Is RTK Accuracy Sufficient for Construction? Comparing Required Accuracy for Grading and Piling

Table of Contents

• Introduction: Required accuracy on site and background

• What is RTK? Mechanism of accuracy and expected performance

• Accuracy requirements for grading work and RTK capability

• Allowable errors in piling work and RTK applicability

• RTK limitations and error factors (satellite environment, vertical accuracy, operational cautions, etc.)

• Advantages beyond accuracy (manpower, time, flexibility)

• Convenience and practicality of simplified surveying with LRTK (accuracy, functions, operational efficiency)

• Summary: Practical accuracy assessment and options

• FAQ

Introduction: Required accuracy on site and background

In construction and civil engineering sites, positioning accuracy requirements have been increasing in recent years. For example, in as-built control (verification of finished dimensions after construction), it is necessary to confirm dimensions and elevations according to the design drawings, and for road pavement thickness, an allowable error of about ±10 mm (±0.39 in) is common. In addition, millimeter-level accuracy may be required for critical parts of structures (e.g., about ±2 mm (±0.08 in) at bridge bearing assemblies). Against such strict accuracy standards, conventional GPS positioning (standalone) produced errors of several meters to about 10 m (32.8 ft), which was insufficient for construction management and surveying work. In fact, typical standalone GPS often deviated by 3-10 m (9.8-32.8 ft), making it unable to meet high-precision tasks.

Against this background, the Ministry of Land, Infrastructure, Transport and Tourism has been promoting the use of ICT technologies through initiatives such as i-Construction to advance surveying and construction methods. One means that emerged to achieve centimeter-level high-precision positioning is RTK positioning (Real Time Kinematic). For surveyors and construction managers on site, RTK has attracted attention as a "new technology that changes conventional wisdom," and it is becoming indispensable. This article examines whether RTK provides sufficient performance for the accuracy demanded on construction sites, comparing it with the accuracy required for grading and piling work. It also provides material to help decide whether to introduce RTK and introduces the latest simplified surveying solution, LRTK.

What is RTK? Mechanism of accuracy and expected performance

RTK (Real Time Kinematic) is a positioning technique that corrects GNSS satellite positioning errors in real time to determine positions with centimeter-level accuracy. A base station (a receiver installed at a known point) and a rover (the worker’s receiver) perform GNSS observations simultaneously and cancel out errors common to both (such as satellite orbit errors and ionospheric delays), achieving high-precision relative positioning. Simply put, it is a technology that "reduces positional errors that were several meters with regular GPS down to a few centimeters by applying differential corrections in real time."

RTK accuracy depends on conditions, but generally it is within a few centimeters for horizontal position and a few centimeters for vertical as well. Specific achievements under favorable conditions include horizontal errors of about 2–3 cm (0.8–1.2 in) and vertical errors of about 3–4 cm (1.2–1.6 in). This is a dramatic improvement compared to standalone positioning and has enabled precise site measurements that were previously difficult. RTK receives correction data in real time using GNSS base station networks (electronic reference point networks) or private correction services (such as Ntrip) and applies them to the rover position. In Japan, the Quasi-Zenith Satellite System “Michibiki” provides a centimeter-level augmentation service (CLAS), and compatible equipment can receive corrections directly from satellites even where the Internet is not available.

As noted above, the expected RTK accuracy is a few centimeters, with a tendency for particularly good horizontal accuracy. GNSS vertical accuracy is generally slightly worse than horizontal and errors can be roughly double (as in the example where horizontal was 2–3 cm and vertical was about 3–4 cm). Even so, obtaining this level of accuracy instantly without optical surveying instruments is significant, and RTK has become a revolutionary solution for as-built control and precise layout work. However, as discussed later, RTK is not omnipotent and accuracy varies with satellite reception conditions and operational methods.

Accuracy requirements for grading work and RTK capability

Grading work refers to leveling the ground with heavy machinery, carried out for road subgrades and site finishing. Height (elevation) accuracy management is critical in grading, and deviations from the design surface must fall within prescribed tolerances. For example, in road work, finish errors for subgrade or pavement thickness are generally specified as around ±1 cm (±0.4 in). In other words, even when leveling a wide area, elevation errors must be kept within a few centimeters.

