Confirm positions by overlaying drawings with AR before construction to prevent construction mistakes

Contents

• Benefits of overlaying drawings with AR for confirmation

• Visualizing boundary lines in AR to prevent construction mistakes

• Displaying underground buried utilities in AR for safe excavation

• Improving layout marking and surveying efficiency by using AR

• Challenges of AR adoption: accuracy and alignment

• Achieving “non-shifting AR display” with high-precision positioning

• Simple surveying and AR utilization starting with LRTK

• FAQ

Benefits of overlaying drawings with AR for confirmation

At construction sites, misreading design drawings or a lack of shared understanding can often lead to unexpected mistakes discovered after construction, resulting in rework. For example, overlooking a slight position shift on a plan may cause a finished structure to be off by several centimeters (a few in) from an adjacent boundary line, or misunderstanding the indicated drainage slope might result in rainwater not flowing properly. Such troubles commonly stem from the difficulty of visualizing the finished form from two-dimensional drawings alone and from a gap between the designer’s intent and what everyone on site understands.

Augmented reality (AR) technology is attracting attention as a means to bridge this gap and improve construction quality. Because design drawings or 3D models can be overlaid on the real scene through a smartphone or tablet camera, the finished form can be intuitively confirmed on site. From site supervisors to craftsmen and clients (owners), everyone can view the same AR image and share an understanding of “what and how things will be built,” preventing mistakes caused by misalignment in perception. Displaying drawing data on site in AR before construction offers the following main benefits:

• Visualizing the finished image: The appearance after completion, which was hard to imagine from plans or sections alone, can be experienced realistically by overlaying it on the actual scene. The building or structure’s placement and sense of height can be grasped at a glance, enabling accurate sharing of the designer’s intent among all site personnel.

• Preventing construction mistakes: By overlaying the design model on the actual scene in AR and checking it, you can immediately detect displacement or interference occurring during construction. For example, if you check the formwork position in AR before concrete placement, you can notice and correct even a position shift of a few centimeters (a few in). Early detection and correction of errors can greatly reduce the risk of rework.

• Facilitating consensus building and improving customer satisfaction: Using AR for explanations to clients and other departments makes it easier to share a completed image that is hard to convey with paper drawings. It helps prevent misunderstandings like “this is different from what I expected,” and enables concrete feedback during the proposal stage. Reaching agreement on the completed form in advance leads to higher satisfaction after handover.

• Improving layout marking and surveying efficiency: Overlaying drawings with AR also revolutionizes on-site marking (layout) work. By visualizing design reference lines and positions on the ground in AR and marking them on the spot, stakeout location setting that previously required skilled surveyors can be performed accurately by anyone. As a result, work time can be shortened and surveying and verification tasks can be conducted efficiently even on sites with labor shortages.

Visualizing boundary lines in AR to prevent construction mistakes

Correctly recognizing site and building boundary lines is extremely important in construction work. A small misunderstanding that causes a building to shift from its intended position and encroach on a boundary can lead to disputes with neighbors or even be considered an illegal structure. Traditionally, confirming boundaries relied on survey maps and on-site boundary markers (stakes/plates) and visual judgment, but mapping lines from drawings onto the site in your head required experience.

With AR, boundary lines and building layout lines indicated in the design can be directly made visible on site. For example, if you load site boundary data into a smartphone AR app beforehand and display it, a virtual boundary line will appear on the bare ground. By comparing the actual boundary markers with the AR line, you can intuitively detect differences of a few centimeters (a few in) that are hard to notice by eye. You can also show planned building exterior walls and layout lines on the ground in AR, allowing you to confirm before foundation work begins whether the “designed building position” maintains an appropriate offset from the boundary. Such pre-checks prevent offset mistakes from the boundary (being too far or too close) and reduce the risk of later rework.

Furthermore, AR display of boundary lines is useful for explaining and obtaining agreement from neighbors. The extent of the site and setback positions, which are difficult to convey on paper, become clear when visualized in AR. Explanations like “this line to this line is the site boundary, and we will install the fence along this line” can be shown overlaid on the real view, making it easier to gain understanding from surrounding people. As a result, troubles caused by differing perceptions about boundaries can be prevented and construction can proceed with confidence.

Displaying underground buried utilities in AR for safe excavation

Buried items such as water and sewer pipes and cables under the ground are major risk factors when carrying out construction. Damaging existing infrastructure by mistake can cause not only schedule delays but also affect local lifelines. Because buried utilities are not directly visible from the surface, workers have historically had to infer their positions and excavate based on pipe layout drawings and other documents.

