What is RTK AR? Thorough Explanation of Introduction Benefits and On‑Site Use Cases

Surveying technology in the construction industry has advanced rapidly in recent years. Traditionally, surveying using total stations and GPS was mainstream, but with the promotion of ICT and construction DX, high‑precision positioning using RTK‑GNSS and drone surveying are becoming widespread on sites. Among these, RTK (Real Time Kinematic) centimeter‑level positioning is becoming an indispensable technology for earthworks construction management and as‑built measurement. Recently, a new method combining RTK and AR (Augmented Reality) called RTK AR has emerged, bringing an era in which high‑precision on‑site surveying and intuitive AR visualization are possible with just a smartphone or tablet. By combining a high‑precision GNSS receiver with devices in the hands of field staff, the device can serve as an all‑purpose surveying tool capable of everything from point cloud measurement to displaying design data.

This article comprehensively explains the mechanism and technical background of RTK AR, the benefits of adoption, differences from conventional technologies, and concrete on‑site use cases such as surveying operations, as‑built control, design comparison, pile driving guidance, boundary verification, and 3D point cloud integration. Finally, we introduce the simplified surveying and AR display functionality of LRTK, a cutting‑edge construction DX solution, to provide readers with hints for on‑site adoption.

Mechanism and Technical Background of RTK AR

To understand RTK AR, first organize the constituent technical elements: “RTK positioning” and “AR visualization.” We will look at the basic principles of both and the new possibilities created by their fusion.

Basics of GNSS and RTK Positioning

GNSS (Global Navigation Satellite System) is a general term for satellite positioning systems including GPS and is widely used in construction surveying. However, standalone GNSS positioning can have errors on the order of several meters, which is insufficient for precision civil engineering surveys. RTK positioning is a method that dramatically reduces this error: a base station (a receiver installed at a known point) and a rover (the on‑site receiver) simultaneously observe satellite signals, and the base station sends its positioning error corrections to the rover in real time, boosting position accuracy to the centimeter level. According to materials from the Geospatial Information Authority of Japan, standalone positioning can have offsets of several meters, while RTK‑GNSS methods report errors reduced to several centimeters. In recent years, environments enabling easier high‑precision positioning have also been established, such as network RTK over the internet (e.g., VRS) that provides correction information without installing a base station, and Japan’s quasi‑zenith satellite Michibiki offering the CLAS (centimeter‑class positioning augmentation service). Instant RTK positioning is also being used for infrastructure measurement and machine control accuracy management, making it a foundational technology now indispensable at civil engineering and surveying sites.

Overview of AR (Augmented Reality) Technology

AR (Augmented Reality) overlays CG models, text, and other information on live video of the real world through smartphones, tablets, or smart glasses. By compositing three‑dimensional design models and instruction information onto the scene, AR virtually extends the real space. AR use has begun in construction—for example, overlaying a completed building model onto a site video for stakeholders to share, or projecting piping routes from drawings onto actual structures during installation for confirmation. Traditionally, construction personnel had to imagine the completed form from two‑dimensional drawings, which sometimes led to rework due to misunderstandings; AR enables intuitive sharing of the finished image, greatly preventing mistakes and improving communication efficiency. Recently, cases combining BIM/CIM models with AR have appeared, enabling translucent display of equipment and piping hidden before finishing to aid inspection and planning for subsequent processes; AR is thereby gaining prominence as a field information‑sharing tool.

Benefits of Combining RTK and AR

So, what becomes possible by combining RTK’s high‑precision positioning with AR visualization? The key point is that it enables stable AR display tied to absolute coordinates. Conventional smartphone AR required marker placement or plane recognition for initial calibration to correctly overlay the scene and the CG model. But as users moved, the camera tracking error caused the model’s position to gradually drift, making precise alignment difficult.

If AR visualization is combined with RTK‑GNSS that always provides centimeter‑level self‑position coordinates, virtual models can be placed directly in earth coordinates (survey coordinate systems), so the model will not shift relative to reality even when the user moves. In other words, it makes “no‑calibration AR” linked to survey coordinates possible. Time‑consuming alignment steps can be omitted; users simply select the design data in the app and the model is immediately displayed at the correct on‑site location. For example, even a structure to be installed in dense undergrowth can be pinpointed and visualized with RTK AR. Since markers appear on the AR screen, it becomes immediately clear where to install it. RTK also allows precise determination of the device’s orientation, so the virtual model’s position and direction remain stable and accurate even when the user walks around and views it from various angles.

