Can you do this with a smartphone!? Easy surveying techniques for the era of smart construction

The world is now in the era of smart construction. ICT is sweeping into construction sites, and tasks that used to rely on experienced surveyors and specialized machines can increasingly be handled with a single smartphone. A prime example is the field of "survey staking" (measuring and marking). Survey staking is the work of accurately indicating positions and elevations that serve as construction references on site; traditionally it has been done with total stations (TS), levels, and batter boards. Recently, however, by using a smartphone together with a compact GNSS receiver, incredibly easy high-precision survey staking has become possible.

This article explains the latest survey staking techniques using smartphones in a way that is easy for beginners to understand. It covers the basic principles of the high-precision positioning technology known as RTK-GNSS, how it integrates with smartphones, and step-by-step procedures and required equipment. It also summarizes the benefits of smartphone staking—labor reduction, speedup, improved accuracy, and reduced workload. In addition, we introduce practical examples of how smartphone staking is useful in various on-site situations such as stake-out for pile centers, as-built management, and integration with ICT construction machinery, and consider where it is superior compared to traditional TS surveying and batter-board methods. At the end of the article, we touch on simple RTK surveying using "LRTK," which combines a smartphone and a compact GNSS device, and propose the potential of this new, easy-to-start staking style that anyone can adopt.

What is RTK-GNSS? How smartphones achieve centimeter-level accuracy

First, let’s understand the core technology behind high-precision smartphone staking: "RTK-GNSS positioning." GNSS is the collective term for global navigation satellite systems such as GPS, and smartphones also include GPS receivers. However, the typical positioning accuracy of built-in smartphone GPS has errors on the order of 5–10 m, which is far from the few-centimeter accuracy required for construction surveying.

RTK-GNSS (Real Time Kinematic GNSS) is a method—also called real-time kinematic—where satellite signals are received simultaneously at two points: a reference station (base) and a rover (mobile). The differential between their positioning data is used to correct errors. Standalone positioning can incur meter-level errors due to satellite clock offsets and signal propagation effects, but RTK cancels out these error factors through relative positioning against the base station, enabling accuracy on the order of 1-2 cm (0.4-0.8 in). For example, while a typical smartphone GPS may be off by several meters, using an RTK-capable surveying instrument can in theory determine your position with errors that are orders of magnitude smaller.

To perform RTK positioning, you normally need to either set up your own base station on site or receive correction data over the Internet from networks of reference stations provided by organizations such as the Geospatial Information Authority of Japan or private companies. The latter typically uses a scheme called NTRIP (network RTK), in which smartphones or GNSS receivers download correction information via mobile communications. In Japan, satellite-based corrections are also available from the quasi-zenith satellite system "Michibiki" via the CLAS (Centimeter Level Augmentation Service). With a CLAS-compatible receiver, you can receive augmentation signals directly from satellites and obtain centimeter-level positioning in real time without using the Internet, even at sites out of mobile coverage such as mountainous areas.

Recent smartphone-connected GNSS receivers (such as the LRTK devices described later) utilize these RTK correction methods to enable high-precision positioning on a smartphone. Using a compact GNSS terminal that pairs with the smartphone via Bluetooth, the smartphone effectively becomes a high-precision surveying instrument. The smartphone mainly serves as the user interface, computing device, and communications hub, while the GNSS terminal performs the high-sensitivity signal reception. In other words, the smartphone acts as the brain and the GNSS sensor as the eyes, and by combining them, centimeter-class positioning—once possible only with specialized equipment—becomes available in the palm of your hand.

Equipment and preparations required for smartphone staking

To start staking with a smartphone, you need the following equipment and preparations:

• Smartphone device: Modern iPhones and Android smartphones have high-performance CPUs and large screens suitable for staking work. Devices with strong dust and water resistance are preferable for on-site use. Using a tablet (such as an iPad) offers the advantage of a larger, easier-to-operate display.

• High-precision GNSS receiver: You need a GNSS receiver capable of centimeter-level positioning, not just sub-meter accuracy. For example, there are RTK-capable compact GNSS modules that attach to smartphones. By connecting such a receiver to the smartphone via Bluetooth or other means, you can obtain high-precision GNSS data instead of relying on the phone’s built-in GPS. Receivers that support not only GPS but also GLONASS, Galileo, and Michibiki (QZSS), and that are multi-band GNSS compatible (using L1 and L5 bands among others), increase satellite availability and improve stability.

• Communication environment or correction data source: RTK positioning requires correction data from a reference station. If Internet connectivity is available on site, you should be prepared to subscribe to an NTRIP-based correction service or use reference station data provided by the Geospatial Information Authority. If work is expected in areas without mobile coverage, ensure the receiver can accept Michibiki’s CLAS signals (a CLAS-compatible device can obtain corrections without communications). You can also bring your own mobile base-station GNSS, but because nationwide reference data are now easily accessible via the Internet, using a dedicated service is becoming the mainstream approach.

