Easy Earthwork Volume Calculations! Streamline Field Operations with Smartphone High-Precision Positioning

Introduction: Why Is "High-Precision Positioning" in Demand Now

The construction industry is increasingly focused on the concept of "high-precision positioning." This interest is driven by challenges such as improving on-site productivity and addressing labor shortages, and initiatives like the Ministry of Land, Infrastructure, Transport and Tourism’s i-Construction have accelerated the adoption of ICT technologies. Traditionally, surveying and as-built management required skilled technicians and significant time. However, recent advances in GNSS (satellite positioning) based high-precision positioning technologies now allow anyone to obtain centimeter-level position information in a short time. For example, RTK (Real Time Kinematic), which corrects satellite positioning errors in real time, and its evolution into cloud RTK services have made the previously difficult combination of low cost and easy high-precision positioning increasingly feasible. Now, combining smartphones with high-precision positioning is bringing a new wave of efficiency to field operations.

On-Site Challenges: The Hassle of Earthwork Volume Calculations and Limits of Traditional Methods

Nevertheless, many sites still struggle with the labor-intensive task of earthwork volume calculation, which is indispensable in civil engineering. For instance, during grading or excavation, it is necessary to measure ground elevations before and after construction to calculate how much fill was placed or how much was excavated. This quantity management directly affects construction costs and transport planning, so it is extremely important, but traditional methods required considerable effort. Traditional surveying used total stations or levels to measure key terrain points one by one, create cross-sections, and calculate volumes from them. On large sites or complex terrain, limited measurement points make it difficult to accurately capture shapes, and missed measurements tend to cause large errors. Also, point-by-point measurement and drawing creation required specialized skills and long working hours.

As a result, volume calculations were not frequently performed, and sites often relied on rough estimates based on experience or intuition. This could lead to rework from unnoticed over- or under-filling, or extra earth transport costs. In addition, surveying on steep slopes or disaster sites is not easy for personnel to enter, creating safety concerns.

The Turning Point Brought by Merging Smartphones with High-Precision Positioning

Amid this situation, the fusion of smartphones and high-precision positioning is creating a major turning point on sites. Previously, centimeter accuracy required dedicated GNSS equipment and base station installation, but the advent of cloud RTK that provides correction information over the internet now enables high-precision positioning with a pocket-sized device and a smartphone. By attaching an ultra-compact RTK-GNSS receiver to a smartphone, it essentially becomes a portable surveying instrument, allowing handheld position measurement and as-built measurement on site. In practice, with simple operational guidance anyone can acquire point cloud data with absolute coordinates on site, so surveying is becoming less the exclusive domain of specialists. Combining smartphone cameras and sensors further enables scanning terrain or structures into point clouds on the spot, or AR display of design data on the screen to check accuracy, opening up a wide range of applications previously not possible.

Practical Earthwork Volume Use Cases (Embankments, Slopes, Excavation, etc.)

So, how exactly does high-precision positioning help with earthwork volume calculations? Here are some key use cases.

• Embankment volume calculation: When placing fill on site, you can accurately determine the volume of placed soil. Scanning the embankment area with a smartphone allows rapid volume calculation. Large-scale embankments (for example, over 200 cubic meters (200 m^3, 7,062.9 ft^3)) that were difficult to measure with traditional cross-section surveys can now be measured accurately in one scan. Comparing measured quantities with design quantities is also easy, enabling early correction of over- or under-filling.

• Soil slope work volume management: For slope work (cut-and-fill, slope shaping), as-built management of slopes that was previously difficult becomes dramatically more efficient. Scanning a slope from which collapsed soil has been removed or an artificially formed slope with a smartphone allows recording the entire gradient and surface irregularities in detail. For example, even for a slope about 100 m (328.1 ft) long, anyone can obtain detailed 3D point clouds simply by walking while pointing the camera. From the resulting point cloud data, you can measure surface area and cross-section shapes of the slope, and instantly check differences from design gradients and any shortage of fill.

• Excavation work volume management: High-precision positioning is also useful for excavation (digging down the ground). By scanning the ground surface before and after excavation and comparing the data, you can accurately calculate how much soil was removed. For example, you can confirm on site from measurement data whether foundation excavation has reached the designed depth or if there has been over-excavation. Volume estimation, which used to rely on the number of dump trucks or the operator’s intuition, can now be performed objectively based on data.

• Volume estimation in disaster recovery: In disaster recovery, smartphone high-precision positioning is powerful. Rapid measurement of deposited soil volumes after landslides or river flooding enables accurate recovery planning. At dangerous collapse sites, 3D surveying of disaster areas by smartphone or drone without sending people close to the hazard provides safety while allowing necessary soil volume to be calculated in a short time. The ability to make decisions on site immediately from obtained data is highly valuable in emergency response situations.

• Design verification and as-built quantity confirmation: Moreover, it is important to compare the current terrain with design data after construction. Overlaying acquired point clouds with the design model allows color-coded visualization of where fill is deficient or excessive relative to the required shape. For example, you can instantly see how many cubic meters of fill are lacking from the design surface or whether any areas were over-excavated. Being able to digitally verify as-built quantities helps prevent rework and greatly contributes to ensuring construction quality.