Furthermore, introducing absolute coordinates into AR enables seamless linkage between design data and on‑site positioning information. Because coordinates on design drawings or CAD data (for example, public coordinate system XYH values) match the survey points or model coordinates obtained by RTK AR, design models can be overlaid on reality without cumbersome coordinate transformations or field calibration. This feature realizes consistent digital data linkage from surveying to design and construction, dramatically improving the efficiency of on‑site verification and instructions.

Differences from Conventional Technologies

To understand the changes RTK AR brings to the site, let’s compare it with conventional surveying and construction management methods. Traditionally, skilled surveyors operated optical instruments and teams installed reference stakes (tomobari) for layout or observed latitude/longitude and elevation point by point. Such work required manpower and time and was often affected by weather and terrain, causing construction delays while waiting for surveying. Also, converting measurement results into drawings or compiling reports was analog and time consuming. Gaps between 2D drawings and the field sometimes led to施工 personnel misinterpreting the design and later corrective work.

In contrast, introducing RTK AR increases cases where one person can efficiently carry out surveying and layout tasks. With simple equipment—smartphone plus GNSS receiver—positioning tasks that used to rely on a veteran’s intuition can be performed intuitively. For example, where workers previously had to set tomobari on site while referencing drawings, RTK AR displays the design positions on the device screen and guides the user, allowing accurate positioning even if tomobari are omitted. Likewise, as‑built verification that used to be performed after completion by surveying and comparing with plans can now be done on the spot by overlaying the design model in AR to immediately detect deviations. Processes that were split into multiple steps—measurement, recording, and verification—can proceed concurrently on site with RTK AR, greatly shortening time and reducing rework.

Another major difference is that expensive specialized equipment is no longer necessary in multiple units. Total stations and 3D laser scanners can cost several million yen each, but an RTK‑capable small receiver combined with a commercial smartphone can be introduced at relatively low cost. If all field staff carry a device and can use high‑precision positioning and AR features individually, inefficiencies caused by waiting for surveying are eliminated. In this way, RTK AR can be seen as the next‑generation field tool that overcomes conventional challenges while balancing accuracy and efficiency.

Benefits of Introducing RTK AR

Here are the main benefits of introducing RTK AR:

• Labor reduction and improved work efficiency: High‑precision positioning and AR allow surveying and layout work that previously required multiple people to be done by a single person. Reducing rework and simplifying preparations can greatly cut labor for surveying and construction management. This helps maintain productivity even on sites with labor shortages and contributes to work style reform.

• Intuitive and easy surveying operations: Operations that required specialized knowledge are now accessible through user‑friendly smartphone app UIs. Visual guidance via AR enables accurate position checks and measurements even by non‑experts, reducing the burden on veteran technicians and aiding skill transfer to younger staff.

• Real‑time on‑site verification: With design models and measurement data displayable in AR on the spot, immediate verification and decision‑making are possible. Deviations in as‑built conditions can be detected and corrected immediately, and progress can be shared instantly, leading to early error detection and fewer reworks. Data can be synced to the office via the cloud, facilitating smooth collaboration between field and office.

• Cost reduction: Because only a smartphone and a small GNSS receiver are needed, the high cost of traditional surveying equipment and large volumes of paper drawings can be reduced, lowering equipment and material costs. Operationally, a single device can serve many purposes as an “all‑purpose surveying instrument,” reducing equipment rentals and outsourced surveying frequency.

• Improved safety: Non‑contact surveying and instruction via AR minimizes entry into hazardous areas. For example, high or slope measurements can be made by pointing a camera from a distance to obtain coordinates, contributing to worker safety. Fewer workers on site also reduce the risk of interference with nearby heavy equipment.

• Data linkage and DX promotion: Positioning data and captured images acquired by RTK AR can be stored and shared digitally and used directly for 3D design comparisons and as‑built documentation. Reducing paper‑based exchanges and centralizing information management enables concrete progress in construction DX. This aligns with initiatives promoted by the Ministry of Land, Infrastructure, Transport and Tourism such as *i-Construction*, and may qualify for subsidy programs in some cases.

Use in Surveying Operations

First, ways to use RTK AR in daily surveying tasks. Surveying work that once relied on experienced surveyors using total stations and rods with assistants for observation and recording is greatly transformed by RTK AR.

For example, in topographic surveying, simply walking around with an RTK‑capable smartphone can sequentially acquire 3D survey points aligned to the reference coordinate. Even on uneven sites, using a smartphone’s built‑in LiDAR scanner or camera enables rapid point‑cloud acquisition and yields a terrain model with absolute coordinates without post‑processing. Survey calculations and drawing work are semi‑automated in the cloud, making the process far more efficient than before.

