Instant On-site Measurement! The New Standard for High-Precision Surveying Completed with Just a Smartphone

Table of Contents

• The need to instantly calculate earthwork volumes on site

• Traditional earthwork measurement methods and their challenges

• Emergence of surveying tools that work with just a smartphone

• Advantages of smartphone point-cloud surveying

• Utilization 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 earthwork volumes on site

In civil engineering, land development, and disaster recovery sites, there is a strong demand for tools that can calculate earthwork volumes on the spot. Quickly understanding the volume of excavation or fill dramatically improves process and cost management efficiency. Traditionally, volume estimation often relied on experience and intuition, and errors could cause rework and increased costs. Being able to instantly determine accurate earthwork volumes on site is an indispensable factor for smooth construction progress and sound decision-making.

Moreover, in recent years the construction industry has been swept by DX (digital transformation), with increased emphasis on improving as-built and quantity management accuracy. Initiatives led by the Ministry of Land, Infrastructure, Transport and Tourism like "i-Construction" have increased the demand for digitizing and streamlining surveying tasks that used to be time-consuming. Within this context, expectations are rising for new surveying tools that enable site personnel themselves to easily obtain immediate results—what we might call “instant on-site earthwork”.

Traditional earthwork measurement methods and their challenges

Various methods have been used to calculate earthwork volumes on site, but each has pros and cons, and there have been hurdles to achieving real-time, easy operation. The main traditional methods for earthwork measurement and their challenges are as follows:

• Manual surveying and calculation: Surveyors using transits or levels take point measurements and calculate volumes using methods such as the average-end-area method. While accurate, this traditional approach requires enormous effort and time and demands specialized knowledge. Performing such meticulous surveying on a busy site every time is not realistic.

• Estimates based on equipment operation or truck counts: On sites, a simple method often used is to estimate volumes from the number of dump truck entries/exits or the number of excavator loads. However, this lacks precision and often diverges significantly from actual volumes. It serves only as a rough guide and cannot be considered an accurate volume.

• Drone photogrammetry: A more recently adopted method is to fly a drone to capture aerial photos, generate 3D models or point clouds from the images, and calculate volumes. While it has the advantage of covering wide areas in a short time, challenges include obtaining flight permission, requiring expert operators, and the need for time-consuming and advanced image processing. It is also susceptible to weather, so it cannot always provide “immediate, anytime” results.

• Terrestrial 3D laser scanners: Ground-mounted high-precision laser scanners can scan sites and generate point-cloud measurements. They produce extremely precise data, but the equipment is expensive, difficult to operate, and typically requires skilled technicians to use on-site. The data volumes are massive, imposing heavy processing burdens, and these systems are not something every site worker can easily use.

As shown above, traditional methods have faced issues in terms of “ease of use,” “immediacy,” and “versatility.” Even when introducing cutting-edge equipment, sites sometimes fail to utilize it fully because of the complexity of operation or long processing times. What has long been sought is a method that allows anyone on a busy site to quickly measure earthwork volumes without special effort.

Emergence of surveying tools that work with just a smartphone

To meet these needs, smartphone-only surveying tools have recently appeared. These tools leverage smartphone cameras and various sensors to scan site topography and fills on the spot, enabling rapid acquisition of detailed 3D data (point clouds) in a short time.

For example, many modern high-performance smartphones include compact LiDAR sensors. LiDAR can instantly measure distances to surrounding shapes several meters ahead. Also, by combining multiple photos or video shot with a smartphone camera, photogrammetry can create 3D models of wide-area terrain. In other words, without special surveying equipment, an ordinary smartphone can quickly become a 3D measurement instrument.

Particularly notable are solutions that combine the smartphone with a high-precision GNSS (GPS) receiver. While a smartphone alone can capture shape data with LiDAR or a camera, its built-in GPS traditionally has meter-level errors. By attaching a dedicated GNSS receiver that supports Real-Time Kinematic (RTK) positioning to the smartphone, positioning errors can be reduced to the centimeter level (centimeter-level (cm level accuracy (half-inch accuracy))). Because high-precision coordinates can be directly appended to the point clouds captured by the smartphone, accurate 3D data aligned to the site coordinate system can be produced on the spot.

