Table of Contents

• Basics of RTK surveying and how accuracy works

• Workflow of LRTK that enables instant cloud sharing of positioning data

• Specific operations of the LRTK app and cloud features (photo positioning, point cloud upload, coordinate navigation)

• Mechanism that changes information linkage between field and office (construction, as-built, reporting)

• Benefits and examples of managing point cloud data and photos in time series

• Implementation effects (time savings, error prevention, remote confirmation, disaster response, etc.)

• Introducing simplified surveying with LRTK

• FAQ

RTK positioning technology has attracted attention in the construction and surveying industries in recent years. Whereas conventional GPS positioning commonly had errors of several meters (several ft), RTK can improve positional accuracy to a few centimeters (a few inches). This article explains the basics of RTK surveying and the mechanisms for achieving high accuracy, and introduces the workflow and features of LRTK, which enables RTK positioning data obtained on site to be shared instantly in the cloud. Let’s take a detailed look at this latest solution that strengthens field–office collaboration and dramatically improves work efficiency.

Basics of RTK surveying and how accuracy works

RTK (Real Time Kinematic) is a positioning technology that corrects satellite positioning errors in real time to achieve centimeter-level accuracy (half-inch accuracy). Specifically, it uses two GNSS receivers: a base station (fixed station) with known accurate coordinates and a rover (mobile station) that performs positioning while moving. By calculating the differences in satellite signals received simultaneously by both, the system computes the errors. The base station creates correction information from its known accurate position and the received satellite data, and sends that correction to the rover via radio or the Internet. The rover applies those corrections to its own observations to obtain high-accuracy coordinates in real time. This relative positioning mechanism makes it possible to reduce errors that were several meters (several ft) in single-point positioning to below a few centimeters (a few inches).

RTK surveying typically achieves accuracies within a few centimeters (a few inches). For example, under good conditions horizontal position errors are about 2–3 cm (0.8–1.2 in) and vertical errors are about 3–5 cm (1.2–2.0 in). This is orders of magnitude more accurate than standalone GPS positioning (errors of several meters (several ft)). Also, if an RTK receiver supports multi-GNSS (GPS, GLONASS, Galileo, QZSS, etc.), the number of usable satellites increases, making positioning more stable and improving accuracy. Error sources that affect satellite positioning, such as ionospheric delay and satellite clock drift, can also be canceled out by receiving correction data from the base station.

RTK can be operated using a privately installed base station in a one-to-one setup, or by obtaining correction information over the Internet from a network of base stations provided by national or private entities—so-called network RTK (VRS methods, etc.). The latter allows you to receive corrections without preparing a base station on site, making RTK positioning easier to use. LRTK supports this network RTK and can provide centimeter-level position information (half-inch accuracy) simply by connecting a dedicated receiver to a smartphone and accessing the correction service.

Workflow of LRTK that enables instant cloud sharing of positioning data

LRTK has a mechanism to store and share the high-accuracy position data obtained by RTK surveying directly in the cloud. By connecting the field and the office directly, it can greatly shorten the time lag in data transfer. Below is an example of a basic workflow using LRTK.

• Positioning and recording on site: Workers use an LRTK receiver attached to a smartphone or tablet to measure the positions of survey points and target objects on site. In addition to point coordinate measurements, they acquire necessary data such as photos and point cloud scans.

• One-tap cloud upload: Once measurements are completed, data is uploaded to the cloud (LRTK Cloud) with a single tap from the LRTK app. Via cellular or Wi‑Fi, high-accuracy positioning data (coordinate values, photos, point cloud files, etc.) is sent instantly from the site.

• Immediate office confirmation: Office staff can access LRTK Cloud via a web browser to view field data in real time. Uploaded survey points are plotted on a map, and photos and acquired point clouds are displayed in the cloud. For example, you can measure distances between two points on the cloud or compare design drawings with measured data.

• Feedback and utilization: Because the field and office always share the latest data, the office can quickly provide feedback to the field. Based on measurement results, additional instructions can be issued immediately, or the data can be used to revise drawings and perform quantity calculations—enabling seamless operations between field and office.

By introducing LRTK, high-accuracy positioning information obtained on site can be shared instantly via the cloud, making the traditional process of waiting until the next day for information transfer between the field and headquarters real-time. The hassle of bringing back data on USB sticks or sending emails is eliminated, and everyone always has access to the latest data.

Specific operations of the LRTK app and cloud features (photo positioning, point cloud upload, coordinate navigation)

LRTK is not just for measuring positions; it includes various functions that support fieldwork. Here are specific operations available in the LRTK app and cloud.

• Photo positioning (geotagged photo capture): When you take photos of the site with your smartphone camera, the capture position (latitude, longitude, and elevation) and camera orientation are automatically recorded with cm level accuracy (half-inch accuracy). On the cloud, photos are linked to map data so you can precisely know “which location and in what direction a photo was taken.” For example, attaching precise position information to inspection photos allows office staff to check and share site conditions in detail without being on site.