Point Cloud Data and Volume Calculation Workflow (Photogrammetry or Scanning → Point Cloud → Automatic Cloud Calculation)

Using high-precision positioning and digital measurement technology, earthwork volume calculations can be performed in the following steps. Let’s review the process from point cloud acquisition by photogrammetry or 3D scanning to automatic cloud-based calculation.

• Acquiring site data: First, measure the current conditions of the area whose volume you want to know. There are two main methods: (a) photogrammetry using a drone or camera: taking many photos of the site and using software to analyze and create a 3D model; (b) 3D scanning with a smartphone or LiDAR-equipped device: walking on the ground while holding up the smartphone to directly scan terrain and objects and acquire point cloud data. In both cases, correcting position information with high-precision positioning at key points prevents accumulated errors and enables precise measurement.

• Generating point cloud data: From the acquired photos or scan data, generate point cloud data, a collection of countless points that represent the terrain. In photogrammetry, point cloud generation can be automated on cloud services, while smartphone scans can create point clouds directly on the device. When combined with high-precision GNSS, the point cloud is assigned real-world coordinates (absolute coordinates), so it aligns precisely with design data or maps when overlaid later. In this way, you obtain a precise 3D model that digitally replicates the site.

• Automatic volume calculation in the cloud: Use the completed point cloud to calculate required earthwork volumes. Upload the data to cloud-based point cloud processing tools, and the software will automatically compute volumes when you specify the target area. For example, you can set a reference plane height to determine fill capacity, or compare the measured terrain point cloud with the design model to compute over- or under-fill in one click. Using a cloud 3D viewer, you can measure distances, areas, and volumes in a browser without installing specialized software, and tasks that were previously difficult—such as measuring the length of the top edge of a slope—can be done instantly. Calculation results can be checked in numeric reports, visualized intuitively as heat maps (color-coded), or output as cross-sections automatically.

Other Applications (Stake Setting, As-Built Management, Fixed-Point Photos, Comparisons)

Smartphone high-precision positioning improves many field operations beyond earthwork volume calculations. Other major applications include:

• Stake setting (layout): Accurately placing stakes or markers on site according to the design drawings. A smartphone compatible with high-precision positioning can navigate direction and distance to the specified coordinates, making layout far more efficient than using tape measures or transits. Workers simply follow arrow guidance on the smartphone screen and mark the spot upon arrival. Multiple stake settings can be completed quickly, allowing staff without surveying expertise to perform accurate layout.

• As-built management: Smartphone positioning is also useful for verifying and recording shapes and dimensions after construction completion. By acquiring high-precision point cloud data, you can thoroughly inspect whether completed terrain or structures match design dimensions and shapes. For example, you can directly measure embankment heights, slope gradients, and foundation excavation depths from point clouds to check deviations from design. As-built checks that were previously done by sampling can now be performed comprehensively and densely with point clouds, dramatically improving proof of quality. Point cloud data can be used directly to prepare as-built documentation, serving as valuable records for future reference.

• Fixed-point photo records: Using a smartphone’s high-precision positioning, it’s easy to attach positional and orientation data to photos for management. Taking photos at predetermined points on a regular basis accumulates fixed-point observation data with consistent position and angle. This enables time-series comparison of construction progress or post-disaster terrain changes. Uploading photos to the cloud allows plotting photo locations on a map for list display or easily comparing past and present photos on drawings.

• Data comparison and AR use: Overlaying high-precision positioning data for comparison is a powerful use case. For example, comparing point clouds scanned at different times reveals terrain volume changes or deformations in detail. Using a smartphone app’s AR (augmented reality) feature, you can overlay a 3D design model on the live camera view to intuitively check differences between as-built conditions and drawings on site. These functions are possible because of high positional accuracy, allowing immediate detection of misalignments or deficiencies that could not be identified by visual inspection alone.

Easy Introduction of High-Precision Positioning with LRTK and Its Effects

Finally, as an easy-to-start solution for on-site use of high-precision positioning, we introduce our LRTK service. LRTK is a system that combines a smartphone, a dedicated compact GNSS device, and cloud services, designed to enable anyone to easily introduce centimeter-class positioning on site. Functions such as earthwork volume calculation, point cloud scanning, stake-setting navigation, photogrammetry, and AR display—as described in this article—are available all-in-one in one app. Offered as a subscription with low initial costs, you can start operating without investing in expensive surveying equipment. Bringing equipment to the site is light—just a smartphone and a pocket-sized receiver—and the simple operation training required allows site staff themselves to perform measurements.

By introducing LRTK, earthwork field measurements that previously took half a day can be completed in tens of minutes, and the data can be shared to the cloud and checked from the office immediately. Efficiency and labor-saving effects from high-precision positioning have been reported in national demonstrations as up to a 70% reduction in work time, greatly contributing to on-site productivity improvements and labor shortage countermeasures. From a safety perspective, it also reduces the need for people to enter hazardous areas. Now that the "era of measuring with smartphones" has arrived, LRTK makes it easy for anyone to incorporate high-precision positioning into the field. Why not ride this new wave of technology and work on innovating field operations, starting with earthwork volume calculations?