RTK generally matches these accuracy requirements. Machine guidance and machine control on heavy equipment equipped with RTK-GNSS control the blade height in real time during work, achieving finish accuracy within a few centimeters. In practice, on ICT construction sites there are increasing cases where work was performed with RTK positioning without installing traditional batter boards and finished within a few centimeters, achieving both efficiency and accuracy. Previously, managing elevation across wide areas required many reference stakes and optical levels, but direct GNSS positioning has greatly reduced the effort of establishing references.

That said, attention to vertical accuracy is essential when using RTK for grading. Even if horizontal position is accurate within a few centimeters, vertical errors of up to about 5 cm (2.0 in) can occur in some cases. Fortunately, grading is often done in open terrain with good satellite reception conditions, and under those conditions RTK errors are on average within a few centimeters both horizontally and vertically, making it practically sufficient. However, in paving works where finish thickness requirements are especially strict, RTK measurements are sometimes subjected to a final double-check with a level. From a quality assurance perspective, combining RTK with optical surveying can ensure accuracy standards are met.

Overall, RTK accuracy for grading work is "sufficiently practical" and has brought substantial efficiency gains. GNSS-guided bulldozers and graders are already active on many sites, achieving designed slopes and heights mostly without physical stakes※. (※ Performing work based solely on data references without installing batter boards or strings.) Introducing RTK allows reduction of work time and manpower while maintaining construction accuracy, which is a significant advantage on site.

Allowable errors in piling work and RTK applicability

Piling work (installing foundation piles at designated positions) requires particularly high accuracy in construction. If piles that support a building or bridge are not driven to the correct position and depth as shown on the drawings, it can cause uneven structural loads and misalignment at joints. Generally, the allowable pile position deviation is said to be about 100 mm (3.94 in) (10 cm (3.9 in)), but this is a design-side upper-limit assumption that includes safety margins; in practice, strict control is exercised to ensure deviations do not exceed this. The allowable deviation for pile positions reflected in structural calculations at the design stage is usually about 100 mm (3.94 in) (10 cm (3.9 in)), but this is an upper limit and site practice aims to make errors as close to zero relative to the drawing position as possible.

Traditionally, pile layout (marking) required surveyors using total stations and tape measures to calculate pile center positions from reference points and mark the ground with wooden stakes or paint. This method required at least two people (an instrument operator and a marker), and relied heavily on experience and intuition, placing a large burden on manpower and skill. On large sites where hundreds of piles must be located, the traditional method is time-consuming per pile, often extending the overall schedule. One report stated that traditional pile position surveying took about six times longer than the latest digital methods, highlighting it as a productivity bottleneck.

To address these issues, direct guidance for pile positions using RTK has drawn attention. By navigating to pile design coordinates in the field with an RTK-capable GNSS receiver, intermediate marking work can be omitted and the surveyor need not attend every placement. Specifically, target coordinates for pile heads are registered in the device, and on site the device (a rover receiver) tells the operator where to place and install the pile. The operator simply adjusts while watching the difference between the current position indicated by the receiver and the target, meaning "anyone can mark pile positions with the same accuracy." The MLIT’s promotion of ICT construction and i-Construction emphasizes GNSS-based accuracy improvements, and RTK introduction for pile guidance is expected to revolutionize accuracy control.

Some large sites already equip pile drivers with GNSS receivers for in-cab monitor-guided piling (machine guidance). However, dedicated equipment is expensive and not widespread in small-to-medium sites. A practical solution that has emerged is handheld RTK-based pile guidance. A worker carries a small GNSS receiver and follows guidance on a smartphone screen to the pile position, enabling a single person to accurately mark a pile location. For example, the screen may display instructions like "move 5 cm (2.0 in) east," so no assistance from another person is needed; the worker moves as directed and places the pile at the receiver position. Recently, AR (augmented reality) features have appeared that overlay virtual target markers on the smartphone camera image to intuitively show "this is the pile location," allowing accurate positioning and making fine adjustments and checks more efficient.

Thus, the applicability of RTK to piling work is expanding. Where satellite positioning is available outdoors, RTK can guide pile positions with centimeter-level accuracy. Caveats include environments where GNSS signals are blocked—such as narrow urban canyons or under piers—where traditional surveying methods remain necessary. However, most new-building piling sites have open skies, allowing RTK to perform effectively. In practice, some sites use RTK for pile center layout and then perform confirmation surveys with a total station afterward to ensure robustness. By using RTK for efficiency and optical methods for final verification, both productivity and quality assurance can be achieved.

RTK limitations and error factors (satellite environment, vertical accuracy, operational cautions, etc.)

