New technology in land improvement surveying: No batterboards with AR, solo surveying with smartphone RTK

A new wave is sweeping surveying work on the sites of land improvement projects, which involve earthworks for large agricultural areas, installation of 畦畔 (aze-han)※, and adjustment of waterway gradients. The traditional practice of installing batterboards (chōhari) using wooden stakes and string, and performing level surveys with two-person teams, is being transformed by the adoption of cutting-edge technologies. The combination of smartphone-based high-precision GNSS called "smartphone RTK" and AR (augmented reality) technology that overlays digital information onto the site is making the revolutionary approach of "no batterboards, solo surveying" increasingly feasible. This article begins with conventional surveying methods used in land improvement and their challenges, then explains the digitalization trend reshaping the industry, the mechanism of solo surveying enabled by new technologies, and concrete use cases. Aimed at everyone from veteran technicians to young construction supervisors interested in improving on-site productivity, we present the latest practical trends.

※畦畔…細長い土手を水田や畑の区画間に盛って作るもの (a narrow earthen ridge created between paddy fields or plots)

Conventional land improvement surveying methods and their challenges

First, let us look back at the traditional surveying methods that have long been used on land improvement sites. In agricultural civil engineering surveying, the mainstream method has generally been installing batterboards using optical instruments such as total stations and auto levels. For example, when establishing the elevation and position of irrigation channels, workers would drive wooden stakes into reference points and fix straightedges horizontally, then string lines to indicate elevations—this so-called batterboard layout would be set up at multiple locations to guide excavation and embankment work. This batterboard process typically required two or more workers: one would set up and sight with a level instrument or total station and take readings, while another would hold the staff (rod) at the designated point. On large fields or long waterways, the number of survey points could be so large that surveying alone could take several days. Even after spending time setting up batterboards, heavy equipment operations or rainfall could shift or dislodge stakes, causing positional drift that required re-surveying and re-establishment. In addition, because survey results were often taken back to the office for comparison with drawings to confirm “which design element does this on-site stake correspond to?”, there was an inefficiency in that as-built confirmation could not be done on site.

These traditional methods also rely heavily on experienced personnel. If human errors such as recording mistakes or calculation errors occur in surveying, they can lead to construction errors, so accurate work required skilled workers who knew the subtleties of the job. However, across the construction industry, the aging of skilled workers and shortage of young talent has become severe. Land improvement associations are also concerned about future labor shortages; securing staff and improving work efficiency are major issues. If surveying must always be performed by teams of two or more as in traditional methods, it becomes increasingly difficult to meet demands for enhanced productivity and workstyle reform.

Main challenges of conventional surveying (summary):

• Labor- and time-intensive: Batterboard setup and total station surveying require at least two people, and even marking a single point is time-consuming. Surveying large agricultural fields can take a whole day or more just for the survey.

• Difficult to ensure accuracy: Traditional positioning using wooden stakes and ink marks is prone to stake placement errors and cumulative errors. Stake displacement or misreading can cause positional drift, which can lead to downstream construction errors.

• Immediate verification is difficult: Because measured data are brought back to the office for comparison with drawings, the finished condition cannot be verified in real time. Problems are often discovered later, causing rework.

• Strong dependence on experienced workers: Operation of surveying equipment and batterboard installation relies heavily on experience. With a shortage of skilled technicians, it is hard to always assign veterans, and young workers alone may not achieve sufficient accuracy.

How digitalization of surveying and construction support is changing the field

Against this backdrop, a wave of digitalization has rapidly swept the construction and surveying world in recent years. Initiatives such as *i-Construction* and ICT construction, promoted by the Ministry of Land, Infrastructure, Transport and Tourism, have encouraged the use of 3D data and IT technologies in surveying and construction processes for civil engineering. The land improvement field is no exception, and DX (digital transformation) of surveying and construction support is gradually penetrating sites.

