Table of Contents

• Importance of cadastral surveys and current challenges

• Visualizing boundary lines with photos and AR

• GNSS/RTK technology and high-precision surveying with LRTK

• Easy data sharing through cloud integration

• Benefits of using AR in cadastral surveys

• The future of cadastral surveys enabled by simple surveying with LRTK

• Frequently asked questions

Importance of cadastral surveys and current challenges

Cadastral surveys are an important nationwide effort to accurately determine land boundaries and areas. Municipalities take the lead in confirming boundaries with landowners present, and they update cadastral maps and land registry information based on survey results. This is also an opportunity to correct inaccurate information based on old Meiji-era maps to reflect current conditions, and cadastral surveys allow the establishment of up-to-date, accurate survey data as a social infrastructure.

By conducting cadastral surveys and clarifying boundaries, property rights can be correctly reflected, which is expected to help prevent boundary disputes and make boundary restoration easier in the event of a disaster. Accurate map preparation also serves as a foundation for safe and smooth land transactions and contributes to regional town planning and infrastructure planning. Despite this importance, as of the end of FY Reiwa 4 the nationwide progress rate of cadastral surveys remained at only about 52%, leaving many areas un-surveyed. Improving productivity is a major challenge when conducting extensive surveys with limited personnel and budgets.

However, several problems have been pointed out in field surveying work. One of the biggest issues is that the crucial land boundary lines are not visible. If stakes or boundary stones indicating boundaries are hidden by vegetation or lost due to aging, it is not easy to determine the exact boundary location on site. Especially in long-uncared-for land or forested areas, boundary markers are often buried and cannot be found.

Invisible boundary lines on site also affect consensus-building with landowners and neighbors. Even if professionals such as licensed surveyors and municipal officials understand the boundaries from survey diagrams, it is not easy for laypeople to imagine “where exactly their land starts and ends” from a drawing alone. As a result, confusion such as “I don’t know whether my land continues beyond here” or mismatched perceptions with neighboring landowners are likely to occur. If such discrepancies appear during on-site boundary confirmation meetings, discussions can take a long time and, in the worst case, may develop into boundary disputes.

Traditionally, surveyors have devised ways to indicate boundaries in the field, such as driving temporary stakes or drawing chalk lines on the ground. But physical markings have limitations: if markers disappear or accuracy is insufficient, it is difficult to share boundaries in a way that satisfies all parties. The difficulty of “showing” boundary lines has led to a lack of understanding and delays in consensus-building at cadastral survey sites.

Visualizing boundary lines with photos and AR

Invisible land boundary lines appearing on site just by pointing a smartphone at the ground—this seemingly futuristic surveying method is becoming a reality. Using AR (augmented reality) technology to display virtual lines and points on camera images, attempts are being made to “visualize” boundaries that were previously unseen. This method, which overturns conventional wisdom, is poised to bring significant change to cadastral survey fieldwork.

For example, AR boundary line displays are powerful in the following situations:

• Use in boundary meetings: At boundary confirmation meetings with neighboring landowners, displaying a virtual boundary line on the smartphone screen allows all parties to share the boundary position at a glance. Information that was hard to convey with drawings or technical terms can be intuitively shown on site through the screen with “this is the boundary,” deepening mutual understanding and smoothing consensus-building. Even if boundary markers are buried in grass and cannot be found, if the boundary coordinates obtained in advance are registered in the app, the smartphone will navigate and indicate the location with centimeter accuracy (half-inch accuracy), allowing exact boundary positions to be identified even before restoring stakes.

• Application to temporary stake installation and fencing planning: AR is also useful when driving temporary stakes along boundaries or planning temporary fencing along site boundary lines before construction. If boundary line coordinates from design drawings or existing survey data are preloaded into the app, virtual stake markers or lines can be shown on the smartphone screen on site. Using those as references makes it possible to accurately locate points even in places where driving stakes was previously difficult, such as on asphalt pavement or bedrock. Tasks that used to require two or more people with an optical surveying instrument and staff can now be done by a single person marking points one after another while viewing the AR display. As a result, installing temporary stakes over wide boundary stretches can be completed in a short time, and work can be done safely with fewer people even in sites with poor footing.

• Use in public–private boundary consultations: AR is a powerful tool in consultations to determine boundaries between public land (such as roads or waterways) and private land. When municipal officials and landowners discuss boundary positions on site, drawings alone can lead to mismatched mental images, but projecting the boundary line onto the ground with AR enables both parties to visually share the same positional relationship. This reduces discrepancies such as “the drawing suggests it goes this far, but it feels different on site,” and helps facilitate on-the-spot consensus. In addition, the virtual boundary lines displayed on site can be recorded as photos or videos and preserved. Such records serve as objective evidence when reviewing consultation contents later.

