Smartphone surveying makes measuring steep slope greening easy

Why slope greening is required on steep slopes

Steep slopes are slopes with sharp inclines that carry a high risk of landslides and other ground failures. Conducting slope greening in such locations plays an important role for both safety and environmental reasons. From a safety perspective, planting vegetation on slopes helps stabilize the soil, preventing the runoff of topsoil and slope collapse caused by heavy rain or strong winds. Grass and tree roots anchor the ground, reducing the risk of sudden landslides and mitigating damage to homes and roads. From an environmental perspective, compared to inorganic measures like simply covering slopes with concrete, greening preserves scenic value and creates slopes that harmonize with the surrounding natural environment. Plants not only prevent surface erosion but also improve soil water retention and provide habitat for insects and small birds. Slope greening on steep terrain is therefore an indispensable approach for balancing disaster prevention and environmental conservation.

However, work on steep slopes involves greater danger than on flat ground. To carry out slope greening construction safely, it is important to accurately understand the slope geometry and select appropriate construction methods and vegetation techniques. Traditionally, specialist surveying teams measured slope heights and gradients and used those measurements to plan earthworks and vegetation. Yet the very task of surveying steep slopes has historically posed major challenges.

Issues with conventional slope surveying

In traditional methods for surveying slope faces on steep terrain, worker safety was a major concern. For personnel to enter a slope and measure angles or heights, it was necessary to erect scaffolding or use safety ropes. Workers had to operate with constant caution due to the risk of slips and falls. After rain when the ground is soft, or on unstable slopes at risk of collapse, simply approaching the slope for surveying could be hazardous.

Moreover, labor and time were significant issues. Conventional surveying uses total stations (optical surveying instruments) or levels to measure key points on the slope one by one. But on steep, uneven slopes, the number of measurable points tends to be limited. Many target points are not visible (line-of-sight is blocked) from the instrument, and mere movement of personnel to the measuring positions can be difficult. As a result, multiple surveying plans and repeated repositioning of equipment are often required to capture the entire slope shape, making the process very inefficient. For example, sometimes only a few points at the top, middle, and bottom of the slope could be measured, leaving finer irregularities and curvature to be inferred from craftsmen’s intuition and experience.

When a small team is rushing to complete work, variations in measurement accuracy are unavoidable. Manual measurements using tape measures or staffs can produce small deviations that translate into large errors across an entire slope. Conventional methods sometimes failed to precisely measure slope angles or to uniformly confirm the thickness of fill, making it difficult to grasp the as-built condition (finished shape). In this way, slope surveying on steep terrain faced the twin challenges of safety risks and limits in efficiency and accuracy.

High accuracy and labor savings brought by smartphone surveying

In recent years, smartphone surveying has emerged as a technology that can radically change this situation. Modern smartphones increasingly include advanced sensors that instantly capture surrounding geometry and technologies that enable high-precision positioning. A representative example is the combination of LiDAR sensors and RTK-GNSS.

LiDAR is a sensor that uses laser light to measure distance to targets; by simply pointing a smartphone, you can acquire the surrounding 3D shape as a set of points. With a high-performance smartphone, moving the device while aiming at a steep slope just a few meters away can capture countless measurement points that cover the entire slope. This is a revolutionary capability that lets you record on-site 3D data as easily as shooting a video.

RTK-GNSS, on the other hand, is a technique that provides real-time correction of satellite positioning errors and previously required expensive dedicated equipment. Today, small RTK receivers can be attached to smartphones, allowing anyone to use centimeter-level positioning. By leveraging RTK (Real Time Kinematic), positional errors that were several meters with built-in GPS can be reduced to several centimeters, enabling highly accurate coordinates to be assigned to the acquired data. In other words, combining “smartphone + LiDAR” with “RTK-based high-precision positioning” turns a handheld smartphone into a high-performance surveying instrument.

This smartphone surveying is particularly powerful on steep slopes. First, worker safety is dramatically improved. Data can be acquired by scanning the slope from a distance without having to forcefully climb onto a dangerous slope, reducing the need to enter hazardous areas for surveying. While some movement is required to thoroughly scan the entire slope, there is no need to carry heavy equipment or repeatedly move scaffolding. Tasks can be performed by a single person, reducing the need to station additional support staff around the site. The ease of measuring anytime with just a smartphone and a small device directly leads to labor savings. Because data acquisition is completed in a short time, situations that were once abandoned as “wanted to measure but currently difficult” can now be addressed quickly.

