Exhibiting at CSPI: Accelerating On-site DX with High-accuracy GNSS × Cloud Integration

Improving productivity and promoting DX (digital transformation) are key themes at construction and surveying sites. The exhibition where the latest technologies and solutions gather is the Construction and Surveying Productivity Improvement Expo (CSPI Expo). At this year’s CSPI Expo, various technologies that accelerate on-site DX are attracting attention, and among them, solutions that combine high-accuracy GNSS (Global Navigation Satellite System) and cloud integration are especially in the spotlight.

This article explains the evolving GNSS positioning technologies (particularly RTK and the new method LRTK) and how they differ from conventional total stations and typical GPS positioning, and considers how cloud integration can realize workflow efficiency and remote data sharing on-site. It also introduces examples and functions of on-site DX that leverage the latest technologies, such as 3D point-cloud scanning and stake-driving support using AR, which have become possible with familiar smart devices like iPhone and iPad.

Furthermore, through concrete use cases across surveying, design, and maintenance management, we examine the ease of use that is effective for small teams and solo work, and the cost advantages compared to conventional equipment. Against the backdrop of on-site challenges such as labor shortages, aging engineers, and increasingly complex tasks, we organize the significance of these solutions and finally introduce a simple surveying system that utilizes LRTK.

Evolution of GNSS Technology and Differences from Traditional Methods

First, let’s look at the advances that high-accuracy GNSS positioning technology brings to the field and how it differs from traditional surveying equipment. Surveying using GNSS (satellite positioning systems) has increasingly been used on-site in recent years as accuracy has improved. In particular, GNSS positioning using the Real-Time Kinematic (RTK) method has become widespread as a technique that achieves centimeter-level accuracy (half-inch accuracy) by using correction information from a base station.

Conventional optical surveying (total stations, etc.) required two-person teams and complex equipment setup and calibration for high-accuracy positioning. Also, common standalone GPS receivers have errors on the order of 5–10 m, making them unsuitable for tasks that require centimeter accuracy such as map creation or stake driving. Therefore, achieving high-accuracy positioning required purchasing expensive RTK-capable GNSS equipment and operating it with expertise—such as communications with base stations and obtaining correction information via networks.

In recent years, a new method called LRTK has emerged to address these issues. LRTK is a technology that combines a compact high-accuracy GNSS receiver with a smartphone to obtain accuracy comparable to conventional dedicated equipment more easily. Details will be introduced later, but by utilizing multiple satellite frequencies and satellite augmentation signals, it becomes possible to keep errors to within several centimeters even in vertical positioning, which was difficult with conventional GPS.

The main differences between traditional methods and GNSS surveying are summarized below:

• Optical surveying such as total stations: Highly accurate, but typically requires two-person operation because of large equipment and target prisms. Each measurement requires setup and line-of-sight assurance, and periodic calibration takes time.

• Conventional GPS positioning: Easy and does not require specialized equipment, but errors are large—on the order of 5–10 m—and vertical measurement accuracy is insufficient. It cannot be used for tasks requiring centimeter accuracy such as topographic mapping or stake-out.

• RTK-GNSS surveying: Uses a GNSS base station and rover with real-time corrections to reduce position errors to a few centimeters. It is highly accurate, but the equipment is expensive and operation requires expertise, and a reliable communications environment is essential.

• Positioning with LRTK: Achieves RTK-equivalent centimeter-level accuracy (half-inch accuracy) with a smartphone and an ultra-compact GNSS receiver. It also leverages satellite augmentation signals such as QZSS (Michibiki), enabling stable positioning even in mountainous areas outside radio coverage. It is cheaper than conventional equipment and easy to carry and operate.

GNSS technology has advanced markedly, making high-accuracy positioning accessible without dedicated equipment. While this has been enabled by advances in smartphones and communications infrastructure, integration with the cloud also plays an important supporting role. Next, let’s look at how cloud utilization improves efficiency and enables remote sharing.

Efficiency Gains and Remote Sharing Enabled by Cloud Integration

Even if high-accuracy on-site data is obtained, true efficiency gains will not follow unless that data can be used quickly. The key here is integration with cloud services. If positional information and point-cloud data collected at the survey site are uploaded to the cloud immediately, office staff and stakeholders at other locations can share the results in real time.

Cloud utilization offers the following benefits:

• Immediate data sharing: By syncing surveying data collected on-site to the cloud on the spot, teams in remote locations can share information in real time. This greatly reduces the time spent waiting for survey result verification or decision-making.

• Remote collaboration: Data uploaded to the cloud can be viewed by stakeholders over the Internet immediately. There is no need to install dedicated software; 3D point clouds and survey results on maps can be checked from a browser. Clients and designers can understand the latest status from their offices and issue appropriate instructions without visiting the site.

