Smartphone-based Cadastral Surveys Made This Easy! With LRTK, Anyone Can Perform Centimeter-Precision Surveying

Table of Contents

• Introduction

• What is cadastral surveying?

• Current status and challenges of cadastral surveys

• How smartphone surveying × RTK changes cadastral surveying

• Benefits of smartphone RTK surveying

• Comparison with traditional methods

• New workflow for cadastral surveys

• Use cases of smartphone surveying

• The future of cadastral surveys and digitalization

• Simple, high-precision surveying enabled by LRTK

• FAQ

Introduction

Accurate cadastral map creation is one of the essential tasks for land management and urban planning. For example, reliable as-built plans are required in many situations such as confirming boundaries between public land like roads and rivers and privately owned land, updating urban planning maps, and reorganizing agricultural land parcels. However, traditional cadastral surveys require surveying specialists and large equipment, taking significant time and manpower. As a result, progress on cadastral surveys has lagged, and in some regions boundaries remain unclear.

Currently in Japan, the nationwide average progress rate for cadastral surveys is about 50%. Decades after the surveys began, roughly half of the land remains un-surveyed, and at the current pace it is said that completion could take several more decades. For un-surveyed land, one must rely on old ledgers and cadastral maps, which can lead to boundary disputes, obstacles to land transactions, delays in infrastructure development, and other problems due to inaccurate boundaries and areas. To break through this situation and accelerate cadastral surveys, improving efficiency and reducing labor in surveying work is indispensable.

In recent years, a combination of smartphone-based surveying and RTK (Real Time Kinematic), an advanced satellite positioning technique, has attracted attention as a new method to solve this issue. By using a smartphone together with a compact high-precision GNSS receiver, anyone can perform centimeter-level surveying on site without specialized surveying instruments. This article explains the mechanism and benefits of the new cadastral survey method using smartphone × RTK, compares it with traditional methods, and introduces on-site use cases. At the end of the article we also touch on the “LRTK” system that realizes this high-precision smartphone surveying.

What is cadastral surveying?

A cadastral survey is the work of investigating each parcel of land to determine the owner, parcel number, and land category, and measuring and recording the boundary locations and land area. Based on the National Land Survey Law, municipalities conduct the surveys, and the results are compiled into a cadastral map (a map showing parcel boundaries) and a cadastral register (a ledger summarizing information for each parcel). During the survey, boundaries are confirmed with the landowner present, and the established boundary points are surveyed to calculate areas. The resulting cadastral maps are lodged with the Legal Affairs Bureau and used to update land registries.

Cadastral surveying is a national-level project sometimes called the “land’s family register survey,” and by preparing accurate land information it helps facilitate land transactions, prevent boundary disputes, and enable efficient infrastructure development and disaster prevention planning. Nonetheless, the sheer volume of work means many regions are behind schedule, and for un-surveyed land, boundary information remains uncertain.

Current status and challenges of cadastral surveys

Although cadastral surveys are proceeding nationwide, more than half of the land remains uncompleted. Issues such as staff shortages, financial constraints, and difficulty coordinating landowner attendance have made speeding up cadastral surveys a challenge for many local governments. Traditional surveying methods require skilled technicians using precise equipment, and surveying even a single area could take a long time. Consequently, problems such as “surveys take too long” and “there are not enough people to carry them out” have become apparent.

Given this situation, the national government has begun promoting efficiency improvements and DX (digital transformation) for cadastral surveys. To make up for the shortage of field personnel and expand surveyed area within limited budgets, introducing the latest technologies to improve work efficiency is essential. It is necessary to digitize cadastral surveys, which were once paper- and manual-centric, and to build a system that can quickly and accurately obtain and share boundary information.

How smartphone surveying × RTK changes cadastral surveying

Enter the new surveying method that combines smartphone surveying and RTK. Smartphone surveying, as the name implies, means performing surveying tasks using a smartphone or tablet. The attempt is to replace position measurements that used to require total stations or dedicated GPS devices with a smartphone’s built-in GPS and camera, and even recent models’ LiDAR sensors (optical distance measurement). Although smartphones are convenient and widely carried, typical GPS accuracy is about 5–10 m (16.4–32.8 ft), far from the centimeter-level accuracy needed for cadastral surveys.

