LRTK Phone is a compact high-precision GNSS receiver that attaches to a smartphone. Your phone instantly becomes a versatile surveying instrument with centimeter-level accuracy (cm level accuracy (half-inch accuracy)), dramatically improving the efficiency of positioning tasks on site. From LRTK beginners to experienced site workers, surveyors, and managers, anyone can easily obtain precise location information and apply it to various measurement and construction management tasks. This article explains how to use LRTK Phone in detail, from basic operations to advanced techniques.

First, we cover an overview of LRTK Phone and basic usage, then introduce advanced on-site features in order: AR-guided coordinate navigation (layout work), point-cloud scanning and as-built management using a smartphone, photo positioning functions, and more. At the end of the article we summarize the benefits of introducing LRTK Phone and include a FAQ answering common questions. If you want to streamline surveying and as-built management on site, please refer to this guide.

Table of Contents

• What is LRTK Phone?

• Basic operations of LRTK Phone

• AR guidance: coordinate navigation anyone can do

• 3D measurement and as-built management by point-cloud scanning

• Precise site records with photo positioning

• Benefits of introducing LRTK Phone

• FAQ

What is LRTK Phone?

LRTK Phone is a high-precision RTK-GNSS positioning device used in combination with a smartphone. It is compact and lightweight (about 125 g, thickness 13 mm (0.51 in)) yet includes a built-in battery and antenna, allowing it to function as a surveying instrument by itself. Attach it to your phone with a dedicated mount or holder and start the dedicated app with one touch, and precision positioning, 3D measurement, and layout (positioning) work that previously required specialized equipment become possible.

Its main feature is centimeter-level accuracy, achieved by correcting signals from multiple satellites such as GPS and GLONASS using RTK (real-time kinematic) technology, enabling position determination with errors within a few centimeters. In addition to geodetic coordinates (latitude, longitude, height), plane rectangular coordinate system values and geoid height are automatically calculated, so non-surveyors do not need to be concerned with unfamiliar coordinate transformation tasks. Acquired position data are plotted on the smartphone map immediately and can be uploaded to the cloud and shared with a single button press.

LRTK Phone is truly a solution that makes your smartphone “a versatile surveying instrument.” For site construction managers and workers, it is a dependable tool that enables precise measurements whenever needed. For professional surveyors, it supports and streamlines everyday surveying tasks. In the next chapter we will look at basic operation and practical usage in detail.

Basic operations of LRTK Phone

Basic use of LRTK Phone is very simple. Below are the basic steps to measure a single-point coordinate on site.

• Attach and prepare the device: Attach the LRTK Phone receiver to your smartphone. Dedicated phone covers and holders are provided for one-touch attachment and removal. Turn on the device and launch the LRTK app on your phone.

• Set the positioning mode: When you start positioning in the app, it will automatically begin acquiring GNSS satellites. For high-precision positioning, connect to a network RTK service (correction data such as Ntrip) or use the LRTK Phone’s supported *QZSS* CLAS signals. When correction information is received and the positioning status becomes “Fix,” you are ready. *Note: Even in areas without cellular coverage, CLAS-compatible models can apply corrections without communication.*

• Measure the point: Move the phone to the point you want to measure and tap the app’s “Position” button. For example, to record the coordinates of a point on the ground, place the supplied staff or an optional monopod at the point, stabilize it, then press the button. The latitude, longitude, and height of that point are recorded. The date/time and positioning status (RTK Fix/Float, etc.) are saved automatically, and you can name the point or add notes.

• Check and save data: Measured coordinates are plotted on the in-app map, and numeric values are displayed on the screen. If needed, take multiple measurements and average them in the app to improve precision (for example, averaging dozens of measurements can approach millimeter accuracy). Data are stored on the phone and can be reviewed in a list at any time.