• Surveying application: Install a dedicated surveying app on the smartphone to perform staking tasks. The app should be able to display real-time position from the GNSS receiver, navigate to target points with distance and direction, and record/export coordinate data. Besides manufacturer-specific apps, there are general surveying apps designed for construction. Familiarize yourself with the app beforehand.

• Pole and mounting hardware (optional): A pole (such as a prism pole) or a simple tripod to stably hold the smartphone and GNSS receiver is convenient. When marking points like pile centers, using the pole tip as a reference helps improve accuracy. A common workflow is to detach the receiver from the smartphone and mount it on the top of the pole while viewing the smartphone screen in hand, aligning the pole tip to the target point.

Procedure for smartphone-based staking

Below is a typical step-by-step procedure when performing staking with a smartphone.

• Equipment setup and positioning readiness: Before going to the site, attach the GNSS receiver to the smartphone and launch the surveying app. Power on the GNSS receiver and pair it with the phone via Bluetooth so it is recognized. Next, set up RTK correction reception. For network-based corrections, configure the NTRIP connection (ID, password, etc.) within the surveying app so you can receive correction data from the base station network. For CLAS, confirm that the receiver is in satellite augmentation mode. If configured correctly, the app will show the solution as Fix, indicating you are ready to obtain real-time centimeter-level positioning.

• Reference-point alignment (localize) and target data setup: In high-precision surveying, aligning to the site-specific coordinate system—called "localize"—is important. This process corrects the offset between the design coordinate system (for example, a plane rectangular coordinate system or a local coordinate system) and the global GNSS coordinates. Specifically, you measure known reference points on site with GNSS, and the app computes the transformation to match those measured values to the coordinates on the plans. After localize is complete, import the target point coordinate data into the app. Load a prepared coordinate list for pile positions or design elevation values, or input numerical values directly on site. Targets will be plotted on the map and you will be ready to stake.

• On-site staking (guidance and marking/observation): Now for the fieldwork. For each designated target point, the app displays the real-time direction and distance from your current position to that point. Move toward the target carrying the smartphone and receiver while following these indications. It feels like being guided to your destination by a car navigation system; without complicated triangulation knowledge, you can head straight to the target. If you use a survey pole, place the pole tip on the ground and make fine adjustments according to the smartphone’s display so the receiver is positioned directly above the target point. When the error is sufficiently small (many apps change the display color to green when the horizontal distance to the target is within a few centimeters), mark the spot. For pile center staking, drive a stake or tack at the pole tip; for ground elevation measurement, read the scale on the pole tip and record the height. For as-built management or other measurements of existing points, press the app’s observe button when you arrive at the point to record coordinate data. You can take multiple observations and average them to improve accuracy if needed. Proceed to stake or measure all target locations on site in this manner.

• Verify and share measurement data: After staking all target points, check the recorded coordinate data. The app may list deviations from design values, and for as-built measurements, automatically calculate heights and distances to check quality. If everything is fine on site, save the data, upload it to the cloud, or send it to the office PC for reporting. One advantage of smartphone staking is extremely smooth data management—there’s no need to transcribe handwritten notes from a fieldbook. With cloud-enabled apps, observed data can be shared with the office immediately and can automatically generate as-built drawings or daily reports. After confirming measurements, perform any additional staking or rework as necessary and complete the on-site tasks.

Benefits of smartphone staking: labor reduction, speed, improved accuracy, reduced burden

Here are the main benefits that smartphones plus GNSS bring to on-site staking:

• Labor reduction (single-person operations): The biggest effect is reduced manpower by enabling one-person staking. Tasks that used to require two people for total-station surveying can be completed by one person when using smartphone staking. Without a second assistant, a single operator can confirm their position and stake points, making it possible to handle surveying efficiently even on labor-short sites. Heavy equipment operators can even get out, perform staking themselves, and resume operation—this not only reduces labor costs but also allows other staff to be assigned to different tasks, improving overall productivity.

• Faster work: Smartphone staking dramatically speeds up surveying tasks. There’s no need for lengthy setup of dedicated instruments or height referencing; you can power on and start measuring immediately. For wide sites with many points, you won’t need to continually reposition equipment or re-establish lines of sight. Because GNSS can work even in locations with limited sightlines, it enables seamless staking across areas interrupted by obstacles. For example, pile position staking that used to take half a day can sometimes be completed in a short time with smartphone staking. Faster staking shortens overall construction scheduling, contributing to shorter project durations and cost savings.

