The DX Revolution in 3D Surveying: Achieving High Accuracy, Low Cost, and Labor Savings with LRTK

In recent years, digital transformation (DX) driven by 3D surveying has been rapidly advancing in surveying and construction sites. By acquiring and utilizing three-dimensional site information that could not be obtained with traditional planar surveying methods as 3D data, productivity, accuracy, and safety have undergone revolutionary changes. Among these technologies, the new solution that combines smartphones and GNSS—LRTK—is a groundbreaking tool that enables anyone to perform 3D surveying, which previously required specialized equipment and large crews, with high accuracy and at low cost. This article explains the basics of 3D surveying, how it differs from traditional methods, its relationship with DX in the construction industry, and how using LRTK can realize higher accuracy, cost reduction, and labor savings. We also describe why LRTK is effective with concrete examples and conclude with a simple surveying method using LRTK.

What is 3D surveying? How it differs from traditional surveying methods

3D surveying is a surveying method that measures the position and shape of target terrain or structures in three dimensions—width, depth, and height—and obtains them as digital 3D data. Various means are used to acquire surrounding point cloud data (a collection of countless 3D coordinate points), including laser scanners, photogrammetry, drone aerial photography, and more recently, smartphone LiDAR sensors. This makes it possible to record the actual shape of a site entirely as a "digital twin," reproducing details that cannot be captured by plans or cross-sections alone.

In contrast, traditional surveying typically used total stations, levels, and GPS receivers to measure the coordinates of individual points at key locations manually, from which drawings were produced. For example, surveying a site of several dozen meters square could require surveyors to spend hours measuring the positions and heights of several dozen points, then use those to create contour lines and cross-sections. Such methods limit the number of measurable points and often require judgment based on experience to fully understand site conditions. By comparison, 3D surveying can measure on the scale of millions of points, allowing the target to be captured as surfaces and enabling wide-area, detailed measurement at once. As a result, the ability to efficiently create comprehensive and precise terrain or structure models without omissions is a major distinction.

Data handling also differs significantly. Traditional surveying deliverables were mainly 2D materials such as paper drawings, PDFs, and CAD drawings, whereas 3D surveying outputs are point clouds and 3D models that can be viewed and analyzed from arbitrary viewpoints on a computer. For example, you can measure the distance between any two points on the acquired point cloud or extract cross-sections afterward; once the data are acquired, additional re-measurement or site revisits are often unnecessary. In this way, 3D surveying stands apart from traditional methods in both measurement density and data usability.

The necessity of 3D surveying for construction DX

The construction industry is also being swept by a wave of DX (workstyle transformation through digitalization), centered on the utilization of 3D data. Since 2016, the Ministry of Land, Infrastructure, Transport and Tourism has promoted efficiency in construction using ICT technologies under the "i-Construction" initiative. As part of this, drone-based 3D surveying, machine guidance (automatic control of construction machinery), and BIM/CIM (design and construction methods using 3D models) have been introduced, and from fiscal 2023 the use of 3D models in public works (mandatory BIM/CIM) began in principle. This has accelerated the sharing of 3D data between contractors and clients, making the use of 3D surveying data on sites indispensable.

Moreover, the construction sector faces issues such as serious labor shortages and the need to respond to work-style reform-related laws (the so-called "2024 issue"). With an aging population of veteran survey technicians and fewer new entrants, and the application of limits on overtime work to construction from 2024, tasks must be carried out efficiently with limited personnel. In this context, labor savings achieved through 3D surveying are highly effective. There are reports of surveying work that used to take several days being completed in a few hours to half a day with drones or laser scanners, and some sites have seen surveying periods reduced to one-quarter of conventional times. This not only shortens time but directly contributes to correcting long working hours and reducing labor burdens. As a key to DX promotion, 3D surveying that digitizes the site as-is is an essential element supporting a productivity revolution.

Data obtained from 3D surveying and its benefits

The representative output of 3D surveying, point cloud data, is effectively a precise copy of the real space. It digitally represents the shapes of terrain, buildings, and structures with countless points, allowing detailed understanding of site conditions without being physically present. By utilizing point cloud data or 3D models derived from it, various benefits that were not possible with traditional methods emerge.

• Detailed current-condition understanding: Point clouds accurately record subtle unevenness and shapes that cannot be captured by paper drawings or flat photos. For example, in aging infrastructure where drawings are missing, point cloud surveying can create and preserve a 3D model of the current condition. This allows the site to be recorded comprehensively and specific areas to be examined in detail later.

• Design and construction optimization: Overlaying acquired point cloud data with design data (CAD or BIM models) makes it intuitive to identify discrepancies between plans and the site. You can simulate on a 3D model of the terrain before construction to optimize heavy equipment access routes and earthwork plans. After construction, comparing the as-built point cloud with the design data lets you check for finished-product deviations, helping prevent rework and ensuring quality.

