Revolutionizing As-Built Management! Real-Time 3D Construction Verification Made Possible 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 improve on-site efficiency and quality. Among these, as-built management—confirming that constructed elements are finished according to the design—is a crucial pillar of quality assurance. However, traditional as-built management has required significant time and effort and has been limited in the area it can measure.

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

What Is As-Built Management? Challenges of Traditional Methods

"As-built management" is the process of verifying that structures and earthworks created during construction conform to the specifications defined in the design, thereby ensuring quality. It is one of the key pillars of construction management alongside schedule and quality management, and involves on-site measurements to verify that the shape and dimensions required by the client have been achieved. For example, even elements that become hidden after completion—such as road subgrade thickness, slope gradients, or the burial depth of pipes—must be reliably measured and recorded during construction to prove later that they were built according to the drawings.

However, several issues have been pointed out with traditional as-built management methods. In typical approaches, site supervisors or surveyors measure positions and elevations point by point using tapes, levels, total stations, and other instruments, and record those values on paper drawings or inspection forms. Photographs before and after construction are also taken as as-built photos. But such records consisting only of points and lines inevitably have limited coverage. Irregularities between measurement points or areas that were missed cannot be recovered later, which can lead to future regrets or disputes such as "the records are insufficient" or "it might differ from the design but there is no evidence."

Moreover, traditional methods require considerable labor and time just to measure and record as-built data. Confirming measurement points one by one by hand 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 checking a few cross-sections and failing to grasp the whole picture. Any omissions in as-built management affect quality assurance, so the field has needed 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 RTK positioning with smartphone-integrated LiDAR scanners and other technologies, enabling anyone to easily perform 3D measurements on site. Measurements of as-built conditions that used to take specialist technicians half a day can be completed in just a few minutes using LRTK.

LRTK consolidates surveying equipment into a compact device that fits in one hand. On site, you connect an LRTK unit to a smartphone such as an iPhone, then simply walk around pointing the camera to perform a real-time 3D scan of the surrounding terrain and structures. Just like recording a video, walking around the site yields high-density point-cloud data consisting of tens of thousands of points. Because the acquired point cloud is assigned absolute coordinates via RTK, there is no need for post-measurement coordinate alignment (georeferencing). From the moment the scan is completed, the point-cloud data is already positioned in the same coordinate system as the design drawings and can be immediately viewed and utilized in the cloud-based 3D viewer described below.

Real-time as-built verification means you can check as-built conditions instantly while working on site. For example, if you scan a slope with LRTK, you can immediately view the acquired point cloud as a 3D model on a tablet or smartphone and compare it with the design shape. Decisions that previously required waiting for a report from the surveying team—such as whether an embankment has reached the design elevation or whether too much has been excavated—can be made in real time on site with LRTK. This prevents rework and allows on-the-spot fine adjustments during construction, reducing variability in quality and ensuring the result meets 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 and area) using the acquired point-cloud data. Point clouds obtained with LRTK faithfully reproduce the site’s terrain and structures as three-dimensional data. By analyzing this point-cloud data, processes that used to require manual creation of cross-sections and volume calculation sheets are completed in an instant.

For example, volume calculations for embankment or excavation soil can be performed on site with LRTK. Upload the acquired point cloud to LRTK’s cloud service and you can measure the volume of a specified region in the browser with a single click. Even large areas of soil can be surveyed by simply walking, without drones or heavy machinery. In fact, LRTK can capture data for embankments exceeding 200 cubic meters in a single scan and compute accurate volumes directly in the cloud. You can also measure the distance between any two points or the area of any selected region from the acquired point cloud with a single button press. Measurements that are difficult on slopes or of complex-bottom areas yield results in seconds when measured on the point cloud.

Another advantage is understanding as-built quantities by comparing with design data. On the LRTK cloud, you can overlay uploaded as-built point-cloud data 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 earth needs to be added or removed to meet the design. The differences are visualized as a heat-map-style color display, so you can intuitively see which parts are overfilled relative to the design and which are under-excavated, quickly identifying areas that need correction. In this way, LRTK greatly streamlines the quantity calculations required for as-built management and supports construction decisions based on objective data rather than experience.

Visualizing As-Built Management with AR

Another innovative feature of LRTK is the visualization of as-built management using AR (augmented reality). With the AR function, digital design and measurement data can be overlaid onto the real scene, allowing you to visually confirm the "completed image" or "as-built deviations" directly on site.

Specifically, load design drawings or a 3D design model into the LRTK app and display them in AR on site. Thanks to precise alignment enabled by RTK, the model is projected onto the real world without misalignment or distortion. For example, at earthwork sites you can display the design embankment model in AR, and the operator can compare the virtual model with the actual soil pile to intuitively judge how much more soil to place. Once the design model is covered by the real soil, there is no need to add more—allowing construction while viewing the completed form. This AR-assisted support is innovative because it is easy to understand even for non-experts and helps secure quality.

LRTK’s AR function can also overlay the aforementioned point-cloud-derived heat-map display on site. Project a heat map showing differences between the as-built and the design onto the ground so that areas overfilled relative to the design appear red and those under-excavated appear blue, making corrective locations immediately obvious. Deviations that were previously checked numerically on drawings can now be confirmed visually on the real object with AR, enabling the client and contractor to share a common image during inspection and rework.