No matter how excellent a technology is, it cannot deliver its intended performance if applied under unsuitable conditions or used improperly. RTK positioning has limitations and factors that degrade accuracy. First and foremost, the satellite signal reception environment greatly affects accuracy. With an open sky and enough GNSS satellites visible, RTK can stably achieve centimeter-level accuracy, but if satellite geometry is poor or the number of visible satellites is low, errors will increase even with RTK. For example, in urban areas surrounded by tall buildings, multipath caused by signal reflections and obstruction of satellite visibility can temporarily cause errors of tens of centimeters, and in the worst case the RTK solution may lose its "fixed" (centimeter) status. In one experiment measuring RTK in a building area, the average error was about 5 cm while maximum deviations reached about 12 cm horizontally and 19 cm vertically. Conversely, open sites without obstacles achieved high accuracy of about 2 cm horizontally and 3 cm vertically. This shows that RTK accuracy varies with environmental conditions: even where satellite signals are somewhat constrained, practical accuracy (errors of several to a dozen centimeters) can often be maintained, but extra caution is required in harsh environments.

Next, the vertical accuracy limitation should be recognized. RTK-GNSS cannot completely eliminate errors in the altitude direction (e.g., tropospheric delay), and vertical accuracy is generally lower than horizontal. A safe estimate is that when horizontal accuracy is 1 cm, vertical may be about 2 cm. Also, GNSS positioning yields ellipsoidal heights, and converting to actual orthometric heights (geoid heights) requires applying a geoid model. In Japan, many sites use the Japan Gravity Datum (such as JGD2011) height systems, so localizing RTK positions to the site height is important. If this conversion is not done correctly, a systematic height bias of several centimeters may occur. Therefore, for tasks where vertical accuracy is critical (such as precise leveling), it is recommended to perform calibration to local known points or to combine RTK with leveling measurements to provide safety margins.

Operational cautions include always keeping the RTK antenna pole vertical and correctly configuring the equipment. Antenna tilt can cause errors of several millimeters to about 1 cm even with slight tilt. Although receivers with IMU-based automatic pole-tilt compensation are now available, they have limits, so the principle of keeping the pole vertical remains. Mistakes in entering the rover antenna height or base station coordinates will create corresponding offsets in positioning results, so pre-checks are essential. RTK delivers results in real time, but this immediacy makes error detection more difficult. Once a fixed (centimeter-level) solution is achieved, users may become complacent, but satellite number and signal conditions change constantly during observation. Periodically returning to known points for check measurements or performing multiple observations at key points and averaging them improves reliability.

Even considering these error factors, RTK-GNSS is an extremely precise and convenient tool when properly used. Understanding its limits and taking measures such as choosing open sky periods, observing away from metal fences and heavy machinery, and monitoring satellite geometry (DOP) will help obtain stable centimeter-level results. Data show that mean errors of a few centimeters can be maintained even in mountainous areas and urban settings, indicating practical accuracy can be secured under some environmental constraints. The key is to complement RTK’s weaknesses operationally (e.g., supplement with optical surveying when needed, use Michibiki in communication-poor areas) so that required on-site accuracy can be largely met.

Advantages beyond accuracy (manpower, time, flexibility)

The benefits of introducing RTK go beyond accuracy alone. Labor saving, efficiency gains, and increased flexibility are significant effects. Traditional surveying and layout work required a technician to operate a total station and an assistant holding a prism, and large sites often needed multiple teams. With RTK positioning, surveying can basically be completed by a single person. A worker carrying a high-precision GNSS receiver can move to points and mark them, enabling response even in sites with labor shortages. The effect of enabling solo work for tasks that formerly required two people—such as pile layout—is substantial and contributes to alleviating the construction industry’s staffing challenges.

Time savings are another major advantage. RTK provides current coordinates at the push of a button, eliminating time-consuming distance and angle setups between points. For example, setting up a total station and performing backsight and rotations to locate one pile could take several to many minutes. With RTK, simply moving and setting the antenna at the target location allows positioning in seconds to tens of seconds. When many points must be measured, this difference is significant—the total surveying time can be reduced to a fraction of traditional methods. At some ICT construction sites, using RTK with a smartphone reduced a day’s worth of as-built measurement to a few hours, and pile layout waiting times were eliminated so other processes did not need to stop. Real-time positioning means you can measure and immediately proceed to the next task, contributing directly to schedule shortening and smoother site progress.

