Instant Point Cloud Data Sharing!
Smart Construction Management with LRTK Phone

In recent years, the importance of utilizing 3D point cloud data for on-site construction management has been increasing in the construction industry. Starting with the Ministry of Land, Infrastructure, Transport, and Tourism’s promotion of "i-Construction," the use of point cloud data has been rapidly expanding, particularly in the construction sector. By utilizing 3D information in as-built management, progress monitoring, and infrastructure inspections, the quality and efficiency of construction can be significantly improved.

However, traditional surveying methods have several challenges. Acquiring point clouds through ground-based laser scanners or drone surveying requires expensive equipment and specialized skills, and data processing and management can be cumbersome. For example, with drone photogrammetry, generating point clouds from flight plans and photos requires significant time and advanced software, with results sometimes taking hours or even days to be obtained. These time-consuming and costly processes have created barriers, making it difficult to immediately share and utilize the acquired point cloud data.

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The new solution that has emerged is smartphone-based surveying, which leverages the power of smartphones to simplify the process. A prime example of this is the LRTK Phone. The LRTK Phone is a pocket-sized, all-in-one surveying system that uses an ultra-compact RTK-GNSS receiver attached to an iPhone, dramatically simplifying RTK surveying and point cloud measurement on construction sites. It supports centimeter-level positioning with Real-Time Kinematic (RTK) technology, and the data collected can be instantly shared via the cloud.

Compared to traditional equipment, the price is very reasonable, and the era is now approaching where each on-site worker can carry their own device. In this article, we will explain in detail the benefits and usage of smart construction management using the LRTK Phone.

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What is Point Cloud Data?
Point cloud data is a type of 3D data composed of countless "points." Each point has X, Y, and Z coordinates (location data) and may also include RGB color information, similar to a color photograph. Therefore, when point cloud data is generated, it can recreate the site’s shape in a realistic and three-dimensional way, allowing for inspection from various angles.

Unlike traditional 2D surveying, point cloud data provides detailed shapes and dimensions, making it valuable in various civil engineering applications such as as-built management (verifying the shape after construction), progress management, and earthwork measurement (calculating excavation and embankment volumes).

Recently, point cloud data has become a key element in construction DX, and is increasingly being recognized as "essential data" in fields such as civil surveying, structural maintenance, and infrastructure management. For example, point cloud data can be used to create 3D models directly from the point cloud, even without drawings, for construction planning, or to reduce labor in as-built inspections. Additionally, with the diversification of data acquisition methods such as drone photography and laser scanning, opportunities to handle point cloud data have increased not only for specialized contractors but also for general construction professionals.

However, traditional point cloud acquisition had its challenges. To obtain high-precision point clouds, a significant initial investment in expensive laser scanner equipment or drone photography was required, along with specialized knowledge and software to generate and process the point clouds. In small-scale projects, the cost often outweighed the benefits, leading to many cases where the technology was not adopted.

In response to this, a new technology combining smartphones and RTK has emerged, making it easy to capture point clouds. By combining commercially available smartphones, such as iPhones, with RTK positioning technology, point cloud scanning can now be easily performed on-site, and the resulting data can be instantly shared and utilized.

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How Construction Management Changes with LRTK Phone
By using the LRTK Phone, the workflow for surveying and measurement in construction management is completely revamped. Below, we will explore the main changes brought about by LRTK Phone.

• Simplification of Surveying Tasks (Achieving Smartphone Surveying): By simply carrying an iPhone with a dedicated case and RTK receiver (LRTK device), anyone can immediately perform high-precision surveying and point cloud scanning. There is no need for complex equipment setup or specialized operation, as position measurement and point cloud acquisition can be done on an intuitive smartphone app. By using the iPhone's LiDAR function to scan the surroundings, a 3D point cloud with global coordinates (world coordinates) can be obtained for all points. Furthermore, with RTK-based self-positioning, there is no distortion in the point cloud being scanned, ensuring high-precision results even while walking. What used to be surveying tasks left to specialized operators can now be handled by on-site workers themselves, directly on-site.

• Real-Time Data Sharing and Remote Management: Point cloud data and surveying information obtained with the LRTK Phone are automatically uploaded to the cloud on-site. There is no longer any need to bring data back to the office for processing on a PC. The uploaded data can be immediately reviewed using the dedicated viewer on LRTK Cloud and shared with stakeholders over the internet. For example, point cloud data of the scanned terrain can be quickly checked by engineers at the headquarters, who can then provide instructions. Distance, area, and volume measurements can be made directly from a web browser without the need for dedicated software, allowing on-site progress and as-built data to be monitored remotely. This real-time information sharing significantly speeds up the PDCA cycle of construction management.

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Point Cloud Data Acquisition Flow Using LRTK Phone
Point cloud data acquisition with the LRTK Phone can be performed with the following simple steps.

1. Attach the Device to the Smartphone: Attach the dedicated RTK receiver for LRTK to the iPhone with a single touch and launch the LRTK app. No complicated cable connections are required, thanks to Bluetooth connectivity.

2. Preparing for High-Precision Positioning: Connect to network-based RTK (Ntrip) or CLAS* on the app to enable real-time centimeter-level positioning. (*In areas without coverage, RTK correction can be received via the CLAS signal from Japan's satellite positioning augmentation service "Michibiki.")

