3D CAD-era Surveying Style: LRTK Anyone Can Use Is Changing the Field

How the Spread of 3D CAD Is Changing the Relationship Between Surveying and Design

In recent years, the construction and civil engineering industries have increasingly used 3D CAD in design, and the relationship between surveying and design is undergoing major changes. Whereas paper drawings and 2D CAD used to be the norm and survey results were passed on to designers as planar drawings or numerical data, the widespread use of 3D models means that terrain and structure information collected on site is now treated as three-dimensional data, making collaboration with design much closer. For example, point cloud data representing existing terrain can be imported directly into design software and used as material for planning. Previously, designers had to interpret drawings prepared by surveyors and then model them, a time-consuming process; but with the spread of 3D CAD, environments are being established in which survey data and design data can be exchanged directly.

This digital trend is also reflected in national policy. The Ministry of Land, Infrastructure, Transport and Tourism is promoting the use of BIM/CIM (three-dimensional building and civil engineering information models) as a productivity enhancement measure, and from fiscal 2023 the use of 3D models has become the norm for direct-managed projects. Full mandatory BIM/CIM for public works is planned for 2027, and the industry as a whole is rapidly moving toward three-dimensionalization and digitization. In other words, we are in a “3D CAD era,” and surveying is being required to shift from paper- and 2D-centered methods to approaches that assume 3D data. If designers and surveyors can share the same 3D information, design and construction can proceed smoothly without discrepancies, leading to greater efficiency and improved quality.

Barriers of Traditional Surveying and On-site Challenges

However, while the importance of 3D data integration is growing, traditional surveying methods face several barriers and on-site challenges. Conventional surveying uses optical instruments such as total stations and levels and fundamentally requires two or more people. One person looks through the instrument while another stands at a distance holding a rod or prism to mark positions, so measuring large sites required many people and long hours. Setting up tripods and mounting equipment is also time-consuming and must be repeated whenever equipment is moved. Naturally, labor and time requirements are high, and when limited personnel must cover multiple sites, surveying can become a bottleneck.

With a shortage of experienced surveying technicians, labor shortages and skills transfer are additional issues. If high-accuracy surveying depends on veteran surveyors, retirements and staff reductions risk weakening on-site capabilities. Moreover, high-precision equipment is expensive, and many companies hesitated to invest. For example, it’s often unrealistic for small projects to equip RTK-GNSS receivers or high-performance laser scanners that cost several million yen. In this way, barriers such as “large-scale equipment requiring specialized knowledge,” “heavy initial and operational costs,” and “difficulty arranging personnel” have hindered the step into surveying DX, even where the importance of data use is acknowledged.

On site there are other complaints like “it’s hard to set up equipment in narrow or steep areas,” “there are spots you can’t measure under trees or behind bridges,” and “it’s hard to notice missed measurements on the spot.” Traditional methods have limits on the amount of data obtainable and are inefficient for capturing complex terrain or structures in their entirety. Against this backdrop, the government has promoted *i-Construction* and other initiatives that emphasize “efficient surveying with fewer people and less time,” pushing surveying DX. On-site demand has been strong for new technologies that enable broad-area measurement by one person in a short time.

What Is LRTK: Smartphone-complete, Small, and Simple GNSS Positioning

An innovative solution that has emerged in this context is LRTK. LRTK, short for “Local RTK,” refers to the ultra-compact GNSS receiver and positioning system developed to realize the high-precision GNSS surveying that used to rely on specialized equipment using just a smartphone. Specifically, it is a palm-sized GNSS unit that attaches to a smartphone or tablet; mounting it on a phone and launching a dedicated app starts centimeter-level positioning in real time. There is no need to set up base stations, perform complicated initial settings, or use dedicated controller terminals—LRTK receiver + smartphone + network connection is all that’s needed to perform high-precision surveying anywhere.

LRTK devices weigh only a few hundred grams and are about 1 cm thick; they are used by sticking them to the back of a smartphone or attaching them with a dedicated mount. They run for long periods on built-in batteries and can continue to be powered from a mobile battery if they run out on site. Hardware-wise they use the latest high-sensitivity chips and support multiple satellite systems (multi-GNSS) such as GPS, GLONASS, Galileo, and BeiDou, and multiple frequency bands like L1/L2, allowing stable satellite acquisition and maintained accuracy even in urban areas. They can also receive the centimeter-class augmentation service (CLAS) signal provided by Japan’s quasi-zenith satellite “Michibiki,” so even in mountainous areas or tunnels where cellular signals are unavailable, correction information can be obtained directly from the satellites and positioning can continue. This capability—maintaining centimeter-level accuracy even outside communication coverage—is a strength not found in conventional RTK equipment.