This combination of smartphone + high-precision GNSS is making precise point-cloud surveying achievable for non-experts with a single button press. Because all that is needed is a pocket-sized device and a smartphone, this approach is attracting attention as a revolutionary, high-precision surveying method that overturns conventional practice on site.

Advantages of smartphone point-cloud surveying

Point-cloud scanning using a smartphone offers many benefits absent from traditional methods. Key points include:

• Speed and immediacy: Walk around the site and scan for a few minutes, and you can get volume calculation results immediately afterward. Operations such as measuring in the evening and instantly confirming that day’s excavation volume are feasible. Data processing is automated, significantly reducing wait times for results.

• Ease of use and labor savings: With only a smartphone and a small positioning device, there is no need to transport heavy equipment or perform complex setup. Intuitive smartphone apps allow anyone to measure, so workers without special training can operate them. The convenience of “taking it out of your pocket and measuring right away” is a major asset on site.

• Improved safety: You can scan from a distance to understand shapes on dangerous steep slopes or in areas with large amounts of sediment. This prevents workers from entering hazardous areas and contributes to on-site safety.

• High-precision results: Combining RTK-capable high-precision GNSS with point-cloud measurement technologies yields data accurate enough for earthwork calculations. It can maintain accuracy comparable to manual surveying while covering broader areas, enabling efficient acquisition of highly reliable data.

• Cost reduction: There is less need to outsource surveying to specialized firms or buy expensive equipment. Leveraging smartphones lowers initial investment and allows on-demand in-house measurement, delivering superior cost performance. Since most site staff already carry smartphones, they can be fully utilized as “one surveying instrument per person.”

• Ease of continued use: Tools that are difficult to operate or usable only by certain personnel rarely persist. Smartphone point-cloud surveying is usable by “anyone, anytime, anywhere,” making it easy to incorporate into daily work. It can become routine on site and, in turn, help raise overall surveying literacy across the team.

Of course, smartphone-based simple surveying cannot match fixed, ultra-high-precision laser scanners in every range or accuracy. However, for routine as-built checks, small-to-medium earthwork confirmations, and disaster-event documentation, it provides the necessary and sufficient accuracy. Above all, the convenience of “measure anytime, instantly” is the greatest strength for continued on-site use. Measuring often and accumulating data will shift construction management from reliance on “intuition and experience” to data-driven management.

Utilization of high-precision positioning technology (RTK)

High-precision positioning via RTK is indispensable when discussing smartphone point-cloud surveying. RTK (Real-Time Kinematic) is a technology that uses correction information transmitted from a reference station to reduce GPS positioning errors to the centimeter level (centimeter-level (cm level accuracy (half-inch accuracy))). A smartphone’s built-in GPS typically has meter-level errors, but using an RTK-capable receiver can limit both horizontal and vertical errors to a few centimeters.

On construction sites, strict alignment to reference points is required, so absolute coordinates are necessary for acquired point-cloud data. By attaching an RTK-GNSS receiver to the smartphone, scanned point clouds can be directly assigned 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 active control point network or augmentation services for the Quasi-Zenith Satellite System Michibiki (such as the centimeter-class augmentation service CLAS), enabling high-precision positioning even where mobile signals are unavailable. This allows stable position-enabled point-cloud data acquisition even in mountainous areas where positioning would normally be unstable. Because of the reliability of high-precision positioning, the earthwork calculations obtained with a 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. The advantages of cloud integration include:

• Immediate sharing: After scanning, data can be uploaded to the cloud from the smartphone with a single tap. It can be shared instantly with office PCs and other stakeholders over the Internet, allowing on-site measurements to be reported and reviewed immediately. Remote supervisors and clients can view information in real time, enabling rapid decision-making.

