Table of Contents

• Introduction

• What is a cadastral survey?

• Current state and challenges of cadastral surveys

• How smartphone surveying × RTK is changing cadastral surveys

• 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‑accuracy surveying realized by LRTK

• FAQ

Introduction

Accurate cadastral maps are indispensable for land management and urban planning. For example, confirming boundaries between public land such as roads and rivers and privately owned land, updating urban planning maps, and reorganizing agricultural plots all require reliable as‑built plan maps. However, traditional cadastral surveys have required specialist surveyors and large equipment, consuming substantial time and manpower. As a result, survey progress has lagged, and in many areas boundaries remain unclear.

Currently in Japan, the nationwide average progress rate for cadastral surveys is roughly 50%. Even after decades since surveys began, about half remain uninvestigated, and at the current pace it is said that completion could take many more decades. For uninvestigated land, people must rely on old ledgers and cadastral maps, and inaccuracies in boundaries and areas can lead to boundary disputes, obstacles to land transactions, and delays in infrastructure development. To break this situation and accelerate cadastral surveys, streamlining and labor reduction in surveying work are essential.

In recent years, a promising solution has emerged: combining smartphone‑based surveying with RTK (Real Time Kinematic), an advanced satellite positioning technique. By using a smartphone together with a compact, high‑precision GNSS receiver, anyone can perform on‑site surveying with centimeter‑level accuracy without specialized survey equipment. This article explains the mechanism and benefits of the smartphone × RTK approach to cadastral surveys, compares it with traditional methods, and presents field use cases. At the end of the article, we also touch on the LRTK system that makes high‑precision smartphone surveying possible.

What is a cadastral survey?

A cadastral survey is the work of investigating each parcel of land to determine the owner, lot number, and land category, and measuring and recording boundary positions and land areas. Under the Land Survey Act, municipalities typically lead these surveys, and the results are compiled into cadastral maps (maps showing parcel boundaries) and cadastral registers (ledgers consolidating information for each parcel). During a survey, boundaries are confirmed in the presence of landowners, boundary points that are agreed upon are measured, and areas are calculated. The resulting cadastral maps are kept at the Legal Affairs Bureau and are used to update land registration records.

Cadastral surveys are a national project often referred to as the “family register of land,” and by organizing accurate land information they facilitate smoother land transactions, prevent boundary disputes, and support efficient infrastructure development and disaster prevention planning. However, the sheer volume of work means progress is slow in many areas, leaving boundary information uncertain for uncompleted parcels.

Current state and challenges of cadastral surveys

Although cadastral surveys are progressing nationwide, more than half of parcels remain uncompleted. Staffing shortages, financial constraints, and the difficulty of coordinating landowner attendances make accelerating surveys a challenge for municipalities. Traditional surveying methods require skilled technicians and precise instruments, and surveying a single district can take a long time. Consequently, problems such as “surveys take too long” and “there are not enough personnel” have become apparent.

In response, the national government has begun promoting efficiency improvements and DX (digital transformation) in cadastral surveys. To offset labor shortages and expand survey coverage within limited budgets, adopting the latest technologies to improve work efficiency is indispensable. There is a demand to digitalize cadastral surveys, which were once paper‑based and manual, and to create systems that can rapidly and accurately acquire and share boundary information.

How smartphone surveying × RTK is changing cadastral surveys

Enter the new surveying approach that combines smartphone surveying and RTK. Smartphone surveying, as the name implies, refers to conducting surveying tasks with a smartphone or tablet. The idea is to replace traditional position‑measurement devices such as total stations and dedicated GPS units with the smartphone’s built‑in GPS and camera, and even LiDAR sensors (recently included on some models) for distance measurement with light. Smartphones are ubiquitous and convenient, but typical GPS accuracy is about 5–10 m (16.4–32.8 ft), far from the centimeter‑level accuracy required for cadastral surveys.

