Table of Contents

• What is LRTK Phone accuracy? Achieving centimeter-class positioning with a smartphone

• Accuracy and challenges of conventional smartphone AR point cloud scanning

• How LRTK Phone improves accuracy

• Comparison with professional surveying equipment: the capabilities of LRTK Phone accuracy

• Possibilities for smartphone point cloud scanning enabled by higher accuracy

• What simple surveying with LRTK enables

• Conclusion

• FAQ

What is LRTK Phone accuracy? Achieving centimeter-class positioning with a smartphone

LRTK Phone is an innovative system that enables centimeter-class high-precision positioning using only a smartphone (especially iPhone). While typical smartphone GPS positioning is said to be accurate only to a few meters, using LRTK Phone allows you to determine positions with an error of only a few centimeters—providing survey-grade accuracy. This is achieved by a dedicated ultra-compact GNSS receiver that leverages the positioning technique RTK (Real-Time Kinematic), a smartphone app, and cloud services. Simply attaching a small device that fits in your pocket to your smartphone provides position information comparable in accuracy to expensive surveying equipment.

This "cm-level positioning (cm level accuracy (half-inch accuracy))" allows accurate coordinates to be attached to any data acquired with a smartphone. For example, if you scan the surroundings with an iPhone’s built-in LiDAR sensor or AR features, the captured point cloud can be georeferenced with latitude, longitude, and elevation in a global coordinate system. Before LRTK Phone, point clouds scanned with smartphones only had relative coordinates and required additional adjustments to align with real-world coordinates. By using the high-precision position information from LRTK Phone, smartphone AR point cloud scans can be given absolute (global) coordinates, enabling 3D data acquisition with scale and positional relationships that match the real site exactly.

Accuracy and challenges of conventional smartphone AR point cloud scanning

3D scanning using AR technology on smartphones has attracted attention as an easy way to obtain on-site three-dimensional data. However, conventional smartphone AR point cloud scanning has had several accuracy-related challenges. Specifically, the following issues were common:

• GPS accuracy limitations: Typical smartphone built-in GPS commonly has errors on the order of several meters, which is insufficient for wide-area surveying or precise alignment. Even plotting on a map can result in meter-scale offsets, making it difficult to use for precise location records.

• Accumulation of AR scan errors: Smartphone AR scans (e.g., iPhone LiDAR scans) obtain point clouds while estimating device position using the device’s IMU sensors and camera. As travel distance increases, errors can gradually accumulate, causing distortions or scale errors in the scanned 3D model. In some cases, errors of a few percent in length or height can occur, posing challenges where precision is required.

• Lack of absolute coordinates: Scan data from a smartphone alone is essentially recorded in a local coordinate system (relative coordinates for that session). When later overlaying with other surveying data or design drawings, manual transformation and alignment to reference points is required, adding work. Especially for surveying applications, the inability to acquire data in an absolute coordinate system such as the national geodetic system was a major limitation.

As described above, because of its ease of use, smartphone AR point cloud scanning has had limits in accuracy, and the conventional view was that it was useful for simple records or visualization but not suitable for precise surveying.

How LRTK Phone improves accuracy

LRTK Phone technology addresses these challenges and dramatically improves the accuracy of smartphone AR point cloud scanning. Here’s how LRTK Phone achieves high precision.

1. Centimeter positioning via RTK-GNSS: LRTK Phone incorporates a high-performance GNSS receiver that acquires signals not only from GPS but from multiple GNSS constellations. Using the RTK method, it receives real-time error correction information from a base station and greatly reduces positioning errors. As a result, in open-sky environments LRTK Phone typically reaches an RTK “Fix” in about 20–40 seconds and can determine the smartphone’s position with astonishing accuracy of approximately horizontal ±2 cm (±0.8 in) and vertical ±4 cm (±1.6 in). Conventional smartphone GPS accuracy of about ±10 m (±32.8 ft) is improved by orders of magnitude through RTK.

2. Integration with the smartphone’s AR capabilities: The high-precision position information from LRTK Phone is integrated into the smartphone’s AR engine (e.g., iPhone ARKit). This ensures the device maintains an accurate real-world pose as it moves through space. While normal AR scans can have some pose estimation error, supplementing with LRTK correction data improves device tracking accuracy, significantly reducing distortions and scale errors in point cloud data. In other words, each point captured by the smartphone’s camera or LiDAR is mapped in real time to the correct geospatial coordinates.

3. Acquisition of point cloud data with absolute coordinates: Through high-precision positioning and AR integration, point clouds scanned with a smartphone are recorded from the start with absolute coordinates (such as standard geodetic reference systems). This produces 3D data that can be used as surveying deliverables on site without special calibration work. For example, when scanning terrain or structures, the point cloud can be immediately overlaid on maps or CAD design data, greatly streamlining post-processing. Additionally, the acquired point cloud can be checked in real time on the smartphone, allowing you to capture missing areas on the spot and verify data quality during acquisition.