RTK also dramatically increases operational flexibility. GNSS surveying does not require line-of-sight like optical instruments, so it is less affected by terrain and obstacles. For example, for surveying both ends of a large site simultaneously, as long as corrections reach the rover, positions up to 1 km away can be measured in real time. In hilly terrain where a traditional survey would require detours to secure line-of-sight, RTK enables direct site visits for positioning. This means measurements can be performed in any order or timing preferred on site, increasing planning freedom. RTK also performs well at night or in adverse weather; since GNSS functions regardless of light and is only mildly affected by rain or snow (excluding radio interference from lightning), it is advantageous. For nighttime checks of batter boards, confirming coordinates with an RTK receiver is safer and more reliable than inspecting targets with a flashlight. RTK’s relative immunity to weather makes it robust for many conditions.

Digitally recorded measurements reduce human error. Manual surveying involves reading numbers and writing them down, which carries risk of transcription errors. RTK records measurements automatically, reducing misrecording. Collected data can be immediately synchronized to the cloud and shared with the team, enabling use for as-built drawings and reports on site. Linking photos and data digitally makes it easy to retrieve which points were measured and their deviations from design values, streamlining inspection documentation and reporting. Thus, RTK’s benefits extend to manpower optimization, time reduction, error reduction, and safety improvement, making it an important element in on-site digital transformation.

Convenience and practicality of simplified surveying with LRTK (accuracy, functions, operational efficiency)

Among solutions promoting field adoption of RTK, LRTK has attracted attention. LRTK is a small RTK-GNSS positioning device and cloud platform developed by Reflexia, a startup originating from Tokyo Institute of Technology. By attaching this device to a smartphone and linking with a dedicated app, anyone can easily perform centimeter-level "smartphone surveying." Traditionally, RTK surveying involved stationary receivers or large antennas, but LRTK is an ultra-compact, lightweight receiver terminal just 13 mm (0.51 in) thick and weighing about 125 g, making it a pocket-sized RTK device. It has a built-in battery and is easy to carry and use on site.

LRTK operates integrated with a smartphone, transmitting positioning data to the app via Bluetooth in real time. With this single small device and a smartphone, users can perform coordinate acquisition, 3D scanning, layout (staking), photo recording, and even AR simulations. For example, taking photos of the site with the smartphone camera while positioning with LRTK tags those photos with high-precision location information and uploads them to the cloud. Selecting a design point on the phone screen enables navigation to that coordinate from LRTK (pile guidance). LRTK also supports 3D point cloud scanning: using smartphone photos or a compatible LiDAR unit, site point cloud data can be captured and georeferenced (positioned in absolute coordinates) by RTK. Collected data is uploaded to the cloud immediately and can be shared with the team in 2D/3D viewers for on-site analysis such as measuring distances, areas, volumes, or comparing with design data. In short, LRTK is an all-in-one platform that allows almost all surveying and measurement tasks to be completed on a smartphone.

LRTK’s accuracy is well established: experiments using the device confirmed position determination to about a few centimeters horizontally and vertically across environments. In open areas, errors of about 2–3 cm (0.8–1.2 in) were observed; in urban or forest-adjacent areas, errors were within several to a dozen centimeters—dramatically better than standalone positioning. Combined with a smartphone, receiving network RTK corrections or Michibiki CLAS produces horizontal accuracy of about ±1–2 cm (±0.4–0.8 in) and vertical accuracy of ±3–4 cm (±1.2–1.6 in) on the phone. This accuracy eliminates the need for traditional fine adjustments with batter boards or strings. Importantly, positions obtained on site correspond directly to public coordinates (known geodetic reference coordinates), so reading design coordinates into the smartphone allows immediate use for construction and verification. A digital workflow from design through construction and as-built control reduces errors and improves efficiency.

From an operational efficiency perspective, LRTK is revolutionary. Its intuitive smartphone UI makes it easy to use, so even less-experienced workers can perform surveying and layout by following app instructions. This helps standardize skills across the workforce and covers shortages of veteran surveyors. Cost-wise, LRTK is far more affordable than traditional dedicated survey instruments, facilitating its adoption as a "one-per-person" high-precision positioning tool. Field managers and workers highly value LRTK’s convenience and usefulness, creating a quiet boom. Its light weight reduces physical burden and fatigue during long outdoor work, contributing to safety. Cloud integration simplifies reporting to the office and improves coordination between field and office.

