Streamlining Volume Calculation with Point Cloud Data:
Fast and Accurate As-Built Quantity Calculation

This article takes an average of 2 minutes and 30 seconds to read

Published February 28, 2025

Basic Knowledge of Point Cloud Data and Volume Calculation

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What is Point Cloud Data?

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Point cloud data is 3D data composed of numerous points (coordinates) and their associated information, such as color and intensity. It is typically obtained using 3D laser scanners or photogrammetry, and allows for highly accurate recording of the shapes of terrain and structures. The large collection of points can represent the shape of objects down to the millimeter level, making it widely used across various industries, including civil construction and manufacturing.

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Differences and Benefits Compared to Traditional Volume Calculation Methods

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In traditional volume calculation, the common method involved creating cross-sectional diagrams from surveyed terrain and calculating the volume using the average cross-section method. This process required personnel to measure the height of survey points at regular intervals on-site, and then manually perform cross-sectional calculations using tools like Excel, which was a labor-intensive task. In contrast, the method using point cloud data involves capturing the surface of the terrain before and after construction, or after embankment and excavation, as 3D point clouds. The volume is then calculated from the differences between these point clouds. Since point clouds measure the entire surface, including fine terrain details and undulations, highly accurate calculations can be made. Additionally, once point cloud data is obtained, volumes can be calculated using mesh methods, allowing for recalculations or volume determination for different areas without requiring additional on-site measurements. Compared to traditional methods, the time required for on-site surveying and calculations is significantly reduced, making the calculation process much faster, which is a significant advantage.

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These efficiency improvements have been demonstrated in actual construction sites. For example, at a major construction company's site, the process of measuring and calculating soil volume, which previously took 4 people 7 days (28 person-days), was completed in 1 day (2 person-days) by switching to a method that creates point cloud data from drone photos and calculates volume. This shows how point cloud data can drastically reduce labor and time while maintaining the accuracy of volume calculations, with a reported error of only around 1% when compared to traditional methods. Point cloud-based volume calculations excel in both accuracy and efficiency, and their importance has been growing in recent years.

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Use Cases in Construction Management, As-Built Management, and Maintenance

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Proper Management through Comparison of Pre- and Post-Construction Volume

In civil construction, point cloud data of the terrain can be obtained before and after excavation or embankment, and the actual soil volume can be calculated from the differences, making it useful for as-built management. For example, in excavation work, the planned soil volume on the design drawings can be compared with the actual amount of soil excavated and removed to check whether the work is proceeding without excess or shortage. Using point cloud data, accurate surface models of the site can be quickly obtained, enabling immediate verification of as-built conditions (soil volume) right after construction. This allows for early planning of additional soil arrangements or disposal plans for excess soil, helping to properly manage project progress and costs. Additionally, by storing 3D data as evidence of as-built quantities, verification with the client becomes smoother. Traditionally, after construction, the process of measuring point elevations using string lines or surveying equipment and creating cross-sectional diagrams was labor-intensive, but with point cloud-based automatic calculations, the workload for site managers is greatly reduced.

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Rapid On-Site Measurement Using iPhone LiDAR Scanning

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In recent years, point cloud measurement has become possible not only with specialized surveying equipment but also with accessible devices like iPhones and iPads. For example, by using iPhone models from the iPhone 12 onward or iPad Pro with a built-in LiDAR sensor, you can scan the surrounding terrain and structures using a dedicated app and obtain point cloud data with tens of millions of points. By simply holding the smartphone and walking around the target, the survey can be completed in just a few seconds to a few minutes. It is so easy that it is often said, "You can perform professional-level point cloud measurement with a device in your pocket, without needing an expensive 3D laser scanner." In fact, construction site technicians are now starting to use point cloud scanning in their daily tasks. Traditionally, detailed 3D measurements required drone operation or the setup of large equipment, but smartphone and tablet-based measurements have a lower barrier for preparation and skill acquisition, allowing "anyone, anytime, easily" to obtain point cloud data.

For example, in small-scale embankment or remaining soil volume measurements, site supervisors can quickly scan on-site and immediately understand the soil volume, helping to adjust heavy machinery operations or arrange dump trucks. Real-time revisions of work plans or soil transportation plans, which were previously not possible on-site, are now becoming achievable with point cloud measurement.

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The point cloud data obtained is displayed in real-time on the tablet screen, and the volume of the required areas is automatically calculated. This ability to immediately quantify soil volume on-site not only improves the accuracy of daily construction and as-built management but also accelerates decision-making. Since it can be used as the basis for ordering missing materials or calculating quantities, as-built quantities can be shared with stakeholders on-site, allowing for immediate additional arrangements or corrective actions.

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Data Management and Utilization with Cloud Integration

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Point cloud data obtained on-site can be further effectively utilized by integrating with cloud services. For example, when point cloud data or photos taken with a smartphone are uploaded to the cloud, the data can be instantly accessed and analyzed from the office or remote locations. Recent solutions allow video data captured with a smartphone to be automatically converted into point clouds and generate a 3D model on the cloud, enabling the verification of soil volume measurement results while still on-site. By accumulating point cloud and as-built models in the cloud, changes in terrain and variations in soil volume can be tracked over time, from pre-construction to post-construction and throughout the maintenance period. For example, during construction, point clouds can be recorded regularly to visualize construction progress, while post-construction data can be used as a baseline to monitor long-term changes. In maintenance scenarios, point clouds before and after a landslide can be compared to estimate the amount of soil displaced, or slope deformations can be identified. Cloud integration makes it easier to manage and share such data centrally, providing the benefit of smooth information sharing among stakeholders, from construction management to maintenance.