4. Dedicated app and cloud services: The LRTK Phone system includes a dedicated iPhone app and a cloud service (LRTK Cloud) for data management and processing. The app’s intuitive UI supports everything from starting positioning to point cloud scanning and AR display in a single workflow. In the cloud, uploaded point clouds can be viewed on 3D maps, and distance, area, and volume measurements or comparisons with design models can be performed. This software support establishes a workflow that enables immediate use of high-precision data collected on site.

Through this hardware–software integration, LRTK Phone dramatically enhances the accuracy and practicality of smartphone AR point cloud scanning.

Comparison with professional surveying equipment: the capabilities of LRTK Phone accuracy

Even if the theory promises high accuracy, you might wonder, “Can a smartphone really achieve that level of precision?” Let’s look at verification comparing LRTK Phone accuracy with professional surveying equipment.

Internal and field validations have confirmed that coordinates obtained with LRTK Phone are comparable to those obtained with class-1 GNSS receivers used by surveyors. Specifically, the same point was measured using both an LRTK Phone and a class-1 GNSS receiver, and the coordinates were compared. The coordinate differences between the two devices were on the order of a few millimeters in both horizontal and vertical directions (in all cases less than 5 mm (0.20 in)), essentially within measurement error and showing nearly identical values. This means that, despite being a small device attached to a smartphone, LRTK Phone achieves sub-centimeter-class accuracy comparable to professional surveying equipment.

In another test, known points were measured dozens of times with LRTK Phone and the average and variance were analyzed to evaluate stability. Results showed minimal variation between measurements, with mean values very close to theoretical values and consistently high repeatability. This demonstrates that LRTK Phone does not just occasionally produce a high-precision reading by chance, but maintains high accuracy consistently over repeated measurements.

Importantly, this level of accuracy is easily obtainable in the field. Traditionally, centimeter-level positioning required large GNSS setups on tripods or total stations operated by trained surveyors. LRTK Phone can achieve comparable accuracy with a smartphone-sized, handheld device, significantly lowering the barrier for field surveying tasks. High precision yet easy to use—this is the greatest strength of LRTK Phone accuracy.

Possibilities for smartphone point cloud scanning enabled by higher accuracy

With LRTK Phone’s dramatic improvement in smartphone AR point cloud scanning accuracy, various applications that were previously difficult become realistic. Here are several possibilities enabled by higher precision.

First, civil engineering and construction site use. Tasks traditionally performed with surveying equipment—such as as-built measurements and pre/post grading surveys—can be completed by walking the site with a smartphone fitted with LRTK Phone and scanning point clouds. For example, even when calculating volumes of large embankments or excavations, accurate volume computations can be obtained from smartphone-scanned point clouds. Because the point clouds have absolute coordinates, they can be immediately compared with design cross-sections or reference elevations to determine how much material needs to be added or removed. LRTK Phone is ideal for regular as-built management, enabling in-house staff to perform measurements more frequently without outsourcing, thus improving the speed and accuracy of progress management and quality control.

Next, infrastructure inspection and disaster site applications. High-precision 3D point clouds are easily obtainable, enabling smartphones to be used for displacement measurements of bridges, tunnels, and for assessing slope failures. For instance, immediately after a disaster, using an LRTK Phone-equipped smartphone allows survey teams to quickly capture detailed 3D data of hazardous sites without prolonged exposure. The data can be shared instantly via the cloud, allowing remote experts to review and plan response measures in real time. The ability to complete initial surveying and documentation with a single smartphone is a major advantage.

Furthermore, integration with AR technology opens new possibilities. Previously, AR with low accuracy produced large misalignments when overlaying virtual design models on site, limiting practical use. With LRTK Phone, BIM/CIM models and other digital data can be displayed precisely aligned to the real world. This lets you view full-scale, accurately positioned representations of designs on site. Applications such as AR visualization of design proposals and AR-guided excavation by showing buried utilities’ positions become viable. High-accuracy AR helps reduce construction errors and improves on-site sharing of design intent, becoming a key enabler for construction DX (digital transformation).

In this way, higher accuracy in smartphone AR point cloud scanning is not merely a technical improvement but has the potential to transform on-site workflows. Affordable, easy-to-use tools that enable anyone to handle high-quality 3D data democratize tasks that used to be reserved for specialists, speeding decision-making and reducing costs.

What simple surveying with LRTK enables

LRTK Phone is not only for point cloud scanning but also a trump card for simple, on-site measurements—“simple surveying.” Traditionally, surveying required specialized equipment and advanced skills, but using LRTK allows site staff to complete small measurements on their own, on the spot.

Here are the main capabilities enabled by simple surveying with LRTK:

• One-touch point surveying: With LRTK Phone attached to your smartphone, you can record coordinates of specific points with a tap. When positioning is in Fix, acquired coordinates for latitude, longitude, and elevation have errors within a few centimeters. For example, boundary points or arbitrary feature locations can be measured accurately by approaching and tapping—no crew required.