Establishing control points and surveying known points also becomes easier. If coordinates of onsite known points are registered in the app, bringing the smartphone to a position will confirm it, and you can record coordinate‑tagged photos as a kind of marking board. When establishing new control points, displaying the prescribed coordinates in AR during stake driving speeds up and improves the accuracy of surveying and setting out.

Moreover, the survey data can be shared to the cloud in real time, allowing coordinates measured on site to be plotted immediately on office CAD drawings. In this way, RTK AR seamlessly connects the workflow from feature observation to drawing, becoming a powerful tool for enabling simplified surveying.

Use in As‑Built Management

“As‑built management” is the quality control task of measuring and recording whether completed structures and ground conform to design shapes and dimensions. RTK AR greatly streamlines as‑built management.

Traditionally, as‑built checks were done after completion by a surveying crew measuring the site and comparing point elevations and cross‑section shapes with design drawings. Photos for reports required people to stand at positions indicated on drawings and be photographed. These tasks tended to be retrospective; if defects were found, rework on site was needed.

With RTK AR, as‑built checks can be made immediately after construction. For example, after paving or embankment, use the smartphone’s 3D scan function to capture a point cloud of the surface, generate a heat map (a color‑coded map of elevation differences) by comparing with the design model in the cloud, and download the heat map to display it in AR on site. The AR display quickly shows areas that are higher or lower than the design. (The color‑coded AR screen allows intuitive understanding of error distribution.) Tasks that used to search for defective spots by checking numeric survey points or paper drawings can now identify them at a glance by viewing colored areas in AR and immediately proceed to corrective work such as additional cutting or filling.

For structural inspections, displaying virtual objects in AR as design guides allows pass/fail judgments on the spot. For example, in tunnel or bridge inspections, projecting a wireframe model indicating design clearance lets you confirm whether actual dimensions meet standards. Inspection results can be saved as screenshots or measurement data and used directly in reports.

Thus, RTK AR turns as‑built management from a retrospective task into a real‑time process, greatly reducing time and effort for quality confirmation. Visualizing quality on site increases responsiveness and ultimately raises construction quality.

AR Comparison and Visualization of Design Data

One of RTK AR’s most intuitive applications is on‑site visualization of design data. Overlaying design information from drawings or BIM/CIM models onto the actual site delivers significant benefits.

For example, displaying the design finished ground model in AR at an earthworks site makes it immediately clear where and how much excavation or fill is required to reach the design surface. Operators can work visually on the tablet screen, seeing differences between current ground and the final form in color and shape instead of relying on intuition. Similarly, displaying a design longitudinal profile in AR during road construction allows continuous comparison of planned elevations and actual conditions to enable immediate correction of as‑built deviations.

AR is also powerful in construction planning for buildings and structures. Projecting 3D models of columns, beams, and equipment onto the site lets you check temporary enclosures and interfaces with existing structures in advance. During planning of erection sequences, you can check crane swing ranges and interference with material storage areas in AR. When construction personnel and designers view the same AR model on site and hold meetings, design intent that would be hard to convey on drawings alone is easily shared, preventing mistakes and misinterpretations.

AR visualization is also effective for explaining projects to clients and nearby residents. Showing a completed model overlaid on the actual landscape rather than a rendering or perspective makes the image easier to grasp and facilitates consensus building. For example, displaying a bridge design in AR at the site during a public briefing helps residents understand faster than paper drawings. In this way, RTK AR contributes to the digital twin by linking the real world and design information to reduce communication loss.

Use in Pile Driving and Layout Work

RTK AR is highly useful for frequent tasks on civil and building sites such as pile driving and layout (setting out). Pile driving guidance involves accurately placing piles or markers at prescribed coordinate locations. Traditionally, a surveyor would set out positions with a total station and another worker would drive piles at the indicated points.

With RTK AR, this pile driving work can be performed with on‑screen navigation. If you preload a list of pile coordinates into the system, selecting a point on site will display arrows or markers on the smartphone screen and provide real‑time guidance such as “Target is NE 0.12 m.” The worker follows the on‑screen directions to fine‑adjust the position and drive the pile at the prescribed location. Compared with earlier methods using laser markers or tape measures, pile driving becomes much faster and more accurate.

