Table of Contents

• The need to instantly calculate soil volumes on site

• Traditional methods of soil volume measurement and their challenges

• Emergence of surveying tools that complete the job with only a smartphone

• Benefits of smartphone point-cloud surveying

• Use of high-precision positioning technology (RTK)

• Data sharing via cloud integration

• Use cases at civil engineering construction sites

• Use cases at land development sites

• Use cases in disaster investigation and recovery

• Simple smartphone surveying enabled by LRTK

• FAQ

The need to instantly calculate soil volumes on site

In civil engineering, land development, and disaster recovery sites, there is a strong demand for tools that can “calculate soil volumes on the spot.” If excavation and fill volumes can be determined quickly, progress management and cost control improve dramatically. Traditionally, soil-volume assessment often relied on experience and intuition; when errors occur, they can lead to rework and increased costs. Being able to immediately derive accurate soil volumes on site is essential for smooth construction progress and sound decision-making.

In recent years the construction industry has also been swept by DX (digital transformation), and improving the accuracy of as-built and progress management has become a priority. Initiatives led by the Ministry of Land, Infrastructure, Transport and Tourism such as “i-Construction” are promoting the need to streamline labor-intensive surveying tasks with digital technology. Against this backdrop, expectations have grown enormously for new surveying tools that enable the site personnel themselves to easily obtain immediate results—the so-called “instant on-site volume” capability.

Traditional methods of soil volume measurement and their challenges

A variety of methods have been used to calculate soil volumes on site, but each has its pros and cons, and doing so in real time and easily has been challenging. The main traditional methods and their issues are as follows.

• Manual surveying and calculation: Surveyors using transits or levels obtain points painstakingly and calculate volumes using methods like the average cross-section method. While accuracy is high, this approach requires enormous time and effort and specialized knowledge. It is not realistic to perform such detailed surveying every time in a busy field.

• Estimates based on equipment operation or truck counts: Some sites estimate soil volume roughly from the number of dump truck trips or shovel loadings. However, accuracy is poor and differences from the actual volume can be large. Such estimates serve only as rough guidelines and cannot be considered precise volumes.

• Drone aerial photogrammetry: A method that has become popular recently is using drones to capture site imagery and generate 3D models or point clouds from photos to compute soil volumes. It has the advantage of covering wide areas quickly, but obtaining flight permissions, requiring specialized operators, and the need for time-consuming, high-skill image processing are drawbacks. Weather also greatly affects operations, so it is not something that can be done “anytime instantly.”

• Terrestrial 3D laser scanners: Ground-based high-precision laser scanners can scan a site and produce point-cloud measurements. They yield extremely detailed data, but the equipment is expensive and difficult to operate, and using a single unit across sites required skilled technicians. The volume of acquired data is vast and processing is demanding, making such systems impractical for casual use by field personnel.

Thus, traditional methods have issues in terms of “ease,” “immediacy,” and “versatility.” Even when the latest equipment is introduced, it is often underutilized because it’s hard to operate in the field or data processing takes too long. What has long been sought is a method that allows anyone on a busy site to quickly measure soil volumes without special effort.

Emergence of surveying tools that complete the job with only a smartphone

Responding to these needs, surveying tools that complete the workflow using only a smartphone have emerged in recent years. By leveraging smartphone cameras and various sensors to scan site topography and fills on the spot, these innovative methods can acquire detailed 3D data (point clouds) in a short time.

For example, recent high-performance smartphones include small LiDAR sensors in some models. With LiDAR, distances to surrounding shapes a few meters ahead can be measured instantly. In addition, by combining multiple photos or videos taken with a smartphone camera and using photogrammetry techniques, wide-area terrain can be modeled in 3D. In other words, without special surveying equipment, a handheld smartphone can quickly transform into a 3D measurement device.

Particularly noteworthy are solutions that combine smartphones with high-precision GNSS (GPS) receivers. Smartphones alone can obtain shape data with LiDAR or cameras, but built-in GPS traditionally had errors on the order of several meters. By attaching a dedicated GNSS receiver that supports Real-Time Kinematic (RTK) to a smartphone, positioning errors can be reduced to the centimeter level (half-inch accuracy). Because highly accurate position coordinates can be directly assigned to the point clouds acquired by the smartphone, accurate 3D data aligned with the site coordinate system can be created on the spot.

