The New Era of Surveying: A Field Revolution with the Fusion of Photogrammetry and RTK! High-Precision, Instant Surveying Achieved with a Smartphone

A major technological innovation is now underway in construction and civil engineering surveying. The fusion of photogrammetry and RTK (Real-Time Kinematic) technology has ushered in an era in which high-precision, immediate site measurements can be performed using nothing more than a smartphone. This article explains the latest trends in surveying using photogrammetry × RTK and introduces how simple, high-precision surveying with a smartphone works and its benefits. We also explore related next-generation technologies that support surveying, such as point cloud scanning, AR (augmented reality), and cloud integration, and consider their potential. At the end of the article, we also spotlight LRTK as a solution that makes these new technologies easy to adopt. Experience the innovative methods that are opening a new era in surveying.

What is Photogrammetry?

Photogrammetry is a technique that measures the shapes and dimensions of terrain and structures from photographs. Using specialized software, common points are extracted from multiple images to generate 3D models and point cloud data. It has rapidly spread in the construction and civil engineering fields because accurate dimensions can be obtained not only from aerial photogrammetry using drones or high-mounted cameras, but also from ground-based photography. A major advantage of photogrammetry is that wide areas can be recorded in a short time, and it enables safe surveying of hazardous locations where people cannot enter. In addition, because orthophotos (distortion-free photographic maps as seen from above) and detailed terrain maps can be created from the acquired images, it becomes easier to intuitively grasp site conditions compared to traditional surveying methods.

However, photogrammetry alone can have limitations in the positional accuracy of the information it provides. Standard photogrammetry aligns the overall model using geotags (location information) embedded in photos and a few known control points (ground control points). But geotags obtained from smartphones or ordinary cameras often have large GPS errors, and meter-level offsets can frequently occur. Therefore, to use photogrammetry for high-precision mapping or construction management, additional control point surveying or alignment to known points has traditionally been necessary. This is where RTK technology comes into play. By combining photogrammetry with RTK, these accuracy challenges can be overcome, enabling faster acquisition of more precise surveying results.

Advances in RTK Technology: Centimeter-Level Positioning

RTK (Real-Time Kinematic) is a satellite positioning (GNSS) technique that achieves real-time centimeter-level positioning accuracy (cm level accuracy (half-inch accuracy)). Specifically, a base station (a fixed station) with known coordinates and a rover (mobile receiver) receive GNSS satellite signals simultaneously, and the base station transmits error correction information to the rover to realize high-precision positioning. Traditionally, performing RTK surveying required expensive equipment such as dedicated GNSS receivers, radios, and a pair of antennas. However, recent technological advances have led to miniaturization and cost reduction of the equipment, making it easier to access the benefits of RTK.

The defining feature of RTK is its extremely high positioning accuracy at the level of a few centimeters (cm level accuracy (half-inch accuracy)). While the accuracy of standalone GPS (GNSS single-point positioning) is typically on the order of several meters, RTK dramatically improves this. This accuracy improvement enables immediate digitization of tasks that require positional precision, such as construction as-built management (post-construction shape verification) and infrastructure inspections. In Japan, the provision of a centimeter-level positioning augmentation service (CLAS) by the Quasi-Zenith Satellite System (QZSS, “Michibiki”) has begun, allowing high-precision positioning without internet access in mountainous areas where mobile signals do not reach, provided a compatible receiver is used. RTK technology is powerful on its own, but its true value is realized when combined with photogrammetry.

The Synergy Created by Photogrammetry × RTK

The fusion of photogrammetry and RTK brings two major benefits to field surveying: a dramatic improvement in accuracy and a dramatic enhancement in work efficiency.

First, regarding accuracy, embedding RTK-acquired positional information into photogrammetry data imparts absolute accuracy to the resulting 3D models and point clouds. This means that the coordinates of any point on the model will essentially match real-world geodetic coordinates, eliminating the need for later transformations or additional control point placements. For example, in drone-based photogrammetry, ensuring accuracy has traditionally required using RTK-equipped drones or placing ground control points prior to flight. However, if corrected camera or capture positions are obtained via RTK at the time of photography, pre-flight ground control work can be greatly reduced. Similarly, in ground-based photogrammetry, if each photo capture point’s position is tracked with RTK during shooting, the resulting point cloud data will immediately conform to the site’s surveying coordinate system.