This is where RTK (Real Time Kinematic) comes in—a high‑precision positioning technique. RTK applies real‑time corrections to GNSS (GPS, GLONASS, QZSS/Michibiki, etc.) positioning data to drastically reduce positioning errors. Specifically, simultaneous GNSS observations are made at a known reference station and at a moving receiver (rover); the reference station’s measurement errors are subtracted from the rover’s position, allowing errors that would normally be on the order of meters to be reduced to several centimeters in real time. RTK has traditionally been used with expensive GNSS surveying instruments handled by licensed surveyors, but recently systems that make RTK accessible on smartphones have appeared.

Smartphone‑compatible RTK systems use a pocket‑sized RTK‑GNSS receiver that attaches to the phone and a dedicated app to turn the smartphone into a high‑precision surveying device. The receiver contains a high‑sensitivity antenna and a positioning chip, and connects to the phone via Bluetooth or similar. Users can press a button on the phone to automatically receive satellite signals, acquire and apply correction data, and compute coordinates. The fact that centimeter‑level positioning can be achieved without specialist knowledge is revolutionary. High accuracy is ensured by obtaining correction data via the internet from the Geospatial Information Authority of Japan’s network of electronic reference stations (GNSS reference stations nationwide) or from commercial correction services. In areas without mobile coverage, such as mountainous regions, centimeter‑level augmentation services (CLAS) distributed by Japan’s Quasi‑Zenith Satellite System “Michibiki” can be received directly for corrections. In short, consistent high‑accuracy positioning can be achieved across urban and mountainous areas throughout Japan.

Benefits of smartphone RTK surveying

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

• Mobility and ease of use: Because the surveying equipment consists only of a smartphone and a small GNSS receiver, the total kit weighs only a few hundred grams. It can be carried in a pocket, eliminating the need to lug tripods or heavy batteries, so surveying can begin whenever needed. If you fix the smartphone to a pole (monopod), surveying that previously required two or more people can be completed by a single person. There is no complex equipment setup; by following the app’s guidance, high‑precision positioning can be started immediately. Its usability by non‑specialists simplifies site preparations and personnel arrangements.

• High‑precision positioning: You might wonder if such high precision is really achievable with a smartphone. But using RTK enables horizontal accuracy of about ±1–2 cm (±0.4–0.8 in) and vertical accuracy of about ±3 cm (±1.2 in). This matches the accuracy of high‑precision GNSS surveying used for first‑class reference point surveys. In actual comparisons where the same point was measured with an expensive survey instrument and a smartphone RTK setup, differences were within a few millimeters (a few tenths of an inch). In flat, open environments, accuracy sufficient for cadastral surveys and infrastructure management can be achieved.

• Rich information capture: Because smartphones have cameras and LiDAR sensors, they can capture not only point coordinates but also surrounding conditions as 3D data. For example, boundary markers and site shapes, and the positional relationships of adjacent roads and buildings can be captured as point cloud data by LiDAR scanning. Each point is associated with latitude, longitude, and height, so detailed dimensional measurements, cross‑sections, or 3D models can be created back in the office. The ability to bring a digital record of the site and analyze it from multiple angles is a strength that paper sketches lack.

• Real‑time sharing and data management: Data captured by smartphone RTK surveying can be saved to the cloud on site and easily shared within a government office or company. Measured points are plotted on a map instantly, allowing you to check the drawn plan while still in the field. After surveying, data can be uploaded to the cloud with a single tap, sharing progress with other staff in real time. Cadastral maps and point clouds can be viewed and downloaded via the internet, enabling office staff to check remotely or coordinate with other departments without visiting the site. Because acquired data are positioned in standard geodetic systems (Japan’s realization of world geodetic systems), they can be imported into GIS software and overlaid with other geographic information, or exported in DXF or CSV formats for use in other systems. The wide range of data reuse enabled by digital data is a major benefit.

Comparison with traditional methods

Let us compare traditional cadastral mapping methods with the smartphone × RTK approach across several perspectives.

