Smartphone RTK Surveying with AR: Centimeter-level accuracy (half-inch accuracy) × Cloud sharing for the future of construction management

Table of Contents

• Introduction

• What is RTK surveying?

• RTK surveying possible on smartphones

• On-site use of AR technology

• Efficiency through cloud sharing of data

• The future of construction management enabled by smartphone RTK surveying

• Simple surveying with LRTK

• FAQ

Introduction

In civil surveying and construction management, a new surveying method that leverages smartphones and the latest technologies is attracting attention. An era has arrived in which centimeter-level positioning that used to require specialized surveying equipment and advanced experience can be easily achieved with just a smartphone, and the surveying data can be shared to the cloud in real time. By combining AR (augmented reality) technology, which overlays digital information on the smartphone camera view, on-site surveying work and construction management are becoming more intuitive and efficient. This article explains in detail the benefits of smartphone RTK surveying and AR utilization, the transformation of the field through cloud sharing, and the future outlook for construction management. At the end, we introduce LRTK as a simple surveying solution that makes these capabilities easy to realize.

What is RTK surveying?

First, let’s cover what “RTK surveying” is. RTK stands for Real Time Kinematic, a positioning method in satellite positioning (GNSS). With ordinary standalone GPS positioning, errors in satellite signals result in position accuracies on the order of several meters. In contrast, RTK positioning transmits error information obtained at a base station (reference station) to a rover in real time, correcting the errors and improving positioning to an error range of several centimeters (several in).

Because it can achieve about ±1-2 cm (±0.4-0.8 in) horizontally and also an accuracy of ±a few cm (±a few in) vertically, RTK is widely used in civil and construction surveying tasks that require high precision, such as installing structures and managing elevations. Note that RTK surveying requires GNSS receivers that support high precision, base station equipment, and a communications environment, and traditionally it has demanded expensive equipment and specialized knowledge and setup. However, recently solutions that make RTK technology easier to use have been emerging. A representative example is the spread of RTK surveying using smartphones.

RTK surveying possible on smartphones

So why has high-precision RTK surveying become possible on smartphones? The background is the evolution of GNSS reception technology and mobile devices. Recently, some smartphones have begun to include high-performance GNSS chips that support multiple satellite signal frequencies, and ultra-compact RTK-capable GNSS receivers that can be attached to smartphones have also appeared. For example, by using a small receiver weighing in the 100 g range attached to a smartphone, the smartphone can instantly become a centimeter-level positioning terminal (half-inch accuracy).

Furthermore, in Japan, by using the centimeter-class positioning augmentation service (CLAS) provided by the domestic QZSS “Michibiki” or network-type reference station services over the Internet, high-precision correction information can be obtained without installing your own base station. The combination of smartphones and these correction services has made stable RTK positioning possible even on-site.

The greatest advantages of smartphone RTK surveying are its “ease of use” and “portability.” Because everything can be completed with a smartphone that fits in your pocket and a small receiver, there is no need to carry heavy tripods or large equipment. The convenience of being able to take it out and measure immediately is a major strength that traditional surveying instruments do not have. Also, the significant reduction in introduction cost makes one-device-per-person operation realistic, allowing anyone on-site to perform surveying tasks with their own smartphone.

There are also advantages unique to smartphones. Positioning data is automatically recorded and saved in the app, and coordinate transformation and note entry can be done on the spot. This reduces the need to record on paper field books and prevents human errors in data. The smartphone’s large screen and intuitive touch operation make surveying app UIs easy to understand, lowering the learning curve compared to traditional surveying equipment. In this way, smartphone RTK surveying maintains high precision while dramatically improving mobility and ease of use.

On-site use of AR technology

AR (augmented reality) utilization is a technology that pairs well with high-precision positioning on smartphones. AR overlays digital information such as drawings and guidelines on the camera view of a smartphone or tablet. Information that was difficult to intuitively grasp from paper drawings or numbers can be visually understood together with the actual site when using AR.

Combining high-precision position information with AR is transforming various surveying and construction management tasks. For example, in layout marking work where you mark positions on the ground according to the design drawings, you can display design reference lines and markers directly on the on-site view seen through the smartphone, making it much easier to locate survey points. Visualizing the positions of buried pipes and cables that are normally invisible by overlaying them on the ground with AR helps prevent near-miss incidents during excavation and is useful for pre-checks. It is also possible to overlay a pre-construction 3D design model on the site scenery to confirm the finished shape as designed.

