Your Smartphone Becomes a Surveying Instrument! Start Easy High-Precision Surveying with LRTK Phone

Table of Contents

• Introduction

• Surveying Challenges and the Need for Smartphone Surveying

• What Is LRTK Phone?

• Features and Functions of LRTK Phone

• On-site Benefits Brought by LRTK Phone

• Conclusion: A New Era of Surveying Opened by Smartphones

• FAQ (Frequently Asked Questions)

Introduction

Surveying work is indispensable on construction sites. However, traditional surveying required specialized technicians and expensive dedicated equipment, so it was not something anyone on site could do immediately. Recently, simple surveying technologies that utilize smartphones have attracted attention. In particular, "LRTK Phone" is an innovative device that turns a smartphone into a surveying instrument capable of centimeter-level high-precision positioning (cm level accuracy (half-inch accuracy)). In this article, we introduce the appeal and benefits of high-precision surveying using LRTK Phone for on-site workers and construction companies with no surveying experience.

Surveying Challenges and the Need for Smartphone Surveying

The construction industry faces shortages of experienced surveyors and issues related to improving productivity. Conventional surveying often requires setting up large equipment such as transits or GNSS receivers and sometimes two or more people to operate them, which takes time and costs. Also, compiling survey results into drawings or data and sharing them with stakeholders requires expertise. Against this backdrop, digitalization and ICT utilization on site—such as the Ministry of Land, Infrastructure, Transport and Tourism’s i-Construction initiative—are strongly sought. Smartphone-based surveying, which combines smartphones with advanced technologies, is expected to be a solution.

LRTK Phone was developed as a next-generation surveying solution to meet these needs. Based on the concept that a smartphone becomes a surveying instrument, it is designed so that anyone can easily obtain high-precision positioning and surveying data.

What Is LRTK Phone?

LRTK Phone (LRTK Phone) is a compact RTK-GNSS receiver device that attaches to smartphones (mainly iPhone and iPad). Just by attaching it like a smartphone case, it can elevate a smartphone’s GPS—which normally has errors of several meters—to centimeter-level accuracy (cm level accuracy (half-inch accuracy)). It is lightweight at about 125 g and compact with a thickness of only about 13 mm (0.51 in), pocket-sized. The antenna and battery are integrated, eliminating troublesome wiring or external power on site.

Combined with the dedicated LRTK app, a single smartphone functions as an all-purpose surveying instrument. Not only can it acquire high-precision position coordinates, but it also enables intuitive execution of various surveying and measurement tasks such as 3D scanning, stakeout position guidance, and projection of design data using AR (augmented reality). LRTK Phone was developed by a startup originating from the Tokyo Institute of Technology and is attracting attention as an innovative technology supporting DX (digital transformation) in construction sites.

Features and Functions of LRTK Phone

• Easy attachment for immediate surveying: LRTK Phone is easy to attach to a smartphone and requires no special setup. Bring it to the site, attach it to your phone, and you can start positioning immediately. You can hold the phone in one hand, place the device at the point you want to measure, and tap the app button to perform surveying. Even without complicated operations or specialized knowledge, you can obtain accurate latitude, longitude, and elevation with a one-touch action.

• Centimeter-level high-precision positioning: The greatest feature is its high positioning accuracy. LRTK Phone supports the RTK (real-time kinematic) method, which drastically reduces positioning errors. It also supports enhancement signals (CLAS) provided by Japan’s Quasi-Zenith Satellite System “Michibiki,” enabling high-precision positioning even in mountainous or infrastructure sites outside network coverage. Achieving centimeter-level positioning, which previously required GNSS receivers and base stations costing several million yen, is now possible with just a smartphone and LRTK Phone. In actual validations, standalone positioning achieved horizontal accuracy of about 10–20 mm (0.39–0.79 in), and by averaging multiple measurements an accuracy of about 5–10 mm (0.20–0.39 in) can be obtained—comparable to professional surveying equipment.

• Various surveying modes (single-point and continuous positioning): The LRTK app offers a range of positioning modes to meet on-site needs. For example, in single-point positioning to record the coordinate of one location, you simply place the device at the target point and press a button to record its coordinates. Point names and timestamps are automatically recorded, and you can add notes. In continuous positioning mode, which acquires position data continuously, you can walk and sequentially measure surrounding terrain. You can measure multiple points at equal intervals or place measurement points along lines or surfaces to capture cross-sections or planform shapes of the terrain.