• Upload to the cloud: After measurement, you can sync data to LRTK Cloud with one tap. Uploading to the cloud allows immediate review of site positioning results from an office PC web browser. Issuing a share link lets clients or partner companies view data without logging in. Site coordinate data can be downloaded in CSV or SIMA format and imported into CAD software for post-processing.

As described above, basic single-point measurement with LRTK Phone is completed by the intuitive operation of “point the phone at the point and press the button.” There is no need to write in paper fieldbooks, greatly reducing mistakes and rework. It is easy enough for beginners to handle after a few minutes of instruction, while providing data comparable in precision to conventional surveying instruments.

AR guidance: coordinate navigation anyone can do

One advanced use of LRTK Phone is the AR guidance function. This feature guides the user to a specified coordinate using AR (augmented reality) display, greatly simplifying layout tasks such as stake driving and positioning.

For example, when you want to drive a stake at a location specified in design plans, traditionally a surveyor would use a total station or measure from a known point with a tape to establish the position. With LRTK Phone’s AR guidance, the target point is displayed on the phone’s map and camera view, and you simply follow arrows and on-screen guides to reach the target. It’s like the phone telling you “dig here” or “drive the stake here.”

Coordinate guidance requires no complicated操作 and is intuitive enough for novice site workers to use, enabling them to find target points with centimeter-level accuracy. Even boundary markers hidden under vegetation or reference points buried under snow can be located by following AR markers on the phone screen. Because construction staff without surveying expertise can perform positioning themselves, waiting times are reduced and staffing can be optimized.

The AR guidance function is useful not only for stake driving during construction but also for inspection and maintenance of completed structures. For example, if previously measured and registered buried utilities are displayed in AR on site, you can avoid accidentally damaging pipes during subsequent excavations. Visualizing boundary lines or design alignments on the ground via AR makes it easier to share the completed-image between client and contractor. LRTK Phone’s AR guidance realizes spatial “visualization” on site, enabling anyone to perform accurate positioning without getting lost.

3D measurement and as-built management by point-cloud scanning

Next is the smartphone point-cloud scanning function. With LRTK Phone and a compatible smartphone, you can perform 3D surveying on site without a dedicated 3D laser scanner. Using the phone’s camera and LiDAR sensor, you can scan surrounding structures and terrain and record them as a dense collection of points (point-cloud data).

Typical smartphone 3D scans lack absolute coordinate information, which can cause distortion when combining multiple scans. However, because LRTK Phone always knows its own position with cm精度で把握 (cm level accuracy (half-inch accuracy)) while scanning, it can assign accurate global coordinates to every acquired point in the point cloud. Even when walking to scan a wide area, you get high-precision 3D data without position drift or distortion. This capability—allowing anyone to obtain point-cloud measurements with absolute coordinates using only a smartphone—significantly lowers the barrier to on-site 3D measurement.

The scanning procedure is simple. Start point-cloud scan mode in the app and move the phone around to survey the area you want to record. In about five minutes of walking while pointing the camera, you can scan a single roadway or a wide slope. Targets that used to be difficult to measure, such as slopes or the undersides of bridges, can be recorded from the ground by simply pointing the phone. LRTK Phone can acquire point clouds of targets up to about 60 m (196.9 ft) away, capturing distant structures reliably. If GNSS reception is lost at several locations during acquisition, the device’s IMU and the phone’s AR technology estimate position to maintain continuous point-cloud recording (an indoor positioning mode is also available for use under bridges and other covered areas).

Point-cloud data acquired in this way can be used for various measurements and analyses on LRTK Cloud. Upload point clouds from the field to the cloud to view the 3D data in a browser on a PC without installing specialized software. You can measure any two-point distance on the point cloud, or calculate area and volume with a single click.

