What is Absolute-Coordinate AR?

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1. The Difference Between Traditional AR and Absolute-Coordinate AR

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Traditional AR technology typically uses a smartphone or tablet camera to align markers or manually set reference points, and then projects 3D models onto the screen. However, this method has led to the following challenges:

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• Positional Drift of the Camera Causes the 3D Model to Shift

• Even after initial setup, the model drifts over time.

• In civil engineering sites where precision is crucial, the errors become significant.

On the other hand, absolute-coordinate AR is a technology that uses RTK technology to correct the position information in real-time while displaying 3D models. This allows the model to be placed based on the accurate coordinates of the construction site, ensuring no drift and eliminating the need for calibration.

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2. The Mechanism of Absolute-Coordinate AR Powered by RTK

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RTK is a positioning technology with centimeter-level accuracy, compared to GPS positioning. This allows the AR model’s display position to remain stable based on the Earth’s coordinate system, so the model stays fixed in place even as the user moves. Specifically, the following features are enabled:

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• Place 3D Models with Accurate Positioning Information

• Models Remain Fixed Even When Moving

• No Need for Coordinate Adjustment on the Construction Site

• No Calibration Required, Making It Easy for Anyone to Use

By utilizing this technology, high-precision AR displays can be applied to all stages of civil construction, leading to a dramatic improvement in the efficiency of construction management.​

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Use Cases in Civil Construction

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1. Design Check Before Construction

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By overlaying the design model onto the actual site using AR before construction begins, pre-construction checks become easier. For example, in bridge or road construction, 3D design data can be displayed in AR, allowing for verification of whether the construction can be done at the correct position and height as per the design. Traditionally, this required comparing with paper drawings, but with AR, it allows for intuitive checks while comparing with the actual environment.

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• Reducing the risk of construction being done at the wrong location

• Pre-emptively checking discrepancies between the design and the site

• Sharing understanding with the client before construction begins

2. Progress Verification During Construction

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During construction, you can verify in real-time whether the structure being built aligns with the design data. For example, before pouring concrete, you can overlay the design model onto the formwork on-site in AR, allowing you to detect and correct any positional or height discrepancies in advance, thus reducing rework.

• Early detection of construction errors

• Immediate verification of areas that need correction

• Smoother consensus-building between the client and contractor

3. Infrastructure Inspection and Maintenance

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Absolute-coordinate AR can also be applied to infrastructure maintenance. For example, during inspections of bridges or roads, overlaying past inspection data with AR allows for visualizing the changes over time. Additionally, AR can be used to visualize underground utilities, reducing the risk of accidentally damaging gas pipes or water pipes during excavation.

• Overlay past data with current conditions for inspections

• Visualize the location of underground utilities to prevent accidents during excavation

• Accurately plan maintenance for roads and bridges

The Advantages and Use of LRTK

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LRTK is the only smartphone-compatible absolute-coordinate AR tool that utilizes RTK technology. Unlike other AR technologies, it does not require markers or manual alignment. By simply attaching the device to a smartphone, you can instantly display AR with centimeter-level positioning accuracy.

The image shows the setup with a dedicated RTK receiver attached to the back of the smartphone, enabling high-precision AR displays.

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Key Features of LRTK:

• High-precision absolute-coordinate AR with RTK positioning

• No need for pre-calibration

• Usable for construction management, surveying, and infrastructure inspection

• Easy data sharing through cloud integration

One of the major strengths of LRTK is that coordinate alignment is not required on-site. In typical AR systems, reference points need to be set up at each site for positioning adjustments, but LRTK utilizes high-precision RTK positioning, allowing the model to be placed at the correct coordinates from the start, significantly reducing the effort required on construction sites.

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The image shows how LRTK ensures design data is accurately placed based on earth coordinates, preventing discrepancies on-site.