This combination of smartphone + high-precision GNSS is making precise point-cloud surveying possible for non-experts with a single tap. Since only a palm-sized device and a smartphone are required, this approach is attracting attention as a new high-precision surveying method that overturns conventional wisdom on the jobsite.

Benefits of smartphone point-cloud surveying

Point-cloud scanning using smartphones offers many advantages that traditional methods lack. The main points are listed below.

• Speed and immediacy: Walking around the site and scanning for a few minutes can produce volume calculation results immediately afterward. It’s possible to measure in the evening and instantly confirm that day’s excavation quantities numerically. Data processing is automated, greatly reducing waiting time for results.

• Ease and labor savings: Only a smartphone and a small positioning device are required, so there is no need to transport heavy equipment or perform complex setup. Intuitive smartphone apps allow anyone to take measurements, so even untrained workers can operate them. The convenience of “take it out of your pocket and measure right away” is a major asset for the field.

• Improved safety: Hazardous steep slopes or areas with large accumulations of soil can be scanned from a distance with a smartphone, allowing shapes to be understood without sending people into dangerous locations. This contributes to worker safety.

• High-precision results: The combination of RTK-capable high-precision GNSS and point-cloud measurement technologies provides data with sufficient accuracy for soil-volume calculations. It can maintain accuracy comparable to traditional manual surveying while covering wider areas, enabling efficient acquisition of highly reliable data.

• Cost reduction: There is less need to outsource surveying to specialist firms or purchase expensive equipment. Using smartphones reduces initial investment and allows in-house measurements as needed, delivering excellent cost performance. With nearly every field staff member carrying a smartphone, they can be fully utilized as “one surveying device per person.”

• Ease of continuous use: Tools that are difficult to operate or usable only by certain people do not persist in use. Smartphone point-cloud surveying is usable by “anyone, immediately, anywhere,” making it easy to incorporate into daily operations. It can become a routine on-site practice and ultimately raise the overall surveying literacy of the site.

Of course, simple smartphone-based surveying cannot match ultra-high-precision fixed laser scanners in measurement range or accuracy. However, for routine as-built checks, medium to small soil-volume confirmations, and disaster-time documentation, smartphone surveying provides the necessary and sufficient accuracy in many field tasks. Above all, the ease of “being able to measure anytime” is the greatest strength for continued on-site use. By casually taking many measurements and accumulating data, construction management can shift dramatically from “relying on intuition and experience” to data-driven management.

Use of high-precision positioning technology (RTK)

An essential element of smartphone point-cloud surveying is high-precision positioning via RTK. RTK (Real-Time Kinematic) is a technique that uses correction information broadcast from a reference station to reduce GPS positioning errors to the centimeter level (half-inch accuracy). General smartphone GPS has errors of several meters, but using an RTK-capable receiver can limit horizontal and vertical errors to the order of a few centimeters.

Construction sites require strict position alignment based on reference points, so absolute coordinates are necessary for acquired point-cloud data. By attaching an RTK-GNSS receiver to a smartphone, scanned point clouds can be given absolute coordinates such as Japan’s plane rectangular coordinate system. This makes it easy to compare acquired point clouds with design drawings or existing survey coordinates and to accurately compare data from different dates.

For example, some smartphone surveying tools utilize the Geospatial Information Authority of Japan’s network of permanent GNSS stations (or centimeter-level augmentation services for the Quasi-Zenith Satellite System such as CLAS) to enable high-precision positioning even where mobile signals are unavailable. This allows stable position-tagged point-cloud acquisition in environments such as mountain areas where positioning would normally be unstable. Because there is reliability in high-precision positioning, soil-volume calculation results obtained by smartphone can be confidently used on site.

Data sharing via cloud integration

Point-cloud data and measurement results obtained with a smartphone can be further leveraged by integrating with cloud services. Cloud integration provides the following advantages.

• Immediate sharing: Scanned data can be uploaded to the cloud from the smartphone with one tap. Data can be shared instantly over the Internet with the office PC and other stakeholders, enabling immediate reporting and review of on-site volume measurements. Remote supervisors and clients can receive information in real time, speeding up decision making.