In this way, visualizing boundary lines with photos and AR solves the “invisible” problem in cadastral surveys and is transforming on-site communication. Next, let us look at the technical background that supports this new method.

GNSS/RTK technology and high-precision surveying with LRTK

To accurately display boundary lines with AR, it is necessary to determine the smartphone’s current position with high precision. Ordinary smartphone GPS has errors on the order of several meters, which cannot pinpoint boundary points. The key here is high-precision positioning using GNSS (Global Navigation Satellite System).

RTK (Real-Time Kinematic) is a method that corrects GNSS positioning errors in real time to achieve centimeter-level accuracy. By receiving correction information transmitted from known reference points (base stations) on the smartphone, and correcting signal errors from multiple satellites such as GPS and Japan’s quasi-zenith satellite “Michibiki,” position determination to the centimeter level becomes possible. However, until now, using RTK in the field required expensive, large dedicated GNSS receivers and antennas to be installed.

With the recent advent of LRTK devices, such high-precision positioning has become much more accessible. LRTK is a compact, lightweight high-precision GNSS receiver that can be attached to a smartphone; it mounts to the rear of the phone with a dedicated cover and connects via Bluetooth or Lightning for immediate use. With a compact design weighing a few hundred grams, it is easy to carry. Combined with a dedicated app, this device enables centimeter-level positioning in real time anywhere in Japan (it supports centimeter-class positioning augmentation services provided by quasi-zenith satellites such as CLAS and network RTK via Ntrip). Gone are the days of carrying heavy tripods and surveying equipment—now a palm-sized LRTK and a smartphone can achieve professional-grade positioning accuracy.

Using the high-precision current position obtained in this way, AR surveying overlays boundary line data on the smartphone screen. Boundary point coordinates and boundary line data obtained in advance from cadastral surveys are loaded into the app, and when the smartphone is pointed on site, the device’s position and orientation are used to draw virtual lines onto the camera image. If GNSS positioning is inaccurate, the virtual line will be offset, but using an RTK-capable LRTK device can specify the device position to the centimeter level, allowing boundary line data to be displayed almost perfectly aligned with the real world. In addition, calibration by aligning with known points on site or cross-referencing boundary data with point clouds obtained by measuring the surroundings with the smartphone’s built-in LiDAR scanner are used to further improve positional and orientation accuracy.

The combination of high-precision GNSS and AR has realized an unprecedented experience of “visualizing boundary lines on site.” The next chapter looks at how this method improves data sharing.

Easy data sharing through cloud integration

Using the LRTK dedicated surveying app, field survey data is immediately saved to the cloud, greatly improving data sharing and record management. Coordinates of boundary points, photos, and notes can be automatically uploaded to the cloud at the time of measurement, eliminating the need to copy them into notebooks later and reducing human error. The date and time each point was measured and the exact position are reliably recorded in the cloud, increasing data reliability.

Once boundary coordinate data is stored in the cloud, it can be reused in the future. For example, when re-surveying the same point years later, calling up and selecting the previously saved coordinates in the app allows the LRTK device to guide you to that point within a few centimeters of error. Even if personnel change or a long time has passed, the exact same point can be easily restored. Photos and notes of boundary markers taken on site are also preserved in chronological order in the cloud, allowing you to review “what happened to a stake installed many years ago” or “what conditions were like during a previous survey.” This helps confirm deterioration or movement of boundary markers and prevents past oversights.

Furthermore, having data in the cloud makes information sharing inside and outside the organization easy. Since data can be accessed over the Internet whenever needed, there is no time lag between collecting information on site and sharing it at the office. As soon as fieldwork is finished, office colleagues can immediately view survey results or take over the work. There is no need to transfer data using paper drawings or USB memory, and multiple people can always refer to the latest information. Centralized electronic data management reduces the risk of losing survey records and provides peace of mind for evidence preservation.

In this way, cloud integration has made storing, sharing, and reusing survey data obtained in cadastral surveys dramatically easier. So what concrete benefits does using AR technology and the cloud bring to cadastral surveys?

Benefits of using AR in cadastral surveys

The new cadastral survey method that combines AR technology and the cloud brings many advantages to field operations. The specific benefits include:

• Intuitive boundary confirmation and consensus-building: By “showing” boundary lines and boundary marker positions on the smartphone screen, landowners and neighbors can intuitively understand the boundaries. What was hard to convey with drawings becomes immediately clear, making it easier to resolve questions or misunderstandings on the spot. As a result, it becomes easier to align the understandings of all parties during boundary meetings and public–private boundary consultations, and the process of obtaining agreement proceeds more smoothly.