• Distance and area measurement without a tape: The dedicated app can use on-site point clouds and photos to immediately calculate distances between two points or areas enclosed by polygons. You no longer need a measuring tape or a surveying calculator; tap required points on the smartphone screen and high-precision lengths and areas are computed automatically.

• Immediate volume and earthwork calculations: You can compute volumes of fills and excavations on site from point cloud data. For example, to know how much soil was produced by Earthworks, scan the area with your smartphone, upload to the cloud, and get an accurate volume calculation in a short time. This enables immediate decisions on truck arrangements and soil disposal planning.

• Stake-out and position guidance: The LRTK app includes a “coordinate guidance (stake-out)” feature that guides the user to a specified coordinate. As you approach a preset target point, the remaining distance is displayed in cm increments on the screen, and it notifies you when you reach the precise location. This enables tasks such as stake-driving, traditionally requiring two people with a total station, to be performed solo with a smartphone. Using AR display, you can show a 3D marker or flag at the target point for visual guidance.

• Geotagged photo records: Site photos taken with the smartphone can be tagged with high-precision location and orientation information. When reviewing photos later, you can accurately know where and in which direction each photo was taken, which is useful for reporting and monitoring changes over time. The cloud also supports plotting photos on a map so photo locations are immediately visible.

With LRTK Phone at the core, surveying and measurement tasks that previously required specialists and expensive equipment become remarkably accessible. The notion of “measure right away whenever the need arises” becomes reality, accelerating decision-making and increasing on-site autonomy. LRTK presents a modern approach to simple surveying suited to today’s fieldwork.

Conclusion

We have examined in detail the accuracy of LRTK Phone—which revolutionizes smartphone AR point cloud scanning—including how it works and practical applications. Achieving centimeter-class positioning with a smartphone and immediately providing point clouds with absolute coordinates is a game changer. LRTK Phone transforms smartphones from mere gadgets into serious surveying tools, accelerating on-site digitalization and efficiency.

The combination of high precision and ease of use that LRTK Phone offers creates new opportunities across many spatial data use cases beyond surveying and construction management. From precise point cloud scanning and simple surveying to AR visualization, workflows that used to be performed separately can now be seamlessly connected with a single smartphone. If your work requires "more convenient and accurate site data" or you want to promote DX, considering smartphone surveying with LRTK is well worth it. Experience the cutting-edge LRTK Phone accuracy for yourself.

FAQ

Q: What does LRTK Phone stand for?

A: "LRTK" is the name of our solution and refers to a high-precision positioning system that utilizes RTK (Real-Time Kinematic) technology. "Phone" indicates its integration with smartphones, so together we call it LRTK Phone. The main difference from ordinary GPS is that real-time correction information dramatically improves positioning accuracy.

Q: What level of positioning accuracy can LRTK Phone achieve?

A: Under favorable conditions (open sky with sufficient satellite visibility) and when an RTK Fix is obtained, you can expect approximately ±2 cm (±0.8 in) horizontally and about ±4 cm (±1.6 in) vertically. Field verifications have shown differences of only a few millimeters when compared to professional surveying GPS, so the accuracy is effectively at a level where errors are hardly noticeable.

Q: How large an area can be measured at once when scanning point clouds with a smartphone?

A: The range of a smartphone AR scan depends on the environment, but as a guideline you can continuously acquire point clouds over distances from tens of meters to hundreds of meters. Using LRTK Phone keeps positional accuracy even over long movements; for example, you can walk along a slope about 200 m (656.2 ft) long and scan it in one to two minutes. For very large areas, you can partition the area and scan multiple times, then merge the data afterward.

Q: Do I need specialized knowledge or certification to use it?

A: No. Basic operations are completed within the smartphone app, which is designed to be intuitive so users without technical expertise can operate it. By simply attaching the LRTK Phone to a smartphone and pressing the app’s start positioning button, high-precision positioning begins automatically and you can follow prompts to scan and measure. With a short training or by reading the manual, anyone on site can perform measurements with surveyor-like accuracy.

Q: Can it be used indoors or where GPS signals are unavailable?

A: In locations where GNSS signals cannot be received (indoors, tunnels, etc.), real-time high-precision RTK positioning will not function. In such cases, relative measurements using only the smartphone’s AR features are possible, but absolute coordinate accuracy cannot be guaranteed. However, workarounds—such as using a previously acquired reference point to operate in a local coordinate system—can mitigate this. The technology delivers maximum benefit in outdoor, open environments, but can still be adapted to various conditions as needed.

Q: Which smartphones are supported?

A: Currently the solution targets iPhone. In particular, iPhones equipped with LiDAR scanners (iPhone 12 Pro and later models) can fully utilize AR point cloud scanning capabilities. Expanding support to other models is under consideration, but the latest iPhones are fully compatible with LRTK Phone features. The app is available on the App Store, so if you have a compatible iPhone you can start trying high-precision positioning right away.