• Automatic analysis and viewer: On the cloud, point-cloud processing and analysis are automated, and volume calculations and cross-sections can be generated 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: Cloud-stored data are securely retained and can be retrieved as needed. It allows centralized long-term management of as-built and earthwork measurement history by site, serving as a “time capsule” for later verification and comparison. This reduces the risk of loss compared to paper documents or files on individual PCs and allows access from anywhere within the company.

• Integration with other systems: Via the cloud, measurement data can be overlaid with CAD drawings or BIM models or exported into report formats. Services that automatically create as-built management reports from point clouds are emerging, enabling consistent data utilization entirely in the cloud.

By connecting to the cloud, valuable on-site data do not remain buried on the operator’s PC but can be shared organization-wide. Information flows from the site to the cloud and from the cloud to the office, enabling collaboration that transcends the boundary between field and office.

Use cases at civil engineering construction sites

Now let’s look at concrete cases where smartphone point-cloud scanning has been applied to site tasks. First, an example of earthwork management in a typical civil engineering construction site.

In road and river works, accurately managing excavation and backfill volumes is critical for schedule and cost control. On one site, what had previously been measured for progress only about once a week was switched to a method where the site supervisor scans excavation areas with a smartphone every day at the end of the shift. With a scan taking only about five minutes of walking while holding the smartphone, they could quantify that day’s excavation and fill volumes and immediately reflect them in daily reports and progress sheets. Volumes of material removed, automatically calculated from the point clouds (converted into truckload equivalents), closely matched estimates based on actual truck transport counts, demonstrating high reliability in capturing site progress.

This enabled quantitative progress management based on data rather than vague impressions like “about X percent complete.” Using measured data to make decisions about the next day’s machinery allocation or earthwork plans reduced idle machine time and material ordering mistakes, improving overall construction efficiency. Some site personnel reported that “we were skeptical at first, but now we feel uneasy if we don’t scan every day,” indicating that smartphone volume measurement has become a daily routine.

Use cases at land development sites

In large-scale land development such as residential lot creation, massive cut-and-fill operations occur. Smartphone point-cloud surveying is also powerful in this context.

In development projects, it is necessary to constantly check differences between estimated earthwork volumes from design and actual on-site volumes. For example, if excavation proceeds more than planned, backfill plans must be revised early; conversely, if fill appears insufficient, additional material arrangements must be considered. By periodically scanning the entire site with a smartphone and overlaying the resulting terrain model with design data, the volume differences between design and actual conditions can be grasped at a glance. Tools in use can automatically color-code acquired point clouds to display elevation differences relative to the design surface, instantly showing where the site is higher or lower than planned.

On one development project, operators recorded as-built shapes with smartphone point-cloud surveys at the completion of each trade and process, checking volume discrepancies against design data step by step. Volume surpluses or deficits that previously only became apparent at interim inspections were now detected in real time, minimizing rework and material waste. At project completion, the accumulated point-cloud data served as a digital record of the finished terrain for future maintenance planning and as-built documentation for clients.

Use cases in disaster investigation and recovery

Smartphone point-cloud scanning is extremely useful in emergencies such as landslides and earthquakes. At disaster sites, rapidly understanding the full extent of damage and formulating appropriate recovery plans is essential.

For example, at a large landslide, quickly estimating the volume of collapsed material helps determine the necessary number of machines and dump trucks and decide recovery strategies. In one heavy-rain disaster, local government staff performed wide-area drone photogrammetry immediately after the event to create a point-cloud model of the entire collapsed slope and calculate volumes. Closer to the site, detailed point-cloud scans with smartphones recorded collapse details, and these were combined with the drone’s wide-area model to analyze damage three-dimensionally. The objective 3D data made it possible to grasp the scale of damage that was hard to interpret from 2D maps alone, greatly aiding the selection of recovery methods.

