3D with Point Cloud Scanning! Secrets to Improving Efficiency at Solar Construction Sites

Background of 3D at Solar Construction Sites

With the growing demand for renewable energy, construction of solar power plants and mega-solar sites is rapidly increasing. These sites require installation of tens of thousands of panels over vast areas, necessitating large-scale earthworks and installation work. However, traditional 2D drawings and manpower-intensive manual work make surveying wide areas and checking progress time-consuming, increasing the risk of gaps between design and actual conditions. Even experienced construction managers find it difficult to translate the information on drawings into a completed site image. In addition, the construction industry faces labor shortages and an aging workforce, making it urgent to move away from traditional analog management in order to carry out efficient construction with limited personnel.

Digitalization (DX) of sites has attracted attention as a solution to these issues. The Ministry of Land, Infrastructure, Transport and Tourism’s i-Construction policy also recommends the use of ICT and 3D data, and site work that incorporates the latest technologies is in demand. If the entire site can be visualized in 3D and consistency with design data can be grasped in real time, not only can the work involved in traditional surveying and reporting be reduced, but mistakes in measurement and design errors that cause rework can also be lessened. 3D conversion using point cloud scanning is likely to be a key element of this DX.

What Is a Point Cloud? Acquisition Methods and Technological Evolution

A point cloud is a collection of “a large number of three-dimensional coordinate data” obtained by laser ranging or photogrammetry. This produces point cloud data that can accurately reproduce the shape of the entire site, including buildings and terrain. Acquisition methods include terrestrial laser scanners (TLS), aerial photogrammetry using drones, and, more recently, easy scans using LiDAR sensors or stereo cameras installed in smartphones.

Thanks to technological advances, acquiring point clouds has become more accessible than ever. 3D measurement that once required expensive dedicated equipment can now be easily generated by processing images taken by drones, smartphone cameras, or even 360-degree cameras in the cloud. In particular, the latest smartphones, combined with high-precision GPS (RTK) for surveying, enable field personnel to obtain point cloud data measured with centimeter-level accuracy (half-inch accuracy) without waiting for specialists. These technological advances are accelerating DX at solar construction sites.

Comparison of Methods: Drones, Smartphones, LiDAR, etc.

There are various methods for acquiring point cloud data, each with its own characteristics.

• Drone (UAV): Drone aerial photography, which provides a bird’s-eye view of wide areas, is suitable for large-area surveys covering several square kilometers or more. Photogrammetry, which generates point clouds by processing many captured photos in the cloud, is effective for understanding terrain and checking progress at vast mega-solar sites. However, drones are subject to flight permission and weather conditions and are weak in blind spots such as under trees or inside tunnels.

• Smartphone: Recent smartphones are equipped with LiDAR sensors and AR cameras, making handheld easy 3D scanning possible. Especially when a smartphone is connected to a small RTK positioning receiver, centimeter accuracy (half-inch accuracy) surveying can be achieved. Smartphones are attractive because they are easy to use, low-cost to introduce, and can be quickly operated by field personnel. However, the surveying range depends on line of sight and sensor performance, so for covering an entire large site in a short time it is effective to combine them with other methods such as drones.

• Handheld LiDAR Scanner: Dedicated handheld LiDAR devices can capture high-precision, detailed point clouds. They are suitable for complex structures or tunnel interiors where drones struggle to acquire data. However, their weight and cost can be significant, so it may be difficult to have multiple units available for daily use.

• 360-degree Camera: Some 360-degree cameras also support point cloud generation and have the advantage of capturing the surroundings at once, especially indoors or in complex sites. However, resolution and accuracy vary by model, so prior verification is necessary to ensure they meet the quality required for construction management.

As shown, drones, smartphones, and LiDAR each have strengths and weaknesses. In practice, it is common to combine appropriate tools while considering site size, required accuracy, cost, and worker skills.

Verifying Consistency by Overlaying Design Data and Point Clouds

By overlaying point cloud data acquired on site with 3D design models or 2D drawings, you can verify construction progress and conformity of the finished condition. For example, by comparing the panel layout or racking height design on the design data with the scanned terrain and installation status, you can immediately see where positional deviations have occurred.

