Table of Contents

• The significance and benefits of visualizing drawings, boundaries, and buried utilities with AR

• Advantages of displaying design drawings on site with AR

• Accurate position verification by AR display of site boundaries

• Improved safety by AR display of underground buried utilities

• Keys to successful AR display (data preparation and alignment)

• Reliability of AR display enabled by high-accuracy positioning

• Making high-precision AR accessible to anyone with LRTK's simple surveying

• FAQ

The significance and benefits of visualizing drawings, boundaries, and buried utilities with AR

When working on construction sites based on drawings, misinterpretation of the design or insufficient shared understanding often leads to construction errors and rework. For example, a structure might end up slightly outside the neighboring property because a small positional offset on the plan was overlooked, or a cable might be damaged during excavation due to misunderstanding the location of a buried pipe shown in the design. Behind these problems lies the difficulty of grasping the completed image from two-dimensional drawings alone and a gap in communicating the designer’s intent to everyone on site.

AR (augmented reality) is gaining attention as a powerful means to bridge these gaps and improve construction accuracy and safety. By overlaying design drawings or 3D models onto the real-world view through a smartphone or tablet camera, you can intuitively confirm the finished form while on site. AR can also display normally invisible elements such as site boundary lines or underground buried utilities, allowing the necessary information to be grasped at a glance. Everyone from site supervisors to tradespeople and owners can view the same AR imagery and share an understanding of “what will be where and how,” preventing troubles caused by mismatched recognition. Below are the main benefits of consolidating drawings, boundaries, and buried utilities into AR visualizations on site.

• Completion image visualization: You can realistically experience the post-construction appearance, which is difficult to grasp from plan or section drawings alone, in the context of the actual site. Arrangements and heights of structures that are hard to imagine from drawings can be checked at a glance, helping to accurately share the designer’s intent.

• Prevention of construction errors: By overlaying design data and current conditions in AR for inspection, you can immediately notice misalignments or interferences during construction. For example, if you confirm the formwork position with AR before pouring concrete, you can correct any misalignment before construction. Early detection and correction of errors greatly reduce the risk of rework.

• Safety through visualization of buried utilities: By confirming the positions of underground gas pipes, communication cables, and the like with AR before excavation, you can greatly reduce the risk of accidentally damaging them during digging. Being able to identify unseen danger points in advance strengthens safety measures.

• Improved consensus building and customer satisfaction: Using AR to explain plans to owners and nearby residents lets you share completion images that are hard to convey on paper. This prevents misunderstandings like “it’s different from what I expected,” and makes it easier to elicit concrete feedback during the planning stage. Gaining agreement while previewing the finished form contributes to higher satisfaction after handover.

• Efficiency in surveying and staking out: AR overlay simplifies on-site positioning work. If design reference lines and points are visualized in AR and marked on the ground, tasks such as driving stakes or stretching reference lines—which once required experienced surveyors—can be carried out accurately by anyone. This can shorten work time and reduce manpower burden.

Advantages of displaying design drawings on site with AR

To display design drawings in AR, you first need digital design data. These can take various forms: three-dimensional models such as BIM/CIM or 3D CAD data, or two-dimensional plan data like CAD drawings or images. If a 3D model is available, you can reproduce the shapes of columns, walls, and other three-dimensional structures in the real space for the most intuitive confirmation. Even if only 2D data such as plans are available, you can display the drawing on the ground in AR or render the design lines as virtual illuminated lines on the ground to understand the necessary positional relationships. The key is to project the points, lines, and shapes contained in the design at the correct scale onto the site.

If you display the prepared design data in AR on site, you can immediately verify whether the planned positions match the actual site. For example, overlaying the building layout on the ground allows you to intuitively check whether it fits within the site and whether it interferes with adjacent structures. If a discrepancy between the drawing and the site is found, the design can be revised or the site adjusted before construction begins, preventing rework. Thus, AR display of design drawings is useful not only for sharing the completed image but also for design verification and pre-checking construction plans.

Accurate position verification by AR display of site boundaries

Accurately identifying site boundary lines is important in building and civil engineering works. Traditionally, you had to rely on boundary markers (stakes or plates) and use tape measures or transits to lay out boundaries on site, but it is not easy to imagine invisible lines connecting points. If boundary markers are buried or lost, or if there is a slight discrepancy between the survey map and actual conditions, confirming the exact boundary becomes more troublesome. As a result, structures can end up slightly outside the site, potentially leading to disputes and forced corrections later.