• Improved efficiency and labor reduction in surveying work: Surveying with a smartphone plus LRTK elevates work that previously required two to three people to a level that can be completed by one person. There is no need to transport and set up heavy equipment; you can take out your smartphone and immediately measure and confirm. When searching for previously installed boundary stakes, the coordinate navigation function can get you to the designated point in a short time. With significant reductions in work time and personnel, small offices can handle many cases in parallel.

• Improved data accuracy and reproducibility: Since survey data is automatically saved to the cloud with position information and timestamps, recording errors are prevented. Once coordinates are obtained, they remain in the cloud, so the same points can be reproduced later using that data. This reproducibility even after long intervals or personnel changes is a major reassurance. In addition, because photos and notes of boundary markers are digitally managed, there are no gaps in information, and the reliability of survey records increases.

• Improved safety: Even when surveying in rugged forests or cliff areas, fewer people are needed, reducing the number of site entries and the time spent on site. Eliminating the need to set up large equipment reduces the risk of working in hazardous locations. Reducing the workload on site contributes to ensuring worker safety.

• Low-cost adoption and flexible operation: LRTK devices are lower cost to introduce than conventional dedicated surveying instruments, so multiple staff members can each carry a unit to the field. Without competition over limited equipment, each person can perform surveying and recording when needed, increasing operational flexibility. As a result, organizational productivity improves, and actively adopting the latest technology leads to added value for customers.

The future of cadastral surveys enabled by simple surveying with LRTK

The method of “simple surveying” using smartphones and LRTK will play an increasingly important role in future cadastral survey fieldwork. With boundary lines now visible on site, on-site confirmation and communication will become dramatically more efficient, and processes that previously took time and effort will proceed much more quickly. Surveyors themselves will be able to perform quick on-site measurements whenever they “just want to measure and check,” enabling flexible responses such as immediately measuring and recording with a smartphone when needed. With a pocket-sized LRTK as a new companion, the era in which you can respond “anytime, anywhere, immediately” from boundary confirmation to various surveys is becoming a reality.

By proactively adopting the latest technologies, surveyors and land and house surveyors will be able to provide clients with faster and more accurate services than before, improving both operational efficiency and the quality of deliverables. The new experience of AR-displayed boundary lines through simple surveying with LRTK will be a key to opening the future of survey work. By adding the latest technology to conventional methods, a next-generation cadastral survey style that balances productivity and customer satisfaction is just within reach.

Frequently asked questions

Q. What is a cadastral survey? A. A cadastral survey is a survey of land boundaries and areas conducted mainly by municipalities. Boundaries are confirmed with landowners present, and results obtained by surveying are reflected in maps and land registries. Clarifying boundaries is an important effort that helps prevent future boundary disputes and facilitates smooth land transactions.

Q. Is precise surveying possible with just a smartphone? A. Standalone smartphone GPS has errors of several meters, but by combining with an LRTK device, centimeter-level precision positioning is possible. Receiving RTK corrections enables smartphone accuracy comparable to conventional surveying equipment. Field verifications have shown that positioning using LRTK achieves results comparable to traditional total station surveying.

Q. Can AR-displayed boundary lines be captured in photos for documentation? A. Yes. Boundary lines and stake positions displayed in AR can be recorded by taking screenshots or photos/videos with the smartphone. When explaining agreed boundary positions to third parties later, AR photos allow immediate sharing of the situation. Saving such AR images as evidence of consultations can be helpful for later review or in case of disputes.

Q. What is LRTK? A. LRTK is the name of a small high-precision GNSS receiver device that attaches to and is used with a smartphone. It supports Real-Time Kinematic (RTK) positioning and turns a smartphone into a surveying device capable of centimeter-precision positioning. It weighs a few hundred grams, is easy to carry, and connects to a smartphone via Bluetooth or Lightning, enabling convenient high-precision surveying.

Q. What is required to introduce AR surveying? A. First, you need the LRTK device itself and a compatible smartphone (currently supported on iOS devices). In addition, you need the LRTK dedicated surveying app and a communications environment to receive RTK correction information (Internet connection and reception environment for the quasi-zenith satellite system). Once these preparations are in place, anyone can experience AR visualization of boundary lines on site simply by loading the coordinates of the points to be surveyed into the app. The operation is intuitive and does not require difficult technical knowledge, so surveyors and cadastral surveyors can quickly start using it.