In summary, LRTK is designed to enable "anyone, immediately, to perform high-precision surveying and measurement," maximizing RTK benefits while lowering operational barriers. The fact that precision surveying, which once required expensive equipment and skilled technicians, can now be done with a small device and a smartphone is significant and directly improves construction productivity. Handheld surveying devices like LRTK may become standard site equipment, allowing each worker to perform surveying, as-built checks, and layout. For technicians, the feeling that their smartphone is a surveying instrument is transforming site management practices.

Summary: Practical accuracy assessment and options

Finally, based on the content of this article, we summarize whether "RTK accuracy is sufficiently practical for construction sites." In conclusion, RTK accuracy is sufficient for many construction surveying and execution scenarios. Grading work typically requires accuracy on the order of a few centimeters, which RTK can achieve; GNSS machine control is widely used for subgrade correction and similar tasks. RTK also aids pile layout by guiding pile centers to drawing-specified positions. Of course, RTK cannot fully replace traditional methods in all cases. For tasks requiring millimeter-level accuracy—such as installing bridge bearings or positioning anchor bolts for machinery—optical surveying and special jigs remain necessary. However, such ultra-high-precision tasks are a minority; most surveying, as-built verification, and layout tasks can be handled practically by RTK.

The important point is to judge based on the required practical accuracy and RTK characteristics. For example, work that requires very tight tolerances such as ±5 mm (±0.20 in) should still rely on precision measurement methods (fine-angle total station measurements or high-precision leveling). Conversely, many civil engineering and surveying tasks that tolerate about ±20–30 mm (±0.79–1.18 in) can be practically performed with RTK alone. Consider the site’s reception environment: RTK performs best in open development sites or riverbed works, while surveying in high-rise urban areas risks intermittent larger errors, so plan for pre-checking reception conditions or arranging auxiliary observations.

Non-accuracy benefits of RTK are also important when deciding adoption. Even if accuracy is comparable to traditional methods, RTK’s added value in efficiency, reduced manpower, and improved safety makes introduction worthwhile. In practice, RTK allows many tasks to be completed by one person in a short time, enables immediate cloud sharing of data, and changes site operation. The emergence of next-generation tools like LRTK further increases RTK’s convenience, allowing staff without a dedicated surveying team to perform measurements and checks as needed. With falling prices and simpler equipment, RTK is becoming an everyday site tool rather than a specialized technology.

Based on the above, practitioners should consider "the accuracy required on their site," "the surrounding reception environment," and "the need for operational efficiency" to decide whether to use RTK. Guidance for using network RTK for reference point surveying and ICT construction GNSS equipment utilization is available, and national-level support exists. Accuracy verification data are accumulating, and findings such as "RTK-GNSS can achieve accuracy comparable to third-class reference point surveys when properly used" are being shared. Ultimately, the recommended attitude is flexible: "use RTK where it can do the job and complement it with other methods when necessary." Leveraging RTK’s centimeter accuracy to boost productivity, while employing traditional methods where millimeter precision is required, will likely become the hybrid standard going forward.

FAQ

Q1: Can RTK positioning completely replace traditional surveying instruments such as total stations and levels? A1: At present, a complete replacement is difficult, but RTK is becoming the main method in many situations. Wide-area layout and as-built measurements where centimeter accuracy is sufficient can be substituted with RTK. However, for tasks requiring millimeter accuracy—such as bridge alignments and precision equipment installation—total stations and optical precision measurements remain indispensable. That said, hybrid use is possible: use RTK for rough positioning and refine the final millimeters with optical instruments. The practical approach is to use each method according to the application and continue complementary use.

Q2: What factors affect RTK accuracy, and how can accuracy be ensured on site? A2: Major factors include the satellite reception environment (sky visibility and multipath), distance to the base station, atmospheric conditions (ionosphere/troposphere), and equipment handling (antenna tilt and configuration errors). To ensure accuracy, first secure sky visibility and capture as many satellites as possible. Avoid observing near tall buildings or metal objects to reduce signal reflections. When using a base station, place it close to the site to shorten baseline distance; for network RTK, use regional VRS services. In areas with poor network coverage, Michibiki’s CLAS can provide corrections. During observations, keep the antenna pole vertical and perform periodic check measurements at known points to verify accuracy. In short, "choose a good environment, handle equipment correctly, and verify results" to maintain RTK’s intended accuracy.