3. Start Point Cloud Scanning: Using the smartphone’s LiDAR scanning feature, walk around and scan the target (such as terrain or structures) that you want to measure. With LRTK, your position is continuously recorded with high precision, and global coordinates are automatically assigned to each point in the acquired point cloud.

4. Immediate Data Verification: Once the scanning is complete, the point cloud data can be immediately displayed on the smartphone. If needed, you can measure the distance between any two points, as well as area and volume, on-site. Since the point cloud data is accurate and free from distortion, you can make on-the-spot judgments about the quality of the as-built conditions.

5. Cloud Sharing: The measurement data is uploaded from the site to LRTK Cloud. By the time you return to the office, the data is already shared with stakeholders, and you can immediately use it to review the 3D point cloud on a web browser or create drawings to be attached to daily reports.

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This seamless flow allows for the entire process, from acquiring point cloud data to sharing it, to be completed in one go, eliminating the time lag of the traditional method of "measuring, bringing it back, processing, and then sharing." The ability to instantly visualize and share on-site conditions is a major advantage of smart construction management.

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Use Cases of LRTK Phone on Construction Sites
LRTK Phone plays a key role in various scenarios in civil engineering construction. Here are a few specific use cases.

• Real-Time As-Built Management: By recording and verifying the shape immediately after construction, such as after concrete pouring or embankment completion, with point cloud data, as-built inspections can be streamlined. For example, you can immediately scan the pavement thickness or slope of embankments on-site and check if they match the design. What used to require waiting for surveying results later can now be done in real-time.

• Benchmark Surveying and Coordinate Positioning: The coordinates of site benchmarks (known points) and arbitrary points can be instantly measured. By using LRTK's averaging positioning function, anyone can easily obtain high-precision benchmark coordinates. The obtained coordinates are recorded in the global coordinate system (public coordinates), ensuring seamless integration with data collected from other devices. This allows for centralized management of site data in a unified coordinate system.

• Earthwork Measurement and Excavation Management: By scanning the terrain before and after excavation or embankment, and comparing the data, the volume of earthwork (soil volume) can be automatically calculated. With LRTK Phone, the entire process from surveying to volume calculation can be completed on-site, allowing for immediate assessment of the amount of soil to be disposed of or the volume of backfill material required. For small-scale excavation tasks, earthwork management can be performed with sufficient accuracy without the need to fly UAVs, as was traditionally done.

• Infrastructure Maintenance and Inspection: Point cloud data is also effective for regular inspections of infrastructure structures such as tunnels, bridges, and embankments. By obtaining point clouds of the structure's surface with the LRTK Phone, cracks or deformations can be recorded in detail. Comparing the current point cloud data with past data allows for tracking changes over time, and inspection results can be saved and shared as 3D models. Being smartphone-based and lightweight, measurements in high or confined spaces become easier, contributing to the digital transformation (DX) of inspection tasks.

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In addition to these, LRTK Phone can also support layout (positioning) tasks with AR, or easily record the current terrain in 3D before construction to assist in planning. The applications of LRTK Phone are diverse. Since it can handle "measuring, recording, and sharing" all with a single device, it contributes to improving productivity for the entire team, including not just construction managers, but also workers and operators, based on the needs of the site.

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Benefits of Implementing LRTK Phone

Let’s review the benefits of implementing LRTK Phone.

1. Efficiency and Labor Reduction in Surveying Tasks: Tasks such as surveying and point cloud measurement, which were traditionally carried out by specialized technicians, can now be done by the on-site staff themselves. This eliminates the need for personnel arrangements and schedule adjustments, allowing measurements to be taken immediately when needed. As mentioned earlier, in some cases, the measurement and analysis process that used to take several hours can be shortened to just a few minutes. Since results are available in real-time, there is no waiting time, enabling a seamless transition to the next task.

2. Improved Data Accuracy and Reliability: The centimeter-level positioning accuracy provided by RTK greatly improves the precision of the data collected compared to traditional GNSS standalone positioning or smartphone-based measurements. Since all point clouds and measurement points are recorded with a common coordinate reference, the reliability of the data is ensured for subsequent processes such as data matching and as-built inspections. Additionally, issues such as point cloud misalignment or distortion that were common with traditional methods are resolved, ensuring that the data can be confidently used in on-site management.

3. Cost Reduction: There are significant cost advantages in terms of initial investment. LRTK Phone leverages existing smartphones and can operate with a combination of a small device and app, keeping initial costs low. It is far more affordable than purchasing expensive laser scanners or surveying equipment or hiring outsourced surveying services. Offered through a subscription (fixed-fee) model, the implementation barrier is set lower. As a result, even small and medium-sized civil engineering contractors can easily adopt the latest RTK surveying technology and point cloud data utilization.

4. Digital Utilization of Data (Promoting Construction Management DX): All data acquired with the LRTK Phone is stored in digital format. Information that was difficult to grasp with paper field notebooks or 2D drawings can now be preserved as 3D data, making it useful for later matching with design data and verifying as-built conditions. Using point cloud and surveying data, it is also possible to semi-automatically create as-built drawings or daily progress reports. This digitalization of site information accelerates the overall DX (Digital Transformation) of construction management tasks.