Table of Contents

• The need to instantly calculate earthwork volumes on site

• Traditional earthwork measurement methods and their challenges

• The arrival of tools that enable point-cloud scanning with 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 assessment and recovery

• Smartphone simple surveying enabled by LRTK

• FAQ

The need to instantly calculate earthwork volumes on site

In civil engineering, land development, and disaster recovery work, there is strong demand for tools that can calculate earthwork volumes immediately on site. For example, quickly understanding the volume of excavation or fill can dramatically improve schedule and cost management. Until now, estimating earthwork volumes has often relied on experience and intuition, and errors could lead to unnecessary rework and increased costs. Being able to calculate accurate earthwork volumes on the spot is essential for smooth construction progress and appropriate decision-making.

In recent years, the construction industry has been swept by DX (digital transformation), and improving the accuracy of as-built management and progress quantity management has become a priority. Initiatives led by the Ministry of Land, Infrastructure, Transport and Tourism such as i-Construction have increased the need to streamline traditionally labor-intensive surveying tasks with digital technologies. In this context, there is growing anticipation for earthwork measurement tools that site staff can easily use themselves to get immediate results.

Traditional earthwork measurement methods and their challenges

Various methods have been used to calculate earthwork volumes on site. However, each method has drawbacks, making real-time, easy measurement challenging.

• Human-powered surveying and calculations: Surveyors use transits or levels to painstakingly obtain control points and calculate volumes using methods such as the average cross-section method. While accurate, this requires enormous time and effort and specialized knowledge. Calling in experts for every busy site is impractical.

• Estimates based on equipment cycles or truck counts: A simple method is to approximate earthwork by the number of dump truck trips or the shovel’s load capacity. However, this lacks precision and often differs from actual volumes. It is merely a rough estimate, not an accurate volume measurement.

• Drone aerial photogrammetry: Recently, drone aerial surveys that generate 3D models or point clouds from photos have become common. They can cover wide areas in a short time, but require flight permissions, specialist operators, and time and skill for image processing. They are also weather-dependent and are not always “instant.”

• 3D laser scanners: Terrestrial high-precision laser scanners can measure point clouds very precisely. However, the equipment is expensive and difficult to handle, and using a single unit across sites requires expert technicians. The data volumes are massive and create heavy processing loads, making them impractical for everyone on site to use casually.

As these examples show, traditional methods have struggled with “ease of use,” “immediacy,” and “versatility.” Even with modern equipment, sites sometimes cannot make practical use of it, or data processing delays render the investment ineffective. What was needed was a method that allowed anyone on a busy site to quickly measure earthwork volumes without special effort.

The arrival of tools that enable point-cloud scanning with a smartphone

In response to these needs, a new class of tools has recently emerged that enable point-cloud scanning with a smartphone. By leveraging a phone’s camera and sensors and walking the site while scanning, you can acquire detailed 3D data (point clouds) in a short time.

For example, some modern high-end smartphones include small LiDAR sensors that can measure surrounding shapes several meters ahead. By combining multiple photos or video with photogrammetry techniques, you can also generate point clouds covering wider areas. In short, a common smartphone can quickly transform into a 3D measurement device without special surveying gear.

One notable advancement is solutions that pair smartphones with high-precision GNSS (GPS) receivers. While a smartphone alone can capture shape with LiDAR or camera data, its positioning accuracy with conventional GPS is typically off by several meters. By attaching a dedicated receiver that supports Real-Time Kinematic (RTK) positioning, centimeter-level accuracy becomes possible. This enables highly accurate position coordinates to be directly associated with the point clouds captured by the smartphone, producing precise 3D data aligned to site coordinate systems.

Thanks to the smartphone × high-precision GNSS combination, high-precision point-cloud surveying is becoming possible with the simplicity of a single button press, even for non-experts. Carrying a palm-sized device attached to a smartphone, you can walk around a large site and digitize the terrain. Time-consuming tasks like establishing control points and post-processing are minimized, and you can now perform earthwork calculations directly from the 3D models produced on site.

Benefits of smartphone point-cloud surveying

Smartphone point-cloud scanning offers many advantages not found in 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. You can, for example, measure daytime excavation volumes on the spot in the evening. Data processing is automated, greatly reducing waiting time for results.

• Ease of use and labor savings: With only a smartphone and a small device, there’s no need to carry heavy equipment or perform complex setups. Intuitive smartphone apps let anyone perform measurements, and untrained workers can operate them. The convenience of “take it out of your pocket and measure anytime” is a major asset on site.

• Improved safety: You can survey dangerous slopes or large stockpiles from a distance with a smartphone, reducing the need for personnel to enter hazardous areas. This contributes to worker safety.

• High-precision results: Combining high-precision GNSS positioning with point-cloud technology yields results that meet the precision required for volume calculations. While matching the accuracy of manual surveying, it can cover larger areas and provide highly reliable data.

• Cost reduction: Less need to outsource to specialists or buy expensive equipment. Smartphone-based approaches reduce upfront investment and allow in-house measurements as needed, improving cost performance. On sites where everyone already has a smartphone, they can effectively become “one surveying instrument per person.”