For example, drone photogrammetry, which analyzes aerial photos to create 3D terrain models, has begun to be used for understanding current conditions of fields and for as-built inspections. Where conventional terrain surveys that took days by manual labor can be completed in hours with drones, dramatic efficiency gains have been demonstrated, proving valuable for creating elevation maps of large agricultural areas. Machine control technology, which equips construction machinery such as bulldozers and backhoes with GNSS and sensors to automatically control them according to design data, is also becoming widespread. Because operators can work while monitoring design surfaces inside the cab, batterboards that were previously indispensable can be largely omitted, improving productivity (in effect, the machinery plays the role of an “electronic batterboard”).

Surveying itself has also benefited from digitalization. Using robotic total stations that automatically track the prism enables one-person surveying where an operator walks with the prism to record terrain, and GNSS surveying equipment using satellites such as GPS and GLONASS has become more accurate and compact. Especially noteworthy is that advancements in satellite positioning and communications have made RTK surveying—centimeter-level positioning in real time—more accessible. In the RTK (Real Time Kinematic) method, a rover (the surveying receiver) receives correction information from a base station and applies it in real time to correct satellite positioning errors. As a result, positioning errors that are normally several meters can be reduced to a few centimeters, making them usable for precise site layout.

The adoption of these digital technologies has the potential to dramatically improve work efficiency and surveying accuracy on land improvement sites. Surveying that once relied on large crews can now often be handled by fewer people in a short time using ICT. And now, by taking these technologies a step further, a next-generation surveying style that allows one person to “measure and verify on site” is becoming a reality. The key to making this possible is the combination of smartphone RTK and AR, which we discuss in the next section.

New “solo surveying” by combining RTK-GNSS and AR technologies

Combining the recently introduced smartphone RTK and AR surveying dramatically transforms on-site surveying for land improvement. Smartphone RTK, as the name implies, is the technology that uses a smartphone as an RTK-style high-precision GNSS receiver. Specifically, by attaching a small GNSS receiver to a smartphone or tablet, connecting to correction services over the internet such as NTRIP or Japan’s quasi-zenith satellite “Michibiki” centimeter-level augmentation service (CLAS), a smartphone can obtain centimeter-accuracy real-time coordinates. This accuracy is generally said to be horizontal 2–3 cm (0.8–1.2 in), vertical 3–4 cm (1.2–1.6 in), and if measured while stationary, errors can sometimes be less than 1 cm (<0.4 in). It is revolutionary that centimeter-level positioning, which used to require surveying equipment costing hundreds of thousands of dollars, can now be achieved with a palm-sized, a few-hundred-gram receiver.

On the other hand, AR (Augmented Reality) overlays digital information onto real-world imagery seen through a camera. In construction, overlaying drawings or models onto the actual site is attracting attention: smartphones or tablets can display design lines and structure models on their screens to enable intuitive verification. The advantage of AR is that information that is difficult to grasp from paper drawings or numerical data can be visualized on site. For example, the planned alignment of a finished water channel can be virtually displayed on the ground, or the design elevation reference surface can be shown translucent; this allows all workers to proceed with a shared mental image of the finished result.

What happens when smartphone RTK and AR are combined? The major change is that surveying, batterboard installation, and verification work that traditionally required two or more people can be completed by one person. Using the centimeter-accurate self-positioning from RTK-GNSS, virtual stakes and reference lines can be displayed on the smartphone screen so that positioning and elevation checks are possible without physically driving stakes. Tasks that used to rely on intuition—holding a paper drawing and estimating “this should be roughly the design position…”—become operations where workers simply point their phones and see “this is the spot”. For example, where total station-based stake driving required going back and forth with a machine and prism and calling out to a partner while carefully driving stakes, AR display with smartphone RTK shows on-screen markers that allow a single person to complete the positioning. Not only is time and labor greatly reduced, but because positions are always verified against GPS-based coordinates, human errors and stake displacement are less likely.