Above all, the most notable aspects are the ease of operation and low adoption barriers. LRTK is controlled intuitively through a smartphone app, and initial setup is completed with just a few taps. Once the device is paired, positioning begins automatically whenever the app is launched, and users don’t need to worry about complex settings. The screen displays current position and accuracy information, and a single tap records a survey point at the desired location. The interface is simple and easy to understand, so anyone familiar with smartphones can use it with almost no training. Compared to conventional equipment that required professionally trained surveyors, this is revolutionary, and LRTK is expected to penetrate the field as a surveying device that “anyone can use.”

The Innovation of “Anyone Can Use It”: Concrete On-site Use Cases

The environment in which “anyone can measure” thanks to LRTK is creating new value in various on-site scenarios. Here are some representative use cases.

• Solo stake-driving and as-built checks: Layout and stake-driving positions that used to require multiple people can be handled by one person with LRTK and a smartphone. By walking the site with a smartphone in hand and following the app’s guidance, the user is guided to coordinates listed on the design drawings. For example, on one site a smartphone with LRTK attached was fixed to a monopod and, by confirming the point to drive a stake via an AR display on the screen, stake-driving that would have taken two people half a day was completed in a short time. Because the smartphone can overlay positions on the 3D model onto the real view, users can intuitively grasp the correct location and elevation. Even non-experts can accurately perform stake-driving and layout, greatly reducing manpower needs and preventing human error.

• Walking survey for point cloud acquisition: LRTK systems can be combined with smartphones equipped with LiDAR sensors or cameras to 3D-scan the surrounding environment. A person simply holds up the phone and walks the site to obtain point cloud data of terrain and structures in a short time. For example, even on slopes with elevation differences or sites with complex shapes, a one-minute scan with a camera can produce detailed 3-cm-level 3D data. Areas that were difficult to cover with drones or fixed laser scanners—tight spaces, under bridges, and beneath trees—can be captured down to the last corner wherever a person can approach. Since the acquired point clouds are immediately georeferenced in world coordinates, there is no need to later match them to control points. Scan data can be visualized in 3D on the cloud so anyone on site can instantly check for missing areas and perform additional measurements as needed, enabling flexible operation.

• High-accuracy photo records and maintenance management: LRTK is not only for coordinates and point clouds but can also be used for photo-positioning by leveraging smartphone cameras. When an inspector photographs a point of interest (e.g., a crack in a structure or equipment installation), the photo file is automatically tagged with the precise latitude, longitude, elevation, and camera orientation of the shooting location. This lets office staff later see exactly where and in what direction a photo was taken at a glance on a map. For inspection tasks, photos can be linked to BIM models or drawings, making it easy to accurately relocate the exact same spot on future inspections. Where site records used to be made by writing on paper drawings or explaining verbally, photo + coordinate data now provides objective documentation, improving efficiency and sophistication in maintenance management.

• Surveying in difficult locations and disaster response: LRTK is powerful even where communications and power are limited. For example, immediately after a disaster, a lone operator with only a smartphone and LRTK was able to survey damage in rubble-filled areas where large equipment could not be brought in. Because satellite augmentation signals can be received directly even outside network coverage, centimeter-level positioning is possible without internet access. By mounting a smartphone on a helmet and walking through an area, necessary data can be collected with minimal entry into hazardous zones. Collected information can later be uploaded to the cloud and shared with stakeholders to accelerate restoration planning. In this way, LRTK leverages the strength of being “measurable by anyone, anywhere, immediately” to offer new solutions in situations where surveying was previously difficult.

The Workflow for Point Cloud Acquisition and 3D CAD Integration

Let’s look at the specific workflow for acquiring point clouds with LRTK and linking them to 3D CAD. First, attach the LRTK receiver to the smartphone and launch the dedicated app. Once positioning is stable and centimeter-level accuracy is assured on the app, switch to the scan mode using the camera and LiDAR and begin measurement. Operation is simple: just walk the area while pointing the smartphone at the parts you want to scan. High-precision position information from LRTK combined with the phone’s sensors generates a three-dimensional point cloud in real time as you move.

For example, a civil earthwork site of about 50 m square can yield a point cloud of several hundred thousand points representing the surface with just a few minutes of walking. As noted earlier, these point clouds are georeferenced in a global coordinate system, so the resulting data can be aligned immediately with design coordinate systems. In practice, point clouds acquired via the LRTK app can be uploaded to the cloud on site and viewed in a browser-based 3D viewer. At that stage, simple edits such as point thinning or noise removal can be performed, and survey deliverables like distance, area, and volume measurements can be completed entirely in the cloud.