• Ease of continued use: Tools that are hard to operate or usable only by specific people rarely persist. Smartphone point-cloud surveying is “anyone, anytime, anywhere,” making it easy to integrate into routine site work. As a result, surveying literacy across the site improves.

Of course, smartphone-based simple surveying cannot match the measurement range and absolute precision of fixed ultra-high-precision laser scanners. However, for as-built checks, small-scale volume confirmations, and disaster documentation, it delivers more than sufficient precision. Above all, the ability to “measure anytime from your pocket” is the biggest strength for ongoing site use. Regular, easy measurements build up data that shift construction management from “intuition and experience” to data-driven management.

Use of high-precision positioning technology (RTK)

A key element of smartphone point-cloud surveying is high-precision positioning via RTK. RTK (Real-Time Kinematic) uses correction information from a base station to reduce GPS positioning errors to the centimeter level. While typical smartphone GPS has meter-level errors, using an RTK-capable receiver can achieve horizontal and vertical accuracy on the order of centimeters.

On construction sites, high-precision alignment with control points is required, so absolute coordinates in point-cloud data are important. Attaching an RTK-GNSS receiver to a smartphone allows the captured point clouds to carry absolute coordinates such as national geodetic coordinates. This makes it easy to compare acquired point clouds with design drawings or existing survey coordinates, and to accurately compare datasets taken at different times.

For example, some smartphone point-cloud tools utilize the Geospatial Information Authority’s reference station network (and CLAS signals from the quasi-zenith satellite system), enabling high-precision positioning even in areas without mobile coverage. With this capability, stable, position-accurate point clouds can be obtained even in environments where positioning was once unreliable. It is precisely because of the reliability of high-precision positioning that smartphone-derived earthwork calculations can be confidently used on site.

Data sharing via cloud integration

Point-cloud data and measurement results captured by a smartphone can be further leveraged by integrating with cloud services. Cloud integration offers the following benefits:

• Immediate sharing: After scanning, data can be uploaded to the cloud from the smartphone with one tap. Through the internet, office PCs and other stakeholders can access the data immediately, allowing on-site measurements to be used for reporting and review right away. Remote supervisors or clients can receive information in real time, enabling rapid decision-making.

• Automatic analysis and web viewers: Point-cloud processing and analysis can be performed automatically in the cloud, quickly producing volume calculations and cross-sectional views. Users can check results in a web browser without operating advanced software. No dedicated high-performance PC or special software is required; anyone can view and measure 3D point clouds simply by opening a URL in some services.

• Data storage and utilization: Data stored in the cloud is securely preserved and can be retrieved when needed. As-built data and earthwork measurement histories can be managed long-term, serving as a “time capsule of the site” for later verification and comparison. This reduces the risk of loss compared to paper documents or local PCs and allows access from anywhere within the organization.

• Integration with other systems: Through the cloud, you can overlay CAD drawings or BIM models, export to reporting formats, and more. Services that automatically generate as-built inspection reports from point clouds have emerged, enabling end-to-end data use in the cloud.

Cloud integration ensures that valuable site data does not remain buried on a single person’s PC but is shared across the organization. Information flows from the site to the cloud and from the cloud to the office, enabling collaboration that transcends the traditional site-office divide.

Use cases at civil engineering construction sites

Now let’s look at concrete scenarios where smartphone point-cloud scanning is applied. First, application to earthwork management at general civil engineering sites.

In road and river works, accurate management of excavation and backfill volumes is essential for schedule and cost control. On one site, progress measurements that had previously been performed only about once a week were changed to an operation in which the site supervisor scanned excavation areas with a smartphone every day at the end of the workday. A scan taking only about five minutes allowed the day’s excavation and fill volumes to be quantified and immediately reflected in daily reports and progress quantity reports. Volumes automatically calculated from point clouds matched the recorded number of dump truck trips almost exactly, reliably capturing site performance.

This enabled quantitative progress management based on data instead of vague estimations like “about X% complete.” Replanning earthwork and arranging equipment for the next day could be decided accurately based on measured data. As a result, unnecessary equipment idle time and material ordering mistakes were reduced, improving overall construction efficiency. On some sites, staff report that although they were initially skeptical, scanning has become part of the daily routine: “Now we don’t feel right unless we scan every day.”

Use cases at land development sites

In residential and land development, large-scale cut-and-fill operations occur. Smartphone point-cloud surveying is powerful in these contexts as well.

At development sites, it is necessary to constantly check differences between planned earthwork quantities and the actual site. For example, if excavation has progressed too far, you may need to revise backfilling plans; if fill is insufficient, you may need to arrange additional material. By regularly scanning the entire site with a smartphone and overlaying the resulting terrain model on the design data, you can immediately see the differences between design and current conditions. Some tools in use color-code point-cloud data to show deviations from the design surface, making high and low areas instantly apparent.

