Table of Contents

• Why on-site earthwork volume calculation is required

• Challenges of conventional earthwork measurement methods

• What an all-in-one smartphone 3D surveying tool is

• Accurately capturing site shapes with point cloud measurement

• Automating volume calculation with cloud integration

• Benefits of introducing a smartphone surveying tool

• On-site use cases

• Simple surveying enabled by LRTK

• FAQ

Why on-site earthwork volume calculation is required

On construction sites and civil engineering works, it is extremely important to accurately know “how much earth has been moved.” Knowing the volume of excavated soil or fill allows you to estimate the number of dump trucks required and to manage construction progress precisely. Conversely, misjudging earth volumes can lead to insufficient truck arrangements and schedule delays, or increased costs for disposing of surplus soil, affecting the entire project. Accurate volume calculations are also indispensable for reporting to clients and for as-built verification. However, calculating volumes instantly on site has not been easy, and traditional methods required time and effort. Site supervisors and workers want to know volumes immediately when needed, but there have been limited means to make that possible.

Challenges of conventional earthwork measurement methods

Traditionally, several methods have been used for on-site earthwork measurement. For example, one approach measures terrain elevations with surveying instruments, creates cross-sections, and then calculates volumes. But this method typically requires multiple crews and takes a long time from surveying to calculation. Because results cannot be obtained immediately on site, decisions about construction often have to be deferred. Accurate readings and calculations are difficult without experienced personnel, making the work prone to being “person-dependent.” Another approach has been to estimate rough volumes based on visual judgment or the number of dump trucks, but this lacks precision and reliability. Moreover, for irregularly shaped spoil heaps or highly undulating terrain, point-by-point measurements may fail to capture the shape fully, resulting in large errors. In this way, conventional earthwork measurement has faced challenges in both efficiency and accuracy.

What an all-in-one smartphone 3D surveying tool is

Recently, an all-in-one smartphone 3D surveying tool has emerged to address these issues. This consists of an ultra-compact surveying device attached to a smartphone and a dedicated app, designed so that anyone can easily perform high-precision surveying. It works with the smartphone’s camera and LiDAR sensor to acquire site data as three-dimensional data. In addition, it incorporates a high-precision GNSS receiver (RTK-capable), achieving centimeter-level positioning accuracy (cm level accuracy (half-inch accuracy)), which is difficult with ordinary smartphone GPS. For example, in Japan, compatibility with the Quasi-Zenith Satellite System Michibiki’s high-precision positioning service (CLAS) ensures stable accuracy even in mountainous areas outside of mobile coverage. As a revolutionary tool that completes on-site measurement with only a smartphone and a small device—without heavy tripods or stationary surveying instruments—it has attracted attention. Such digital surveying technologies also align with construction DX initiatives promoted by the Ministry of Land, Infrastructure, Transport and Tourism, such as *i-Construction*, and are expected to become even more widespread.

Accurately capturing site shapes with point cloud measurement

One of the main features of an all-in-one smartphone 3D surveying tool is the ability to digitize the entire site shape via point cloud measurement. Point cloud measurement records the surface of an object as a three-dimensional set of innumerable points (point cloud data). There is no need to measure each height and write it down as in conventional surveying; simply walk around the site holding the smartphone to scan the surrounding terrain, fills, and excavations. The LiDAR sensor on LiDAR-equipped smartphones measures on the order of hundreds of thousands of points per second to capture shape, and the GNSS in the small surveying device provides absolute coordinates (latitude, longitude, height) for each point, so the acquired point cloud includes accurate position information. Even complex terrain or large mounds of earth can be captured in detailed shape data much faster than manual measurement. For example, even a pile of soil with irregular heights and slopes can be visualized as point cloud data, dramatically improving the accuracy of volume calculations.

Automating volume calculation with cloud integration

Once point cloud data is acquired, the next step is to calculate volume from that data. All-in-one smartphone 3D surveying tools can automate this earthwork volume calculation process. Dedicated apps or cloud services can instantly compute volumes from the acquired point clouds. For fill, for example, the system analyzes the difference between the fill surface and the ground surface from the point cloud to calculate the volume. Where previously survey data had to be taken back to the office for drafting and volume formula application, this work can now be completed on site. Processing massive point cloud data is handled by high-performance servers in the cloud, so you can get results quickly without worrying about load on the smartphone. Cloud integration also allows measurement results to be shared instantly over the internet. Measured volumes can be shared with headquarters and stakeholders immediately, reducing the need to return to the office to prepare reports. It is revolutionary in that anyone can obtain accurate volumes with the push of a button, without specialized CAD software or complex manual calculations. Furthermore, cloud platforms can perform advanced analyses such as generating cross-sections or measuring distances and areas from point clouds. Because they can be used in a browser without installing dedicated software, it is easy for site and office staff to discuss using the same data.