• Work time: With traditional surveying, a total station was aimed at each target and each point measured with care. After fieldwork, drawings had to be cleaned up by hand or digitized in CAD at the office, so it could take days from survey start to completed drawings. With smartphone × RTK, measured data are plotted on a digital map on the spot. For example, by walking along a boundary and continuously measuring, coordinates can be obtained at a rate of several points per second to render a trace, and this can be checked on site as a plan. If a point was missed, it can be noticed immediately and remeasured, so in some cases survey and drawing can be completed the same day.

• Required manpower: Traditional methods required at least two people—a skilled surveyor and an assistant—for fieldwork. Tasks such as transporting and setting up heavy equipment and placing target prisms relied on manpower. With smartphone × RTK, a smartphone and a small GNSS receiver are sufficient, and surveying can basically be done by one person. By fixing the phone to a pole and treating it like a selfie stick, points in hard‑to‑reach places can be measured alone. This lowers personnel coordination overhead and allows efficient operation with fewer people.

• Measurement accuracy: In terms of accuracy, modern smartphone RTK systems achieve positioning precision comparable to conventional high‑end equipment, as mentioned above. Total station surveys can ensure millimeter‑level precision, but smartphone RTK errors are within a few centimeters in flat areas, which is acceptable for cadastral mapping and infrastructure management. LiDAR‑derived point clouds from smartphones can also capture fine terrain and structural details that were previously overlooked, enabling comprehensive site documentation. Where official reference point installation or formal accuracy verification is required, a hybrid approach with traditional methods may be desirable, but for routine tasks smartphone RTK accuracy meets most requirements.

• Data shareability: Survey deliverables that were once paper drawings or local CAD files can be acquired as cloud‑based digital data from the outset with smartphone × RTK. Data can be shared instantly upon completion of fieldwork, enabling colleagues in the office to verify results in real time. Plan maps and point clouds can be jointly viewed and edited over the network, allowing multiple departments to work concurrently. Because acquired data are managed in a unified global geodetic coordinate system, integration with existing GIS and other systems is seamless. The ease of data utilization and information sharing is a significant advantage over paper‑based workflows.

New workflow for cadastral surveys

When creating cadastral plan maps using smartphone × RTK, fieldwork typically follows these steps.

• Boundary confirmation: Before surveying, confirm parcel boundaries (fence lines) in the presence of stakeholders. Check whether boundary markers (stakes or stone markers) remain in the correct positions and whether any parts are unclear. This process remains vital and unchanged from traditional surveys; when using a smartphone, it is smooth to display past cadastral maps or public maps on the phone and cross‑check them while aligning boundary recognition.

• On‑site positioning and data capture: Once boundaries are agreed, use smartphone × RTK to measure boundary points and topographic data. Attach the RTK receiver to the smartphone and launch the surveying app. At a boundary marker, fix the smartphone to a pole and place it perpendicular to the marker, and tap the app button to record the high‑precision coordinates of that point. Then, by walking slowly along the boundary and executing continuous positioning, you can digitize the entire boundary trace with several‑centimeter accuracy (a few inches). Also scan the area with the smartphone’s LiDAR to capture surrounding terrain and structures; this yields detailed 3D point cloud data reflecting elevation differences and the positions of adjacent roads and buildings. Each measurement point is automatically assigned an ID and timestamp, and point clouds include global coordinates, so these data serve as foundational information for subsequent drafting.

• Creating plan maps (drafting): Using the boundary point coordinates and point clouds collected on site, create the cadastral plan map. If the smartphone app provides a simple drafting feature, you can connect the captured data on site and draw a digital cadastral map. For more precise drafting, upload the data to the cloud and open it on an office PC to trace accurately with dedicated software or CAD. For example, displaying the point cloud from a top‑down view and tracing the boundary and building outlines with a mouse will produce an accurate plan. Coordinates from smartphone RTK are already based on public coordinate systems (plane rectangular coordinates or modern geodetic systems such as JGD2011/2024), so the produced drawings reflect true‑world dimensions and coordinates. Completed plans can be exported in common formats such as DXF for submission or use in other systems.