AR also enables immediate on-site comparison of design values with actual conditions, allowing instant judgment of as-built quality. For instance, rather than walking around measuring the height of embankments and later checking drawings, AR can display design elevation markers (virtual horizontal lines or surfaces) on the smartphone, so workers can directly see whether embankments are too high or too low by color or position. This real-time conformance check facilitates early detection of errors and reduces rework. From a safety standpoint, solo high-precision surveying has advantages: dangerous steep slopes or deep excavations can be surveyed without personnel entering the hazard by acquiring data remotely using a smartphone camera and LiDAR scanner. Clear AR guidance reduces misunderstandings and communication errors on site. Thus, the fusion of RTK and AR for solo surveying offers significant on-site benefits not only in labor reduction but also in safety assurance and quality improvement.

Intuitive positioning achieved with a smartphone plus a small RTK receiver

So how exactly is solo surveying performed using a smartphone, an RTK receiver, and an AR app? Let us look more closely at the mechanism and operation image.

In preparation, a dedicated small RTK-GNSS receiver is attached to the latest smartphone with one touch and connected via Bluetooth or the like. In Japan, receiving CLAS signals from the Michibiki satellite or accessing public reference station correction services over the internet makes it possible to achieve high-precision positioning without setting up your own base station. Start the dedicated app and begin receiving correction information, and the smartphone will thereafter continuously update its position at centimeter accuracy. The setup is extremely simple and requires no complex initial configuration or instrument calibration. The receiver contains its own battery and, once charged, surveying can begin immediately on site.

When starting a survey, load the design data or the coordinates of the points to be measured into the smartphone app. If the design drawings are CAD data (such as DXF or DWG), they can be imported and displayed directly, and if only paper drawings are available, key points or line coordinates can be entered into the app for use. After preparation, simply walk around the site with the smartphone in hand. For example, if you register the coordinates corresponding to the centerline of an embankment in sequence, the app will continuously compare the current position and provide navigation such as “2.3 m (7.5 ft) north to the next point” and “0.5 m (1.6 ft) to the right.” As you approach the target, a “virtual stake” marker appears over the camera view on the smartphone. Because it looks as if a stake has been driven there, you can finish staking by placing a physical stake or flag at your feet. If necessary, you can indicate positions using only virtual stakes on the screen, allowing accurate point layout even on rock or concrete surfaces where driving physical stakes is difficult.

Smartphone RTK apps typically include functions for recording survey points and various measurements. For example, pressing a button at a location where “I want to drive a stake here” instantly acquires and saves that coordinate. Saved points are automatically given identifiers or numbers and displayed as markers on the screen, so the same location can be recognized at a glance when re-surveying. Functions to calculate distance and elevation difference between two points on site are also available. Using this, one can easily perform tasks such as calculating and marking the position that is 50 m (164.0 ft) from a channel start point where the elevation difference should be 10 cm (3.9 in). Some systems even include camera- and LiDAR-based 3D scanning, allowing you to walk around with the smartphone to acquire surrounding terrain as point cloud data. Because the acquired point cloud is automatically georeferenced to Earth coordinates (latitude, longitude, elevation), you can later compare it with the design model to visualize errors by color and perform volume calculations on site.

The sequence of operations is intuitive for anyone accustomed to taking photos with a smartphone. Modern smartphone RTK app UIs are refined, and new users can often learn to use them quickly with short guidance. It is fair to say that in this era, anyone who can use a smartphone can handle part of the surveying. On sites where veterans once led teams with paper drawings and asked juniors to run measurements, smartphone RTK has lowered the barrier to surveying tasks.

Use cases unique to land improvement

Solo surveying with smartphone RTK + AR is powerful in many land improvement scenarios. Below are several agricultural civil engineering-specific use cases and their concrete benefits.

• Installation of embankments (aze-han): Embankments built along field boundaries are installed frequently in field development work. Traditionally, batterboard stakes were driven along the embankment centerline and elevation references were set at regular intervals. With smartphone RTK and AR, the embankment design line can be projected on site as a single virtual line. Workers simply follow the on-screen line to place stakes or add embankment material, allowing omission of physical batterboards while still achieving accurate position and elevation. On long embankments, missing or shifted intermediate stakes can cause alignment or elevation defects, but a digital guide line removes that concern. After embankment construction, scanning the height with a smartphone while walking along provides immediate comparison with design elevation, enabling quality control such as adding fill to low areas.