This point-cloud measurement function dramatically streamlines as-built management in civil engineering. For example, after embankment or cut works, scan the terrain and compare it with the design 3D model to instantly calculate the required fill or cut volumes. LRTK Cloud can automatically align the design model with the as-built point cloud and display differences as a color-coded heat map. Green or blue areas match the design, while red areas indicate under- or over-fill at a glance. Since output can be produced in data formats compliant with the Ministry of Land, Infrastructure, Transport and Tourism’s “as-built management guidelines,” point clouds acquired with LRTK Phone can be used as deliverables for inspection submission.

Previously, volume calculations and shape checks for as-built management required survey teams to measure numerous points on site or to bring heavy laser scanning equipment. After introducing LRTK Phone, site workers themselves can acquire 3D point clouds in a short time and perform necessary calculations on site. On large projects it can be combined with drone surveying for even more efficient point-cloud acquisition, but for small to medium sites LRTK Phone alone enables “walk-and-measure, immediate output.” This convenience increases the frequency of as-built checks and production tracking, improving quality control accuracy.

Precise site records with photo positioning

LRTK Phone also includes a handy photo positioning function for site records and reporting. This records the precise coordinates and camera orientation (azimuth) of the photo location together with photos taken on the phone. While regular smartphone photos can retain geotags, typical accuracy is coarse—on the order of several meters—and insufficient for construction management. With LRTK Phone, you can save the photo location to cm精度 (cm level accuracy (half-inch accuracy)), making photos a much more reliable site record.

Usage is simple. In the LRTK app’s “positioned photo” mode, take a picture and the corresponding coordinate data (latitude, longitude, height) and shooting direction are automatically linked to the photo file. For example, when inspecting a bridge, you might photograph a crack in a girder. Later it can be difficult to know exactly where on the bridge the photo was taken, but with positioned photos, the photo’s location and direction are recorded, allowing you to overlay the image on point-cloud data or drawings in the cloud to identify the exact spot where the crack was found.

An advanced use is the object positioning feature. Using a LiDAR-equipped phone, you can measure the coordinates of an object located some distance from the camera. For example, points on signs in restricted areas or high-up points on structures that are hard to reach directly can be measured from a distance by aiming the phone camera. Internally this is an application of photo positioning that estimates object location by combining measurements from multiple directions and AR technology. Object positioning is an advanced feature available on the latest phones (such as Pro models with high-performance LiDAR sensors) and further extends the range of on-site measurements.

Combining positioned photos with point-cloud data takes site records to the next level. For instance, when you scan an entire bridge in 3D and manage a set of positioned photos at key points in the cloud, you can link the structure’s shape with details at specific locations. With photos and coordinates paired, the effort to create photo logs is reduced and you can reliably identify “the same location as last time” during future inspections.

Benefits of introducing LRTK Phone

As we have seen, LRTK Phone brings a variety of revolutions to on-site positioning work. Here are the benefits of introduction organized by user perspective.

• For beginners and non-specialist staff: Because it is smartphone-based and intuitive, it is easy to use without specialized surveying knowledge. Training costs are low, and LRTK beginners can become proficient in a short time. Site workers who were not accustomed to operating surveying equipment can now perform necessary measurements themselves, expanding their scope of work.

• For site workers: The small device fits in a pocket and can be carried at all times, so you can take it out and measure whenever you need to. There is no time-consuming setup of heavy equipment in the warehouse. Checking stake positions or conducting quick as-built inspections can be completed by site staff themselves, reducing waiting times and simplifying workflow. AR guidance to visualize buried objects also contributes to improved safety.

• For surveyors and technicians: As a multifunctional surveying instrument combining high-precision RTK-GNSS and various sensors, it meets the accuracy and reliability demands of professionals. A single person can handle single-point surveys, point-cloud measurements, positioned-photo records, and continuous measurements for longitudinal/cross-section acquisition, contributing to team labor savings and improved efficiency. Tasks that were previously outsourced can be brought in-house, and frequent as-built checks that were impractical before can now be performed, improving workflow.

