished by one person in about 30 minutes with LRTK. We can reallocate freed-up time to other tasks, which is a big help.” Point cloud measurement and automatic processing have drastically reduced surveying workload.

• Labor savings and improved safety: Because on-site measurements can be completed with fewer people and in less time, LRTK not only helps alleviate labor shortages but also reduces work in hazardous high or steep areas. One site supervisor said, “I used to be nervous measuring steep slopes every time, but with LRTK we can safely acquire data from a distance.”

• Improved accuracy and reliability: LRTK’s high-precision RTK positioning and LiDAR scanning allow much more detailed site records than before. “If you save the point cloud data, you can measure dimensions at any location later, which gives a different level of reassurance. We can respond quickly to client requests for confirmation,” said one user, praising the increased reliability of as-built records.

• Improved communication: The AR features have smoothed information sharing with owners and workers. “Even customers not used to drawings can understand at a glance when they see the AR-displayed finished image on site,” said another, noting LRTK’s effectiveness as a visual explanation tool.

Thus, the benefits of LRTK adoption go beyond mere surveying efficiency. Reports indicate improvements in quality control accuracy, site safety, and communication among stakeholders. These field voices testify to LRTK’s usefulness in the era of 3D construction.

Conclusion: The Future of 3D Construction with LRTK

In the construction industry where 3D construction is becoming mainstream, LRTK is a groundbreaking tool that transforms the concept of as-built management. It makes real-time as-built verification and comprehensive 3D records for quality assurance—previously impossible with conventional methods—accessible to anyone. Combining high-precision RTK positioning with smartphone connectivity, LRTK is easy to adopt not only for large-scale projects but also for small and medium-sized sites. Its usability enables site personnel without specialized surveying knowledge to operate it, while delivering results with precision comparable to professional surveyors.

Aligned with national initiatives promoting ICT construction and i-Construction, the use of 3D data for construction management will increasingly become standard. All-in-one measurement solutions like LRTK are expected to spread as key tools in site DX (digital transformation).

A future where site workers swap paper drawings and tape measures for tablets showing 3D models while checking work is just around the corner. LRTK, which innovates as-built management, can be seen as a key technology that achieves both work-style reform and quality control on construction sites.

Bonus: What Is Simple Surveying with LRTK?

Finally, as a bonus, let’s touch on LRTK’s other attraction: the “simple surveying” function. LRTK is not only powerful for as-built management but is also effective for routine simple surveying tasks. Even without specialized surveying equipment or advanced knowledge, with just LRTK and a smartphone you can easily obtain high-precision position information and various measurements.

For example, if you need coordinates of a point on site, you can obtain accurate coordinates (plan coordinates and elevation) on the spot with LRTK. After switching to positioning mode, once RTK reaches Fix (centimeter-level accuracy) in a few tens of seconds, you can record the measurement point with one tap and save it to the cloud. Tasks that used to require a surveying company—like establishing control points or inspection measurements—can now be handled in-house immediately.

LRTK also includes many inventive surveying support functions, such as a “photo-based target positioning” feature that measures the position of distant targets from photos, and a “coordinate navigation” function that guides you to an arbitrary point on an existing drawing. It truly feels like your smartphone becomes a substitute for a total station, allowing site personnel to perform necessary surveying themselves immediately—this is LRTK’s simple surveying.

In this way, LRTK is both a tool that revolutionizes as-built management in the era of 3D construction and a democratizing tool that enables anyone to perform everyday surveying. If you hesitate to introduce ICT to your sites because it seems difficult, consider starting with simple surveying using LRTK. You’ll likely be surprised by its ease of use and usefulness. The future of your site will be opened up by your smartphone and LRTK.