• 3D point cloud scanning: By combining with the smartphone camera or LiDAR sensor (on supported models), you can easily perform 3D measurements of the site. Simply walk while holding the smartphone and LRTK Phone continuously provides centimeter-level knowledge of your position, enabling acquisition of surrounding structures and terrain as a 3D point cloud. Normally, scans with a smartphone alone can suffer from distortion when moving long distances or lack absolute coordinates (world coordinates). However, with LRTK Phone, every obtained point cloud is tied to global geodetic coordinates, so integrating multiple scans does not produce misalignment. For example, even for road sections of about 50-60 m (164.0-196.9 ft), a worker can walk from end to end while scanning to generate a high-precision terrain point cloud model aligned to design coordinate systems. From the resulting point cloud data, you can calculate distances between arbitrary two points or the volumes of embankment/excavation on the spot. Tasks that previously required dedicated 3D laser scanners or drones can now be completed with a single smartphone.

• Guidance for stakeout and position marking: LRTK Phone not only measures but also serves as a tool to indicate positions. Traditionally, marking design coordinates on site (stakeout) required a surveyor to go on site with surveying instruments. The LRTK app includes a coordinate guidance function that displays arrows and guides on the smartphone screen toward a specified target coordinate. Users simply follow the guidance to find the target location with centimeter accuracy. This enables personnel with limited surveying experience to perform stakeout tasks. Also, using AR technology, a virtual stake can be displayed for locations that are difficult to approach directly, such as steep slopes or beyond obstacles, allowing safe and efficient position marking.

• On-site projection of design data via AR: LRTK Phone integrates with AR functions to overlay 3D design data or previously acquired point cloud data onto the real-world view. For example, if you upload a 3D model of a planned structure (retaining walls, levees, etc.) to the LRTK cloud, you can project that model at actual scale through your smartphone on site and compare it with surrounding terrain. Typical smartphone AR requires placing markers or manual scale adjustments to align objects, but with LRTK the hassle is unnecessary. Because your position is constantly known with high accuracy, LRTK realizes AR that does not drift even when walking. This makes it easy for clients and contractors to share the completed image on site together and to identify discrepancies between design and as-built conditions on the spot.

• Photogrammetry and record-keeping: On-site investigations often involve taking photos for records. With LRTK Phone, the smartphone’s orientation (bearing) and the shooting location’s coordinates are automatically recorded when a photo is taken. The photos can later be plotted on a map or on a point cloud with their shooting locations, so you can immediately see where and in which direction a photo was taken. This makes it easy to replicate “taking a photo from the same location and angle as before,” which is useful for comparing aging in infrastructure inspections or for before-and-after construction records.

• Cloud integration and data sharing: All data acquired with the LRTK app can be uploaded to the dedicated LRTK cloud with one tap. office staff can instantly check surveyed points and point cloud data shared from the field on a web browser map or 3D viewer. There is no need to install special software on a PC; you can measure distances, areas, and volumes on the cloud, or perform difference checks by overlaying point clouds with design models (displayed as as-built heat maps). Coordinate data obtained on site can be exported in CSV or CAD formats, allowing smooth integration into existing drawing creation workflows.

• Compact, lightweight, and easy to carry: LRTK Phone is a small device that fits in a pocket, so workers can carry it around the site at all times. The convenience of being able to quickly take measurements when needed is a major advantage in daily construction management. Small checks of as-built conditions, intermediate inspections, or locating buried objects—tasks that would normally require calling the surveying team—can be handled on the spot by your own staff. If everyone on site has a “one-per-person” surveying tool, the way on-site work is conducted will change dramatically.

• Intuitive operation anyone can use: Unlike specialized surveying instruments, LRTK runs on a smartphone app with an intuitive user interface. Start buttons and functions are displayed with easy-to-understand icons, so even first-time users can operate it without confusion. The app automatically performs coordinate transformations (such as conversion to plane rectangular coordinate systems or geoid height calculations) so users do not need to think about complex matters. The ease of being able to act immediately when you want to “measure” or “view” is the key to spreading ICT utilization among non-technical on-site staff.

On-site Benefits Brought by LRTK Phone

Introducing LRTK Phone brings various benefits to construction sites.

• Improved productivity: By reducing waiting time for surveying and allowing measurements whenever needed, work coordination becomes smoother. For example, tasks such as as-built management that used to require outside surveying contractors can be measured and checked on site by in-house staff, reducing schedule delays. Real-time data sharing eliminates communication loss between the site and the office.

• Cost reduction: Instead of equipping multiple expensive total stations or GNSS surveying instruments, provisioning several relatively affordable LRTK Phone units allows many staff to survey simultaneously while keeping initial costs down. It also reduces the frequency of outsourcing surveying work, cutting labor and subcontracting costs. Benefits such as preventing rework and reducing correction costs through early detection are also expected.

• Addressing labor shortages: With the aging and shortage of specialized surveyors, LRTK Phone provides an environment where non-specialist workers can take part in surveying tasks. This reduces dependence on experienced personnel for some tasks, alleviating bottlenecks caused by labor shortages. In training new staff, starting with smartphone surveying to get accustomed to on-site measurement can broaden the base of future surveying personnel.