Q3: What is LRTK and how does it differ from conventional RTK devices and other GNSS receivers? A3: LRTK is an ultra-compact RTK-GNSS receiver and surveying app that pairs with a smartphone. Unlike traditional RTK equipment that needed dedicated controllers and stationary antennas, LRTK enables centimeter accuracy by simply attaching a small receiver to a smartphone. Differences include outstanding portability and ease of use (pocket-sized weight), an intuitive smartphone app UI with coordinate guidance, AR display, and cloud integration, and multifunctionality such as photo tagging and point cloud capture. While conventional devices focused mainly on positioning, LRTK is an integrated platform for positioning, imaging, and layout. Its acquisition cost is also lower, facilitating wider adoption. In essence, LRTK retains RTK performance while greatly improving usability and versatility.

Q4: Can RTK be used in forests or indoors? What about environments where satellites are not visible? A4: Use in forests or under trees is more challenging but sometimes possible. When canopy blocks much of the sky, the number of visible satellites drops and RTK may lose its fixed solution. Modern GNSS receivers support multiple frequencies and constellations, improving reception even under foliage, so limited positioning may still be possible, but accuracy often degrades and errors of tens of centimeters are likely. In fully indoor environments (inside buildings or tunnels), RTK is generally not usable because satellite signals are blocked; in those cases, optical distance measurement or local positioning systems (total stations or indoor positioning) are necessary. Semi-indoor environments (under bridges or in building shadows) depend on surroundings: if too few satellites are visible, RTK becomes difficult. If about 30–40 degrees of sky view is maintained, fixed solutions may be temporarily sustained with augmentation signals. The rule of thumb is "can you see the sky?"—if not, take measures such as finding open spots or extending measurements from outdoor reference points.

Q5: How reliable is RTK vertical accuracy? Does RTK make leveling unnecessary? A5: RTK vertical accuracy is slightly inferior to horizontal accuracy but is practically within a few centimeters; under good conditions about 3 cm (1.2 in) vertical accuracy can be expected. However, precise leveling can measure height differences with millimeter accuracy, so for extremely high-precision height control leveling remains useful. For general civil works, RTK is increasingly used for reference heights and as-built height checks. But for long longitudinal profiles or settlement monitoring where strict stability and precision are required, precision leveling is still the standard. Thus, RTK does not immediately render leveling unnecessary; instead, use leveling for key control points and perform RTK surveys referenced to those points to improve overall confidence. A practical approach is to use RTK for routine height checks and perform periodic verification with leveling.

Q6: What is needed to start RTK surveying? What preparations are required on site? A6: To perform RTK surveying, you basically need a GNSS receiver (rover), a base station (or a network correction service), a means to receive correction data, and a data display device. Specifically:

• RTK-capable GNSS receiver: Use a dual-frequency GNSS antenna/receiver capable of centimeter-level positioning. Options range from smartphone-connected small receivers (e.g., LRTK) to handheld integrated GNSS units.

• Base station (or network correction service): If installing a local base station, set the antenna on a known point and ensure power and communications. Alternatively, you can use the Geospatial Information Authority’s reference station network or commercial RTK correction services (Ntrip) over the Internet, eliminating the need for a local base. In Japan, many use private VRS services or carrier-provided RTK services. In mountainous areas without network access, Michibiki CLAS can provide corrections directly from satellites.

• Communication devices and software: To receive corrections on the rover, use a mobile router or smartphone tethering to provide Internet access (using an Ntrip client-capable app). For private base stations, UHF low-power radios can transmit corrections. Use manufacturer controllers or smartphone/tablet surveying apps to configure the receiver and display coordinates. If using LRTK, install its dedicated app on the smartphone.

• Coordinate system settings: Set the reference coordinate system (e.g., a specific global or plane coordinate system) in the app and input known site control points. If localization to local coordinates is required, observe several known points to compute coordinate transformation parameters.

• Checks and verification: Before starting, measure a known control point with the rover to confirm correct correction data and coordinate settings.

Once these are prepared, the rover can be taken to a point, and observation initiated; results appear in real time and can be saved as needed. While initial setup of communication and coordinate transformation can be confusing, after construction the system can be powered on and ready to measure quickly. In short, prepare appropriate RTK equipment, ensure access to correction data, and calibrate using local known points to begin surveying. Note that when using RTK-GNSS for public surveying in Japan, follow the Geospatial Information Authority’s procedures and accuracy control guidelines.