Similarly, for marking lines on concrete slabs, AR can project guideline lines to assist layout. For example, displaying wall locations or piping routes on the floor in AR and marking along those lines allows complex dimensioning to be completed by a single person. The need to repeatedly consult drawings or set up tripod‑mounted laser tools is eliminated, saving time and labor.

Moreover, virtual tomobari and stretched‑line displays in AR let everyone on site share “invisible references.” For instance, before excavation, displaying the design excavation bottom as a virtual plane in AR lets the machine operator intuitively understand how deep to dig. Previously, operators read numbers on tomobari, but AR visual cues reduce mistakes. This use of virtual tomobari enables labor‑saving construction where physical stakes or lines are no longer required in some cases.

Use in Boundary Verification

RTK AR is also powerful in land surveying and boundary stake‑out meetings. When indicating parcel boundaries or construction site limits, traditional methods used wooden stakes, plastic tape, or transit lines—methods that can be hard for stakeholders to visualize and may not communicate exactly.

With RTK AR, precomputed boundary point coordinates can be visualized on site as line segments. For example, if you register the coordinate set of an adjacent boundary from cadastral survey maps in the system, AR display on site can draw the boundary line on the ground as a virtual line or fence. All participants can view the same boundary line through their smartphones or tablets, immediately sharing “where the property begins and ends.”

This is highly effective for land negotiations and boundary disputes. Because it appeals visually to third parties, it helps prevent troubles caused by differing boundary recognition. When surveyors search for boundary markers, AR navigation to preregistered known points prevents missing stones hidden by vegetation.

AR can also be applied to locating underground utilities. If GIS contains polylines of buried water, sewer, or cable routes, displaying those polylines in AR makes invisible piping paths visible from above ground. For road excavation work, previsualizing buried pipes in AR helps machine operators intuitively identify caution zones and supports safety measures. Municipal infrastructure management can also more easily reconcile differences between drawings and actual buried facilities, improving maintenance efficiency.

Integration with 3D Point Cloud Data

RTK AR is a powerful tool for leveraging on‑site 3D data. Recently, 3D point cloud data from terrestrial laser scanners and drone photogrammetry have begun to be used in construction management. RTK AR pairs exceptionally well with processes for acquiring and using such point cloud data.

On the data acquisition side, RTK AR facilitates point cloud capture with absolute coordinates. Point clouds scanned by a smartphone or tablet camera/LiDAR are normally recorded in the device’s local (relative) coordinate system. However, combined with RTK’s high‑precision position information, survey coordinates can be immediately attached to captured points, allowing scan results to be placed directly in public coordinate maps or CAD drawings. For example, when surveying a bridge pier with a terrestrial laser scanner, post‑processing adjustments to align the point cloud to control points were previously necessary; with RTK AR, point clouds are created already aligned to coordinates, substantially reducing post‑processing.

On the data utilization side, overlaying captured point clouds and existing 3D design models in AR enables intuitive comparison and analysis. The heat‑map visualization for as‑built management mentioned earlier is one example. You can also switch between pre‑ and post‑excavation terrain point clouds in AR to confirm on site where and how many meters were excavated. Systems with functions to instantly compute and display volumes from point‑cloud differences exist, making on‑site earthwork quantity management feasible.

Integration of point clouds and AR is also attracting attention in disaster response. For example, overlaying pre‑ and post‑landslide point cloud models on site can quickly estimate collapsed volumes and identify secondary risk areas. Point clouds measured at disaster sites can be shared via the cloud so a remote headquarters can assess the situation via AR. In this way, RTK AR turns point cloud data from mere digital records into a visualization tool for the site, maximizing the data’s value.

Points and Cautions for Introduction

While RTK AR is highly useful, there are several points to be mindful of during introduction and operation. The main ones are below.

• Appropriate accuracy management: RTK AR achieves centimeter‑level accuracy, but millimeter‑level accuracy (for example, in precision equipment installation or displacement monitoring) is still better served by optical instruments like total stations. It is important to use each method appropriately according to required accuracy and combine them as needed.

• Dependence on GNSS reception environment: High‑precision RTK positioning generally requires adequate satellite reception. In urban canyons between tall buildings, in forests, or inside tunnels, satellite signals may be blocked, increasing errors or preventing a Fix (integer solution). In such cases, measures such as using local coordinate offsets from nearby known points or using an indoor mode (relative positioning from a once‑fixed location) while maintaining a Fix in GNSS‑reception areas are recommended. For critical survey and setting out tasks, periodically performing known‑point checks to confirm no significant positioning drift is advisable.