Importing the finished 3D point cloud into 3D CAD software or BIM models is also smooth. LRTK cloud services allow data to be exported in major point cloud and model formats (LAS, PLY, DXF, FBX, etc.), so they can be imported into common CAD and point-cloud processing software. For example, earthwork calculation software or design CAD can overlay the acquired existing-condition point cloud with the design model to check cut-and-fill balances or generate as-built heat-map comparisons and other advanced analyses. Whereas previously survey data had to be taken back to the office and imported and aligned in software, LRTK’s workflow enables a seamless field → cloud → design environment chain. As a result, design updates and construction quantity calculations can be completed the same day the measurements are taken, supporting immediate decision-making.

In addition to point clouds, coordinate lists of survey points and photo-attached reports can be generated automatically, streamlining what used to be manual record creation. By sharing a cloud-generated URL with stakeholders, even those without specialized software can view 3D data and survey results in a browser. In this way, LRTK functions not merely as a device but as a platform that encompasses data acquisition, utilization, and sharing—realizing a next-generation surveying workflow suited to the 3D CAD era.

BIM Connectivity: A Foundation for Coordinate Alignment and Attribute Assignment

LRTK is highly compatible with BIM and can serve as a surveying foundation in the 3D data era. BIM (Building Information Modeling) links various information to 3D models from design through construction and maintenance, but it requires alignment between the real-world coordinate system and the model’s coordinate system. Point clouds and coordinate measurement data obtained by LRTK are always recorded as absolute coordinates in a public geodetic system, so if BIM models are created to the same standard, discrepancies with the field will not occur. In other words, LRTK’s role as a high-precision bridge between “field coordinates” and “digital models” enables real-time linking between BIM and the site.

Specifically, the latest site conditions measured by LRTK can be immediately imported into BIM/CIM models for comparison with design values, or conversely, coordinate data from BIM models can be sent to on-site smartphones for AR display to assist construction. For example, in excavation work, scanning the terrain with LRTK immediately after work and comparing it to the design model allows on-the-spot confirmation of as-built status and immediate calculation of achieved quantities. If discrepancies or deficiencies are found, decisions on additional excavation or filling can be made quickly. A process that used to take days—surveying, bringing data back to the office, CAD conversion, and as-built inspection—can now be completed in near real time.

In maintenance, attaching various on-site data as attribute information to BIM models enhances the fidelity of the digital twin. If coordinates of cracks or inspection results obtained by LRTK photo-positioning are linked to the model, detailed historical information that couldn’t be preserved on drawings can be managed centrally in 3D. Associating LRTK positioning information with arbitrary points on the model and leaving notes or photos makes it easier to relocate the exact spot for the next inspection and to track condition changes over time. With the advantage of coordinate consistency and high precision, LRTK smooths the flow of data between site and model as a foundational tool for BIM utilization.

Moreover, LRTK’s cloud platform can integrate with BIM/CIM software via APIs, enabling scenarios where acquired data is automatically reflected in models or model information is shared with on-site apps. In the future, measured data could be incorporated instantaneously into digital twins so all stakeholders make decisions based on the same up-to-date information—an ideal construction management scenario that may become common. Toward such a future, the high-precision coordinate foundation provided by LRTK will play a significant role.

A New Surveying Style Enabled by Ease of Adoption

LRTK has literally transformed high-precision surveying, once the domain of specialists, into something anyone, anywhere, immediately can do. Its ease of adoption is bringing fresh change to on-site surveying styles. First, there is a significant reduction in initial costs. Where centimeter-accurate RTK equipment once required investments of several million yen, smartphone-based LRTK is relatively affordable, making it realistic to equip individuals with their own units. In practice, some companies have started issuing LRTK devices to all field staff so each person can perform surveying and recording as needed. This eliminates the need to “wait for the surveying team” and speeds up decision-making. If each worker adopts the tool for daily use, surveying will cease to be a special event and will instead become an extension of routine tasks.

Furthermore, the spread of LRTK normalizes solo surveying and promotes workforce reduction of tasks that once relied on manpower. With labor shortages worsening, the benefit of technology that enables precise measurements by one person is immeasurable. Survey results are shared to the cloud in real time, allowing supervisors and colleagues to view and provide advice on the spot. Because even newcomers can achieve results close to veterans if they can operate the device, LRTK is an effective measure against skills shortages. Also, as more surveying work that was previously outsourced is brought in-house, costs can be reduced and know-how internalized. If site supervisors and designers themselves can “take a quick measurement,” the boundary between design and construction will narrow and more agile on-site responses will be possible.

Thus, the new surveying style enabled by LRTK is not merely a technological innovation but a change affecting site culture and workstyles. From the era of paper drawings and craftsmen’s skills to one that leverages digital data and smart devices—at this turning point, LRTK symbolizes the “new surveying style for the 3D CAD era.” Combining high-precision yet easy-to-use surveying with cloud-based data utilization enables site management with unprecedented speed and accuracy. If your current site faces surveying challenges, adopting such accessible new technologies could transform your workflow into something astonishingly efficient and smart. As a step to transform your site, consider simple surveying with LRTK and cloud utilization.