• Maintained or improved accuracy: Properly used, RTK positioning via GNSS can consistently maintain accuracy on the order of 1-2 cm (0.4-0.8 in). Even inexperienced staff can achieve stable accuracy regardless of who performs the work, because the app provides guidance and calculations. Manual methods using tapes or levels are subject to human error and misreading, whereas digital positioning minimizes such variance. The app also displays error values in real time, allowing you to monitor accuracy on the spot, ensuring a robust checking system. As a result, staking mistakes are greatly reduced compared to traditional methods, improving quality control.

• Reduced workload: Because the setup is lightweight—just a smartphone and a compact receiver—there is no need to carry heavy tripods or long staffs. Even novices can operate intuitively using the smartphone, reducing mental strain. The app performs complicated calculations and coordinate determinations, so workers just follow the on-screen instructions. Physically demanding tasks such as installing batter boards or repeatedly measuring points in extreme heat or cold are reduced, contributing to improved safety and working conditions. Overall, smartphone staking reduces both the physical and psychological load on workers, enabling safer and more comfortable operations.

Applying smartphone staking to pile-center layout: accurate positioning even by inexperienced workers

Pile driving (stake-out) and chalking (marking reference lines before concrete placement) are situations where smartphone staking particularly shines. Traditionally, workers extended many tapes based on plan coordinates or used a total station to measure angles and distances to establish pile centers—procedures that relied heavily on skilled craftsmen and could be stressful for inexperienced workers.

With smartphone + GNSS staking, the smartphone provides navigation toward pre-set target coordinates. The screen shows an arrow and distance from the current position to the pile center, decreasing in real time like “X cm remaining.” Guided like a car navigation system, you can head straight to the target without complex survey knowledge. Some systems even overlay guidance arrows or target markers via the smartphone camera using AR (augmented reality). By following guidance markers while viewing the real ground through the screen, workers can intuitively identify pile locations without staring at plans. This reduces rework and positioning errors even for inexperienced staff.

Once at the pile center, mark the point and install the pile or batter board. Staking that used to require repeated measurements and fine tuning is dramatically streamlined with smartphone staking. Multiple-person efforts are replaced by a single person completing the task quickly, greatly shortening lead time before foundation work can commence. Because the digital guidance is followed, human error is minimized and rework is avoided.

As-built management with smartphone staking: verify quality immediately with 3D measurement

Smartphone staking is also powerful for as-built management, where you check the shape and dimensions of completed work. Traditionally, staff measured representative points with tapes or levels and later compared values with design drawings in the office, limiting the number of measurement points and consuming time.

With smartphone + GNSS, you can perform direct 3D measurement on site and understand as-built status immediately. For example, combining the LiDAR scanner on an iPhone or iPad with a GNSS receiver enables scanning of terrain, embankments, and excavations to acquire dense 3D point cloud data. Each point can be assigned coordinates with cm accuracy (cm level accuracy (half-inch accuracy)), allowing immediate volume calculations and cross-section generation from the data. In practice, some earthwork sites have used point clouds obtained via smartphone staking to instantly calculate the volume of remaining soil and optimize the number of dump trucks required. For pavement thickness and structural dimensional inspections, overlaying the design model with measured point clouds enables immediate judgment of acceptability. Digital measurement eliminates the need to handwrite values in a field notebook and perform office calculations later; on-site automatic computation and instant verification minimize rework and additional arrangements, enabling rapid quality control.

Moreover, as-built data collected via smartphone staking can be shared through the cloud to coordinate in real time with site managers and designers. Accumulating daily as-built measurements helps visualize progress and supports construction management. Using accurate as-built information captured by smartphone improves both quality control and schedule management, enabling efficient, waste-free construction.

Complementary use with ICT construction machinery: supporting coordinated human–machine operations

In recent years, GNSS-equipped ICT construction machinery (machine control) like bulldozers and backhoes has been introduced, allowing operators to construct surfaces according to design from their seats. However, even with ICT machinery, human verification and fine measurements are still necessary. Smartphone staking serves as a complementary tool to ICT machinery.

Smartphone staking is useful in the preparation stage before operating ICT machinery. To make machine control function correctly, you need to confirm site reference points and calibrate the machine’s system to the local coordinate system. Previously, surveyors entered the machine work area to perform measurements, but with smartphone GNSS you can quickly re-measure reference points and verify design data. Rapid setup shortens the time until ICT machinery can begin operation.

Smartphone staking is also effective for on-the-fly self-checks during construction. For example, on a large-scale reclamation site, a machine operator might carry a tablet-mounted GNSS to measure trench depths as they work and verify burial depths for pipelines. Where previously a survey team would be called in to check levels, operators can now check immediately, minimizing work interruptions while maintaining quality control. Supervisors and inspectors can track as-built progress with a smartphone alongside changing terrain, creating a dual-check system of human and machine. If the machine’s GNSS experiences trouble, the smartphone can serve as a backup so work can continue without stoppage.