• Point cloud upload: LRTK allows you to upload acquired 3D point clouds to the cloud for centralized management. Point clouds generated by iPhone LiDAR scanners or drone photogrammetry can be uploaded on site and displayed in a 3D viewer in the cloud. You can rotate and zoom the point cloud in the browser, measure distances, areas, and volumes, and perform comparisons with design models (difference checking). The ability to immediately share large point cloud data with stakeholders without bringing a high-performance PC to the field is a major advantage.

• Coordinate navigation (position guidance): The LRTK app also includes a function to navigate users to specified coordinates. When you input coordinates of pre-set stakeout points or known points, the smartphone screen shows the direction and distance to the destination. Using AR technology to overlay markers for the target point on the camera view allows intuitive layout and stakeout. This enables tasks like staking out or marking positions—which traditionally required multiple people—to be carried out efficiently and accurately by one person.

With these functions, LRTK serves as an “all-purpose surveying tool.” From point surveying to photo documentation, 3D scanning, navigation, and AR-assisted intuitive fieldwork, everything can be done with a single smartphone plus LRTK, making it useful in a wide range of field operations.

Mechanism that changes information linkage between field and office (construction, as-built, reporting)

The real-time information sharing brought by LRTK significantly transforms the collaborative processes between the field and the office. In surveying during construction, as-built management, and daily reporting, the following new workflows become possible.

First, in construction management, the results of field surveying and stakeout can be checked immediately by headquarters or designers. For example, if the installation position of a reference point is measured on site, the coordinates are immediately shared in the cloud, allowing the office to check the deviation from planned positions on the design drawings. If there is an error or rework is needed, it can be pointed out and corrected while the field personnel are still on site, preventing wasted rework later.

Next, as-built management is also more effective. Point cloud data and coordinate information measured from the completed structure are uploaded to the cloud the same day, so quality control personnel and designers can remotely verify the as-built condition. They can visualize deviations from planned sections in 3D or immediately calculate as-built quantities, enabling cloud-based checks. This accelerates inspection and acceptance processes and reduces discrepancies in understanding between the field and the office.

Furthermore, reporting tasks benefit greatly. LRTK Cloud accumulates point clouds, photos, and record data by date, streamlining the creation of daily reports and other reports. There is no need to reorganize field data from scratch; you can compile reports by referencing the cloud data. LRTK also includes a feature to automatically generate forms in the cloud based on measurement data, reducing the reporting burden on field engineers.

Thus, LRTK dramatically speeds up and improves the accuracy of information linkage between field and office. The need to bring data back on USB or report conditions by phone is eliminated, and both sides can always share the same latest information. The entire flow from construction to inspection and reporting becomes smoothly connected, improving productivity and quality control.

Benefits and examples of managing point cloud data and photos in time series

In LRTK Cloud, all uploaded positioning data are organized and stored in time series. By centrally managing point clouds, coordinates, and photos along with timestamps, it becomes easy to trace changes from the past to the present. This brings various benefits and expands use cases.

One benefit is recording and comparing construction progress. For example, if you 3D scan terrain at a civil engineering site once a week and accumulate point cloud data, you can overlay weekly terrain models in the cloud to compare them. This makes it easy to understand excavation and embankment volumes over time for scheduling management or to demonstrate progress with objective data. Changes that used to be tracked only by cross-sectional surveys or photos can now be quantitatively followed in 3D.

Time series management also proves powerful in disaster response and infrastructure inspection. For instance, if you survey a landslide site with LRTK and then regularly record point clouds and photos during recovery work, you can verify changes in damage and recovery effectiveness over time. Stakeholders can share time series data in the cloud and make remote decisions.

Photos are similarly useful for recording aging and changes over time. If inspection photos of infrastructure or structures are saved in the cloud with precise capture positions, you can easily compare them with photos taken months or years later at the same locations. The progression of crack widening or ground subsidence becomes obvious when photos aligned by position are displayed in time series.

By managing and sharing data obtained with LRTK in time series, you can reliably track changes from past to present and use them for analysis. Project histories can be reviewed with data for reporting, post-verification, and future planning, providing persuasive materials.

Implementation effects (time savings, error prevention, remote confirmation, disaster response, etc.)

Finally, here are the main effects of implementing LRTK in the field.

• Reduced work time: The entire flow from surveying to data sharing and drawing updates is sped up. RTK surveying can be completed by one person and data can be shared with the office on the spot, reducing personnel needs and travel time between the site and headquarters. Processes such as surveying → drawing creation → quantity calculation, which once took days, can be greatly streamlined.

• Prevention of human error: Handwritten transcription errors and point misidentification can be reduced. Because positioning data are automatically saved to the cloud, omissions in field notes and reporting are less likely. Real-time verification by multiple people enables early detection of errors through double-checking.

• Remote status confirmation: Managers and engineers in remote locations can grasp site conditions without traveling. By monitoring shared real-time survey data and photos, the office can oversee field work and issue instructions, reducing travel costs and enabling prompt decision-making. Remote support by experienced engineers can also improve field work quality.