• Integration with GIS: The created cadastral data realize their full value when integrated into the municipality’s GIS or other management systems. For instance, importing new cadastral maps into an integrated GIS allows overlaying with existing land registry and road ledger information for reference, enabling multiple departments to share and utilize the data. Assigning attributes such as lot number, land category, and owner to each parcel is easily done on the GIS by entering the information for the corresponding polygon. Coordinates obtained by smartphone RTK are based on the recently revised world geodetic systems, so they maintain high consistency with the Geospatial Information Authority’s base maps and other open data. By centrally managing data in a GIS, digital cadastral management without reliance on paper becomes possible, allowing immediate access to needed information.

Use cases of smartphone surveying

Smartphone × RTK surveying is useful not only for cadastral surveys but also for various municipal tasks and civil engineering/construction scenarios. Here are three concrete examples.

Surveying and drafting for road occupancy areas

In road management, when temporarily occupying a road for construction or events, it is necessary to accurately measure and map the occupied area. Traditionally this involved tape measures and pavement reference marks, followed by time‑consuming hand sketch clean‑up. With smartphone × RTK, a staff member can walk from edge to edge with a smartphone, and the trace will be digitized as a high‑precision plan. The system can automatically calculate the area and dimensions of the occupied portion, significantly reducing the work to prepare application documents. Because data can be sent to the office via the cloud and shared immediately, application review and coordination with related agencies can proceed quickly.

Boundary confirmation and consensus building between public and private land

For urban planning changes, road widening, or acquiring land for public facilities, clear maps showing the boundary between public and private land are essential. If source maps are low accuracy, misunderstandings can lead to disputes. By quickly and accurately measuring boundary points with smartphone × RTK and producing up‑to‑date cadastral maps, all stakeholders can share the same information. Presence or relocation of boundary markers can be visually confirmed from point cloud data, and the smartphone’s AR features can even project boundary lines on site. This increases transparency and reliability in boundary confirmation work and is expected to shorten the time needed to reach agreement.

Damage assessment at disaster recovery sites

When disasters such as heavy rains or earthquakes occur, rapid assessment of affected areas is necessary to plan recovery and determine damage. Smartphone × RTK surveying is powerful in disaster response. Staff can scan collapsed roads or landslide sites with smartphone LiDAR to obtain detailed 3D models on site. Volumes of collapsed soil and flooded areas can be measured from point cloud data, allowing quick extraction of numerical values needed to prioritize and design restoration work. Tasks that previously required waiting for specialized survey contractors can now be performed promptly by municipal staff to generate as‑built plans and cross‑sections, greatly improving initial response speed. Acquired data can be shared in real time with disaster response headquarters to facilitate smooth coordination and decision‑making.

The future of cadastral surveys and digitalization

Incorporating smartphone × RTK into cadastral surveys is expected to dramatically improve survey efficiency going forward. In municipalities facing labor shortages and budget constraints, if staff can complete necessary surveys by simply going to sites with a smartphone, survey pace will accelerate considerably. The cadastral survey projects that were once expected to take decades to complete could make substantial progress with new digital technologies.

Centralized cloud and GIS management of high‑precision data obtained by smartphones also promotes DX (digital transformation) of cadastral information. Digitalizing boundary confirmation tasks that relied on paper drawings and manual labor makes information sharing among stakeholders easier and speeds up decision‑making. In the future, combining drone aerial photography, AI image analysis, and smartphone RTK could further streamline cadastral map updates. In any case, digital technologies in cadastral survey workflows are now an inevitable trend, and smartphone surveying could be the trump card.