In addition, the accuracy of smartphone surveying is practically sufficient. Each point in LiDAR-acquired point cloud data is assigned coordinates corrected by RTK, ensuring high reliability for distance, area, and angle measurements on slopes. The accuracy is now comparable to that of specialized instruments, making it possible to digitize slope geometry. As a result, surveying on steep slopes is shifting from being a “dangerous and difficult task” to a “safe and quick operation.”

Advantages in slope management enabled by point cloud data

The enormous number of measurement points that can be obtained with a smartphone—i.e., point cloud data—offers various advantages that conventional surveying could not provide. The greatest feature is the ability to capture the slope’s current condition as a surface (entire area). For example, scanning a steep slope in its entirety records everything from surface irregularities to subtle variations in slope angle, allowing complex topography that cannot be fully captured by flat drawings or a few measurement points to be recorded in detail as if the slope were copied.

By utilizing this high-density 3D data, slope greening planning and as-built management can be revolutionized. Whereas gradient was previously calculated by measuring a few representative cross-sections and averaging, point cloud data allows you to measure angles freely at any location on the slope. Visualizing the angle distribution and curvature across the entire slope helps identify dangerously steep spots without overlook. If embankment or imported soil is applied to the slope, the thickness can be verified from the point cloud. Overlaying pre-construction terrain data and post-completion point clouds makes it easy to analyze and color-code areas that are too thin or excessively filled. Such point cloud analysis results are also compelling materials for quality control.

Furthermore, as-built records using point cloud data contain overwhelmingly more information than photos or paper records and retain value into the future. If the completed slope after greening is stored in the cloud as point cloud data, you can later reproduce the original terrain in 3D when planning maintenance years later and compare it with the current condition. This enables quantitative assessment of vegetation growth and erosion progression and makes it easy to identify areas needing repair. Sharing data with other contractors or government bodies provides objective evidence to explain the as-built condition. Digital records that preserve the entire slope complement conventional partial drawings and photo records powerfully.

Once point cloud data is acquired, secondary uses are also flexible. If you later need a cross-section or a measurement from a different angle, there is no need to return to the site. Additional measurements or drawing production can be performed on the data, reducing human error. In slope greening, covering the surface with vegetative mats after construction can make verification of the underlying ground difficult, but if you record the terrain beforehand with point clouds, unseen parts are stored in the data for peace of mind. In this way, leveraging point cloud data obtained by smartphone dramatically improves the quality of slope management.

Rapid assessment and AR use at difficult or disaster sites

Steep slopes also include difficult-to-access areas and disaster sites damaged by heavy rain or earthquakes where approaching in person is challenging. In such places, it is crucial to quickly understand conditions and take countermeasures, but there may be no time to bring in large surveying equipment or construct scaffolding. Smartphone surveying proves effective even in emergencies. Because only a lightweight smartphone and a positioning device are required, it can respond with mobility to unstable slopes immediately after a disaster. For example, if part of a slope collapses after heavy rain, once the surrounding area is declared safe, a worker can scan the slope with a smartphone and acquire terrain data of the collapsed area in minutes. By instantly calculating the volume of displaced soil from that data, estimates for temporary sandbags or the amount of fill needed for restoration can be obtained immediately. Emergency responses that previously relied on visual assessment and experience can now be handled quickly and accurately based on data.

Additionally, 3D data obtained by smartphone surveying can be shared instantly via the cloud with internal and external stakeholders, making it easy to solicit expert opinions remotely. Visualization of conditions is crucial in disaster response, and by allowing all stakeholders to simultaneously review a point cloud model, discussions and decision-making—including input from off-site engineers—can proceed rapidly.

Moreover, smartphones’ AR (augmented reality) capabilities become a valuable support tool on steep slope sites. By using AR, acquired point cloud data or design models can be overlaid on the real landscape. For instance, overlaying a post-repair design model on a collapsed slope lets you see the intended shape through the current collapse, intuitively showing where and how much to fill for restoration and simplifying restoration planning. During construction, you can directly compare the current slope point cloud with the design on site. Viewing the planned completion line through the smartphone against the present condition lets you instantly check finishing discrepancies. Using heatmap visualizations to show thickness excesses and shortages allows on-the-spot detection of areas lacking sprayed greening material or insufficient fill.

AR visual support also contributes to safety. For example, predefining hazard zones or work boundaries and displaying those boundaries through the smartphone can alert workers. Even inexperienced staff can more easily understand spatial instructions like “danger beyond this point” or “fill to this height” through AR displays. In environments where on-site judgment is difficult, such as steep slopes, AR—which makes digital information visible—is a powerful tool.