Next, in terms of work efficiency, the simultaneous use of photogrammetry and RTK dramatically speeds up the workflow from data acquisition to deliverable creation. Previously, photos were taken in the field and data processing was performed in the office, followed by separate GNSS survey data integration for position correction. In contrast, combining RTK, which enables real-time positioning, allows positional information to be linked to photos instantly during field capture. If needed, a provisional point cloud model can be generated on the spot to check for missed captures or uncovered areas. As a result, the need to return to the field is reduced and the overall lead time of surveying projects is shortened. This combination of accuracy and efficiency—photogrammetry × RTK—is attracting attention as the next-generation surveying style.

Simple, High-Precision Surveying Achieved with a Smartphone

In recent years, solutions that realize the fusion of photogrammetry and RTK on a smartphone have emerged. Smartphones are ideal surveying platforms because they are equipped with high-performance cameras and sensors, powerful processors, and intuitive user interfaces. By pairing a compact RTK-capable GNSS receiver with a smartphone, the device can function as a portable “lightweight surveying instrument” that one person can carry.

For example, by attaching an RTK antenna/receiver to a smartphone, the phone can obtain centimeter-precision positions in real time (cm level accuracy (half-inch accuracy)). Simply launching a dedicated app and walking while photographing the site with the smartphone camera will continuously record photo data with positional information. Because high-precision coordinates are attached to each captured photo, the point clouds and 3D models generated later through photogrammetric processing will already contain accurate positioning information from the start.

Advantages of smartphone-based surveying include:

• Ease of use: Compared to specialized surveying equipment, smartphone surveying is intuitive and accessible to anyone. Data acquisition can be performed by simply following the app’s instructions, without complex setup or advanced knowledge.

• Small, lightweight equipment: The required hardware is just a smartphone and a palm-sized GNSS receiver. There’s no need to carry heavy tripods or large surveying instruments, making it easy to work in confined sites or at heights.

• Real-time situational awareness: The positioning status and coverage area can be displayed on the screen in real time, reducing missed captures or insufficient data. Data can be checked immediately on site, and additional photography can be performed as needed.

• Extensibility and updates: As a smartphone app, functionality and performance can be enhanced via software updates. Integration with new sensors or implementation of AI analysis features can be accommodated, allowing flexibility for future technological advancements.

With these characteristics, surveying tasks of “measure” and “draw” can be completed on the spot with just a smartphone.

Visualizing the Site with Point Cloud Scans

Point cloud data derived from photogrammetry is a powerful means of visualizing site conditions. A point cloud is a collection of numerous points that make up the surfaces of objects, with each point including 3D coordinates and color information. Whereas point clouds were traditionally captured with specialized equipment such as laser scanners, advances in photogrammetry now allow high-density point clouds to be generated from photographs.

Using a smartphone + RTK for point cloud scanning, it is possible to continuously capture photos while walking to collect data on structures located approximately 50–60 m (164.0–196.9 ft) away. The vast number of photos collected are processed in the cloud or on the device to reconstruct a colored, detailed point cloud model. Because RTK corrects the positions, the generated point cloud already conforms to geodetic coordinates, greatly reducing the need for later integration or correction. With this method, wide roads or development sites can be scanned in a short time (on the order of a few minutes), and the resulting point cloud can be used to freely measure distances, areas, and volumes or to create cross-sections.

Moreover, if point cloud data is acquired in a manner that complies with the Ministry of Land, Infrastructure, Transport and Tourism’s as-built management guidelines, that data can be submitted as official inspection deliverables. Traditionally, as-built verification required manual checks and on-site attendance, but with accuracy-assured point clouds, digital inspections become feasible. In this way, photogrammetry and RTK point cloud scanning provide a digital replica of the site that enables detailed office-based review later.

Overlaying Design and Site with AR Technology

AR (augmented reality) technology that leverages surveying data has become far more practical through the combination of photogrammetry × RTK. By viewing the site through a smartphone or tablet screen and overlaying digital drawings or models onto that view, design plans and actual conditions can be intuitively compared. What might seem like mere AR display becomes powerful when paired with RTK-enabled high-precision alignment.

Standard smartphone AR estimates position using built-in GPS and sensors, which can gradually drift relative to the real world. However, with RTK-corrected positions on a smartphone, 3D models and design lines can be continuously kept in the correct coordinates. For example, on a road construction site, overlaying the as-designed model and current terrain data in AR makes it immediately apparent whether fills and cuts are being executed according to plan. Drift-free AR allows all stakeholders on site to share an as-built heatmap (a color-coded map showing deviations from design), preventing rework caused by misaligned understanding.