That’s where RTK (Real Time Kinematic) comes in—a high-precision positioning technology. RTK applies real-time corrections to satellite positioning data from GNSS systems (GPS, GLONASS, QZSS, etc.) to dramatically reduce positioning errors. Specifically, both a reference station with known accurate coordinates and a rover unit conducting observations while moving simultaneously collect GNSS measurements, and the reference station’s error component is subtracted from the rover’s position. This method can reduce errors that were typically several meters down to a few centimeters, enabling real-time precise positions. RTK has traditionally been used with expensive GNSS surveying equipment handled by surveyors, but in recent years systems that make RTK easily usable with smartphones have appeared.

Smartphone-compatible RTK systems transform a phone into a high-precision surveying instrument using a pocket-sized RTK-GNSS receiver that attaches to the smartphone and a dedicated app. The receiver contains a high-sensitivity antenna and a positioning-dedicated chip, and connects to the phone via Bluetooth, etc. Users can press a button on the phone screen and the system automatically handles satellite signal reception, retrieval and application of correction data, and coordinate calculations. The fact that centimeter-level positioning can be achieved without specialized knowledge is revolutionary. High precision is ensured by obtaining correction data via the Internet from the Geospatial Information Authority of Japan’s electronic reference point network (nationwide GNSS reference stations) or from commercial correction services. In areas without network coverage, such as mountainous regions, centimeter-level augmentation service (CLAS) from Japan’s Quasi-Zenith Satellite System (QZSS, “Michibiki”) can be received directly for corrections. In other words, high-precision positioning can be performed consistently across sites nationwide, from urban areas to mountain regions.

Benefits of smartphone RTK surveying

The advantages that smartphone + RTK surveying brings to cadastral survey sites can be broadly summarized as follows.

• Mobility and ease of use: Because the surveying equipment consists only of a smartphone and a small GNSS receiver, the total weight of the equipment set is very light—just a few hundred grams. You can carry it in your pocket to the field, eliminating the need to lug tripods or heavy batteries, and you can start surveying whenever you want. If you fix the smartphone to a pole (monopod), surveying that previously required two or more people can be completed by one person. There is no complex equipment setup; by following the app’s instructions you can begin high-precision positioning easily. The fact that non-specialists can handle it reduces the need for elaborate preparation and personnel arrangements at each site.

• High-precision positioning: You might wonder whether such high accuracy can really be achieved with a smartphone. However, by using RTK technology, horizontal positioning accuracy of about ±1–2 cm (±0.4–0.8 in) and vertical accuracy of about ±3 cm (±1.2 in) can be obtained. This matches the accuracy of traditional first-order GNSS surveying. In practice, comparisons of the same point measured with expensive surveying instruments and smartphone RTK have shown differences on the order of a few millimeters (a few hundredths of an inch). In flat, open environments, the accuracy required for cadastral surveys and infrastructure management can be satisfactorily achieved.

• Rich information capture: Because smartphones have cameras and LiDAR sensors, you can record more than just point coordinates; you can capture the surrounding environment as 3D data. For example, boundary markers and the shape of a parcel, and the positional relationships of adjacent roads and buildings can be obtained as point cloud data using a smartphone’s LiDAR. Each point can be tagged with latitude, longitude, and elevation, so back in the office you can perform detailed measurements, cross-sections, and 3D model creation. Bringing back a digital record of the scene as observed on site and analyzing it from various angles is a strength that paper sketches cannot match.

• Real-time sharing and data management: Data acquired by smartphone RTK surveying can easily be saved to the cloud on site and shared immediately within the municipality or organization. Measured points are instantly plotted on a map, allowing you to confirm the created drawing while still in the field. After surveying, you can upload data to the cloud with one tap and share progress with other staff in real time. Cadastral maps and point cloud data can be viewed and downloaded over the Internet, enabling office-side checks and cross-departmental information sharing without visiting the site. Acquired data are referenced to standard geodetic systems (world geodetic systems of Japan coordinates), so they can be imported into GIS software, overlaid with other geographic information, and exported in DXF or CSV formats for transfer to other systems. The broad utility of digital data is another major advantage.