Visualizing site boundary lines with AR greatly reduces these concerns. If you prepare boundary line data from known point coordinates in advance, AR can clearly display virtual lines or walls indicating the site boundary. Lines that do not exist on the ground become visible through the device, allowing anyone to intuitively grasp boundary relationships. For example, checking the boundary line in AR before excavating with heavy machinery prevents over-excavation beyond the site. When placing a building, AR instantly shows the required setback from the boundary, preventing errors from mistaken measurements. AR boundary display reduces the number of times you need to call a surveyor to re-lay out the boundary, improving construction management efficiency.

Improved safety by AR display of underground buried utilities

In excavation work such as road or land development, it is extremely important to grasp the locations of underground water/sewer pipes, gas pipes, and communication cables. Traditionally, people referenced buried utility drawings on paper or marked the ground with markers to raise awareness, but accurately visualizing real positions on site was difficult and left room for human error. If, for example, a gas pipe is accidentally damaged by an excavator, it can cause not only construction delays but also serious disasters.

By visualizing the positions of underground utilities with AR, you can perceive buried, “invisible” targets as if through a see-through view. For example, checking underground piping routes on a tablet AR screen before excavation clarifies where workers should be careful. Information such as “a gas pipe runs under here” or “the conduit runs in that direction” is visualized, making it easier to excavate cautiously or switch to hand-digging as needed. As a result, a significant reduction in buried utility damage incidents and a dramatic improvement in safety can be expected. Also, when planning routes for new installations that take existing buried utilities into account, AR helps you visualize the positional relationships, making it easier to plan routes without clashes or interference. In fact, domestic construction companies have developed systems that combine GNSS positioning and AR to overlay buried utility drawings onto real scenery, and their effectiveness on site has been reported.

Keys to successful AR display (data preparation and alignment)

To accurately display drawings, boundary lines, and buried utilities in AR, careful preparation and alignment are essential. Below are the main points and procedures for successful AR display.

• Data digitization and preparation: Prepare in advance the digital data for the information you want to display on site, such as drawing data, boundary coordinates, and buried utility locations. If you only have paper drawings, scan or convert them to CAD; digitize buried utility route diagrams as much as possible. It is desirable to format these data so they can be imported into smartphone/tablet AR apps (e.g., DXF, LandXML, OBJ, IFC).

• Unifying coordinate systems: Unifying the coordinate systems of the prepared data is the key to accurate alignment. If the design drawings or survey data include absolute coordinates such as latitude/longitude or a plane rectangular coordinate system, the device’s GPS position can generally be used to automatically place the model in the correct location. If the drawings are created in a site-specific local coordinate system, you will need to measure multiple known points on site and align the virtual model by translating and rotating it to match (for example, by specifying two or more corresponding points). Confirming reference point coordinates on site in advance and using the same references in the design data will make the day’s work smoother.

• Methods for on-AR alignment: AR apps offer several ways to align virtual models. One method is to place printed markers or QR codes at known positions on site and fix the model by scanning them with the camera. Another is to manually move and rotate the virtual model in the app to match local landmarks (such as a corner of a wall or the edge of a road). However, for large sites, these manual methods have limitations for achieving high accuracy. Coordinate-based alignment using GPS is effective here. If the design data include absolute coordinates, models can be automatically positioned based on the current location obtained from GNSS (Global Navigation Satellite System). The larger the site, the more powerful this coordinate-based alignment becomes.

• Use of high-precision equipment: Standard smartphone GPS accuracy can introduce errors in AR display, so when handling critical positional information such as boundaries or buried utilities, it is important to use high-precision GNSS receivers. For example, by using an integrated smartphone high-precision GNSS receiver like the LRTK Phone, RTK-based centimeter-level positioning (cm level accuracy (half-inch accuracy)) becomes possible, enabling accurate model placement without the hassle of marker installation. Using high-precision positioning equipment makes initial AR alignment much easier and more reliable, improving the efficiency and accuracy of the entire operation.

By carrying out the above preparations, AR display on site will be much smoother, and you will be able to accurately overlay drawings, boundaries, and buried utilities in the intended locations.

