Visualizing Drawings, Boundaries, and Buried Utilities Together on Site with AR

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 boundary lines

• Improved safety by AR display of underground buried utilities

• Key points for successful AR display (data preparation and alignment)

• Reliability of AR display brought by high-accuracy positioning

• Achieving high-precision AR for anyone with simplified surveying using LRTK

• FAQ

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

When working on a construction site based on drawings, misinterpretation of design documents or insufficient sharing of the intended image often leads to construction errors and rework. For example, a slight positional deviation on a plan view that was overlooked can result in a finished structure protruding over the property boundary, or a misunderstanding of the location of a buried pipe shown in the design can lead to damaging a cable during excavation. Behind these problems lies the difficulty of grasping the completed image from two-dimensional drawings alone and the gap where the designer’s intent is not fully conveyed to everyone on site.

AR (augmented reality) is attracting attention as a powerful means to bridge these gaps and improve construction accuracy and safety. By overlaying design drawings and 3D models onto the real scenery through a smartphone or tablet camera, the completed form can be intuitively confirmed on site. In addition, boundaries and underground utilities that are normally invisible can be displayed in AR, allowing required information to be grasped at a glance. From site supervisors to craftsmen and owners, everyone can view the same AR imagery and share “what will be where and how,” preventing troubles caused by differing recognition. Below are the main benefits gained by visualizing drawings, boundaries, and buried utilities together on site with AR.

• Visualization of the completed image: You can realistically experience the post-construction appearance, which is hard to grasp from plan or section drawings alone, aligned with the actual site scenery. The placement and heights of structures that are difficult to imagine from drawings can be confirmed at a glance, helping accurately share the designer’s intent.

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

• Safety through visualization of buried utilities: By confirming the locations of underground gas pipes, communication cables, and the like in AR before excavation, you can greatly reduce the risk of accidentally damaging them during digging. Being able to grasp invisible hazardous spots in advance leads to strengthened safety measures.

• Improved consensus building and customer satisfaction: Using AR for explanations to owners and neighboring residents allows you to share the completed image that is hard to convey with paper drawings. This prevents misunderstandings like “it’s different from what I expected,” and enables eliciting concrete opinions from the planning stage. Achieving agreement while previewing the completed form contributes to improved satisfaction after handover.

• Efficiency in surveying and staking-out work: AR overlays simplify on-site position-setting tasks. If you visualize design baseline lines and points in AR and mark them on the ground on the spot, tasks such as driving stakes or stringing lines that traditionally required skilled surveyors can be performed accurately by anyone. This can shorten work time and reduce personnel burden.

Advantages of displaying design drawings on site with AR

To display design drawings in AR, you first need digital design data. This can take various forms, such as 3D models like BIM/CIM models or 3D CAD data, or 2D plan data such as CAD drawings or images. If a 3D model is available, you can reproduce the shapes of columns, walls, and other three-dimensional structures in real space, which provides the most intuitive confirmation. Even when only 2D data such as plan drawings are available, you can display the drawing as if laid on the ground in AR or draw the design lines as virtual luminous lines on the surface to grasp required positional relationships. The key is to project the points, lines, and shapes in the design data onto the site at the correct scale.

If you display the prepared design data in AR on site, you can immediately check whether the planned positions match the actual site. For example, by overlaying a building layout on the ground, you can intuitively check whether it fits within the site and whether it interferes with adjacent structures. If discrepancies between the drawing and the site are discovered, design revisions or on-site adjustments can be made before construction starts, preventing rework. Thus, AR display of design drawings is useful not only for sharing the completed image but also for design verification and pre-construction planning.

Accurate position verification by AR display of site boundary lines

In building and civil engineering works, accurately knowing site boundary lines is important. Traditionally, boundaries were laid out on site by relying on boundary markers (stakes or plates) and measuring with a tape measure or transit, but it is not easy to imagine an invisible line connecting points. If boundary markers are buried or lost, or if there is a slight discrepancy between the survey map and the actual conditions, confirming accurate boundaries becomes more time-consuming. As a result, structures may end up slightly outside the site and later be required to be corrected, causing trouble.