Simple, high‑accuracy surveying realized by LRTK

One solution that brings smartphone RTK surveying within reach is LRTK. LRTK is a smartphone‑linked 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 surveys. No cable connection is necessary; pairing via Bluetooth completes preparation. Starting positioning from the dedicated app automatically obtains correction data and instantaneously displays the current position with centimeter accuracy.

With LRTK, one person can smoothly carry out the cadastral survey workflow described earlier—from measuring boundary points to drafting and cloud sharing. Its high‑performance antenna and positioning engine enable stable, high‑precision performance not only in open outdoor areas but also in environments with some surrounding obstructions. LRTK supports the Geospatial Information Authority of Japan’s electronic reference points and can receive real‑time corrections via mobile communication nationwide. Moreover, even at sites without mobile coverage, it can directly receive CLAS signals from Michibiki (QZSS), allowing positioning to continue without loss of accuracy in mountainous areas.

Integration with the smartphone’s camera and LiDAR is well supported: taking photos within the LRTK app saves images with cm‑accuracy position and orientation information (cm level accuracy (half‑inch accuracy)). It also offers point cloud acquisition by LiDAR scanning and AR projection of boundary lines, providing an all‑in‑one feature set useful for cadastral surveys and construction management. Captured data are automatically synchronized with LRTK’s cloud service, enabling real‑time situational awareness of the field from the office.

Thus, LRTK opens advanced surveying capabilities to non‑specialists and makes “centimeter‑accuracy surveying anywhere by anyone” a practical reality. For municipalities and companies considering efficiency improvements and on‑site DX for cadastral surveys, adopting LRTK is a realistic and effective option. Experience cutting‑edge smartphone surveying and use it to improve productivity in cadastral survey operations.

FAQ

Q: What is a cadastral survey? A: A cadastral survey is a national project to investigate each parcel of land to determine the owner, lot number, and land category, and to measure and record boundary positions and areas. Municipalities lead the work, producing cadastral maps (maps showing parcel boundaries) and cadastral registers (ledgers of land information).

Q: Is it possible to conduct 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 official cadastral survey deliverables, prescribed procedures and involvement of professionals may be required, but on‑site surveying itself can be adequately conducted with a smartphone.

Q: What is LRTK? A: LRTK is the name of a surveying system that enables centimeter‑class positioning by attaching a small RTK‑GNSS receiver to a smartphone. It consists of a dedicated device and app, turning a smartphone into a high‑precision surveying tool. It is designed for ease of use by non‑specialists and streamlines surveying tasks in cadastral and other fieldwork.

Q: How accurate is smartphone surveying? A: Typical built‑in smartphone GPS accuracy is about 5–10 m (16.4–32.8 ft), but smartphone surveying using RTK yields horizontal and vertical errors on the order of a few centimeters. Under favorable conditions, it can achieve accuracy comparable to professional surveying instruments.

Q: Are qualifications or special skills required for surveying? A: Operating a smartphone surveying system is generally intuitive and does not require special skills or qualifications. However, to treat survey results as official outcomes, supervision or verification by qualified surveyors may be desirable. Anyone can perform on‑site data collection, and collaboration between specialists and assistants can improve efficiency.

Q: What equipment and preparations are needed for smartphone surveying? A: Required items are a smartphone (or tablet), an RTK‑capable compact GNSS receiver (e.g., an LRTK device), and surveying software. If internet connectivity is available at the site, you can obtain correction information from the Geospatial Information Authority’s electronic reference points for real‑time positioning. In areas with poor connectivity, LRTK can receive CLAS signals from Japan’s Michibiki satellites for direct correction. A pole (monopod) to mount the phone and spare batteries can also help stabilize fieldwork.

Q: How much does it cost to introduce the system? A: Smartphone surveying systems are much lower cost than traditional dedicated surveying instruments. High‑end GNSS receivers and total stations often require investments in the millions of yen, whereas a smartphone paired with a compact receiver can be introduced for a fraction of that cost. Reusing existing smartphones is also a financial advantage. Additionally, cost savings are expected from reduced personnel and shorter work times.