Comparison with traditional methods

Let’s compare the traditional cadastral map creation method with the smartphone × RTK-based method from the following perspectives.

• Work time: Traditional surveying required aiming a total station at targets for each boundary point, taking time for each measurement. After field surveying, it was common to spend days cleaning up hand-drawn maps or digitizing them in CAD in the office before the drawings were complete. In contrast, smartphone × RTK surveying plots measured data on a digital map on the spot. For example, if you walk along a boundary line while continuously positioning, you can collect coordinates at a rate of several points per second and draw the track, confirming the plane map in the field. If any points were missed, you can immediately notice and re-survey, enabling completion of drawing in as fast as the same day.

• Required personnel: Traditional methods required a minimum two-person team of a skilled surveyor and an assistant for field work, due to the need to transport and set up heavy equipment and place target prisms at survey points. With smartphone × RTK surveying, essentially one person can perform the survey with just a smartphone and a compact GNSS receiver. By mounting the smartphone on a pole and treating it like a selfie stick, you can measure points in hard-to-reach places solo. This reduces manpower coordination and allows efficient work with fewer people.

• Measurement accuracy: As noted, the latest smartphone RTK systems achieve positioning accuracy comparable to traditional high-precision equipment. Total station surveys can ensure millimeter-level accuracy, but smartphone RTK can keep errors within a few centimeters in flat areas, making it practically sufficient for cadastral mapping and infrastructure management. Additionally, point clouds from smartphone LiDAR scanning can capture fine terrain and structure details often overlooked in conventional surveys, enabling comprehensive documentation of site conditions. For cases requiring official reference point installation or formal accuracy verification, a hybrid approach combining traditional methods may be preferable, but for routine work smartphone RTK accuracy satisfies most requirements.

• Data shareability: Survey results once managed as paper drawings or local CAD files can be acquired as cloud-native digital data from the outset with smartphone × RTK. Data can be instantly shared to the cloud upon survey completion, making it easy to confirm results with colleagues. Plane maps and point clouds can be viewed and edited collaboratively online, allowing multiple departments to work in parallel. Because acquired data are managed in a unified world geodetic coordinate system, they integrate seamlessly with existing GIS and other systems. The ease of data utilization and information sharing is a major advantage over paper-based methods.

New workflow for cadastral surveys

When creating planar cadastral maps using smartphone × RTK, the field workflow follows these steps.

• Confirm parcel boundaries: Before surveying, confirm the parcel boundaries with stakeholders present. Check whether boundary markers (stakes or stone markers) remain in appropriate positions and whether any parts are unclear. This step remains important as in traditional surveys, and when using a smartphone it is smoothest to display past cadastral maps or public maps on the phone screen and cross-check to align boundary recognition.

• On-site positioning and data capture: Once boundaries are confirmed, use smartphone × RTK surveying to measure boundary points and terrain data. Attach the RTK receiver to the smartphone and launch the surveying app to be ready. At points where boundary markers exist, fix the smartphone to a pole, place it directly over each boundary point, and tap the app to record high-precision coordinates. Then, by slowly walking along the boundary line and performing continuous positioning, you can trace the entire boundary with a few-centimeter accuracy. Additionally, scan the area with the smartphone’s LiDAR to capture surrounding terrain and structures. This yields detailed 3D point cloud data reflecting land elevation differences and the positions of adjacent roads and buildings. Each survey point is automatically assigned a point number and timestamp, and the point cloud contains world coordinates, making these data foundational for subsequent drafting.

• Creating the plane map (drafting): Based on the collected boundary point coordinates and point cloud data, create the cadastral plane map. If the smartphone app provides basic drafting features, you can connect the acquired data on site to draw a digital cadastral map. For more precise drafting, upload the data to the cloud and open them on an office PC for careful tracing in dedicated software or CAD. For example, display the point cloud in a top-down view and trace the boundary lines and building outlines with the mouse to draw an accurate plane map. Coordinates obtained via smartphone RTK are already based on public coordinate systems (plane rectangular coordinate system or the latest geodetic datums such as JGD2011/2024), so created maps have dimensions and coordinates aligned to real space. Finished plane maps can be exported in common formats like DXF for submission or further system use.

