One-person surveying is possible! Labor savings and DX of 3D surveying realized with LRTK

In recent years, the construction and surveying industries have rapidly adopted 3-dimensional surveying (3D surveying). 3D point cloud data, which can digitally capture terrain and structures in their entirety, can visualize complex site conditions that were difficult to grasp with conventional 2D drawings or photographs, and is attracting broad attention from design through construction and maintenance. On the other hand, many still associate conventional 3D surveying with expensive laser scanner equipment or UAV (drone) photogrammetry. It has required specialized surveying teams and large upfront investments, making it difficult for small and medium-sized sites to adopt.

However, new technology is now greatly lowering these barriers. Using a solution called “LRTK,” which combines a smartphone with a compact RTK-GNSS receiver, you can perform 3D surveying at centimeter-level accuracy remarkably easily. Surveying work that used to require multiple people can be done as one-person surveying with LRTK. It greatly reduces labor and time, streamlines (saves labor on) site surveying operations, and because the acquired data can be used digitally as-is, it rapidly accelerates DX (digital transformation). This article explains the benefits and practicality of implementing 3D surveying with LRTK, comparing it with conventional technologies.

How 3D surveying is changing sites and the latest trends

First, what is 3D surveying? The core of 3D surveying is point cloud data, a 3D dataset representing object or terrain surfaces as a collection of countless points. By assigning X, Y, Z coordinate values (and color information, etc.) to each point, site shapes can be accurately recorded as they are. There are several acquisition methods—laser scanners, photogrammetry, MMS (mobile mapping systems)—but all are characterized by the ability to acquire wide-area 3D information in a short time. For example, point clouds of an urban intersection measured by the latest terrestrial laser scanner reproduce building and road details with high-density points.

The advantage of these 3D surveying technologies is that they can digitally record the entire site. Complex terrain and as-built conditions that could not be captured with planar drawings or limited photographs can be acquired without gaps using point cloud data, allowing arbitrary cross-sections to be cut later or necessary dimensions to be re-measured—enabling versatile data reuse. From a single set of 3D data you can visualize discrepancies between design drawings and actual constructed elements, or automate volume and quantity calculations, dramatically improving the accuracy and efficiency of construction management and as-built control. In one field case, using a tablet’s LiDAR for crack inspection of structures reduced the work that used to take 1–3 days for photo composition and drawing to just a few minutes, and cut outsourced inspection workload by 30–40%. In this way, 3D surveying is fundamentally transforming how site records are handled.

With the Ministry of Land, Infrastructure, Transport and Tourism promoting i-Construction (ICT construction), 3D surveying using drones and mobile devices is rapidly permeating sites. Site measurements that used to rely on veteran surveyors are becoming tools that anyone can use thanks to digital technology. One of the latest trends is the emergence of LRTK-based simplified 3D surveying using smartphones and RTK.

“3D surveying anyone can do” realized with a smartphone + RTK

Recent smartphones are equipped with LiDAR sensors, enabling instantaneous scanning of surrounding spaces and acquisition of point cloud data up to several meters (several ft) ahead. By combining the smartphone’s built-in LiDAR with high-precision positioning enabled by RTK-GNSS (real-time kinematic) technology, 3D surveying that once required specialized equipment has been transformed. Specifically, by mounting a compact RTK-GNSS receiver (LRTK device) that can be attached to iPhones or iPad Pro, and receiving correction data from a base station over the network, the smartphone itself quickly becomes a surveying instrument with centimeter-level accuracy.

With smartphone + RTK surveying, you can continuously scan the surroundings simply by walking around with the phone in hand, and global coordinates are assigned to all acquired point clouds. For example, in a small-scale bridge inspection, a worker can hold a smartphone under girders and piers to LiDAR-scan the structure and obtain the entire 3D point cloud by a single person on site. Since the LRTK RTK receiver provides correction information that continuously adjusts the smartphone’s position to cm-level during scanning, there is no worry that the point cloud will gradually drift or distort while walking. Because precise coordinates are assigned to all acquired points, accuracy is maintained even as the measurement area expands, making it reliable for measuring as-built conditions of long structures or distances between distant points.

In practice, the ease of being able to obtain coordinate-tagged point clouds with a single pocket-sized device is revolutionary. Surveying tasks that once required tripods or fixed equipment are increasingly completed with just a smartphone. LRTK devices weigh only a few hundred grams, have built-in batteries, and do not require complicated cable connections. Simply “hold up your smartphone and walk” to generate accurate 3D models of terrain and structures in a short time. The simplicity makes them usable by site supervisors and foremen without specialist surveying training; many such staff are beginning to adopt them. LRTK, which enables “anyone, immediately, to perform high-precision 3D surveying,” can be considered a new on-site optimum.