In a 2023 earthquake case, a local contractor that happened to have adopted smartphone point-cloud equipment scanned the affected areas with smartphones and immediately shared point clouds and photos with relevant agencies. Because centimeter-level positioning could be obtained using satellite correction signals even in mountain areas without mobile coverage, they could accurately record the condition of severed roads. The data assisted in planning recovery work and damage assessment, speeding up initial response.

Thus, simple point-cloud surveying with smartphones or drones becomes a powerful tool for on-site documentation and reporting in emergencies. Where visual inspection and manual surveying previously provided only partial understanding, digital technology now makes it possible to obtain wide-area and detailed information in a short time. The acquired data support everything from recovery plan development to later verification, greatly aiding disaster response.

Simple smartphone surveying enabled by LRTK

As described above, tools that allow point-cloud scanning with a smartphone and on-site volume calculation can have revolutionary effects in many situations. One of the products supporting such simple smartphone surveying is LRTK. LRTK is a solution that transforms a smartphone into a centimeter-class surveying instrument and consists of a high-precision GNSS terminal, a dedicated app, and cloud services.

LRTK’s greatest feature is that by attaching a compact RTK-GNSS receiver to a smartphone, high-precision positioning becomes possible, and anyone can easily acquire point-cloud data using the smartphone camera. On site, simply holding the smartphone equipped with the LRTK device and pointing the camera while walking allows scanning of surrounding structures and terrain. Absolute coordinates are automatically attached to the acquired point clouds, and area, distance, and volume measurements are executed on the cloud immediately. Measurement results can be confirmed on the smartphone screen and saved to the cloud with a single tap to share with stakeholders as needed.

LRTK also provides point-cloud measurement quality that complies with the Ministry of Land, Infrastructure, Transport and Tourism’s “as-built management guidelines,” ensuring accuracy sufficient for official as-built measurement deliverables. Features tailored to civil construction needs include functions that instantly calculate embankment volumes on site and display surpluses or deficits relative to design values. Even for vast sites producing earthwork volumes on the order of tens of thousands of cubic meters, dividing the site into sections and scanning sequentially makes measurement feasible.

Cloud integration features are also well developed: point-cloud data and positioning information acquired with LRTK can be synchronized to a 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 data by email or USB and enabling real-time connection between site and office. With this cloud utilization, the three elements of “high precision,” “ease of use,” and “cloud integration” come together—LRTK is changing surveying and civil construction sites as a new everyday tool that anyone on site can use. If you have challenges with earthwork calculations or surveying tasks, consider trying smartphone surveying using LRTK. Cutting-edge technology should dramatically improve your site’s productivity and safety.

FAQ

Q: What level of accuracy can be expected when measuring point clouds with a smartphone? A: If you combine a smartphone with an RTK-capable high-precision GNSS receiver, horizontal and vertical errors can be kept to a few centimeters (centimeter-level (cm level accuracy (half-inch accuracy))). This is accurate enough for typical civil engineering as-built checks and earthwork calculations and can 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 measure using an intuitive app. Complex device setup and surveying calculations are automated, so people without specialized knowledge can easily operate it. After a 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 example, for a fill about 30 m (98.4 ft) square, you can acquire the necessary point-cloud data by walking around for a few minutes holding a smartphone. Volume calculations are automatically processed on the cloud, so you can get results in under about 10 minutes in total.

Q: Can it be used where there is no network environment on site? A: It depends on the tool, but in the case of LRTK, it uses Michibiki’s high-precision augmentation signal (CLAS), so centimeter-level positioning is possible even in areas without mobile reception. Synchronizing with the cloud can be done after moving to a location with reception; in offline environments, data can be saved on the device and uploaded later.

Q: What advantages does smartphone surveying have over drone surveying? A: Drones excel at quickly surveying wide areas, but they have constraints such as flight permission, weather, and piloting skills. Smartphone surveying is more maneuverable and can measure in places where drones cannot be used—indoors, in tunnels, or under covers. Because it is easy to use routinely, smartphones are better for small, frequent measurements and progress management that do not justify flying a drone. Using both appropriately allows a more efficient on-site measurement strategy.