Benefits of introducing a smartphone surveying tool

Introducing an all-in-one smartphone 3D surveying tool to the site offers many advantages. The main benefits are summarized below.

• Immediate results and improved efficiency: Whereas traditional workflows from surveying to volume calculation could take days, this tool can deliver results the same day. Reduced waiting times speed up construction progress management. Because on-site data is shared via the cloud immediately, supervisors and other departments can confirm it right away, accelerating decisions and instructions and preventing rework.

• Labor savings and countermeasures for labor shortages: Since a single person can perform measurements with just a smartphone and a small device, there is no need to assign multiple people to the site. This is a major benefit for the construction industry, which faces serious labor shortages. Enabling site staff to measure themselves without relying on experienced surveyors also reduces the burden of human resource development.

• High precision and high reliability: RTK-GNSS dramatically improves positioning accuracy, enabling measurements with horizontal errors of about 1–2 cm (0.4–0.8 in) and vertical errors around 3 cm (1.2 in), versus about 5–10 m errors for ordinary smartphone GPS. Volume calculations based on these high-precision data are highly reliable, eliminating errors from visual estimates and manual calculations. This contributes to improved as-built verification accuracy and overall quality control.

• Improved safety: There is less need to carry heavy tripods or surveying instruments into hazardous areas, reducing physical burden. Because measurements can be taken from a safe distance with a small device and smartphone, surveying-related risks are reduced. For example, road-side surveying traditionally required traffic controllers and significant time, but switching to quick smartphone surveying reduces workers’ exposure time on the road and enhances safety.

• Data sharing and utilization: Measurement data can be shared internally and externally via the cloud, allowing stakeholders to check results in real time. Even if a client cannot visit the site, sharing 3D data and figures online lets them understand the situation. Accumulated volume data in the cloud also has future value—for example, it can be used as reference for estimating similar projects or planning schedules.

• Cost reduction: Because surveying can be completed with fewer people and in less time, labor, heavy equipment, and equipment costs can be significantly reduced. Reducing downtime for surveying also shortens construction schedules, yielding indirect cost savings.

On-site use cases

What specific on-site scenarios can an all-in-one smartphone 3D surveying tool help with? Below are some examples.

• Verifying volumes of fills and backfills: When new fill is placed on site, you can measure and record the volume of the newly placed soil immediately. By comparing with design quantities, you can instantly tell whether additional soil is needed or whether there is surplus. The same applies to backfilling—site staff can check on-site whether backfill has reached the specified height.

• Managing excavated volumes: In excavation work, managing the volume of soil removed is important. By scanning the terrain before and after excavation with a smartphone, you can accurately calculate how much soil was removed. This enables precise management of the number of dump trucks required and appropriate arrangements for disposal sites. Tasks previously estimated from truck counts and payloads are replaced by data-driven management, reducing waste and uncertainty.

• Measuring stockpiles of spoil and materials: Scan piles of spoil, gravel, or crushed stone on site and calculate their volumes to monitor inventory. Regular measurements show material depletion at a glance, preventing missed ordering or shipping opportunities. Changes that are hard to see in photos or by eye can be quantified, improving inventory control.

• As-built verification and reporting: If completed fills or developed terrain are captured as point clouds, you can use them to verify whether construction matches the design. Overlaying the design model with the current point cloud highlights areas lacking height or places with excess fill via color mapping, and you can calculate the volume needed for corrections. These results can be shared via the cloud with supervisors or clients and presented as 3D views or colored maps for intuitive understanding. Report preparation becomes smoother, and explanations for inspections and handovers become easier.

In this way, all-in-one smartphone 3D surveying tools can be applied to many on-site tasks including earthwork volume calculation, significantly improving work efficiency and quality control.