Comparison with conventional surveying methods – differences from TS, drone, and GNSS surveying

To clarify the advantages of one-person 3D surveying with LRTK, here is a comparison with conventional representative surveying methods.

• Total Station (TS) surveying: A staple of terrestrial surveying, TS can measure one point at a time with high accuracy, but typically requires two people (an instrument operator and a prism person). Surveying wide areas with TS takes a long time to observe many points, increasing workload. Because terrain is inferred by interpolating between measured points, sparse measurements limit the ability to capture terrain details. It is also hard to track afterwards who measured which point, leaving reliance on notes and photos.

• UAV (drone) photogrammetry: This method generates 3D terrain models from aerial photos taken by a camera mounted on a drone. It covers large areas quickly and can complete surveys that normally take days within a few hours. However, aviation laws and pilot qualifications are required, and it cannot be used in environments where drones cannot fly such as urban areas, indoors, or under bridges. Ensuring photogrammetry accuracy may require many ground control points and post-processing of data, which takes time. Also, areas that cannot be photographed—such as the back sides of structures or ground covered by trees—won’t yield point clouds, potentially necessitating follow-up surveys.

• Conventional GNSS surveying: Surveying with GPS/GNSS receivers can be done by one person in open-sky conditions. Using network RTK services or a rover+base set can achieve real-time positioning at centimeter accuracy. However, conventional GNSS surveying involves acquiring coordinates point-by-point, so many measurement points are needed to capture a surface. Signal reception issues can cause interruptions or errors, and in areas surrounded by buildings or inside forests accuracy may be insufficient. Dedicated equipment is also expensive, and purchasing multiple units imposes a significant cost burden.

As described above, conventional methods each have merits but are constrained by personnel, time, and cost. In contrast, smartphone surveying with LRTK can acquire surface 3D data in a short time with only one person, addressing these limitations. For example, a several-hectare site survey that took three days with TS could be completed in half a day with drone photogrammetry in some reports. Experiments have shown that surveys using drones equipped with laser scanners reduced measurement time to one-sixth and halved overall work schedules compared to conventional methods. LRTK can achieve similar efficiency improvements in a more accessible way. Another advantage of using a smartphone is the ability to check results on site immediately. If any required points are missed, you can re-measure on the spot, and you can instantly calculate dimensions and volumes from the point cloud, reducing the need to return to the office for redrawing and recalculation.

Benefits of introducing LRTK – achieving labor savings, high accuracy, and low cost

Based on the above, here are the main benefits of introducing 3D surveying with LRTK.

• Major labor savings (efficiency): Surveying that previously required 2–3 people can be completed by one person, greatly easing personnel arrangements and schedule coordination. With the same workforce you can perform more surveying tasks, reducing labor costs and contributing to workstyle reform. Because point clouds acquire surface information at once, re-measurements are reduced, cutting rework. As noted above, there are cases where 3D measurement reduced work from “days to minutes,” so productivity gains can be very large.

• Centimeter-level high accuracy: LRTK secures positioning accuracy of a few centimeters or less via RTK-GNSS. It meets the accuracy required by the Ministry of Land’s as-built management guidelines (approximately ±a few centimeters (±a few in)), and is sufficient for general civil engineering surveys and as-built checks. Because it is easy to measure repeatedly, operational workflows that perform successive measurements during construction are more feasible, enabling rapid on-site progress while ensuring accuracy. Be mindful of error fluctuations due to positioning environment and weather, but countermeasures are the same as in conventional GNSS surveying and do not require special skills. Corrections and verifications using known points can be performed as needed to safely use the results.

• Low-cost adoption: Previously, introducing 3D laser scanners or high-performance UAV surveying equipment required investments of several million to tens of millions of yen. Compared to that, starting surveying with a smartphone + LRTK greatly reduces initial costs. If you already have a LiDAR-capable smartphone or tablet, you only need to obtain a GNSS receiver. Even if purchasing both device and receiver new, total costs are reported to start from around ¥200,000–¥300,000, making it far more economical than assembling dedicated surveying equipment. The price of LRTK Phone devices has not been publicly disclosed, but they are described as “ultra-affordable so each person can have one,” making it feasible to equip all workers without heavy budgetary burden. Operating costs are modest—mainly cloud service fees and communications—and software updates are delivered online, keeping long-term operational costs low.