Thus, smartphone staking is not redundant even on sites with high-tech machinery; rather, it becomes a bridge connecting human judgment and digital technology. Combining dynamic machine operations with detailed human measurement and verification further improves overall site productivity and quality. With a smartphone becoming an accessible small surveying instrument for everyone on site, the traditional boundary between surveying and construction is blurring, enabling teams to collectively improve construction accuracy.

Comparison with traditional methods: total station and batter-board vs. smartphone staking

Differences from total station (TS) surveying

While total station surveying offers high accuracy, it lags behind smartphone staking in terms of operational efficiency and flexibility. TS requires at least two people to set up the instrument and hold a prism, whereas smartphone staking can be completed by one person. TS also requires optical lines of sight, so terrain and obstacles may force repeated repositioning. When surveying wide areas, TS coverage is limited to each setup location, requiring the instrument to be moved and orientation to be re-established repeatedly. In contrast, GNSS-based smartphone staking can continuously position across the entire site as long as the sky is visible. Even in obstructed spots, people can go directly to the location to measure, greatly reducing setup losses.

In terms of data processing, TS observations often need to be brought back from memory or transcribed from notes for CAD drawing, whereas smartphone staking digitizes data on site and shares it to the cloud. Naturally, for tasks requiring millimeter-level precision—such as bridge joint alignment—or in GNSS-denied environments like indoors or tunnels, TS remains indispensable. However, for routine civil surveying and positioning tasks, smartphone RTK increasingly meets required accuracies, and smartphone staking is becoming superior in mobility for everyday staking tasks.

Differences from batter-board (yarikata) installation

Batter-board installation—using wooden stakes and string to form a reference frame—has long been a cornerstone of civil works, but its labor and time requirements can be significantly reduced with smartphone staking. Batter-board workflows require driving stakes, fixing horizontal boards, and setting heights with leveling tools before excavation—many steps that can take a team of skilled workers more than half a day to complete. With smartphone staking, you can mark the necessary points with GNSS and sometimes proceed directly to excavation or installation without erecting batter boards. This is especially impactful for long stretches such as road improvement or reclamation projects where traditional batter-board installation demanded substantial manpower; smartphone staking delivers dramatic labor savings.

Batter boards can also require removal and reinstallation as construction progresses, and are vulnerable to being knocked over by machinery or moved by ground loosening due to weather. Smartphone staking allows you to re-measure whenever needed, providing accurate references without relying on temporary fixtures. Machine operators no longer have to search for batter boards to confirm elevations; they can check on their handheld devices for safer and more reliable verification. That said, tasks that require continuous reference lines—such as some reinforcement layout chalking—still benefit from batter-board or chalking work. In short, many temporary reference-setting tasks that once took time and effort can now be replaced by digital staking, enabling construction with minimal necessary batter-board use.

Start simple RTK surveying with smartphone + compact GNSS: LRTK

As a concrete solution for the “easy staking techniques” of the smart-construction era, a smartphone surveying system called LRTK has emerged. LRTK is a next-generation surveying device composed of an ultra-compact, high-performance GNSS receiver that mounts to the smartphone and a dedicated app. The receiver that attaches to the back of a smartphone weighs only about 100–150 g, and Bluetooth connectivity eliminates complicated wiring. It feels like the smartphone itself has become the surveying instrument, and after powering on you can obtain high-precision positioning within a few minutes.

Technically, a major feature is support for both network-based RTK corrections (NTRIP) and satellite augmentation from Japan’s quasi-zenith satellite "Michibiki" (CLAS). In urban and plain areas you can connect to network RTK via mobile networks, and in mountainous or disaster-stricken areas with poor communications you can receive augmentation directly from satellites. The receiver is multi-band capable and can use multiple satellite systems simultaneously, enabling higher satellite acquisition rates and more stable positioning than older equipment. With a one-touch coordinate alignment (localize) at a known point on site, the device will subsequently display results in Japan’s plane rectangular coordinate system, making it easy to use even for non-surveyors.

Using these integrated smartphone + GNSS tools, centimeter-accuracy surveying that once required specialized instruments and advanced knowledge becomes accessible to anyone. Indeed, one-per-person positioning devices like LRTK are expected to be a trump card for improving productivity in the construction industry, which faces chronic labor shortages. Intuitive smartphone app interfaces allow young staff who are new to RTK surveying to become productive in a short time. The surprising surveying experience of "Can a smartphone really do this?" is already beginning at the forefront of site DX. Take this opportunity to introduce a new surveying style using a smartphone and compact GNSS, and experience its benefits and potential—you will likely see long-held assumptions about staking work change dramatically.