• For managers and executives: Using LRTK Phone accelerates site digitalization and DX. Since site data are immediately consolidated to the cloud, progress and construction quality can be reviewed remotely, speeding decision-making. Equipping each employee with surveying capability increases productivity and reduces labor and outsourcing costs. It also represents the adoption of advanced technologies aligned with the Ministry of Land, Infrastructure, Transport and Tourism’s i-Construction and ICT construction initiatives, which can be leveraged to strengthen competitiveness and demonstrate quality improvements.

In summary, LRTK Phone is a groundbreaking tool that combines ease of use with high precision. With simple LRTK surveying, measurement tasks on site no longer belong only to specialists; site staff become data collectors in a new workflow. Harness this technology to overturn conventional practices and enhance the efficiency and sophistication of surveying and measurement tasks at your sites.

FAQ

Q: How does LRTK Phone achieve high-precision positioning?

A: LRTK Phone combines a high-precision GNSS receiver with a smartphone to perform RTK (real-time kinematic) positioning. By applying correction information from multiple satellites and network-based corrections (or QZSS CLAS signals), it improves positioning accuracy to approximately 1–2 cm. This enables surveying-grade positioning far more precise than a phone’s native location function.

Q: Can beginners use it? Is special training required?

A: Yes. Basic operations are very simple, so beginners can use it immediately. Positioning is done by pressing a button in the smartphone app, and AR displays are intuitive. While surveying knowledge is not required, having a minimal understanding of concepts such as coordinates makes the data easier to use. The manufacturer provides manuals and support, and on-site training is short.

Q: Are there restrictions on smartphone models or conditions?

A: LRTK Phone is basically used with iOS smart devices (smartphones and tablets) running the dedicated app. High-end current models have superior camera and sensor performance, allowing full use of LRTK Phone features. Models equipped with LiDAR scanners enable advanced functions such as point-cloud scanning and object positioning. The recommended devices are the latest Pro series smartphones. Check official information for detailed supported models.

Q: Is the positioning accuracy really centimeter-level? What kind of errors can be expected?

A: Under proper satellite reception and with RTK corrections in a Fix solution, horizontal position accuracy is about ±1–2 cm (±0.4–0.8 in), and vertical accuracy is about ±2–4 cm (±0.8–1.6 in). This is far more precise than GNSS handhelds or smartphone GPS alone. Static averaging and capturing multiple satellites in an open area can further improve accuracy. However, obstructions and atmospheric conditions can occasionally increase error, so for important survey deliverables it is recommended to take multiple measurements for confirmation.

Q: Can it be used in remote mountain areas or sites without infrastructure where there is no coverage?

A: Yes, LRTK Phone can be used even outside cellular coverage. Coverage-capable models can receive correction information without the internet from private high-precision GNSS services or Japan’s QZSS CLAS, maintaining centimeter-level positioning in remote mountain areas or disaster sites. However, in environments where satellite signals are completely blocked—such as underground or inside tunnels—positioning is difficult. In such cases, use the LRTK app’s indoor positioning mode to track position relative to a reference point established where signals are available.

Q: How long does the battery last? Can it be used for long periods on site?

A: LRTK Phone runs on a built-in battery and is designed for continuous use for about half a day to a full day under typical surveying operations (actual life varies by usage and environment). If battery runs low, you can charge and use it with a mobile battery. The device is also designed with durability in mind and can withstand some rain and dust outdoors, but avoid extreme conditions such as prolonged heavy rain; using a waterproof case or cover is recommended.

Q: How can measurement data be utilized? Can it interoperate with other software?

A: Measured data can be used immediately as maps and point clouds in the LRTK app and LRTK Cloud. Point data can be exported in CSV or SIMA formats, and point-cloud data in LAS format, allowing import into common CAD and point-cloud processing software. Conversely, design drawings and 3D models can be uploaded to LRTK Cloud for comparison with on-site point clouds. Because the cloud enables stakeholders to review data without special viewers or high-performance PCs, collaborative data review is convenient.