• Ease of use without specialist knowledge: LRTK’s simplicity is a major attraction. Positioning and point cloud acquisition can be performed by following buttons on a surveying app screen, so even non-expert personnel can operate it after short training. Traditionally, analyzing survey results and generating drawings required specialized software knowledge, but LRTK automatically plots data on maps in the cloud and can perform distance, area, and volume calculations with one click. The app supports complex coordinate transformations and reference-plane settings, so users unfamiliar with hardware or coordinate systems won’t be confused. It is said that “LRTK replaces all the site’s writing tools,” since it digitizes notes and calculations. In short, you can perform high-precision surveying with your own staff without hiring specialized personnel.

The future of on-site DX opened by 3D surveying data

Point cloud data easily obtained with LRTK becomes powerful material to drive site DX (digital transformation). Site management that once relied on paper drawings and verbal explanation can become intuitively understandable to everyone by sharing 3D data. For example, overlaying a design model on a point cloud obtained during construction allows immediate verification of whether the as-built matches the design. Automatically generating cross-sections or heat maps (error distribution maps) from point clouds aids quality control. This not only streamlines surveying and inspection workflows but also facilitates objective, data-driven consensus building, smoothing communication between clients and sites.

Because LRTK uploads acquired data to the cloud immediately, remote stakeholders can share information in real time. Point clouds and coordinate information measured on site can be checked instantly on office or headquarters PCs, greatly improving the speed of decision-making. Recently, advanced cases have emerged that combine drone or robot automated measurement with real-time point cloud transmission for remote supervision from headquarters. This increases safety by allowing situation assessment without sending people into hazardous areas and boosts productivity by reducing travel time.

LRTK also pairs well with AR (augmented reality) technology, opening new possibilities for site DX. By AR-displaying absolute-coordinate 3D point clouds or design data through a smartphone view, you can visualize buried pipes before excavation or share completed-image overlays on site. Digitizing aspects that previously relied on craftsmen’s intuition makes it easier for less-experienced workers to perform tasks safely. By linking various digital tools to 3D data acquired by LRTK, it becomes possible to promote comprehensive DX from construction management through inspection and maintenance.

In practice, some local governments equipped all civil engineering offices under their jurisdiction with 3D point cloud processing systems, DX-ing as-built management for roads and rivers, and reported significant improvements in safety and productivity. In a major construction company’s tunnel project, a proof-of-concept used quadruped robots and drones equipped with LiDAR to automatically measure inside and outside the tunnel and instantly share the acquired point clouds remotely. This allowed headquarters to grasp site progress and as-built conditions without being on site, pointing toward future remote construction management that does not rely on manned inspections. Introducing 3D surveying and digital technologies to sites via LRTK can be the first step toward such cutting-edge approaches.

Conclusion: Start 3D surveying that achieves labor savings and DX

3D surveying enabled by the combination of smartphones and point cloud technology overturns the conventional image of “expensive and specialized” and is evolving into an accessible tool anyone can use. The advent of LRTK makes it easy for small- and medium-sized sites to start 3D surveying and data utilization. Its effects range from increased efficiency in routine tasks such as as-built control and earthwork volume calculation to quality assurance through improved accuracy of site records. Most importantly, point cloud data that digitally records and accumulates the site’s “as-is” will become an indispensable new tool for future construction management.

That said, when introducing new technology to a site, concerns such as “Can we really use it effectively?” and “Will it achieve the promised accuracy?” are natural. LRTK is a site-oriented solution developed to dispel these concerns. By attaching a pocket-sized device to a smartphone, you can automatically perform cm level accuracy (half-inch accuracy) positioning and point cloud acquisition, and the data can be shared to the cloud instantly. Prices are dramatically lower than those of conventional surveying instruments, making adoption easier for small companies and local governments. If you feel “I want to try this on my site,” please check the [LRTK official site](https://lrtk.lefixea.com/). They can consult on initial implementation and arrange demos so you can experience the ease and accuracy on an actual site.

Now is the time to make 3D surveying—a low-cost ally—work for you to improve productivity and enhance safety and quality control on your sites. Accurately recording the site’s “as-is” in 3D and fully leveraging the data will bridge the gap between design and construction and lead to more efficient and safer site operations. Take this opportunity to take a step forward and ride the wave of site DX. You will surely feel, “This will work at our site!”

LRTK dramatically improves surveying accuracy and operational efficiency on site. Details of this solution, suitable for the i-Construction era, are also available on the official website. For product questions or implementation inquiries, please feel free to contact us via the [inquiry form](https://www.lrtk.lefixea.com/contactlrtk). Use LRTK to evolve your site to the next stage.