Reliability of AR display enabled by high-accuracy positioning

To fully utilize AR visualization in business, ensuring alignment accuracy is indispensable. Relying only on smartphone GPS and standard AR functions can result in position errors ranging from several tens of cm (several tens of in) to, in some cases, over 1 m (3.3 ft). Such errors may be acceptable for rough image checks but are unsuitable for tasks that require precise positioning like stake driving or pipe laying. For example, if an AR-displayed boundary line is 50 cm (19.7 in) off from the actual position, it is dangerous to rely on that information for construction.

This is where introducing high-accuracy positioning technology becomes important. Using satellite positioning correction techniques called RTK (Real Time Kinematic) can track device positions with errors on the order of a few centimeters. Connecting a high-precision GNSS receiver to a smartphone or tablet for positioning allows AR models to be matched almost exactly with real positions. Because vertical accuracy can also be kept within a few cm (a few in), you can reproduce reliable “life-size virtual models” that include ground boundary lines and the depths of buried pipes. Improving positioning accuracy in this way turns AR display into a tool that can reliably support on-site decision-making.

Making high-precision AR accessible to anyone with LRTK's simple surveying

The LRTK series is a solution that achieves centimeter-level GNSS positioning (cm level accuracy (half-inch accuracy)) on construction, civil engineering, and surveying sites, enabling reduced work time and significant productivity improvements. Devices such as the smartphone-integrated “LRTK Phone” allow operators to easily perform precise positioning that previously required specialized surveying equipment. LRTK supports initiatives such as the Ministry of Land, Infrastructure, Transport and Tourism’s i-Construction and strongly promotes on-site digitalization and DX.

LRTK systems are particularly designed to be easy for non-surveying specialists to use. By following the screens of a dedicated app, anyone can perform high-precision positioning and confirm locations via AR. Complex equipment setup and difficult calculations are processed in the background, so users only need to follow intuitive UI prompts. With a short training session, even those without extensive surveying experience can immediately apply the system to daily construction management. The LRTK terminal equipped with a GNSS antenna itself becomes a site reference point, enabling accurate model placement without special marker installation—an operational advantage on site.

Combining simple surveying with LRTK and AR technology makes visualization of drawings, boundaries, and buried utilities even easier and more reliable. If you are considering AR adoption on your sites, LRTK can strongly support that realization. For details, please visit the official LRTK website and feel free to contact us. LRTK will evolve your sites to the next stage.

FAQ

Q: What equipment and preparations are needed to display AR on site? A: You need a smartphone or tablet and a compatible AR app. Recent iPhones and iPads have AR functionality (ARKit) built in, so simple AR displays are possible without additional equipment. However, to accurately overlay drawings and boundaries, it is recommended to use a high-precision GNSS receiver such as the LRTK Phone in combination. Also, prepare the design drawings and boundary/buried utility data in the device or on the cloud in advance, and adjust coordinate systems as needed for a smooth start.

Q: Can I perform AR display with only 2D drawing data? Do I need 3D models? A: AR display is possible with only 2D data such as plans. Even without 3D models, you can project drawing lines or shapes onto the ground or display markers and symbols at important points. For example, you can overlay a CAD drawing (DXF) or an image file as a background in AR and check discrepancies with the site. However, if you can prepare 3D data that represents column and wall heights, you can perform three-dimensional interference checks, so providing 3D data is desirable if possible.

Q: What is the positional accuracy of AR display? A: Standard smartphone built-in GPS and standalone AR functions can yield errors on the order of several tens of cm (several tens of in) to several meters. This is acceptable for basic checks but may be insufficient for precise staking out or boundary verification. On the other hand, positioning with high-precision GNSS can reduce errors to a few cm (a few in) horizontally and vertically, enabling AR overlays that almost match the design drawings and providing the centimeter-level accuracy necessary for actual construction.

Q: Is specialized knowledge or training required? Can site staff use it? A: Advanced skills like operating specialized CG software are not required; generally, anyone can use the system by following the instructions of a compatible app. LRTK’s UI is designed for users with limited surveying experience, allowing positioning and AR display via button operations. With a short training course, site staff can quickly apply it to daily construction management.

Q: Do I need to install markers or reference points in advance? A: When using LRTK, special marker installation is generally unnecessary. GNSS allows the device itself to constantly know its reference position and display models at the designated coordinates. However, in GPS-denied places such as building interiors, you will need to use ARKit’s plane detection or printed markers to align models. In such cases, using easily identifiable landmarks (corners of walls, floor patterns, etc.) as references improves alignment accuracy. For wide outdoor sites, coordinate alignment with LRTK is the most efficient method.