• Setting and verifying waterway gradient: Proper gradient in channels and drains is crucial for agricultural water supply. Normally, construction proceeds while measuring channel bottom elevation with an auto level, but AR surveying can display a virtual guide for the specified gradient to guide excavation. For example, for a design of “total length 100 m (328.1 ft) with an elevation difference of 50 cm (19.7 in) (1/200 slope),” you can set the reference at the start point and input it into the app; the camera view will then display a virtual guideline descending at that gradient. Operators can compare the virtual guideline to the actual excavation surface and maintain a correct gradient. Intermediate checks can be done by one person walking with a smartphone to immediately detect sectional loosening or insufficient gradient. This is especially useful in buried pipe (culvert) work, where detecting gradient defects after burial makes correction difficult; AR real-time verification reduces that risk.

• Field formation and leveling: Smartphone RTK + AR is also effective for tasks like leveling paddy fields to residential standards or terracing slopes into stepped fields. Displaying the designed ground model in AR allows visualization of height differences with a color-coded heatmap between current ground and planned surface. Areas needing fill can appear red and over-height areas blue, enabling intuitive decisions on where and how much to excavate or fill while walking the site. Previously, multiple level surveys were needed and batterboards had to be re-established, but point cloud heatmaps make it easy to see excess or deficit volumes at a glance, simplifying instructions to machine operators. Point cloud data captured by a smartphone can also be directly used for as-built documentation, dramatically reducing time to prepare inspection materials.

In these land improvement-specific scenarios, smartphone RTK + AR surveying contributes to efficiency and quality improvement. Checks that were often omitted due to labor constraints can now be performed quickly by one person, raising the overall level of construction management. Even on large sites where veterans had to shoulder surveying tasks alone, digital technology allows younger staff to cover them more easily and becomes a trump card for addressing labor shortages.

Ensuring accuracy and efficiency while omitting batterboards

While smartphone RTK and AR enable batterboard-less surveying and layout, is on-site accuracy and efficiency truly assured? Here are some approaches and ideas unique to digital technologies.

From an accuracy standpoint, omitting physical batterboards means relying on GNSS coordinate-based position management. With high-precision RTK-GNSS, any point on site can at any time return national geodetic coordinates (X, Y, Z), so each point is managed as an absolute reference. Traditional methods often used local references like batterboards or existing structures, so if those reference stakes moved, all dependent points would shift. RTK surveying eliminates that worry: each point exists as an independent reference value. In extreme cases, important points can be re-measured with RTK and recorded to reset cumulative errors as work progresses.

To balance efficiency and certainty, AR provides visual feedback that is highly useful. Humans can instantly perceive slight misalignments visually, but grasping them from numeric values on a drawing is not easy. Displaying design lines and models on site with AR lets workers intuitively see, for example, that “5 cm of fill is still needed” as color intensity or line offset. This feedback can be as clear as—or clearer than—temporary batterboards or string checks. Moreover, by moving the smartphone and scanning the site, one can grasp offsets at multiple points at once. By using AR guidelines as a digital batterboard, the overall accuracy of the site can be managed even without physical batterboards.

Of course, batterboard-less construction has caveats. For instance, traditional batterboard meetings where all construction stakeholders gather may be lost if information is purely digital and not well shared. Therefore, practices such as having multiple people view the AR screen together to ensure shared understanding, or using a few key physical stakes as supplementary reference lines in a hybrid approach, can be effective. The crucial point is to ensure that everyone can view the latest design information. Paper drawings and batterboards risk update omissions when design changes occur, but digital data managed centrally can be updated instantly and automatically synchronized to all smartphones and tablets taken to site, enabling smooth construction without rework.

In one field case, a renovation of an agricultural water channel experimentally omitted most batterboards and performed key reference measurements with smartphone RTK; surveying and marking manpower was reduced by half while meeting design accuracy. Workers said, “At first I was skeptical that it would be OK without batterboards, but trusting the on-screen guides and verifying the as-built showed it matched the drawings, which was surprising,” indicating a major shift in field perception. As trust in digital technologies grows, sites that traditionally always used batterboards will increasingly adopt these new practices.