• Construction management and safety improvement: 3D scanning is powerful for measuring hazardous areas where people cannot enter. For example, for deep excavations or slopes at risk of collapse, laser scanning from a distance can safely measure shapes. Calculating volumes from point clouds streamlines the management of fill and excavation quantities. In practice, using a laser scanner to check pile inclination and displacement in bridge foundation excavation reduced work time and greatly improved safety compared to manual measurements.

• Maintenance and inspection: 3D surveying is also used for post-construction infrastructure inspections. For roads and bridges, laser scanners can capture surface shapes during regular inspections and detect fine cracks or deformations by comparing with past point clouds. Since differences in point clouds can quantify displacement, anomaly detection that used to rely on craftsmen’s experience can now be performed objectively based on data. Research is also progressing on AI-based automatic extraction of deteriorated areas, promising labor savings and higher sophistication in inspection work.

• Accumulation of construction records: Recording sites before and after work as point clouds preserves information that photos and drawings cannot fully capture for future reference. For example, in disaster recovery, drone scans of collapsed terrain before and after landslides are used to compare changes. 3D construction records are useful for future project planning and for verifying issues when problems arise, helping to preserve veteran technicians' knowledge as digital data.

By leveraging the data obtained through 3D surveying, rapid and accurate decision-making becomes possible, dramatically improving productivity, safety, and quality on site.

What is LRTK? A 3D surveying revolution achievable with a smartphone

However, there used to be a barrier to enjoying these benefits: expensive equipment and specialized knowledge were required. Introducing large laser scanners or dedicated surveying drones could cost hundreds of thousands of dollars, making them hard to adopt for small to medium-sized sites. That’s where LRTK (a system provided by Lefixea) comes in. LRTK is a pocket-sized device attached to a smartphone or tablet that integrates RTK-GNSS receiver functionality and 3D scanning into a versatile surveying tool.

Specifically, by attaching the ultra-compact GNSS receiver "LRTK Phone" to an iPhone or iPad, launching the LRTK app, and simply pointing the device around the site, the surrounding environment can be instantly converted into 3D point cloud data. Because it combines photogrammetry using the phone’s camera (and LiDAR sensor in some cases) with centimeter-class positioning via GNSS, the resulting point clouds are tagged with high-precision global coordinates. You can immediately measure distances, areas, and volumes on the generated point cloud—so, for example, you can scan a pile of fill or spoil in minutes and instantly calculate accurate soil volumes. Tasks that previously required hiring specialists or moving earth with heavy machinery can now be completed by your own staff simply walking with a smartphone.

LRTK is truly a revolutionary solution that allows one person to scan a site alone. The device itself is lightweight and fits in the palm, making it easy to carry to the site.

Furthermore, the LRTK series includes multiple devices tailored for different uses. For instance, if you want to survey a wider area at higher density, using the dedicated 3D laser scanner "LRTK LiDAR" enables long-range laser measurement that used to be expensive to be achieved at low cost and high speed.

Other devices include wearable units that allow workers to scan their surroundings simply by walking, and helmet-integrated GNSS receivers, providing easy positioning and point cloud acquisition both outdoors and indoors.

By combining these tools according to site scale and purpose, 3D data can be utilized in every situation. The availability of accessible technologies like LRTK that bring high-precision point cloud measurement into daily operations—previously possible only by specialized contractors—signals that the DX of 3D surveying is becoming a reality.

How LRTK delivers high precision, low cost, and labor savings

Here are the concrete effects of introducing LRTK from the perspectives of accuracy, cost, and labor savings.

• Improved positioning accuracy: LRTK is equipped with an RTK-capable GNSS receiver, improving position information that normally has errors of several meters under standard GPS to a high precision of about 1–2 cm. This ensures that acquired point clouds and surveyed points have accuracy comparable to public-survey reference points and can be used directly for design checks and as-built management. LRTK devices also support Japan’s [Quasi-Zenith Satellite System "Michibiki"](https://ja.wikipedia.org/wiki/準天頂衛星システム) centimeter-class augmentation information (CLAS), enabling high-precision positioning even at sites without internet access, such as mountainous areas. Advanced attitude correction functions compensate for antenna tilt, maintaining stable positioning accuracy.

• Reduced introduction and operating costs: As mentioned, LRTK allows you to start 3D surveying without purchasing large dedicated equipment or expensive surveying devices. With just the device and a compatible smartphone, initial investment costs are greatly reduced. Expensive 3D laser scanners that used to cost hundreds of thousands of dollars are no longer necessary, and combining an ordinary drone with LRTK can achieve high-precision 3D surveying. Insourcing tasks previously contracted to external surveying companies also reduces outsourcing costs. Cloud services for data sharing minimize transport and communication costs for transferring data between the field and the office.