• Integration with GIS: The cadastral map data created can be most valuable when integrated with the municipality’s GIS or other management ledger systems. For example, importing the new cadastral map into an integrated GIS allows overlaying it with existing land registries and road ledgers for cross-reference and cross-departmental use. Linking attributes such as parcel number, land category, and owner to each parcel polygon is easily completed by inputting the data in the GIS. Because coordinates obtained via smartphone RTK adhere to the recent world geodetic datum, high consistency with the Geospatial Information Authority’s base map information and other open data is maintained. Centralized GIS management enables digital cadastral administration without relying on paper maps, allowing rapid use of required information when needed.

Use cases of smartphone surveying

Smartphone × RTK surveying is expected to be useful not only for cadastral surveys but in various municipal operations and civil engineering/construction scenarios. Here are three concrete examples.

Surveying and drafting of road occupancy areas

In road management, when temporarily occupying roads for construction or events, the occupied area must be measured and drafted accurately. Traditionally, measuring road width and occupancy zones with tape measures and road markers and cleaning up hand sketches took time. With smartphone × RTK surveying, an officer simply walks from one edge of the road to the other with a smartphone, and the trace is digitized into a high-precision plane map. The occupied area’s area and dimensions can be automatically calculated from the acquired data, greatly reducing the effort to prepare application documents. Moreover, by sharing data to the office via the cloud, confirmation of applications and coordination with relevant agencies can be done quickly.

Boundary confirmation and consensus building between public and private land

For changes in zoning, road widening, or acquisition of land for public facilities, clear maps showing boundaries between public and private land are indispensable. If the base map used in discussions is of low accuracy, misunderstandings can escalate into disputes. Using smartphone × RTK surveying to quickly and accurately measure on-site boundary points and create up-to-date cadastral maps ensures all parties share the same information. Presence or relocation of boundary markers can be visually confirmed from point cloud data, and with the smartphone’s AR function you can even project the boundary line onto the field for visualization. This increases transparency and reliability of boundary confirmation and is expected to shorten the time needed for consensus building.

Damage assessment at disaster recovery sites

When disasters such as heavy rain or earthquakes occur, it is necessary to promptly assess site conditions to plan recovery and perform damage assessment. Smartphone × RTK surveying is powerful in disaster response. Staff can visit damaged areas and scan collapsed roads or landslide sites with the smartphone’s LiDAR to obtain detailed 3D models on the spot. Volumes of collapsed soil and inundation extents can be measured from point cloud data, enabling immediate calculation of figures needed to prioritize recovery work and design. Tasks that once required waiting for specialized surveyors can now be handled quickly by municipal staff who generate plane maps and cross-sections. Acquired data can be shared in real time with disaster response headquarters, smoothing information sharing and decision-making among stakeholders.

The future of cadastral surveys and digitalization

Introducing smartphone × RTK into cadastral surveying is expected to dramatically improve survey efficiency. Even municipalities struggling with staff shortages and budget constraints could greatly accelerate survey pace if staff can complete required surveying simply by visiting sites with a smartphone. Cadastral survey projects that once seemed unlikely to finish within decades may advance significantly with new digital technologies.

Centralizing high-precision smartphone-acquired data in the cloud and GIS also leads to cadastral information DX (digital transformation). Digitizing boundary confirmation tasks that relied on paper maps and human work facilitates information sharing among stakeholders and speeds up decision-making. In the future, combining drone aerial photography and AI image analysis with smartphone RTK could further streamline cadastral map updates. In any case, the use of digital technologies in cadastral surveys is now an inevitable trend, and smartphone surveying could become the trump card.