AR also excels at guiding construction and inspections. In pile-driving operations, pile heads must be placed at positions defined in the design; using the AR guidance features of an RTK-capable smartphone can navigate workers to pile locations so that even inexperienced workers can accurately locate pile points. Similarly, if the positions of underground utilities are recorded by point cloud scanning in advance, a smartphone AR app can project those buried utilities translucently during subsequent excavations, preventing accidental damage by heavy machinery. By combining photogrammetry-derived data with AR, site visualization and construction quality improvement have become more accessible.

Cloud Integration for Data Sharing and Efficiency

Cloud integration plays an important role in photogrammetry × RTK solutions. The large volumes of photos and generated point cloud models acquired in the field previously had to be processed on a local high-performance PC and the results distributed to stakeholders. Modern systems allow one-tap uploads from a smartphone app to the cloud for automatic processing and analysis.

With 3D model generation and various calculations performed on the cloud, users need only capture photos in the field, greatly reducing post-processing effort. Furthermore, deliverables uploaded to the cloud can be shared instantly via the web. For example, when a surveyor captures a point cloud on site and syncs it to the cloud, supervisors and clients in the office can immediately access and review the data. Without installing dedicated software or preparing high-performance PCs, anyone with a browser can check the site in a 3D viewer and perform measurements or add comments as needed.

This cloud integration smooths collaboration between field and office, making real-time construction management and remote inspections increasingly feasible. Because data is securely stored in the cloud, the risk of device loss and the burden of backups are reduced, and historical data can be retrieved later for trend analysis. Photogrammetry × RTK integrated with the cloud is thus not just a data acquisition tool but a comprehensive DX solution covering post-acquisition utilization as well.

The Dawn of a New Surveying Era: A Future Where Everyone Has a Personal Surveying Device

The fusion of photogrammetry and RTK is opening a future where not only specialist surveyors but everyone on site can handle high-precision surveying data. Surveying was once performed using specialized instruments such as total stations and levels operated by skilled technicians. Now, an environment is emerging where each person can carry a personal surveying tool—smartphone plus a small RTK receiver—and take measurements whenever needed.

This trend is accelerating as part of construction DX (digital transformation), contributing to improved field productivity and workstyle reform. With a personal surveying device, it becomes routine to quickly measure current conditions between tasks, immediately share the data to the cloud, and collaborate with stakeholders. Without waiting for a specialized surveying team, autonomous data acquisition and decision-making enable faster project decisions. Municipalities have also begun pilots in which staff use tablets or smartphones for infrastructure inspections and manage and analyze that data in the cloud. In disaster scenarios, officials themselves can rapidly measure and model collapsed areas to use the results for damage assessment and restoration planning on the same day.

Thus, the new era of surveying is one in which anyone can be both a data collector and a data user. At its core is the fusion of photogrammetry and RTK, with the familiar device of the smartphone maximizing that potential.

Conclusion: Realize a Field Revolution with Photogrammetry × RTK

The latest technologies combining photogrammetry and RTK are bringing unprecedented efficiency and accuracy to construction and civil engineering sites. They enable 3D digitization of site conditions at speeds once unthinkable and support waste-free, safe, and secure site management by allowing all stakeholders to proceed with construction while sharing information. A true field revolution—a “new era of surveying”—is underway.

One notable solution in this space is LRTK. LRTK is a smartphone-based lightweight surveying system that enables anyone to achieve centimeter-precision surveying (cm level accuracy (half-inch accuracy)) through the fusion of photogrammetry and RTK. The combination of a small GNSS receiver that attaches to a smartphone and a dedicated app provides all-in-one functionality such as point cloud scanning, AR display, and cloud synchronization, and adoption is already progressing in municipalities and companies. Technologies like LRTK not only dramatically streamline labor- and time-intensive surveying tasks but also directly drive DX advancement on site.

The world of surveying is on the cusp of significant change. By adopting the new photogrammetry × RTK methods and leveraging the latest technologies, why not revolutionize your construction management and infrastructure maintenance? LRTK, which allows high-precision, instant surveying with a smartphone, will strongly support that first step. Experience the surveying style of the new era on site and get ahead of the future standard.