• Device handling and power management: Using smartphones and GNSS receivers on site requires equipment management such as dust/water protection and drop prevention. Commercial smartphones are not as rugged as dedicated devices, so protective cases, straps, and housings for rainy conditions are recommended. Also, operating all day consumes significant battery on both the phone and receiver, so prepare spare batteries or portable chargers and charge as needed.

• Coordinate system consistency: Construction surveying in Japan may use public coordinate systems (Plane Rectangular Coordinate System) or local coordinate systems (site‑specific origins). When introducing an RTK AR system, confirm its compatibility with these coordinate systems. Many systems support the Japanese Geodetic Datum (JGD2011) and geoid heights, and offer functions to set site‑specific coordinate origins and rotations. Configure coordinates according to your company’s practice to ensure design data and positioning data are consistent. Misconfiguration can cause AR displays to be off by several meters, so exercise caution.

• Initial introduction and training: For successful adoption of new technology, provide field staff training and a trial operation period. Start with a simple project to become familiar with operation, and prepare operation manuals and internal rules. Support for staff unfamiliar with digital tools is important. Fortunately, RTK AR centers on intuitive tasks like viewing AR screens, so it tends to be easy to learn, but ensure staff are well informed about basic positioning principles and data‑sharing procedures beforehand.

By attending to these points during operation, you can maximize the benefits of RTK AR. Appropriately leveraging the technology within its limitations can even improve safety and quality management beyond conventional methods.

On‑Site Use Cases

Finally, here are examples of how RTK AR is actually used on site and the outcomes achieved.

• As‑built checks in large‑scale earthworks: At one earthworks site, daily checks of embankment and cut/fill were performed with RTK AR, enabling same‑day correction of as‑built defects. Terrain point clouds from drones and smartphone LiDAR were used to create heat maps, which were displayed in color on a tablet while walking the site, allowing immediate marking and cutting of over‑height areas. As a result, issues that had previously been caught only during pre‑handover inspections were addressed in advance, completing the project with zero rework.

• Labor savings in pile driving and control point setting: On a road improvement site, a surveying team used RTK AR for control point setup and structural position pile driving. Work that previously required three people and half a day was completed by one person in less than an hour using a tablet, achieving substantial labor and time savings. AR guidance kept pile placement errors within a few centimeters, and post‑verification showed good results. The site manager commented that “even non‑experts can drive piles accurately and can be entrusted with the work,” earning praise.

• Municipal boundary meetings: A municipality introduced RTK AR for land acquisition briefings. Officials loaded boundary coordinate data into a tablet and displayed them in AR for landowners on site; participants immediately understood “how far the road will extend,” leading to smooth agreement. Where boundary stakes and drawings had been hard to visualize, AR provided persuasive visual confirmation. The municipality has expanded AR use to other meetings and roadway ledger management.

• Infrastructure inspection and buried asset management: A highway maintenance company displays GIS‑registered repair locations and buried pipe positions in AR during inspections. With systems like LRTK that can receive Michibiki augmentation signals (CLAS), high‑precision positioning is possible even outside cellular coverage. For example, during bolt‑looseness inspections in a tunnel ceiling, workers confirmed premarked inspection points projected in AR and achieved zero missed inspections. AR translucency of buried pipelines reduces the risk of accidentally damaging pipes during excavation. Municipal infrastructure management benefits from easier verification of underground facilities previously plagued by drawing discrepancies, improving maintenance efficiency.

As shown above, RTK AR is being practiced across various sites and demonstrating its effects. From surveying companies to construction firms and municipal infrastructure departments, RTK AR is a widely applicable technology regardless of scale or use case.

Conclusion

By combining GNSS high‑precision positioning and AR visualization, RTK AR is a solution that brings transformative changes to surveying and construction sites. Reports from the field cite numerous benefits: alleviating labor shortages, dramatically improving work efficiency, enabling real‑time quality checks, and promoting smooth information sharing among stakeholders. In today’s construction industry, which demands operational efficiency and digitalization (construction DX), RTK AR is becoming the new standard in surveying and construction management.

One tool that easily provides both simplified surveying and AR display functionality is the smartphone‑compatible high‑precision GNSS solution LRTK. By introducing LRTK, anyone can perform centimeter‑level positioning and intuitive AR visualization with a handheld smartphone, dramatically improving on‑site surveying accuracy and efficiency. If you are interested, please check the details at the [LRTK official site](https://www.lrtk.lefixea.com/). Embrace cutting‑edge RTK AR technology to achieve smart site operations that balance accuracy and efficiency.