Previously, GNSS errors were large, and even if AR displays were used there would be discrepancies with actual positions. However, with RTK positioning achieving centimeter-level accuracy (half-inch accuracy), virtual objects on AR can be made to align almost exactly with the physical space. Therefore, AR-based surveying guides and design information displays have become practical at a usable level. Seamlessly overlaying on-site conditions and design information with smartphone AR is expected to reduce mistakes and oversights even by less experienced technicians, and help the whole team share the same on-site image more easily.

Efficiency through cloud sharing of data

Another reason smartphone RTK surveying and AR utilization are so powerful is cloud sharing of data. Traditional surveying required taking site-acquired data back on a USB memory stick or hand-written notes to the office PC for drawing and reporting. This caused time lags between the site and the office and made information sharing cumbersome.

However, if you collect surveying data with a smartphone, you can upload it to the cloud on the spot. Coordinates, elevation information, photos, and notes are automatically saved to the cloud and can be accessed by all stakeholders via the Internet. For example, immediately after a measurement on site, an office staff member can view the latest data on the web and issue instructions if necessary. Because daily progress can be shared instantly, communication with construction managers and clients is smoother, and decision-making speeds improve.

Cloud sharing also makes secondary use and analysis of surveying data easy. If uploaded coordinate data can be plotted on a map to calculate distances and areas, or volumes can be computed from point cloud data using cloud tools, you can grasp necessary figures on-site right away. Since cloud data always shares the latest version, the risk of stakeholders referring to outdated information when drawings or models change is reduced. Paper and USB handoffs become unnecessary, promoting digitalization and paperless operations.

Furthermore, cloud data can be used to automatically generate daily reports and forms, and to download point clouds and coordinate data in CSV or CAD formats.

In this way, cloud sharing of surveying data collected by smartphones removes the boundary between site and office, speeds up information sharing and decision-making, and greatly contributes to overall construction efficiency.

The future of construction management enabled by smartphone RTK surveying

The combination of smartphone RTK surveying with AR and cloud has the potential to fundamentally change construction management itself. Equipping each on-site worker with high-precision surveying functionality levels the measurement tasks that previously relied on specialists, enabling anyone to collect data whenever needed. This will be a significant help in the construction industry, where labor shortages are becoming severe. Also, because site conditions are shared as digital data in real time, construction managers can grasp progress and quality immediately and address issues early. In other words, management that tended to rely on “intuition and experience” can shift to objective, data-driven, and rapid decision-making.

Moreover, smartphone RTK surveying and AR utilization align with the Ministry of Land, Infrastructure, Transport and Tourism’s promotion of DX (digital transformation) in construction. When surveying, design, and construction processes are connected and centrally managed as digital data, there is potential for future development into advanced construction management methods such as BIM (Building Information Modeling, integrating 3D models with schedule and cost information) and digital twins. Accurate 3D data collected on-site can be reflected in cloud models, and virtual simulations and progress checks in virtual space are becoming realistic possibilities.

Overall, the spread of smartphone RTK surveying will bring the following benefits to the field:

• Anyone can perform high-precision surveying: Even non-specialists can handle centimeter-level accuracy (half-inch accuracy) with simple training, allowing on-site staff to perform necessary surveys independently.

• Real-time site visualization: Because surveying data is shared instantly, progress and finished shape can be understood in real time. Current conditions can be grasped and appropriate instructions issued even from remote locations.

• Improved construction quality and safety: Accurate position information makes it easier to detect and correct deviations or mistakes against design on the spot, reducing rework and ensuring quality, which in turn contributes to accident prevention and stronger safety management.

• Dramatic productivity improvements: Time spent on surveying and inspections is reduced, decreasing downtime for setup. Faster decision-making through rapid data sharing contributes to shorter schedules and cost savings.

• Promotion of digitalization and paperless processes: Drawings and reports are digitized, and information exchange between site and office is completed digitally. Accumulated data can be used for future design and construction planning, contributing to company-wide DX efforts.

Thus, the technological innovation centered on smartphone RTK surveying has the potential to redraw the future of construction management. An environment where all on-site information is shared in real time and all stakeholders collaborate based on the same latest data will form the foundation for efficient, high-quality manufacturing.

