Table of Contents

• Traditional earthwork quantity management methods and challenges

• Innovation in earthwork quantity management with AR technology

• Point cloud data and automated earthwork quantity calculation mechanism

• AR earthwork quantity management use cases that come alive on site

• Smartphone surveying "LRTK" — benefits and convenience

• Conclusion: How AR technology and LRTK transform on-site earthwork quantity management

• FAQ (Frequently Asked Questions)

Are you able to quickly grasp excavation and fill volumes on civil engineering sites on the spot? Traditional methods require time and effort for surveying and calculation, and it is not easy to know accurate earthwork quantities instantly when needed. However, we are entering an era in which anyone—not just specialists—can easily measure on-site earthwork quantities by using a smartphone and AR (augmented reality) technology. This article整理s traditional methods of quantity calculation and their challenges, explains the mechanism of automated volume calculation using the latest AR technology and 3D point cloud data, and introduces how the smartphone surveying device "LRTK," which combines the iPhone’s LiDAR sensor and RTK-GNSS, enables site personnel to perform high-accuracy surveying and AR visualization without specialist skills. We will also look in detail at concrete use cases on civil construction sites—such as as-built management, progress quantity assessment, on-site confirmation with clients, and support for heavy equipment operators—and how AR changes on-site earthwork quantity management.

Traditional earthwork quantity management methods and challenges

Calculation of earthwork quantities (excavation and fill volumes) in earthworks has mainly relied on analog surveying methods and experience. Representative methods and their challenges are as follows.

• Measurement using TS surveying (total station): This method sets up a surveying instrument (TS) on site, measures the elevation and position of many points, digitizes the terrain, and calculates volumes. It yields high accuracy but is extremely time-consuming for surveying wide areas. Multiple people and skilled operators are required, and obtaining results immediately on site is difficult.

• Average cross-section method (cross-section method) for earthwork quantity calculation: A time-honored method used in road construction. Terrain cross-sections are measured at regular intervals, cut and fill areas for each section are calculated and averaged, and the result is multiplied by the section length to obtain volume. It requires careful field surveying and manual calculations on drawings, lacks speed, and cannot fully reflect terrain changes between sections.

• Drone photogrammetry: Recently popularized aerial photogrammetry using drones is also used for earthwork quantity calculation. From aerial images, 3D models and contour lines can be created and cut/fill volumes automatically calculated, making it effective for grasping quantities over large sites. However, it is constrained by weather and flight permits, requires specialized image analysis software and skills, and it is difficult to produce immediate results from flight to analysis—requiring a certain amount of time and cost.

• Rough visual estimates based on experience: In some cases, veteran heavy equipment operators or site supervisors estimate earthwork by eye, saying “about how many dump truck loads.” However, estimates based on human intuition have large errors and can lead to disputes with clients or issues in progress quantity assessments.

As described above, traditional methods involve challenges such as high time and labor requirements, the need for specialized knowledge and experience, and lack of real-time capability. Especially in progress control and as-built inspections, even when you want accurate quantities immediately, time lags occur while acquiring surveying data and calculating quantities. Also, conveying earthwork quantities with only 2D drawings or numbers is not intuitive, making it difficult to share the situation with clients or within the company.

Innovation in earthwork quantity management with AR technology

A promising new technology that can solve these challenges is AR (augmented reality)-based earthwork quantity management. AR technology allows superimposing virtual information onto real site views, making it possible to visually confirm surveying results and design data on the spot. For example, by viewing the site through a smartphone or tablet camera and overlaying a design ground surface or pre-/post-construction terrain models onto that image, you can intuitively see at a glance “where and how much fill is needed” and “how much the design surface deviates from the existing condition.” Tasks that used to require comparing paper drawings or installing stakes to check elevations can be performed by overlaying the completed model on the real view through the camera, making it easier for less-experienced technicians to understand spatial discrepancies. Digital visualization can also compensate for parts that previously relied on veteran intuition, greatly smoothing communication with clients and other departments.

AR is especially powerful when linked with 3D models for real-time visualization. Just by pointing a smartphone at the site, you can see a heatmap that color-codes cut and fill volume differences, or numeric displays showing “how many centimeters (how many inches) remain to be excavated.” Without waiting for survey results, you can immediately grasp discrepancies and issue correction instructions on the spot, contributing to shorter schedules and fewer mistakes.

However, AR displays on ordinary smartphones and tablets have historically relied on GPS or image recognition for positioning, causing virtual objects to shift when the user moves. That makes them unsuitable for civil-engineering sites requiring precise alignment. The key to stabilizing model displays on AR with high-precision positioning is the use of RTK-GNSS (real-time kinematic positioning) combined with the smartphone’s built-in LiDAR scanner for point cloud measurement.