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Further Efficiency Gains through the Use of LRTK

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Features of LRTK and Its Differences from Other Systems

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One solution that is gaining attention for making the use of point cloud data on-site even easier is LRTK (a high-precision positioning system provided by Lefixea). LRTK is an RTK positioning device integrated with a smartphone, where a compact antenna is simply attached to an iPhone or other devices, enabling centimeter-level positioning via network RTK. This significantly improves the GPS accuracy of the smartphone, allowing accurate position coordinates to be assigned to data captured by the smartphone's built-in LiDAR scanner or camera.

Unlike other systems, LRTK enables high-precision 3D surveying, which previously required drones combined with GNSS reference stations or expensive laser scanners, to be performed with just a smartphone. For example, even when performing LiDAR scans with an iPhone Pro, using LRTK ensures that the acquired point cloud data is of high precision, with position errors reduced to just a few centimeters. This results in quality terrain data that can be used directly for as-built management and inspections. Additionally, there is no need for specialized knowledge to operate dedicated equipment, making it easy for on-site technicians to use in their daily tasks. Compared to other 3D measurement methods (such as TLS—ground-based laser scanners or UAV photogrammetry), LRTK has lower initial setup costs and excels in mobility, allowing for quick and flexible measurements whenever needed.

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Easily scan on-site and
check soil volume in real-time.

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By utilizing LRTK, it is possible to perform point cloud scanning and calculate soil volume in real-time on-site. For example, when scanning embankments or stockpiles with a smartphone using the LRTK-compatible app, the volume is instantly calculated from the acquired 3D point cloud data, and the results can be viewed on the smartphone screen or via the cloud. Since LRTK point cloud data is already tagged with high-precision location information, elevation differences with the reference surface and comparisons with other design data can be made accurately on-site. This significantly reduces the time that was traditionally spent analyzing point cloud data on a computer after acquisition, enabling immediate tracking of as-built quantities right after scanning. As a result, quick responses such as "deciding whether stockpile disposal is needed that day" or "immediately checking embankment volume and placing additional orders" are now possible. In fact, LRTK's cloud service provides a feature where, by simply uploading the scan data, the embankment and excavation volumes are automatically displayed on a 3D point cloud model, with the claim that "simply scanning the embankment will quickly generate the calculation results." In this way, LRTK is expected to be a tool that nearly eliminates the time gap between on-site measurements and data analysis, enabling real-time as-built management.

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Benefits of Cloud Storage and Utilization

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LRTK excels in cloud integration for measurement results, allowing data obtained on-site to be instantly shared and stored. Point cloud data and positioning photos (field photos with location coordinates) obtained through the LRTK app are automatically synchronized with the LRTK cloud, making it easy to review details on a PC in the office or share data with other project members. Since the point clouds stored on the cloud can be managed chronologically, multiple point clouds obtained at different stages of construction can be compared to monitor progress, and they can also be used for future risk assessments and maintenance planning. LRTK Cloud also integrates with photo data, enabling the recording and viewing of both location-tagged photos and point cloud models to document the condition of inspection sites, making it useful for infrastructure inspections and asset management. In this way, LRTK provides an integrated system that enables "positioning, point cloud acquisition, and cloud sharing" in a one-stop solution, strongly supporting the digitalization of the site and improving operational efficiency.

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Future Outlook and Conclusion

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The use of point cloud data for volume calculation is expected to become increasingly widespread in the civil engineering industry. Supported by initiatives like i-Construction promoted by the Ministry of Land, Infrastructure, Transport, and Tourism, the ICT digitalization of 3D surveying and as-built management is becoming a standard process. In the future, it will become commonplace on construction sites to "calculate as-built quantities from point cloud data." On-site, workers will use tablets or smart glasses to continuously perform 3D scanning, accumulate real-time construction data on the cloud, and receive instant feedback through AI analysis, creating a realistic vision of smart construction. Point cloud data will not only be limited to volume calculation but will have broad applications, such as automating as-built inspections, enhancing construction records, and building digital twins for maintenance.

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In this context, smartphone-integrated surveying devices like LRTK offer an innovative solution for the era of "one device per person." Traditionally, 3D measurements were requested from specialized departments or surveying companies, but with this technology, on-site staff can regularly conduct measurements themselves. This will significantly enhance both the accuracy and speed of construction management. As LRTK becomes more widespread, workflows that immediately digitalize all as-built data and use it for decision-making on-site will become standard. For example, it will become possible to review the previous day's as-built point cloud early in the morning and fine-tune the construction plan, reducing unnecessary rework and material loss. Moreover, the increased use of point cloud data will also contribute to safety. In areas where access is difficult, such as steep slopes or locations prone to collapse, remote scanning can be used to assess soil volume, reducing the need for dangerous surveying work and decreasing the risk of labor accidents.

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Finally, as discussed in this article, point cloud data-based volume calculations enable the rapid and high-precision determination of as-built quantities, accelerating the construction PDCA cycle. We have highlighted the differences from traditional methods, specific use cases, and further efficiencies brought about by the introduction of new technology like LRTK, all of which directly contribute to improved site productivity. Moving forward, integrating such 3D technologies effectively will help achieve optimal as-built management and efficient construction management, strengthening competitiveness in the civil engineering industry. As the adoption of point cloud data expands, site visualization and digital transformation (DX) are expected to accelerate even further. Why not try point cloud scanning with a smartphone or volume measurement with LRTK on your site? You’ll likely experience the new way of construction management that high-precision and high-efficiency as-built quantity calculations bring.