Specifically, point cloud data is imported into visualization software and aligned based on 2D/3D design data. If geographic coordinates are unified using RTK positioning, this task becomes straightforward. After alignment, using a function that color-codes plan-to-actual differences makes it easy to identify locations that do not meet the design height or where piling positions are shifted. Comparing and checking in 3D in this way eliminates the labor of cross-checking survey results on paper as was done conventionally.

If the design data is created in 3D CAD (BIM/CIM), the design model and the as-built point cloud can be overlaid and manipulated on the screen, allowing comprehensive checks including hidden parts. Before crane delivery of panels or before racking installation, overlaying the current terrain and the predicted completion model in AR enables intuitive decisions about whether to add or remove soil to achieve the required elevation, preventing discrepancies after construction.

Streamlining Earthwork Volume Calculation, Pile Inspection, and Site Formation Progress

Using point cloud data streamlines progress management and quality inspection of earthworks. For earthwork volume calculation, the current terrain point cloud and the design terrain data can be compared to automatically calculate cut-and-fill volumes. Volume calculations that were previously performed manually for each work zone are automated, allowing quick on-site understanding of work results. This improves accuracy in heavy machinery deployment planning and schedule adjustments and makes it easier to predict surplus or shortage of soil.

For piling work for racking or foundations, comparing pile positions derived from point cloud data with design data allows verification of installation position and height errors on the spot. For example, marking pile locations with a smartphone linked to RTK or scanning the installation with a smartphone camera after completion to compare the installation status speeds up inspection tasks. If pile position deviations or insufficient depth are found, they can be identified during construction, reducing rework.

Furthermore, overall progress checks for site formation are simple with point clouds. By scanning the current terrain periodically with drones or terrestrial scanners and comparing with design data, you can visualize how much work has progressed and whether it is being finished as planned. Changes in 3D shapes, which were difficult to grasp with conventional site photos or 2D drawings, can be captured from a bird’s-eye perspective using point clouds.

Connecting Site, Office, and Design Teams via the Cloud

Point cloud data, photos, and survey information uploaded to the cloud can be shared among field, office, and design personnel, smoothing project-wide information coordination. For example, location-tagged photos and point cloud data taken and recorded by field personnel with a smartphone are automatically saved to the cloud, allowing designers and supervisors in remote offices to check them in real time.

This greatly reduces the time spent preparing reports after returning to the office and the work of exchanging documents by email. Design teams can always access the latest site information, enabling timely design changes and additional instructions. With progress and as-built data managed in the cloud, referencing past data, comparing records, and centralizing inspection records become easy. Information sharing among multiple sites and different contractors is also simplified, enabling everyone to work from the same 3D data.

Realizing Site DX with LRTK: Point Cloud Scanning, RTK Positioning, AR Display, and Cloud Integration

To realize the site DX described above, a workflow using the smartphone app “LRTK” is effective. LRTK includes functions that allow site surveying and point cloud scanning with a single smartphone. 3D point cloud data obtained by scanning the current terrain is automatically uploaded to the cloud and can be viewed and shared instantly in a browser. If design data is uploaded to the same cloud, overlaying the point cloud and design model to check differences is simple.

LRTK also supports RTK positioning, enabling centimeter-level position measurement with a small GNSS receiver connected to a smartphone. This allows piling positions and height surveys to be completed using only a smartphone, eliminating the need to transport heavy surveying equipment. Moreover, using the AR function, you can overlay the design model on the smartphone or tablet screen before construction, visually checking deviations from the current condition.

Combining these functions, LRTK dramatically improves information sharing and inspection efficiency at solar construction sites. Point clouds and survey data acquired on site are accumulated in the cloud on the spot and instantly shared with office managers and designers. Being able to confirm consistency between drawings and actual conditions with a single smartphone shortens verification tasks and suppresses variability in construction quality. Visual explanations using AR displays also help build consensus with owners and inspection agencies.

Introducing LRTK enables a move away from traditional personnel-dependent, analogue management of solar construction sites to realize next-generation DX sites. By leveraging the benefits of 3D visualization via point cloud scanning, labor reduction, design/as-built difference management, inspection efficiency, and smartphone compatibility, you can improve construction productivity.