• Automatic analysis and viewers: Cloud services automatically process and analyze point-cloud data, generating volume calculation results and cross-sectional diagrams in a short time. Users can view results in a web browser without operating advanced software. Some services allow anyone to view and measure 3D point clouds by simply opening a URL, eliminating the need for high-performance PCs or specialized software.

• Data storage and reuse: Data stored in the cloud are safely preserved and can be retrieved as needed. Centralized long-term management of as-built data and soil-volume measurement histories for each site enables later verification and comparison as a “time capsule” of the site. It reduces the risk of loss compared to paper documents or files kept on a single person’s PC and allows access from anywhere within the organization.

• Interoperability with other systems: Via the cloud, measurement data can be overlaid with CAD drawings or BIM models, or exported into report formats for other systems. Services that automatically generate as-built management forms from point clouds are emerging, enabling unified data utilization in the cloud.

By linking to the cloud, on-site data do not remain trapped on an individual’s PC but become shared organizational assets. Information flows from the field to the cloud and from the cloud to the office, enabling collaboration that transcends the boundary between site and office.

Use cases at civil engineering construction sites

Now let’s look at concrete cases of using smartphone point-cloud scanning in on-site operations. First, applications for soil-volume management at typical civil engineering sites.

In road and river works, accurately managing the quantities of excavated and backfilled soil is critical for schedule and cost control. At one site, what had previously been measured only about once a week was changed so that the site supervisor scans excavation areas with a smartphone at the end of each workday. With a scan that takes only about five minutes of walking while pointing the smartphone, the day’s excavation and fill volumes were obtained numerically and immediately reflected in daily reports and progress reports. The truckload-equivalent removal volumes automatically calculated from the point clouds closely matched estimates based on actual dump truck trips, providing highly reliable progress monitoring.

This enabled quantitative progress management based on data instead of vague impressions like “it feels about X percent complete.” With measured data, decisions on next-day equipment allocation and earthwork planning could be made accurately, reducing unnecessary equipment waiting time and material ordering mistakes and improving overall construction efficiency. On some sites, staff commented, “We were skeptical at first, but now we’re uneasy unless we scan every day,” showing how smartphone volume measurement has become a daily routine.

Use cases at land development sites

In large-scale land development such as residential land formation, massive cut-and-fill operations take place. Smartphone point-cloud surveying is also highly effective in these development sites.

During land development, it is necessary to continuously check differences between the volume estimated at the design stage and the actual on-site volumes. For example, if excavation is progressing faster than planned, backfill plans need to be revised early; conversely, if fill is likely to be insufficient, additional materials must be ordered. By periodically scanning the entire site with a smartphone and overlaying the resulting terrain model with the design data, design vs. actual soil-volume differences can be identified at a glance. Some tools automatically color-code the acquired point-cloud data to show elevation differences from the design surface, instantly revealing where the site is higher or lower than planned.

At one development project, as-built shapes were recorded with smartphone point-cloud surveying upon completion of each work type or process, and discrepancies from the design volumes were checked each time. Volumes that previously became apparent only during mid-term inspections could now be identified in real time, minimizing rework and material waste. At project completion, the accumulated point-cloud data serve as a digital record of the completed terrain, useful for future maintenance planning and handover documentation to the client.

Use cases in disaster investigation and recovery

In emergencies such as landslides or earthquakes, smartphone point-cloud scanning is extremely useful. Rapidly grasping the full extent of damage and formulating appropriate recovery plans is essential at disaster sites.

For example, at a large landslide site, quickly estimating the volume of collapsed material allows determination of the required heavy equipment, number of dump trucks, and recovery strategy. At one heavy-rain disaster site, municipal staff used drones immediately after the event to perform wide-area photogrammetry and create a point-cloud model of the entire collapsed slope to calculate volumes. In nearby areas they performed detailed smartphone point-cloud scans to record the collapse details and combined this with the wide-area drone model for three-dimensional analysis of damage. The objective 3D data made it possible to grasp the disaster scale that was hard to understand from flat maps alone, greatly aiding consideration of recovery methods.

In another 2023 earthquake case, a local construction company that had just introduced smartphone point-cloud equipment scanned the disaster site with smartphones and shared point clouds and photos with relevant agencies immediately. Even in mountainous areas without mobile coverage, centimeter-level positioning was obtained using satellite-based correction signals, allowing precise documentation of severed roads. This data helped in planning recovery work and damage assessment and sped up initial response.

