What is RTK AR? Basics of High-Precision AR Positioning Technology for Construction and Surveying

Table of Contents

• Introduction

• Basics of RTK Positioning and AR Technology

• Use Cases of RTK AR in Construction and Surveying

• Simple Surveying Achievable with LRTK

• For more details about LRTK, please see the links below.

• FAQ

Introduction

In recent years, the use of digital technologies in the construction and surveying industries has advanced, and on-site ICT and AR (Augmented Reality) technologies have attracted attention. For example, AR technology that superimposes a design model onto real-world views via tablets or smartphones is expected to be useful for sharing the finished image and for construction verification. However, conventional AR often lacks sufficient alignment accuracy, and relying on GPS (GNSS) position information, which can have errors of several meters, makes it difficult to overlay virtual models precisely at the intended locations. This is where the approach called RTK AR comes in. RTK AR is a technique that combines the high-precision positioning method RTK positioning with AR technology to overlay virtual information onto the real world with centimeter-level accuracy (half-inch accuracy). This article explains the mechanism and background of RTK AR from the basics and introduces concrete examples of how it can be used in construction and surveying. At the end of the article, we will also introduce LRTK, a solution that makes RTK AR easy to deploy.

Basics of RTK Positioning and AR Technology

First, to understand RTK AR, let’s cover the two key elements: the basics of RTK positioning and AR technology.

RTK positioning (Real Time Kinematic) is a method that corrects GNSS (Global Navigation Satellite System) positioning errors in real time to achieve high-precision positioning. Standalone positioning (standalone GPS) typically incurs errors of several meters due to satellite signal errors, but RTK cancels out errors through relative positioning with a base station (a reference receiver placed at a known point), improving accuracy to about 1–2 cm (0.4–0.8 in) of error. For this reason, RTK-GNSS has been widely used in sites that require high accuracy, such as earthwork quality control and establishment of survey control points. However, traditional RTK surveying required setting up one’s own base station on site or preparing specialized surveying equipment, and its operation involved advanced knowledge and effort.

On the other hand, AR technology (augmented reality) overlays virtual objects and information onto the real-world view seen through a camera. With the spread of smartphones and tablets, AR is becoming familiar to general users, and the construction industry is exploring applications such as overlaying expected completion visualizations and visualizing work instructions. A key to AR display is correctly knowing the device’s position and orientation; typical mobile devices estimate their pose using built-in GPS, inertial sensors, and camera image analysis (SLAM). Individually, these methods often yield absolute positioning accuracy of only around several meters or may accumulate error over time. For example, with a horizontal error of 3 m (9.8 ft) outdoors, a virtual structure displayed on site would appear significantly displaced from its actual position, making it difficult to use for construction checks or surveying. Thus, standard AR displays currently face challenges in terms of accuracy.

Combining the two to dramatically improve AR display accuracy is the concept behind “RTK AR.” Specifically, an AR-capable device (smartphone, tablet, etc.) is paired with an RTK-capable high-precision GNSS receiver to obtain centimeter-level positioning information in real time while rendering AR content. This allows digital information to be placed accurately based on geographic coordinates, enabling virtual objects to be overlaid at the intended real-world locations. In other words, it becomes possible to place AR virtual models at the exact coordinates measured by GNSS. RTK AR is transforming AR technology—which was previously difficult to use due to large errors—into a practical tool for tasks such as surveying and construction management.

Use Cases of RTK AR in Construction and Surveying

Now let’s look at several concrete use cases enabled by RTK AR. High-precision AR alignment brings new value to workflows in construction sites and surveying.

• Intuitive marking of construction points (AR staking): Stake-out work to locate where structures or control points should be installed has traditionally been done with surveying instruments or layout tools. With RTK AR, a device can display target point positions on screen in real time to guide on-site marking. For example, based on coordinate data from drawings, AR can show where to drive stakes on the ground, enabling even non-experts to intuitively and accurately set out positions. Visual guidance improves work efficiency and reduces human error.