• Rapid disaster response: LRTK is powerful in emergencies. If one person goes to a disaster site to measure and photograph conditions with LRTK, that data can be shared immediately with the disaster response headquarters. This reduces the need for many people to enter dangerous sites, ensuring safety while rapidly assessing the situation. Sharing data in the cloud with relevant agencies supports faster deliberation and decision-making on response measures.

These effects mean that implementing LRTK not only improves surveying accuracy but directly contributes to overall operational efficiency and reliability. As part of promoting field DX (digital transformation), it can deliver significant results.

Introducing simplified surveying with LRTK

For those who want to introduce high-accuracy RTK surveying but think “costs and operations look burdensome…,” LRTK is an ideal solution. A centimeter-level surveying environment (half-inch accuracy) can be built with just a smartphone and a compact GNSS receiver, making tasks that previously required specialized surveying equipment much easier.

LRTK was developed with the concept of “one device per person in the field” and aims to be a simplified surveying system that anyone—not only surveyors but also construction managers and technicians—can use. The dedicated app is simple to operate, with positioning and data sharing completed in one tap. No complicated settings or procedures are required, and even field staff new to RTK can intuitively use it.

Additionally, because LRTK supports network RTK, the conventional need to set up a dedicated base station is eliminated. Packing the necessary equipment compactly and enabling immediate measurement and sharing on site is truly the next-generation “simplified surveying.”

LRTK has already been adopted by some municipalities and construction companies, achieving results in as-built management for road construction and emergency surveying at disaster sites. Such cases demonstrate the usefulness and reliability of LRTK.

If you are considering a new surveying style that balances accuracy and efficiency, why not start with simplified surveying using LRTK? This system that connects the field and the office in real time will be a powerful move for future operational improvements.

FAQ

Q: Is a dedicated base station required for RTK surveying? A: It is not always necessary to prepare your own base station. LRTK supports correction information services from network RTK (such as VRS), and by using correction data distributed from the Geospatial Information Authority of Japan or private base station networks, high-accuracy positioning is possible. LRTK also supports the centimeter-level augmentation service (CLAS) provided by Japan’s Quasi-Zenith Satellite System “QZSS,” so centimeter-level positioning is attainable even without a base station on site.

Q: Can it be used in locations without Internet on site? A: Yes. LRTK receivers can achieve high-accuracy positioning even outside Internet coverage by receiving CLAS signals from QZSS. If communication is not available on site, positioning data are stored on the receiver and can be uploaded to the cloud later when returning to coverage. While real-time sharing is not possible, surveying itself can proceed without issue.

Q: What equipment and preparations are required to use LRTK? A: All you need is an LRTK GNSS receiver and a compatible smartphone/tablet (currently iPhone or iPad). Install the dedicated LRTK app on your iOS device and attach the LRTK receiver. High-accuracy positioning requires correction information, so connect to the Geospatial Information Authority’s reference station data or a private VRS distribution service over the Internet as needed (service subscriptions may be required). For LRTK Cloud use, register the prescribed account and you can manage and share data via a web browser without special server construction or software installation.

Q: Can you really achieve centimeter-level accuracy? A: Yes—under appropriate conditions, errors within a few centimeters (a few inches) can be achieved. In open-sky conditions with signals from multiple satellites and applied corrections, typical accuracies are about 2–3 cm (0.8–1.2 in) horizontally and 3–5 cm (1.2–2.0 in) vertically. LRTK receivers are multi-GNSS capable and can track many satellites, making them less susceptible to satellite geometry and environmental effects and maintaining stable high accuracy. The LRTK app also includes functions to average positioning results, and there have been cases reporting errors of less than 1 cm (less than 0.4 in) under certain conditions.

Q: How can I view data shared in the cloud? A: Office users log in to LRTK Cloud from a PC web browser to view data uploaded from the field. Survey points and photo locations are plotted on a map, and you can list each point’s coordinates, elevation, acquisition time, and note fields. Point cloud data can be displayed as 3D models in the cloud, allowing you to move the viewpoint and measure distances, areas, volumes, and create cross-sections. You can also overlay design drawings or CAD data on the cloud for comparison with current point clouds. All of this is completed on the web, so no dedicated software installation is required. As long as there is Internet access, stakeholders can share and view the latest data from anywhere.

Q: Is the equipment difficult to operate? Can beginners use it? A: LRTK is designed to be user-friendly for beginners. Starting and stopping positioning and saving data are handled intuitively with buttons in the app, and recording of positional information and timestamps is automated. Even without specialist knowledge, following on-screen guidance enables high-accuracy positioning and cloud sharing, so non-surveying specialists can start using it immediately. Manuals and support systems are available if you need assistance.

Q: Can it be used on any device? A: Currently, LRTK supports only iOS devices (iPhone and iPad) and is not available on Android devices. LRTK receivers are connected to iPhone or iPad for use. Especially on recent iPhone Pro series models from iPhone 12 onward that include a LiDAR sensor, LRTK’s point cloud scanning features and camera-based coordinate measurement functions (measuring coordinates of distant objects with the camera) are available.