A new field where veteran experience and young workers’ smartphone skills merge

When introducing new technology, concerns often arise about a gap between older veterans and younger staff in digital skills. However, smartphone RTK + AR surveying offers an excellent opportunity to fuse veteran experience with young workers’ IT skills.

In traditional surveying, veterans would work in pairs to guide and teach younger workers. Veterans would use their judgement to say, “Measure this next” or “Make the stake 5 mm higher,” while juniors followed instructions and gradually learned. Even with smartphone RTK, veteran roles do not disappear. Rather, veterans are freed from instrument operation and can concentrate on applying their accumulated wisdom and judgement. Smartphone operation can be handled by newcomers, allowing veterans to take a supervisory position, advising and checking at key moments. Young workers benefit from using familiar smartphones to operate as instructed and immediately check results, which makes the purpose of tasks easier to understand and accelerates learning. Viewing the data together on screen and discussing “This is the design line” or “This level of discrepancy is acceptable” helps make veterans’ tacit knowledge visible and transmissible to juniors.

Moreover, smartphone RTK’s simplicity lowers the bar for new hires. Surveying used to be a task that required qualifications or years of practice before being entrusted to staff, but with basic smartphone and app operation, newcomers can handle parts of on-site surveying. In one construction company, a first-year employee used LRTK (described below) to try measuring a slope’s as-built condition and obtained satisfactory results, boosting their confidence. Veteran employees remarked with a wry smile, “When we were young it took years to learn surveying, but today’s kids have such tools from the start.” Thus, cross-generational team operation to embed digital technology into the field can ultimately improve overall productivity.

In land improvement sites facing labor shortages, combining veterans’ knowledge and juniors’ tech skills using a common tool like smartphone RTK is key to sustainable site operation. Veterans can comfortably pass on know-how, and juniors can upskill by using cutting-edge tools—creating a new collaborative style.

Conclusion: Start labor-saving, high-precision solo surveying with smartphone RTK “LRTK”

We have explained the emerging trend of AR utilization × batterboard-less × solo surveying in land improvement surveying. Smartphone RTK + AR technologies that address the challenges of conventional methods and offer efficiency and accuracy suited to an era of labor shortages hold great promise for agricultural civil engineering. While digitalization of surveying and construction will not happen overnight, it is worthwhile to try new measurement methods even on small sites or partial processes.

Finally, one concrete solution that makes solo surveying easy to implement is “LRTK.” LRTK consists of an ultra-compact RTK-GNSS receiver that attaches to a smartphone, a dedicated app, and cloud services. With just a smartphone and LRTK, anyone can start simple surveying the same day. Initial setup is as easy as attaching the receiver and launching the app—no complex operations or adjustments are required. On site, the system provides AR-guided navigation that intuitively guides you to stake positions and allows one-tap coordinate recording and cloud saving. It also includes high-precision point cloud capture using iPhone LiDAR and camera, enabling 3D as-built scans and earthwork volume calculations with a single device. The collected data can be shared via the cloud within the company and used for report preparation, enabling integrated operation connecting the field and the office.

Introducing a smartphone RTK solution like LRTK allows land improvement associations and contractors to perform high-quality surveying and construction management with fewer people. What was once hard labor becomes light work with a smartphone in hand, reducing batterboard installation time and survey waiting times and boosting overall project productivity. Above all, workers will gain satisfaction and confidence using modern technology, smoothing the transfer of skills to the next generation.

We encourage you to consider AR surveying for solo surveying at your sites. You may feel uncertain at first, but once you try it you will surely be impressed by its convenience and accuracy. The future of land improvement sites—where you can measure, verify, and record with just a smartphone and a small receiver—is just around the corner. Embrace the new technology of no batterboards, solo surveying with smartphone RTK to make future land improvement projects smoother and higher quality.

※For details on LRTK and inquiries about implementation, please refer to the official site (LRTK product page: https://www.lrtk.lefixea.com/) or contact us.