• On-site overlay of design data: RTK AR uniquely allows displaying a model of the planned building on vacant land before construction, enabling clients and stakeholders to share the envisioned result. Unlike plans or CG alone, seeing the life-size model overlaid on the site provides realistic visualization, smoothing explanations to clients and consensus building. Thanks to RTK’s precise alignment, the model and the actual terrain have almost no mismatch, enabling realistic visualization and on-the-spot review or adjustment of design changes while confirming the finished appearance.

• As-built control and quality checks: AR can be applied to verify whether constructed elements are located and dimensioned according to design (as-built control). For example, displaying the design model over the constructed object in AR lets you visually check discrepancies between the design model and the actual object. With RTK AR, the model’s display position is precisely corrected, making any misalignment immediately obvious and allowing intuitive judgment on whether the object is within allowable tolerances. This enables quick self-checks before detailed as-built measurements with surveying instruments, facilitating early detection of rework or defects.

• Visualization and surveying of buried utilities: By pre-acquiring the location information of underground pipes and cables and later displaying that information in AR, buried utilities can be visualized while invisible during excavation, helping to prevent damage accidents and assisting maintenance planning. In addition, one can follow the AR-displayed route of a buried utility on the ground to survey and record new points using just a smartphone. Combining RTK’s accurate coordinates with AR’s intuitive visualization enables an easy fusion of surveying and visualization on site.

• Comparison and analysis with point cloud data: RTK AR is also effective when using point cloud data captured by drones or terrestrial laser scanners on site. For example, by overlaying pre-construction terrain point clouds and post-construction as-built point clouds in AR and visually inspecting differences on site, you can immediately grasp fill/cut volumes and the quality of leveling work. Processes that used to require returning to the office for analysis with specialized software can be intuitively checked and decided on site with AR, contributing to faster decision-making and improved work efficiency.

As shown above, RTK AR is revolutionizing various on-site processes—measuring, displaying, and verifying. By combining high-precision position information with visual AR representation, the traditional separation between surveying tasks and construction management/inspection work is narrowing, allowing on-site staff to grasp and decide on situations immediately. Because the operations are intuitive and easy to understand, non-specialists can also handle them, supporting labor-saving and skill transfer. Overseas surveying equipment manufacturers are also releasing products that integrate cameras and IMUs into GNSS receivers to guide and measure via AR, and RTK AR is drawing attention as the next-generation technology for surveying and construction.

Simple Surveying Achievable with LRTK

While RTK AR holds great promise, there are hurdles to on-site use, such as preparing high-precision GNSS equipment and dedicated software. To make high-precision positioning more accessible and usable by anyone on site, the solution LRTK has been developed. LRTK is an all-in-one surveying system that attaches a dedicated ultra-compact RTK-GNSS receiver to a smartphone and enables one-touch high-precision positioning from a mobile app. A major feature is that accurate global positioning coordinates (WGS84) can be obtained on site without complicated base station setup or specialized configuration.

For example, by attaching an LRTK device to an iPhone and launching the dedicated app, you can obtain real-time centimeter-level positioning (half-inch accuracy). Using those high-precision positions, you can complete point surveying on a map, record coordinates on photos, acquire 3D scan data, and display or guide to target points in AR—all with just a smartphone. Tasks that previously required specialized surveying equipment and multiple personnel can be accomplished easily by a single person using LRTK, potentially transforming on-site workflows. With a high-performance receiver that supports multi-GNSS and multi-band, LRTK is robust to satellite environments and supports Japan’s quasi-zenith satellite Michibiki’s centimeter-level augmentation service (CLAS) as well as existing network RTK services. This enables flexible high-precision positioning depending on the situation, such as receiving corrections via CLAS in mountainous areas without communication coverage or using nationwide electronic reference station networks via the Internet. In short, LRTK is a groundbreaking tool that turns a smartphone into a high-precision surveying instrument, and combined with an intuitive UI designed for non-experts, it greatly contributes to improving the efficiency of on-site surveying and positioning tasks.