• Improved safety: Surveying in hazardous locations (e.g., measuring distances on roads or on steep slopes) can be done quickly and safely with LRTK Phone. Remote scanning and AR projection allow site conditions to be assessed without workers entering dangerous areas. Displaying stakeout positions via AR also helps prevent construction at incorrect locations, contributing to safety and quality assurance.

• Enhanced quality control: Using LRTK Phone, as-built conditions can be sequentially recorded as digital data. By comparing with design models and color-coding construction accuracy, or by accumulating fixed-point observation data to track changes over time, quality control can be advanced. Shifting from paper records and verbal handovers to data-driven objective management reduces mistakes and oversights.

• Promotion of on-site DX: LRTK Phone is a tool that embodies digital transformation (DX) on site. With a single device, surveying, recording, verification, and sharing can be completed digitally, transforming previously analog workflows. It can produce deliverables compliant with the Ministry of Land, Infrastructure, Transport and Tourism’s “ICT earthworks” and as-built management guidelines, streamlining documentation for clients. For companies aiming to advance on-site DX, LRTK Phone is an ideal first step.

Conclusion: A New Era of Surveying Opened by Smartphones

With LRTK Phone, the new era in which “a smartphone becomes a surveying instrument” has become a reality. Even on-site workers with no surveying experience can perform centimeter-accurate positioning and data measurement by intuitively operating a smartphone. This contributes not only to improved productivity, safety management, and quality assurance on construction sites, but also ensures that each worker can enjoy the benefits of digital technology.

Surveying, which traditionally was left entirely to specialists, has become more accessible with the advent of LRTK Phone. In the future, smartphones may become as commonplace as hammers or shovels as standard “surveying tools” on construction sites. Take this opportunity to experience simple surveying you can easily start with LRTK Phone. The world of high-precision surveying opened by a single smartphone will change on-site norms.

FAQ (Frequently Asked Questions)

Q: Do I need any special qualifications or knowledge to use LRTK Phone? A: No, no special qualifications are required. Basic operations are completed within the smartphone app, and you can perform positioning and measurement by simply pressing a button. The app automatically handles coordinate transformations and data processing so that users without surveying expertise can operate it intuitively.

Q: What equipment and preparations are required? A: All you need is the LRTK Phone device and a compatible smartphone (currently iPhone or iPad iOS devices). LRTK Phone is provided as a dedicated smartphone cover or attachment and is easy to install. Install the dedicated app and you can start positioning immediately. If you use network-based RTK, a communications environment is required, but using Michibiki CLAS allows positioning even outside network coverage.

Q: Is positioning accuracy really centimeter-level? A: Yes, under appropriate conditions centimeter-level accuracy can be obtained. In open outdoor environments with good satellite visibility, horizontal positions are within about 1–2 cm (0.4–0.8 in) and vertical errors are on the order of a few centimeters. However, achieving high accuracy requires good satellite reception and radio conditions. Errors can increase in areas with building shadows or dense trees, but even in such cases positioning is significantly more accurate than conventional smartphone GPS.

Q: Can it be used indoors or inside tunnels? A: Since it is satellite-based positioning, direct positioning is generally not possible indoors, underground, or inside tunnels where satellite signals do not reach. However, by using reference points obtained near entrances for relative positioning, or by combining AR technology to estimate indoor locations, the range of applications can be expanded with creative approaches. Currently it is primarily intended for outdoor use, but future technological developments may enable simple indoor positioning as well.

Q: How are data saved and shared? A: Acquired positioning data and point clouds can be saved on the smartphone and uploaded to the LRTK cloud as needed for storage and sharing. Data uploaded to the cloud can be viewed from a PC web browser and shared with stakeholders. Coordinate data can be exported in CSV or DXF formats for use in your CAD software or GIS systems. Local data management without using the cloud is also possible, allowing operation according to internal rules.

Q: Is LRTK Phone expensive? A: LRTK Phone is offered at a price point that is easier to adopt compared to traditional surveying instruments. Exact pricing requires inquiry, but it offers cost performance superior to assembling separate instruments for each surveying function, providing an all-in-one solution. Considering reduced outsourcing for surveying and productivity improvements, it is a product with clear investment benefits.

Q: What durability and battery life can be expected? A: LRTK Phone is designed ruggedly for on-site use. It operates reliably against light rain, wind, and dust common on construction sites. The battery is built-in and allows continuous use for several hours on a full charge (depending on usage). For long workdays you can operate while charging with a mobile battery, so it supports surveying throughout the day.

Q: Will it be available for Android devices in the future? A: The currently provided LRTK Phone targets iOS devices, but future Android support may be considered depending on user demand. High-precision positioning is technically possible on Android smartphones, so development to expand supported devices could be pursued. Please check official information for the latest support status.