Point cloud data and automated earthwork quantity calculation mechanism

The foundation of AR-based earthwork quantity management is automated volume calculation technology based on 3D point cloud data. Point cloud data are collections of countless points captured by laser scanners or photogrammetry, digitally representing site terrain and structures in three dimensions. Each point has X, Y, Z coordinates (and optionally color information), and a dense distribution of points can precisely reproduce fine surface undulations.

Traditionally, obtaining high-density point cloud data required expensive 3D laser scanners or specialized surveying equipment. Recently, however, anyone can easily acquire point cloud data using LiDAR sensors built into the latest smartphones. Simply scanning the surrounding terrain with a smartphone can create a 3D model on the spot and even calculate volume immediately. The fact that site staff can routinely collect terrain data themselves without large drones or other equipment is revolutionary.

By overlaying the acquired as-built point cloud model with the design-side 3D model (planned ground surface), you can identify the areas and amounts where soil must be cut (cut) or filled (fill). Visualizing those differences by color-coding according to elevation difference produces an “earthwork heatmap.” For example, areas higher than the design surface (where excess soil remains) can be shown in red, while areas that have been over-excavated and are too low can be shown in blue, intuitively indicating ground surface deviations by color. A quick glance reveals where and how much adjustment is needed and helps prioritize work.

Calculating volumes from point cloud data consisting of millions of points dramatically improves quantity calculation accuracy compared to conventional surveys of a few dozen points. Because even minute surface undulations are captured, cut and fill quantities can be managed more accurately than before.

AR earthwork quantity management use cases that come alive on site

Smartphone surveying with LRTK and AR displays for earthwork quantity management are useful in many aspects of civil construction. Below are some representative use cases.

• As-built management: For as-built management (as-built inspection) to verify whether the finished work matches the design, comparing the as-built point cloud terrain with the design data allows accurate verification of completed cut and fill shapes. Overlaying the design model and on-site discrepancies as a color-coded heatmap in AR makes it obvious where corrections are needed. Measurement results that comply with the Ministry of Land, Infrastructure, Transport and Tourism’s “Guidelines for As-built Management” can be confirmed on the spot, increasing the reliability of inspections.

• Progress quantity assessment: For objectively evaluating the progress quantity of earthworks, periodically scanning the site with a smartphone and calculating earthwork volumes lets you precisely show how many cubic meters of soil were removed or placed. While conventional practice was to perform surveys and quantity calculations at month-end, AR surveying enables immediate measurements as needed, helping to level out progress reporting and manage施工量 accuracy. Attaching screenshots of the AR screen to reports for clients also enhances persuasive power.

• On-site confirmation with clients: Difficulty conveying completed image or survey results to non-construction stakeholders can be resolved on site with AR. When guiding a client or inspector around the site, overlaying information such as “this is the designed fill area” or “this much excavation is lacking” on the real view through a smartphone makes it easy to share the situation at a glance. Points that were hard to convey with drawings or reports become intuitively understandable when superimposed on live imagery, helping prevent disputes due to divergent recognition.

• Support for heavy equipment operators: Even veteran heavy equipment operators may find it hard to always know the exact position of buried structures or the target finish elevations. By pre-scanning buried pipes and other subsurface elements with LRTK and displaying their positions in AR during excavation, operators can perceive normally invisible buried objects as if through a see-through view simply by looking at the smartphone screen. When excavating or filling to the design surface, projecting appropriate grade lines and elevation guides in AR enables anyone to shape the terrain as intended without relying on intuition. These capabilities directly improve safety and prevent construction errors, enhancing overall construction quality.

Other use cases include rapid estimates of soil removal at disaster sites, management of spoil stockpiles in yards, and as-built checks for foundation excavation. There are many situations where you want to measure and decide immediately with just a smartphone. AR-based earthwork quantity management enables “measure when you need it,” accelerating the on-site PDCA cycle as a tool.

Smartphone surveying "LRTK" — benefits and convenience

Finally, the main benefits of introducing the smartphone surveying device "LRTK" are summarized. The overwhelming convenience compared to conventional methods can be seen from the following points.

• Real-time: Data measured on site can be checked immediately, allowing real-time grasp of the construction status. Volumes are known right after surveying, and measurement errors or design differences can be detected and corrected immediately, reducing rework and additional work.

• High accuracy: RTK-GNSS provides positioning accuracy within a few centimeters (within a few inches), and AR displays keep model-to-reality deviations very small. Virtual staking and elevation checks can be performed with pinpoint accuracy, enabling measurements comparable to conventional temporary stake and layout methods.