Furthermore, AR usage aids on-site communication beyond as-built management. Visualizing the completed image on the spot facilitates explanations to clients and information sharing among site staff. For example, at a road construction site, if the planned pavement lines and elevations are displayed in AR, inspectors can make pass/fail judgments by "seeing the real thing rather than the drawing" during on-site inspections. This prevents rework due to misunderstandings and ensures all stakeholders share the same completed image.

Compliance with MLIT Standards and Reliability

Even with cutting-edge technology, you may wonder, "Can this really be used for official inspections?" Rest assured: LRTK measurements conform to the Ministry of Land, Infrastructure, Transport and Tourism’s Guidelines for As-Built Management (draft). MLIT has recently developed guidelines for as-built management using 3D measurement technologies as part of promoting ICT construction, introducing as-built management using drones, terrestrial laser scanners, photogrammetry, and other methods into public works. Point-cloud scanning with LRTK complies with these guidelines and is recognized as an official as-built management method for earthworks, slopes, paving, river works, and other applications.

On sites that have adopted LRTK, the high-precision point-cloud data is being used for as-built inspection documentation. You can extract required cross-sections from the acquired point cloud and assemble them into the prescribed formats, or export DXF drawings from the LRTK cloud for deliverables. Since these data are acquired in global positioning coordinates, the effort previously required for establishing control points or coordinate transformations can also be reduced. In addition, support is provided to help adopting companies prepare materials for submission to MLIT, so even those attempting 3D as-built management for the first time can proceed with confidence.

Adoption records are steadily increasing. While specific company names are withheld, LRTK is already in use at various domestic construction sites. At one river revetment project, overlaying point clouds acquired with LRTK and the design model in AR allowed quick checks of revetment block finishing positions, resulting in smooth as-built reporting to the client and passing inspection on the first try. In road construction, there have been cases where on-site AR verification of finished pavement elevations and gradients achieved zero rework later. Thus, LRTK’s reliability in line with MLIT standards and its usefulness on site have been recognized, and adoption is steadily spreading.

On-Site Feedback and Benefits of Adoption

Many positive comments have come from sites actually using LRTK. Here are some examples.

• Large reduction in work time: "What used to take 2–3 people half a day for as-built measurement can be done by one person in about 30 minutes with LRTK. We can now allocate the freed time to other tasks, which is a big help." Point-cloud measurement and automatic processing have dramatically reduced surveying labor.

• Labor savings and improved safety: Since on-site measurements can be completed by a small number of people in a short time, LRTK not only helps address labor shortages but also reduces dangerous work on high or steep slopes. One site supervisor said, "I used to be nervous every time we measured a steep slope, but thanks to 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 we keep the point-cloud data, we can measure any dimension later, so the peace of mind is completely different. We can respond quickly to client verification requests," said one person praising the improved reliability of as-built records.

• Improved communication: Some noted that AR has improved information sharing with clients and workers. "Even clients unfamiliar with drawings immediately understand when we show the AR-displayed completed image on site," demonstrating LRTK’s power as a visual explanation tool.

As these examples show, the benefits of LRTK adoption go beyond mere surveying efficiency. Reports indicate advantages across the board: improved quality control accuracy, enhanced site safety, and smoother communication among stakeholders. These on-site voices attest to LRTK’s usefulness in the 3D construction era.

Conclusion: The Future of 3D Construction with LRTK

In an industry where 3D construction is becoming mainstream, LRTK is a revolutionary tool that transforms the concept of as-built management. It makes real-time as-built verification and comprehensive quality assurance via surface 3D records—previously impossible with traditional methods—easy for anyone to perform. 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. It offers operability suitable for site personnel without specialized surveying knowledge while producing results comparable to specialist providers.

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 likely to spread as key tools for on-site DX (digital transformation).

The future where sites that once struggled with paper drawings and tape measures instead check construction using tablets and 3D models is just around the corner. LRTK, which revolutionizes as-built management, can be seen as a key technology enabling both work-style reform and quality management on construction sites.

Bonus: What Is Simple Surveying with LRTK?

As a final bonus, let’s touch on LRTK’s other attractive feature: the "simple surveying" function. LRTK is powerful not only for as-built management but also for routine simple surveying tasks. Even without specialized surveying equipment or advanced knowledge, LRTK and a smartphone let you easily obtain high-precision position information and various measurements.

For example, if you need the coordinates of a point on site, you can use LRTK to obtain accurate coordinates (planar coordinates and elevation) on the spot. If you start the positioning mode and within a few dozen seconds RTK fixes (cm-level accuracy (half-inch accuracy)), you can record measurement points with one tap and save them to the cloud. Tasks that were previously outsourced to surveying companies—such as control point surveys and as-built inspections—can now be handled immediately in-house.

LRTK also includes many inventive surveying support functions, such as "image-based positioning" that measures the position of a distant target from a photo, and a "coordinate navigation" feature that guides you to arbitrary points on existing drawings. It truly gives the feeling that a smartphone becomes a total station, enabling site personnel to perform necessary surveying themselves—this is LRTK’s simple surveying.

Thus, LRTK is both a tool that transforms as-built management for the 3D construction era and a democratizing tool that enables anyone to perform everyday surveying tasks. If you have hesitated to introduce ICT to your site because it seemed difficult, consider starting with simple surveying using LRTK. You will likely be surprised by its ease of use and utility. The future of your site will be opened up by your smartphone and LRTK.