At one development site, the as-built condition was recorded by smartphone point-cloud surveying at the completion of each process, and deviations from the design earthwork were checked step by step. Deficiencies and excesses that previously would only have been discovered at midterm inspections could now be identified in real time, minimizing rework and material waste. At project completion, the point-cloud data served as a digital record of the final shape, useful for future maintenance and handover documentation.

Use cases in disaster assessment and recovery

In emergencies such as landslides or earthquakes, smartphone point-cloud scanning is extremely useful. Rapidly grasping the full extent of damage and planning recovery work is essential.

At large landslide sites, quickly estimating the volume of displaced soil determines the number of machines and dump trucks required and helps shape remediation strategies. In one heavy-rain disaster, local government staff used drones for wide-area photogrammetry immediately after the event to create point-cloud models of collapse slopes and estimate volumes. Nearby, smartphone scans captured detailed point-clouds of collapse areas; combining both datasets enabled three-dimensional analysis of damage. This provided objective data on the extent of damage that could not be captured by plan views alone, greatly aiding the selection of recovery methods.

In a 2023 earthquake case, a local contractor that had recently adopted smartphone point-cloud equipment scanned damaged areas and immediately shared point clouds and photos with related agencies. Even in mountainous areas without mobile coverage, using satellite augmentation signals enabled high-precision positioning and accurate recording of severed road conditions. These data contributed to recovery planning and damage assessment, speeding up initial response.

Thus, simple point-cloud surveying using smartphones and drones becomes a powerful tool for on-site documentation and reporting in emergencies. Where visual inspection and manual surveying once covered only limited areas, digital technologies now provide wide-area, detailed data in a short time, supporting recovery planning and post-event verification.

Smartphone simple surveying enabled by LRTK

As shown above, tools that enable point-cloud scanning with a smartphone and on-site earthwork calculation deliver revolutionary effects in many situations. One such product that realizes smartphone simple surveying is LRTK. LRTK is a solution that turns a smartphone into a centimeter-class surveying instrument, comprising a high-precision GNSS terminal, a dedicated app, and cloud services.

LRTK’s distinguishing feature is that attaching a small RTK-GNSS receiver to a smartphone enables high-precision positioning, and using the phone’s camera makes point-cloud acquisition simple for anyone. On site, hold a smartphone fitted with the LRTK device, point the camera, and walk to scan surrounding structures and terrain. The acquired point-cloud data are automatically assigned absolute coordinates, and area, distance, and volume measurements are performed on the cloud right there. Measurement results can be checked immediately on the smartphone screen, and with one tap the data can be saved to and shared via the cloud.

LRTK is also capable of point-cloud measurements that comply with the Ministry of Land, Infrastructure, Transport and Tourism’s “as-built management guidelines,” providing quality suitable for official as-built measurement deliverables. For example, functions such as instant calculation of fill volumes on site and immediate display of surplus/deficit against design values are provided to meet civil construction needs. Even volumes on the order of tens of thousands of cubic meters at large sites can be measured by scanning sequentially by area.

Cloud integration is robust as well: point clouds and positioning data acquired with LRTK are synced to a dedicated cloud with one button. Anyone can view the 3D data in an installation-free web viewer, allowing seamless sharing with clients and designers. There is no need for email attachments or USB transfers—connecting site and office in real time is a major advantage.

In this way, LRTK’s smartphone simple surveying is gaining attention as a solution that combines “high precision,” “ease of use,” and “cloud connectivity.” As a new everyday tool that anyone on site can use, it is transforming civil construction and surveying. If you face challenges with on-site earthwork calculations, consider smartphone surveying with LRTK. Cutting-edge technology can dramatically improve your site’s productivity and safety.

FAQ

Q: How accurate is point-cloud scanning with a smartphone?

A: By combining a dedicated RTK-GNSS receiver, you can achieve horizontal and vertical accuracy on the order of a few centimeters. This is sufficient for general construction as-built checks and volume calculations, and measurements can meet national standards.

Q: Can people without special knowledge or qualifications use it?

A: Yes. Smartphone point-cloud surveying is designed for intuitive app operation. Complex equipment setup and surveying calculations are automated, so people without surveying expertise can use it easily. Many staff can start using it after on-site training.

Q: How long does measurement take?

A: It depends on the target and area, but for example, measuring a 30 m (98.4 ft) square stockpile can be done by walking around with a smartphone for a few minutes to capture point-cloud data. Volume calculations are processed automatically in the cloud, so you can get results in well under 10 minutes in total.

Q: You mentioned using the cloud—what if there is no network at the site?

A: In the case of LRTK, correction signals from quasi-zenith satellites can be used, enabling positioning even where mobile signals are unavailable. Cloud synchronization can be performed after moving to an area with reception. You can also save data on the device offline and upload it later when convenient.

Q: Compared to drone surveying, what are the advantages of smartphone surveying?

A: Drones can survey wide areas quickly but have constraints such as flight restrictions, weather, and operator skill. Smartphone surveying is more maneuverable and can be used indoors or under cover. Its ease of everyday use makes it better suited for small-scale measurements and frequent progress monitoring. Using both appropriately allows a more efficient site surveying strategy.