• Intuitive 3D visualization: Terrain undulations that are hard to grasp from 2D drawings or numbers are immediately apparent with 3D models and AR heatmaps. Height deviations are shown in color, making it easy for less-experienced technicians to understand and allowing data to supplement what used to rely on veteran intuition.

• Labor and manpower reduction: Surveying can be completed with just a smartphone and a small GNSS receiver (LRTK), eliminating the need for large equipment or multiple personnel. One person can handle surveying and inspections over a wide site, helping address labor shortages and improve operational efficiency. Moving and setting up equipment is greatly reduced, freeing time for other tasks.

• Data integration and DX promotion: Data acquired on site is automatically saved and shared in the cloud, removing the need for manual transcription. Accumulated point clouds and surveying data can be easily applied to CAD drawings or incorporated into CIM models in later stages, strongly promoting digital transformation (DX) of construction. Being able to retrieve and compare past data at any time also helps improve quality control accuracy.

By adopting LRTK and enjoying these benefits, anyone can easily perform high-accuracy earthwork measurement and AR visualization with a single smartphone. What used to be “work that surveying specialists took days to complete” can now be “completed on the spot by the site representative.” For everyone involved in earthworks, the barrier to surveying and as-built management is greatly lowered, yielding significant improvements in both productivity and safety.

Conclusion: How AR technology and LRTK transform on-site earthwork quantity management

Traditionally, earthwork measurement and as-built verification often relied on experienced surveyors, and waiting for results was the norm. But AR technology and the smartphone surveying device LRTK are overturning that convention. With an iPhone and LRTK, simply walking around the site produces accurate earthwork volumes instantly and allows intuitive confirmation in AR—a new style of civil surveying has emerged.

With LRTK, site agents and construction managers without surveying expertise can perform measurements and inspections at needed times and locations and promptly make decisions based on the data. Centralizing everything with data instead of paper drawings and conventional instruments reduces human error, and visual sharing with AR facilitates explanations and consensus building with clients. Trial implementations have already begun on public works sites, and the era of transforming sites with a “one-person, one-surveying device” using smartphones and the cloud is becoming realistic.

As earthwork quantity management is undergoing major change, why not bring this latest technology to your site? For more information on LRTK, please also visit the [LRTK official site](https://www.lrtk.lefixea.com), and feel free to contact us via the [inquiry form](https://www.lrtk.lefixea.com/contactlrtk) for consultation on implementation. Advance your site to the next stage with the cutting-edge smartphone simple surveying system LRTK.

FAQ (Frequently Asked Questions)

Q: Do I need expensive equipment to introduce AR or 3D surveying on site? A: No. With the latest smartphones and a small device (e.g., LRTK), large-scale equipment is unnecessary. LRTK is a palm-sized high-precision GNSS receiver that can be attached to a smartphone, enabling centimeter-level (half-inch) positioning. Compared to conventional surveying equipment, the cost and equipment barriers to introduction are significantly lower.

Q: Can people without surveying experience use it? A: Yes. LRTK’s dedicated app is designed for intuitive operation, and basic usage can be learned in a short training session. By following on-screen guidance, surveying is completed and results can be visually confirmed in AR, so even those without surveying experience can use it with confidence.

Q: Can survey data acquired with a smartphone be used for official documents and inspections? A: Yes—if measured with sufficient accuracy, it can be submitted as official as-built measurement results. Point cloud data obtained with LRTK are assigned absolute coordinates in the World Geodetic System, and can be stored in formats that comply with the Ministry of Land, Infrastructure, Transport and Tourism’s as-built management guidelines. Therefore, data from smartphone surveying can be used for as-built documentation and quantity reports that were previously prepared by surveyors, and have sufficient accuracy and reliability for public inspections and document submission.

Q: What advantages does it have compared to drone photogrammetry? A: AR surveying with a smartphone has the major advantage of requiring no flight permits or advanced piloting skills like drones, and it is comparatively less constrained by weather, allowing immediate measurement when needed. It is also suitable for narrow areas and capturing fine shape changes, and can be used many times a day. Drone surveying excels at capturing overall conditions of vast areas, but each execution requires preparation and analysis time. The two are complementary: use drones for periodic wide-area surveys and smartphone AR surveying for daily progress management and detail checks.

Q: Is it compatible with any smartphone? A: Currently, the LRTK series is compatible with iPhone (LiDAR scanner-equipped models are recommended). It is used by attaching a dedicated smartphone-case-type device to an iPhone, so it is generally compatible with iPhone 12 Pro and later models (support for additional devices may expand in the future). Any increase in supported devices through updates will be announced on the official site.