Simple surveying enabled by LRTK

One concrete example of a tool that realizes the above-site volume calculation and 3D surveying advantages is LRTK. LRTK is a device with a compact RTK-GNSS receiver that attaches to a smartphone with a single touch and is used together with a dedicated app. This turns an ordinary smartphone into a high-precision surveying instrument. Its compact design includes both battery and antenna, and everything fits in one hand. Without transporting and setting up total stations that can weigh several kg, surveying can be completed with a smartphone in hand using LRTK. With LRTK, anyone can begin on-site point cloud surveying after a short training session and instantly calculate the volumes of fills and excavations. Positioning accuracy reaches levels comparable to traditional professional instruments—about horizontal 1–2 cm (0.4–0.8 in) and vertical around 3 cm (1.2 in). Acquired point cloud data can be uploaded to LRTK’s cloud service for analysis, and accurate volume results can be obtained within minutes of scanning on site. For example, even large volumes exceeding 200 cubic meters can be captured by simply walking with a smartphone in hand when using LRTK. Tasks that previously required specialist operators with heavy machinery or optical instruments are being transformed by LRTK into accessible “simple surveying” anyone can perform. LRTK also includes non-surveying site support functions such as guidance for stake/pile positions and AR visualization of underground buried objects. As a solution that promotes on-site DX and dramatically improves efficiency and accuracy, LRTK is attracting attention. Its adoption is rapidly increasing at domestic construction sites, and it is expected to be a key driver for advancing site DX. By leveraging such advanced tools, on-site earthwork volume calculation can be carried out more quickly and reliably. Consider adopting new technologies to pursue smart site operations that balance productivity and safety.

FAQ

Q: Can it be used without special qualifications or surveying knowledge?

A: Yes, as long as you can perform basic smartphone operations, you can use it without specialized knowledge. The dedicated app’s interface is intuitive and easy to understand, allowing surveying with simple operations like tapping the point you want to measure or starting a scan. Complex settings and calculations are processed automatically in the background, enabling “simple surveying” that anyone can handle. In practice, many sites report that workers using the tool for the first time could start immediately after a brief explanation.

Q: Are there limitations on measurement range or distance?

A: It depends on the tool’s performance, but the effective range of typical smartphone-mounted LiDAR is on the order of several tens of meters. For example, LRTK can acquire point clouds of objects up to about 60 m (196.9 ft) away. If you need to measure a very large site at once, you can divide the area and scan each section, then merge the point clouds later. Basically, as long as the target is within line of sight, measurement is possible.

Q: What level of accuracy can be achieved for volume calculations?

A: Volumes can be calculated with errors on the order of a few centimeters. Combining high-precision positioning from RTK-GNSS with point cloud measurement yields highly accurate shape data that serves as the basis for volume calculation. Therefore, calculated volumes are extremely reliable compared to conventional manual estimates. However, accuracy may vary slightly depending on the measurement environment (e.g., nearby tall buildings or dense trees).

Q: How long does measurement and volume calculation take?

A: It depends on the survey area, but for small sites it can be completed in a few minutes. For example, scanning an embankment a few tens of meters across can finish in under about 5 minutes of walking with a smartphone. Cloud processing of the acquired point clouds also takes a few minutes, allowing you to check accurate volume results on site. Compared with conventional surveying, which required days for data organization and calculation, this represents a drastic time reduction.

Q: What advantages does this have over drone surveying?

A: Smartphone all-in-one tools excel in ease of use and immediacy compared with drone surveying. Drone surveying has the advantage of capturing wide areas from above, but it is subject to weather and flight permission constraints, and creating point clouds from photos takes time. In Japan, drone operation may also require qualifications and permits. In contrast, tools like a smartphone with LRTK allow you to start walking and measuring as soon as you arrive on site and get results via the cloud on the spot. They also work well in narrow areas and indoors, which is another major advantage.

Q: How are survey data stored and utilized?

A: Acquired data are stored in the cloud and can be viewed or downloaded as needed. Point cloud data and measurement results are uploaded to a dedicated cloud service and can be checked in a browser as a 3D view or numeric report. Data can be downloaded as CSV or drawing formats for use in other software. You can also issue shareable links so clients or subcontractors can view data without logging in, facilitating smooth information sharing among stakeholders. Accumulated cloud data can be used for internal documentation or as reference material for future projects.

Q: Can measurements be taken in rain or at night?

A: Basically yes, but you should take environment-appropriate precautions. LiDAR ranging functions in low-light conditions, so nighttime measurement is possible. However, take care to ensure safe footing, and if you are using the smartphone camera for imaging, lighting may be required. Light rain generally does not interfere with operation, but droplets on the sensor or lens can affect accuracy. Devices are designed to be water-resistant to some extent, but avoid using them in heavy rain and wait for calmer weather when possible.

Q: What smartphones are supported?

A: Most modern smartphones are supported in many cases. Dedicated devices attach to and are used with smartphones, and support both iOS and Android platforms so you can use your own device. LiDAR-equipped models are optimal for higher-density 3D scanning, but non-LiDAR phones may still generate point clouds via photogrammetry. Check the provider’s compatibility information for detailed supported models.