Effects of completing surveying with a single smartphone: reduced personnel, improved efficiency, and lower training costs

Introducing smartphone surveying greatly contributes to on-site personnel reduction and efficiency. Conventional slope surveying required multiple people and high-level skills from surveyors. Now, the work can be completed with a smartphone that on-site supervisors or workers can operate alone and intuitively. This can help alleviate labor shortages and optimize staff deployment. If you no longer need multiple people clinging to a dangerous slope, those personnel can be allocated to other important tasks.

In terms of efficiency, smartphone surveying delivers overwhelming time savings compared to traditional methods. Time losses from transporting and setting up surveying equipment or waiting for suitable weather and instrument availability are reduced, enabling quick measurements whenever needed. Since the workflow from data capture to analysis is automated, once scanning is finished on-site you can immediately begin volume calculations and drawing creation. Where surveying results previously had to be taken back to the office for CAD drafting before as-built checks could be performed, a single smartphone can now complete these tasks on the spot. This shortens the construction management cycle and helps meet schedules and implement safety measures earlier.

A noteworthy benefit is reduced training costs. Smartphone surveying is designed to be simple to operate and usable without special certifications or years of experience. Intuitive app interfaces and automatic error-correction mechanisms allow surveying beginners to achieve a certain level of accuracy. This offers a solution to skills transfer issues arising from the retirement of veteran engineers. Even without relying on seasoned practitioners’ instincts, digital tools provide objective data that raise the overall technical level of the field. Additionally, completing tasks with a familiar device like a smartphone lowers the psychological barrier to digital tools and positively impacts human resource development that promotes on-site DX.

LRTK enables integrated management of surveying, point clouds, AR, and cloud

To fully exploit the benefits of smartphone surveying, a system that seamlessly handles surveying through to data utilization is important. Enter the comprehensive solution called LRTK. LRTK combines a small RTK-GNSS receiver attachable to a smartphone, a dedicated app, and cloud services into an integrated platform. With this single solution, you can centrally manage surveying, point clouds, AR, and cloud storage.

Specifically, you attach the LRTK device to the smartphone on site, launch the app, and start surveying. Real-time, high-precision corrected positions are obtained and coordinates are automatically assigned to the point cloud captured by the phone’s LiDAR. By walking along the target slope and scanning, a high-density point cloud can be produced in just a few minutes. Remarkably, the subsequent processing is also simple. The acquired point cloud data is immediately converted into the preset coordinate system (such as public coordinates), so you won’t struggle later to align coordinates. With a single button, you can upload to the cloud, enabling data viewing and sharing from office PCs or tablets. In short, the series of processes that once required contracting specialists or complex equipment is designed to be completed with only a smartphone and LRTK.

LRTK also includes functionality to overlay point cloud data acquired on the smartphone with design data for AR display. For example, you can easily overlay the design finish line on a scanned steep slope 3D model and check on-site deviations. Point cloud data accumulated in the cloud is managed centrally within the company, enabling real-time sharing of progress and as-built conditions and facilitating remote construction management. The ability to keep data from each site from becoming scattered and to integrate it with safety information and construction history for unified management is another major advantage.

In this way, LRTK completes processes such as measuring, recording, comparing, and sharing on a single platform. For complex and hazardous sites like steep slope greening, the smooth data linkage enabled by LRTK’s integrated management is especially effective. Continuous data connectivity blurs the boundary between the field and the office and accelerates DX across the entire project.

The future of DX spreading through steep slope greening

With technological advances, the wave of digital transformation (DX) is inevitably arriving at slope greening for steep terrain. By combining smartphone surveying, point cloud data, and AR, tasks that once relied on manpower and experience are becoming data-driven, enabling safe, efficient construction that everyone can agree on. From slope safety evaluation to greening quality control, a future where everything is managed by digital data is now within reach.

Introducing cutting-edge smartphone surveying solutions like LRTK will drastically change slope greening operations on steep terrain. There will be no need to fear surveying in hazardous locations, and real-time 3D measurement will allow optimal decisions to be made consistently. Data-driven construction reduces waste and minimizes environmental impact. Above all, enabling everyone on site to use digital tools will strengthen organizational DX capability. This aligns with industry-wide initiatives such as the Ministry of Land, Infrastructure, Transport and Tourism’s *i-Construction*, enabling smart construction suited to the times.

Slope greening on steep terrain is a noble task that contributes to people’s safety and a rich environment. By incorporating DX into those sites, we can create a better future for both workers and local communities. LRTK, which allows easy surveying with a smartphone, will be a reliable partner that supports the first steps toward that future. Why not break free from conventional thinking and actively use new technologies to revolutionize steep slope greening sites? By making digital technology your ally, you can achieve forward-looking construction with improved safety, quality, and efficiency. Take this opportunity to realize the DX of steep slope greening through LRTK adoption and step into next-generation site creation.