AR visualization of underground buried utilities solves this problem. If you preload position information of buried pipes and cables (drawings or survey data) into an AR app, you can simply point your smartphone at the site and the subsurface piping will be displayed as if transparent. Just like an X-ray view of the ground, you can immediately see what pipes are buried where, greatly reducing uncertainty when deciding excavation locations.

For example, if information indicates “a water/sewer pipe runs at a depth of 1 m (3.3 ft) from here,” the app can display a pipe model at 1 m (3.3 ft) below ground in AR. Workers can then excavate while visually confirming the pipe route through the screen and can quickly detect potential near-misses with existing pipes. Displaying buried utilities in AR helps prevent accidental excavation and improves both safety and construction efficiency. It also facilitates explanatory visualization of underground structures for supervisors and inspection witnesses, making information sharing among stakeholders smoother.

Improving layout marking and surveying efficiency by using AR

AR is transforming not only design confirmation but also on-site measurement tasks like layout marking and as-built surveying. Traditionally, positioning stakes and checking structure heights required experienced surveyors carefully using transits and levels. With AR, anyone can intuitively confirm positions and dimensions according to the design.

For example, overlaying a rebar placement drawing in AR during rebar work allows you to check on the spot whether the number and spacing of rebar match the drawings. If there is a misalignment, it can be detected and corrected immediately, preventing rebar errors that would otherwise be discovered later. In roadworks or land development height inspections, projecting design finished elevation lines in AR and overlaying them on embankments or cut surfaces enables you to confirm the finish. This allows you to instantly find errors such as “it looks flat but is actually a few centimeters (a few in) higher/lower,” and decide on site whether to correct insufficient compaction or over-excavation.

AR is also powerful for layout marking. Since reference lines and column positions from drawings can be directly displayed on the ground or structure in AR, the effort of measuring with tape or chalk lines and then marking is greatly reduced. For example, if points showing column positions or grid lines are visualized on the floor in AR, you can simply trace and mark those points to set accurate positions. Even without relying on the intuition and experience of skilled workers, simple surveying enables high-accuracy layout marking, allowing young or small teams to work efficiently.

Challenges of AR adoption: accuracy and alignment

Despite these conveniences, to make AR truly useful on site you must overcome issues of accuracy and alignment. AR apps that run only on regular smartphones or tablets can show models shifted by tens of centimeters to several meters due to GPS and sensor errors in the device. Indoors, the camera can correct its position using features of walls and floors, but in wide outdoor civil engineering and construction sites with few reference features, position drift and scale distortions tend to occur.

Also, overlaying drawing data on site requires matching the model coordinates in virtual space with real-world survey coordinates (alignment). Many AR apps require placing markers (such as QR codes) on site and scanning them with a camera, or manually aligning the model to known points on site. These alignment tasks are time-consuming and prone to remaining errors due to marker placement mistakes or human adjustment inaccuracies.

In terms of accuracy, achieving the centimeter-level precision required by construction sites with AR requires additional measures. Especially when using AR over a wide site, position errors of several meters can make the overlayed drawings diverge significantly from reality. To make AR a reliable tool on site, centimeter-level high-precision positioning and a low-effort method for matching coordinates are needed.

Achieving “non-shifting AR display” with high-precision positioning

A promising approach is to combine AR with high-precision positioning technology to realize a “non-shifting AR display.” A representative technology is RTK-GNSS (real-time kinematic GPS), which reduces positioning errors to within a few centimeters by adding correction information to satellite positioning. While a standard smartphone’s built-in GPS may have errors of several meters, RTK-GNSS provides the accuracy necessary for civil engineering and construction management.

LRTK is a solution developed to make RTK-GNSS easy to use on site. By attaching a dedicated small antenna to a smartphone or tablet and receiving correction data (such as VRS) from base stations via the Internet, you can continuously measure your position with centimeter-level accuracy. Feeding that high-precision position information into an AR app allows automatic and accurate alignment between design data and the real world.

The biggest advantage of introducing high-precision positioning is that it eliminates cumbersome on-site alignment tasks. For example, conventional workflows required setting up equipment to match reference points on the drawing and installing stakes as markers, but with LRTK you simply stand at the location with your smartphone. Design models are projected exactly at their designated positions in accordance with world geodetic coordinates, so initial alignment adjustments are almost unnecessary.