Simple, high-precision surveying enabled by LRTK

One solution that makes smartphone RTK surveying accessible is LRTK. LRTK is a smartphone-integrated RTK-GNSS system developed to turn a smartphone into a centimeter-precision positioning device. By attaching a compact RTK receiver that fits in the palm to a smartphone, anyone can easily perform high-precision surveying. No cable connection is required; pairing via Bluetooth to the smartphone completes setup. Starting positioning from the dedicated app automatically retrieves correction information and instantly displays the current position with centimeter accuracy.

With LRTK, a single person can smoothly perform the cadastral survey workflow described above—from measuring boundary points to drafting and cloud sharing. Its high-performance antenna and positioning engine maintain stable high precision not only in open outdoor areas but also in environments with some surrounding obstructions. LRTK supports the Geospatial Information Authority’s electronic reference points and can receive real-time corrections nationwide via mobile communications. Moreover, even at sites without mobile coverage, it can directly receive the CLAS signal from QZSS (Michibiki), so positioning continues without loss of accuracy in mountainous areas.

LRTK’s integration with smartphone cameras and LiDAR is also comprehensive: taking photos within the LRTK app saves image data with cm level accuracy (half-inch accuracy) position and orientation information. It also provides point cloud acquisition from LiDAR scanning and AR boundary projection functions, delivering an all-in-one feature set useful for cadastral surveys and construction management. Acquired data are automatically synchronized to LRTK’s cloud service, allowing the office to monitor site conditions in real time.

Thus, LRTK opens advanced surveying technology to non-specialists, enabling “centimeter-precision surveying anywhere by anyone.” For municipalities and companies considering efficiency improvements and on-site DX for cadastral surveys, adopting LRTK is a practical and effective option. Experience cutting-edge smartphone surveying and consider using it to boost productivity in cadastral survey operations.

FAQ

Q: What is cadastral surveying? A: A cadastral survey is a national project that investigates each parcel of land to determine the owner, parcel number, and land category, and measures and records boundary locations and areas. Municipalities lead the surveys and produce cadastral maps (showing parcel boundaries) and cadastral registers (ledgers of land information).

Q: Is it possible to perform cadastral surveys with a smartphone? A: Yes. By combining a smartphone with a high-precision RTK-GNSS receiver, anyone can perform centimeter-level surveying. When using the results as formal cadastral survey deliverables, prescribed procedures and involvement of professionals may be required, but the on-site surveying itself can be sufficiently performed with a smartphone.

Q: What is LRTK? A: LRTK is the name of a surveying system that enables centimeter-class positioning by attaching a compact RTK-GNSS receiver to a smartphone. It consists of a dedicated device and app and turns a smartphone into a high-precision surveying instrument. It is designed to be usable without specialized knowledge and streamlines surveying tasks in various field situations including cadastral surveys.

Q: How accurate is smartphone surveying? A: Typical smartphone built-in GPS has an accuracy of about 5–10 m (16.4–32.8 ft), but smartphone surveying using RTK achieves horizontal and vertical errors on the order of a few centimeters. Under good conditions, it can reach accuracy comparable to professional surveying equipment.

Q: Are qualifications or special skills required for surveying? A: Operating smartphone surveying systems is intuitive and generally does not require special skills or qualifications. However, to treat surveying results as official cadastral deliverables, supervision or validation by licensed surveyors may be desirable. Since anyone can collect on-site data, specialists and assistants can collaborate to work efficiently.

Q: What equipment and preparations are needed for smartphone surveying? A: You need a smartphone (or tablet), an RTK-capable compact GNSS receiver (e.g., an LRTK unit), and surveying application software. If Internet connectivity is available at the site, you can obtain real-time corrections from the Geospatial Information Authority’s reference stations. In areas with poor connectivity, LRTK can receive CLAS corrections directly from the QZSS (Michibiki). In addition, a pole (monopod) for fixing the phone and spare batteries help stabilize field operations.

Q: How much does it cost to introduce the system? A: Smartphone surveying systems are significantly lower cost than traditional surveying equipment. High-precision GNSS receivers and total stations once required investments in the millions of yen, but a smartphone plus a compact receiver can be introduced at a fraction of that cost. Utilizing existing smartphones is another cost advantage. Cost savings from reduced personnel and shortened work time are also expected.