By visualizing site boundary lines with AR, such concerns are greatly reduced. If you prepare boundary line data in advance from known point coordinates, you can clearly display virtual lines or walls indicating the site boundary in AR. Lines that do not exist on the ground become visible through the device, allowing anyone to intuitively grasp the positional relationships of boundaries. For example, when excavating with heavy machinery, checking the boundary line in AR prevents over-excavation outside the site. When placing a building, the required setback from the boundary can be instantly seen in the AR display, preventing measurement errors. AR display of boundary lines reduces the number of times you need to call a surveyor to re-establish boundaries, contributing to more efficient construction management.

Improved safety by AR display of underground buried utilities

In works involving excavation such as road construction or land development, it is extremely important to know the positions of underground water/sewer pipes, gas pipes, and communication cables. Traditionally, people referred to paper as-built drawings or marked the ground with paint to raise awareness, but it was difficult to accurately imagine the actual positions on site, leaving room for human error. If a gas pipe is accidentally damaged by an excavator, it can lead not only to delays in construction but also to serious disasters.

By visualizing the positions of underground utilities in AR, you can grasp the invisible underground objects as if looking through the ground. For example, if workers check the underground pipe routes on a tablet AR screen before excavation, they will clearly know where to take care. Information such as “a gas pipe runs under here” or “a conduit extends in that direction” is visualized, making it easier to excavate cautiously or switch to hand-digging when necessary. As a result, a significant reduction in utility damage accidents and a dramatic improvement in safety can be expected. Also, when planning new routes considering existing utilities, AR lets you understand the positional relationships between the two, making it easier to design routes without collisions or interferences. 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.

Key points for 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.

• Digitize and prepare data: Prepare in digital form the information you want to display on site, such as drawing data, boundary coordinates, and positions of buried utilities. If you only have paper drawings, scan or convert them to CAD, and digitize as much as possible the route maps of buried utilities. It is desirable to format these data so they can be imported into smartphone/tablet AR apps (e.g., DXF, LandXML, OBJ, IFC).

• Unify coordinate systems: Unifying the coordinate systems of the prepared data is 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 model can generally be displayed at the correct position by matching them with the device’s GPS location. If drawings use a site-specific local coordinate system, you need to measure multiple known points on site and correspondingly translate and rotate the virtual model to align it (for example, by indicating two or more corresponding points). Confirm site reference point coordinates in advance and align the design data to the same reference to make on-site work smoother.

• Methods for alignment in AR: AR apps offer several methods for aligning virtual models. One is to place printed markers or QR codes at known locations on site and have the camera read them to fix the model. Another is to manually move and rotate the virtual model in the app to match local landmarks (e.g., a corner of a wall or an edge of a road). However, these manual methods have limitations when aligning accurately across a wide site. Coordinate-based alignment using GPS is effective in such cases. If the design data contain absolute coordinates, the model can be automatically placed based on the current position obtained from GNSS (Global Navigation Satellite System). The larger the site, the more powerful this coordinate-based alignment becomes.

• Use of high-precision equipment: Because standard smartphone GPS accuracy can introduce errors in AR displays, it is important to use a high-precision GNSS receiver when dealing with critical location information such as boundary lines or buried utilities. For example, using an LRTK Phone, a smartphone-integrated high-precision GNSS receiver, enables RTK-based centimeter-level (cm level accuracy (half-inch accuracy)) positioning, allowing accurate model placement without complicated marker setups. Using high-precision positioning equipment makes initial AR alignment much easier and more reliable, improving overall work efficiency and accuracy.

With the above points in mind during preparation, AR display on site will proceed much more smoothly, allowing you to accurately overlay drawings, boundary lines, and buried utilities at the intended locations.