Simple surveying with LRTK

As a solution that lets you easily enjoy the benefits of smartphone RTK surveying, AR, and cloud sharing on actual sites, “LRTK” is noteworthy. LRTK is a positioning system composed of an ultra-compact RTK-GNSS receiver integrated with a smartphone, a dedicated app, and a cloud service. By simply attaching the dedicated device to your smartphone, it becomes a pocket-sized surveying instrument that anyone can use to achieve centimeter-level positioning (half-inch accuracy).

With LRTK you can realize the various functions described in this article with a single device. For example, by pointing the smartphone at the point you want to measure and tapping once, you can obtain a high-precision single-point coordinate and save it to the cloud. Acquired coordinates and elevation information are automatically plotted on a map and recorded with date/time and notes. There is also a function to average measurement values over several seconds to further improve positioning accuracy; by averaging, errors can be reduced to the level of a few millimeters (a few in). That accuracy is said to rival traditional Class 1 GNSS surveying instruments.

LRTK goes beyond simple positioning to meet various measurement needs on site. It can work with the smartphone camera and LiDAR to obtain 3D point cloud data for earthwork volume calculations, automatically record high-precision position coordinates and orientation for captured photos, and provide guidance to registered coordinates on the smartphone screen with arrows or radar displays. It also supports AR display of design data for on-site verification. It is truly a tool that turns a smartphone into an all-purpose surveying instrument.

Data acquired with LRTK can be uploaded to the cloud service (LRTK Cloud) with one touch. Uploaded coordinate points are instantly visualized on a web map, and distance/area measurements and point cloud checks can be done in the browser. When sharing with stakeholders, simply sending a URL issued in the cloud lets them view the latest data, smoothing information sharing between site and office.

In practice, LRTK has already begun to be introduced at many sites, and the new work style of “a smartphone becoming a surveying instrument” is quietly spreading.

Thus, LRTK is a next-generation simple surveying tool designed to be easy for beginners while maximizing the benefits of smartphone RTK surveying. It will be a powerful helper for incorporating high-precision surveying into daily work and promoting on-site DX. Experience the centimeter-level world achievable with just a smartphone through LRTK.

FAQ

Q. What is RTK surveying? A. RTK surveying is a method that uses correction information from a base station to correct GNSS positioning errors in real time and determine positions with centimeter-level accuracy (half-inch accuracy). While ordinary GPS positioning has errors on the order of meters, RTK achieves dramatically higher accuracy by using special receivers and systems.

Q. Can a smartphone really achieve centimeter-level accuracy? A. Yes, it is possible. By combining recent smartphones (especially high-end models) with dedicated small GNSS receivers, and using multi-frequency GNSS and high-precision correction information (for example, Michibiki’s CLAS or network-type reference station services), centimeter-level positioning can be achieved. In practice, RTK positioning with a smartphone and external device has been confirmed to reach accuracies comparable to dedicated surveying instruments. For example, with LRTK, standalone positioning can achieve horizontal and vertical errors in the 1 cm range (about 0.4 in), and by averaging measurement values the error can be reduced to a few millimeters (a few in), as demonstrated.

Q. What can be done on site using AR technology? A. AR (augmented reality) allows you to overlay drawings and position information on the site view through a smartphone screen. For example, it can assist layout marking by projecting reference lines from drawings onto the actual ground, or visualize the routes of underground pipes from above ground. Because it enables intuitive understanding of spatial relationships, it helps prevent work errors and facilitates communication.

Q. What are the benefits of sharing surveying data in the cloud? A. Sharing surveying data in the cloud allows on-site collected information to be shared immediately with other team members. There is no need to bring data back to the office physically; progress and results can be reported and checked in real time, improving communication. Also, because data is centrally managed in the cloud, construction can proceed based on the latest information, reducing mistakes and rework.

Q. Can it be used at sites outside mobile coverage? A. There are ways to perform high-precision positioning even where mobile communications are unavailable. For example, devices that can receive CLAS signals provided by Japan’s Michibiki can obtain correction information from satellites without an Internet connection and enable RTK positioning. LRTK devices include CLAS-compatible models, allowing centimeter-level positioning in mountain or other out-of-coverage areas. Alternatively, installing reference points in advance and using that data can maintain positioning accuracy offline.

Q. Can people with little surveying experience use it? A. Yes. Smartphone RTK surveying systems are designed for intuitive operation. Following the app screen and pressing buttons completes surveying, and complex settings and calculations are automated. Visual AR guidance also enables accurate positioning and verification even by non-experts. With a short training session to learn the basics, beginners can use it effectively.