Thus, simple point-cloud surveying using smartphones and drones has become a powerful tool for field recording and reporting in emergencies. Digital technologies now allow wide-area, detailed information to be obtained rapidly—even at disaster sites that previously could only be partly surveyed by visual inspection or manual methods. The data collected are used from recovery planning to later verification, significantly supporting disaster response.

Simple smartphone surveying enabled by LRTK

As described above, tools that allow point-cloud scans with a smartphone and on-site volume calculations bring revolutionary effects in many situations. One product that supports this simple smartphone surveying is LRTK. LRTK is a solution that turns a smartphone into a centimeter-level (half-inch accuracy) surveying instrument, consisting of a high-precision GNSS terminal, a dedicated app, and cloud services.

The greatest feature of LRTK is that by attaching a compact RTK-GNSS receiver to a smartphone it enables high-precision positioning while allowing anyone to easily acquire point-cloud data with the phone’s camera. On site, an operator simply holds an LRTK-equipped smartphone and walks while pointing the camera to scan surrounding structures and terrain. The acquired point-cloud data are automatically tagged with absolute coordinates, and area, distance, and volume measurements are executed on the cloud right away. Measurement results can be checked on the smartphone screen immediately, and with one tap can be saved to the cloud and shared with stakeholders.

LRTK also provides point-cloud measurements that conform to the Ministry of Land, Infrastructure, Transport and Tourism’s “as-built management guidelines,” offering accuracy sufficient to submit as official as-built measurement results. Functions tailored to civil engineering needs—such as instantly calculating fill volumes on site and displaying surplus/deficit relative to design values—are included. Even for tens of thousands of cubic meters of soil across large sites, dividing the area into sections and scanning sequentially allows accurate measurement.

Cloud integration features are also well developed: point-cloud data and positioning information acquired with LRTK can be synchronized to the dedicated cloud with one button. Using an installation-free web viewer, all stakeholders including clients and designers can view 3D data, eliminating the need to transfer files via email or USB and connecting sites and offices in real time. With this cloud-enabled functionality, LRTK’s combination of “high precision,” “ease of use,” and “cloud integration” is transforming civil construction and surveying work by becoming a new everyday tool that anyone on site can use. If you have challenges with soil-volume calculations or surveying tasks, consider smartphone surveying enabled by LRTK. Cutting-edge technology can dramatically boost your site’s productivity and safety.

FAQ

Q: What level of accuracy can be expected when measuring point clouds with a smartphone? A: By combining a smartphone with an RTK-capable high-precision GNSS receiver, horizontal and vertical errors can be confined to the order of a few centimeters (half-inch accuracy). This is sufficient for typical civil engineering as-built checks and soil-volume calculations and allows measurements that meet national standards.

Q: Can smartphone surveying be used without special knowledge or qualifications? A: Yes. Smartphone point-cloud surveying is designed so anyone can perform measurements with intuitive app operations. Complex equipment setup and surveying calculations are automated, so people without specialist knowledge can easily use it. After short on-site training, many staff can start using it immediately.

Q: How long does a measurement take? A: It depends on the object and area, but for a fill of about 30 m (98.4 ft) square, walking around with a smartphone for a few minutes can acquire the necessary point-cloud data. Volume calculation is automatically processed on the cloud, so the entire workflow can take less than about 10 minutes.

Q: Can it be used where there is no network coverage on site? A: It depends on the tool, but in the case of LRTK, centimeter-level positioning is possible using high-precision augmentation signals for the Quasi-Zenith Satellite System (such as CLAS), so centimeter-level positioning can be achieved even in areas without mobile coverage. Cloud synchronization can be done later after moving to an area with signal; in offline environments data can be stored on the device and uploaded in batch afterward.

Q: What are the advantages of smartphone surveying compared to drone surveying? A: Drones are strong at quickly surveying wide areas but have constraints such as flight permissions, weather, and piloting skills. Smartphone surveying is more nimble and can measure in environments where drones cannot operate—indoors, tunnels, or under linings, for example. Smartphones are also easier to use on a daily basis, making them better suited for frequent progress checks and small-scale measurements. Using both appropriately allows building a more efficient site-measurement system.