Dramatically Improve On-Site Surveying Accuracy and Work Efficiency with LRTK

The LRTK series achieves centimeter-level GNSS positioning (half-inch accuracy) in construction, civil engineering, and surveying, enabling time savings and significant productivity gains on site. It is a next-generation solution that supports the Ministry of Land, Infrastructure, Transport and Tourism’s *i-Construction*, and strongly promotes digital transformation (DX) in the construction industry.

For more details about LRTK, please see the links below.

• [What is LRTK?｜LRTK Official Site](https://www.lrtk.lefixea.com/)

• [LRTK Series｜Device List Page](https://www.lrtk.lefixea.com/lrtk-series)

For product inquiries, quotes, or consultations on implementation, please feel free to contact us via the [inquiry form](https://www.lrtk.lefixea.com/contactlrtk). Let LRTK evolve your site to the next stage.

FAQ

Q1. What is RTK AR? A. RTK AR is a technology that combines high-precision positioning called Real Time Kinematic (RTK) with augmented reality (AR). By leveraging RTK’s centimeter-level positioning (half-inch accuracy), virtual objects displayed on smartphones or tablets can be aligned with the real world without displacement. RTK AR enables accurate positioning alignment that was difficult with conventional GPS accuracy, making AR a practical tool for construction sites and surveying.

Q2. What do I need to use RTK AR? A. Basically, you need the following: ① an RTK-capable GNSS receiver (a device capable of centimeter-level positioning), ② positioning correction information (corrections from a base station radio signal, a network correction service, or, in Japan, CLAS signals from the Michibiki quasi-zenith satellite), ③ an AR-capable device (a smartphone or tablet with camera and sensors), and ④ a dedicated application (software that can acquire GNSS positioning information and reflect it in AR content). If you can receive GNSS signals outdoors, combining these elements enables RTK AR. For example, connect a small RTK GNSS receiver to a smartphone, receive correction data, and display the design model with a compatible app to experience high-precision AR on site.

Q3. In what situations is RTK AR useful? A. RTK AR is expected to be useful in many construction and surveying scenarios. For example, for positioning and staking, AR can visualize coordinate points from drawings so stakes can be placed intuitively and accurately. By overlaying design models on site you can share the expected finished look in the real scene, and with as-built control you can check discrepancies between constructed objects and design data on site. You can also display buried pipes and cables in AR to reduce excavation risks, or overlay point cloud data on site to instantly grasp fill/excavation volumes. In short, RTK AR enables intuitive on-the-spot measuring, visualization, and verification, contributing significantly to workflow efficiency and accuracy improvement.

Q4. What kind of product is LRTK? A. LRTK is a product consisting of an ultra-compact RTK positioning device that works with a smartphone and cloud services. It comprises a small GNSS receiver (LRTK device) that can be attached to a smartphone, a dedicated app, and a cloud system, enabling easy real-time centimeter-level positioning (half-inch accuracy) on site. Its major feature is that RTK surveying, which previously required specialized instruments, can be realized with just a smartphone, covering high-precision GNSS positioning, 3D scanning, and AR positioning display all in one. It is designed to be usable without expert knowledge and truly functions as a “high-precision positioning tool anyone can use,” revolutionizing on-site work.

Q5. Can LRTK make it easy to introduce RTK AR? A. Yes. LRTK significantly lowers the barrier to RTK AR. With just an LRTK device and a smartphone, you can achieve centimeter-level positioning (half-inch accuracy) immediately without complex base station setup or advanced surveying skills. Therefore, tasks that used to be performed by veteran surveyors can be carried out accurately by field personnel who view AR displays on site. The dedicated app reflects positioning data into AR through an intuitive interface, so you can start using high-precision AR features with simple operations. As a result, the cost and technical barriers to adopting RTK AR are reduced, allowing more sites to leverage high-precision AR technology.