• Labor savings and one-person operation: Because LRTK is compact and lightweight, surveying tasks that previously required a team can be completed by one person. For example, even for a large site, there is no need for staff to carry prisms while positioning; a single person can walk the site and finish the work. Post-acquisition processing is also automated—uploading to the cloud yields quick model generation and analysis—so office drafting work and manual calculations are reduced. In short, both personnel and time required for surveying are drastically reduced, which is a major advantage for sites struggling with staffing shortages.

• Dramatic increase in work speed: High-density data can be acquired in a short time, significantly speeding up fieldwork. What used to take a full day for as-built measurement can sometimes be completed in tens of minutes with LRTK and a smartphone. Being able to check results on the spot enables real-time decision-making, further accelerating work. For example, scanning a site in the morning, calculating volumes, and using that data to plan earthworks in the afternoon enables a rapid PDCA cycle. The speed contributes directly to shortening overall construction schedules and strengthening competitiveness.

As described above, introducing LRTK improves accuracy, cost, and efficiency in surveying. In addition, benefits such as data shareability and usability align well with the DX era. Survey data uploaded to the cloud can be shared instantly among stakeholders, allowing remote monitoring and support of site conditions. The smartphone-based operation is intuitive and easy to learn, so even personnel without special training can handle it. These comprehensive advantages explain why LRTK is so effective.

Comparison with other 3D surveying methods and how to choose

There are various 3D surveying methods in use today besides LRTK. Each has strengths and is best used according to site conditions or combined with others to maximize benefits.

• Drone (UAV) photogrammetry: This method generates 3D models from aerial photos taken by small unmanned aircraft. Because it can capture wide areas quickly from above, it is suitable for terrain surveys of development sites and disaster site assessments. High-precision drones equipped with RTK-GNSS have recently appeared, allowing georeferencing of point clouds derived from aerial photos. However, drones struggle to capture the backsides of structures or indoor spaces and are affected by radio environment and flight restrictions.

• Terrestrial laser scanners (TLS): Tripod-mounted laser scanners obtain point clouds by emitting 360-degree lasers from the ground, making them strong at capturing the fine details of complex structures like bridge piers or plant piping. However, these devices are large and difficult to transport, and covering wide sites requires multiple setups and data integration, which can be time-consuming and labor-intensive.

• Mobile mapping / wearable surveying: Mobile mapping equips sensors on a vehicle to scan while driving, while backpack or helmet-mounted systems scan while walking. These are effective for continuous outdoor and indoor surveys, and are used for applications such as pedestrian flow simulation and tunnel measurement.

• Conventional GNSS surveying / total station: For single-point reference surveying or pinpoint tasks like stake positioning, conventional instruments remain useful. GNSS receivers and total stations are particularly effective when high-precision single-point positioning is required, such as setting out stakes or verifying boundaries. Since LRTK also has GNSS receiver capabilities, it can be used as an extension of traditional single-point surveying.

These methods are not mutually exclusive; combining them compensates for each other’s weaknesses. For example, in tunnel construction in mountainous areas, the interior can be precisely scanned with TLS, the exterior terrain obtained by drone photogrammetry, and the two point clouds merged to build a seamless integrated model. Also, using high-precision positioning data acquired by LRTK to geotag drone photos allows point clouds generated from non-RTK drones to later achieve survey-grade accuracy. In this way, LRTK functions as a hub that complements other measurement methods and enables comprehensive, high-precision digitization of entire sites.

Conclusion: Start the DX revolution in 3D surveying with LRTK

The adoption of 3D surveying and the utilization of its data are central themes in the DX revolution of the construction and surveying sectors. Converting a site into digital data and feeding insights back into design and construction management allows projects to be executed with unprecedented efficiency and accuracy. Facing challenges such as labor shortages and work-style reforms, it is necessary to adopt new technologies with flexible thinking beyond conventional methods.

Fortunately, with accessible and powerful 3D surveying tools like LRTK, the era in which anyone can obtain high-precision 3D data whenever needed has arrived. As a practical first step, we recommend conducting a trial simple survey using LRTK at your own sites. For example, attach an LRTK device to a smartphone, establish RTK positioning, then use a standard commercial drone to photograph the site from above and combine those images with LRTK positioning data to generate point cloud data—this method lets you experience the benefits of 3D surveying without expensive equipment. Comparing the obtained point cloud models with conventional drawing results will clearly show differences in data volume and accuracy, letting you appreciate the potential of site DX.

The DX revolution in 3D surveying has the potential not only to improve operational efficiency but to change industry norms and work styles themselves. Take this opportunity to adopt cutting-edge technology like LRTK on your sites and realize high accuracy, low cost, and labor savings, riding the wave of 3D utilization that will become the standard of the future. As LRTK-based 3D surveying becomes commonplace, the nature of surveying will transform, creating new opportunities for value creation. LRTK may well become the key to that future on construction sites.

For detailed feature introductions and case studies of LRTK, please check the [LRTK official site](https://www.lefixea.com/lrtk).