Moreover, centimeter-level positioning provided by LRTK dramatically improves AR display stability. Even when walking across a large site, the model will remain fixed in the correct position without drifting or floating in the field of view. In standard AR, models can slowly shift as you move, but high-precision GNSS corrections act as the “eyes” of AR and keep the model accurately stationed. This allows safe use of AR for surveys spanning multiple locations or for broad as-built inspections.

High-precision position information is also effective for vertical alignment. RTK-GNSS can measure elevation (height) precisely, so the vertical reference of models displayed in AR can also be accurately matched. Whether showing the depth of buried utilities in AR or verifying embankment heights in earthworks, the displayed positions reflect true measured elevations, increasing trustworthiness.

Simple surveying and AR utilization starting with LRTK

To fully utilize AR on construction sites, two keys are required: high-precision positioning and digitized design data. LRTK supports the site DX (digital transformation) simply by providing both. With only a small antenna attached to a smartphone, you can handle everything from uploading drawing data and applying high-precision corrections to AR display verification and even point cloud measurement.

For example, you can upload design drawings (CAD data, BIM models) to the LRTK cloud and then launch the smartphone app on site to immediately display the drawings in AR for position confirmation. No complex equipment setup or specialized skills are required; intuitive operation lets you start simple surveying right away. Marking stakeout positions can be done accurately even by newcomers by checking them in the app. Combined with the LiDAR scanner in recent smartphones and tablets, you can instantly capture 3D point clouds of construction sites and apply them to as-built checks and earthwork volume calculations.

In this way, LRTK allows tasks that traditionally relied on specialist technicians—site surveying and verification—to be performed easily by anyone. By visualizing drawings, boundaries, and buried utilities in AR to prevent construction mistakes, and by using simple surveying to achieve both high efficiency and high accuracy in site management, you can significantly improve on-site workflows. If you are facing challenges in confirming positions or preventing mistakes before construction, consider updating your site practices with an AR solution using LRTK.

FAQ

Q: Do I need special equipment or expensive devices to use AR? A: No — in general, recent smartphones and tablets are sufficient to leverage AR technology. You can start simply by installing a free or dedicated AR app on your existing device without specialized AR glasses. However, if you require high accuracy, attaching a small GNSS antenna (for example, LRTK’s antenna) to improve positioning accuracy will enable more reliable AR displays.

Q: Is smartphone GPS alone sufficient for AR drawing display? A: For simple checks, a smartphone’s built-in GPS can be used, but its accuracy will typically be on the order of several meters. To achieve the precision required in construction, a system that can correct positioning to centimeter-level, such as RTK-GNSS, is necessary. For example, ordinary GPS can produce discrepancies between drawing positions and actual positions, and wall positions might differ by tens of centimeters (tens of inches). For important position verification, we recommend combining AR with high-precision positioning.

Q: How should I prepare drawing data for AR display? A: First, prepare digital design or model data (CAD files, BIM models, or even image files). While 3D data is ideal, 2D drawing data can also be placed on the ground in AR or converted into lines for display. Using a cloud service such as LRTK, you can upload your drawing files and easily call them up on site to overlay them in AR.

Q: Is AR adoption progressing in the construction industry? A: Yes. Driven by initiatives such as “i-Construction” promoted by the Ministry of Land, Infrastructure, Transport and Tourism, the use of AR and 3D data is rapidly spreading. Not only large construction firms but also small and medium-sized sites are increasingly using tablets for drawing sharing and AR construction checks. Against a background of more young technicians and labor shortages, AR contributes to site improvement as an easy-to-use digital tool.

Q: Can we rely solely on AR position verification and omit traditional surveying? A: AR is essentially an auxiliary tool, and final inspections and critical reference setting should still be confirmed using conventional surveying equipment. However, AR is highly effective for interim checks during construction and for simple alignment tasks. By continuously monitoring design versus construction with AR and performing traditional surveying at key points, you can prevent mistakes while maintaining a balance of efficiency and quality.

Q: What are the costs and effort to introduce AR on site? A: The barrier to AR adoption is not as high as you might think. You can use existing devices such as smartphones and tablets, and many AR apps are low-cost or free. Even when adding high-precision positioning, small GNSS antennas (like LRTK) are more affordable than total stations and do not require special licenses. Preparations include digitizing design data and uploading it, but once the workflow is established, on-site operation is simple. Considering the cost of traditional surveying equipment and rework, the benefits of AR adoption are likely worth the investment. It is also possible to start with small projects or trial implementations in parts of the workflow, and then scale up as you become familiar. With national and industry-level encouragement for 3D data use such as BIM/CIM, the more you digitize drawings, the more benefits you will gain from AR adoption.