Reliability of AR display brought by high-accuracy positioning

To fully utilize AR visualization in business, ensuring alignment accuracy is indispensable. Relying only on smartphone GPS or standard AR functions can result in display position errors of tens of centimeters (tens of cm / several inches) to, in some cases, more than 1 m (3.3 ft). This level of error is acceptable for rough image confirmation but is not suitable for tasks requiring precision such as stake-driving or pipe laying. For example, if an AR-displayed boundary line is offset by 50 cm (19.7 in) from its actual position, it would be dangerous to rely on that information for construction.

This is where introducing high-accuracy positioning technology becomes important. Using a correction technology for satellite positioning called RTK (Real Time Kinematic) can track device positions with an error range of a few centimeters. By connecting a high-precision GNSS receiver to a smartphone or tablet, you can align AR models almost perfectly with real-world positions. Because both horizontal and vertical directions can be brought within a few centimeters (within a few inches), you can reproduce reliable “life-size virtual models” including ground boundary lines and the depths of buried pipes. By improving positioning accuracy in this way, AR display becomes a tool that can meaningfully support on-site decision-making.

Achieving high-precision AR for anyone with simplified surveying using LRTK

The LRTK series is a solution that realizes centimeter-level (cm level accuracy (half-inch accuracy)) high-precision GNSS positioning on construction, civil engineering, and surveying sites, enabling shortened work times and significant productivity improvements. Devices such as the smartphone-integrated “LRTK Phone” make precise position-setting, which previously required specialized surveying equipment, easy to perform. They also support i-Construction promoted by the Ministry of Land, Infrastructure, Transport and Tourism, strongly backing digitalization and DX of field operations.

LRTK systems are designed to be easy to use even for staff without surveying expertise. By following the dedicated app’s screens, anyone can perform high-precision positioning and AR-based position checks. Complex equipment settings and difficult calculations are handled in the background, so users just follow an intuitive UI. After a short training session, even those who are not veteran surveyors can immediately apply the system to daily construction management. The LRTK terminal equipped with a GNSS antenna itself serves as a site reference point, allowing accurate model placement without special marker installation, which is a significant operational advantage on site.

By combining this simplified surveying with AR technology, visualization of drawings, boundaries, and buried utilities becomes even more accessible and reliable. If you are considering AR use at your sites, LRTK can strongly support that realization. For details, please visit the LRTK official website and feel free to contact us. LRTK will evolve your site to the next stage.

FAQ

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

Q: Can AR display be done with only 2D drawing data? Is a 3D model necessary? A: AR display is possible with only 2D data such as plan drawings. Even without 3D models, you can project drawing lines and shapes onto the ground in AR or display markers and symbols at important points. For example, you can overlay CAD drawings (DXF) or image files on AR as a background and check discrepancies with the site. However, if you can provide 3D data that expresses the heights of columns and walls, you can also perform three-dimensional interference checks, so preparing 3D data is desirable if possible.

Q: How accurate is the AR display position? A: Standard smartphone-built GPS and standalone AR functions can produce offsets ranging from several tens of centimeters to several meters. This is fine for rough checks but insufficient for precise staking or boundary verification. On the other hand, positioning using high-precision GNSS can reduce errors to within a few centimeters in both horizontal and vertical directions, allowing AR overlays that almost match the design drawings. The ability to secure centimeter-level accuracy suitable for actual construction is a major difference.

Q: Is specialized knowledge or training required? Can site staff use it? A: Advanced CG software skills are not required; in principle, anyone can use it by following the prompts of the supported app. The LRTK system’s UI is designed for users with limited surveying experience, allowing positioning and AR display with button operations. After a short training session, site staff can quickly apply it to routine construction management.

Q: Is it necessary to install markers or reference points in advance? A: When using LRTK, special marker installation is generally unnecessary. GNSS allows the device itself to continuously know its reference position and display models at the specified coordinates. However, in GPS-denied environments such as inside buildings, you will need to use ARKit’s plane detection or printed markers to align models. In such cases, placing easy-to-identify landmarks (corners of walls, floor patterns, etc.) as references improves accuracy. For wide outdoor sites, coordinate alignment with LRTK is the most efficient approach.