• Centralized data management and analysis: Survey data accumulated in the cloud is managed centrally and can be retrieved and analyzed as needed. For example, acquired point clouds can be overlaid with multiple models in a cloud 3D viewer to measure arbitrary distances, areas, and volumes. Accumulating time-series data helps understand long-term changes and supports quality control of deliverables.

In this way, cloud integration makes the flow from surveying to data sharing and analysis seamless, enabling efficient operations that transcend the boundaries between on-site and remote locations.

New On-site DX Features Enabled by iPhone and iPad

So, what new on-site DX features can be realized in an environment that leverages high-accuracy GNSS and the cloud? The keyword is smartphone utilization. Modern iPhones and iPads are equipped with high-performance cameras and LiDAR sensors, and when combined with a compact GNSS receiver device, they transform into powerful mobile surveying tools.

Here are the main functions that can be realized with a single smart device:

• High-accuracy coordinate measurement: While receiving GNSS real-time corrections, latitude, longitude, and height can be measured and recorded with a single tap. The system supports Japan’s plane rectangular coordinate system and automatically calculates geoid height, so the acquired coordinate values can be used directly as public survey deliverables.

• 3D point-cloud scanning: By photographing the surroundings with an iPhone’s LiDAR scanner or camera and simultaneously attaching high-accuracy position data in real time, it is easy to generate a point-cloud model with absolute coordinates. Without special laser scanners or drones, simply walking with a smartphone lets you measure structures and terrain in surface and three-dimensional forms, and perform analyses such as earthwork quantity calculations immediately after acquisition.

• Stake-out assistance (coordinate navigation): Input the coordinates of stake positions or reference points specified in the design, and the smartphone screen will display arrows and distance information to guide you to the target point. The worker can move following the on-screen directions and identify the position to drive the stake with centimeter-level precision (half-inch accuracy). Because accurate layout can be done without specialized surveying skills, stake-out work can be streamlined.

• Design data visualization with AR: If design drawings or 3D model data are imported into a smartphone app, they can be overlaid on the site imagery. AR displays aligned with real-world coordinates via GNSS allow instant confirmation of whether a structure’s position and elevation match the design. Additionally, registered underground utility locations or boundary lines can be visualized on the video to warn during excavation work or assist in as-built inspections.

• Photo measurement and record-keeping: Photos taken with a smartphone camera are automatically tagged with high-accuracy capture position coordinates and orientation information. Since you can immediately identify on a map from which point and in which direction a photo was taken, time-series comparison and report creation are streamlined.

Thus, many measurement and design tasks that previously required dedicated equipment or expert skills can now be handled one after another with a single smartphone. Each field technician carries their own surveying tool and can use it whenever needed. The “one device per person” mobile surveying instrument is truly becoming a reality.

Next, let’s look at the specific tasks where these technologies demonstrate effectiveness, from surveying to design, construction, and maintenance management.

Use Cases in Surveying, Design, and Maintenance Management

DX tools based on high-accuracy GNSS and smartphone apps are useful in various phases of civil engineering and construction projects. Here are some representative use cases:

• Surveying (topography and as-built management): New technologies greatly improve the efficiency of on-site topographic surveying and as-built management. For example, walking the site with a smartphone to perform point-cloud scanning allows you to digitize the entire terrain in detail instead of estimating based on a few representative points as before. As a result, earthwork calculations and cross-section generation can be done on the spot, reducing missed measurements and estimation errors.

• Design and construction: In the design stage, on-site point-cloud data can be used to simulate how planned structures will harmonize with their surroundings. During construction, overlaying the design model with AR enables immediate confirmation of whether structures are at the design-specified position and elevation. Early detection of errors or mistakes helps prevent rework and ensures quality.

• Maintenance management and disaster response: These technologies are also powerful for infrastructure inspections and disaster-site surveys. Regular scanning of existing structures such as bridges and tunnels allows detection of displacement and signs of deterioration from the data. In the event of a disaster, rapid point-cloud surveying of affected areas and cloud sharing of that data can speed up restoration planning. The approach significantly reduces the manpower and time required for on-site surveys while enabling safe recording of site conditions.

Smart GNSS and 3D technologies can be applied across the project lifecycle, contributing to fundamental efficiency improvements and sophistication of operations.

Portable Surveying Tools That Support Small Teams and Solo Work

Another major advantage of on-site DX tools is that they allow tasks to be completed by small teams or even a single person. As labor shortages become more serious, the ability for individuals to handle advanced surveying tasks is a significant strength.

• One-person surveying: Traditionally, two people were required to operate surveying instruments and set prism targets, but with a smartphone and GNSS device combination, one person can perform observations. For stake-out, attaching a smartphone to a monopod lets a single operator accurately locate stake positions without an assistant.

• Reduced equipment transport burden: The compactness of the entire system that fits in a pocket eliminates the need to carry heavy tripods and surveying instruments to the site. This not only shortens survey preparation time but also makes measurements at high or confined locations easier.

• Cost benefits: The combination of a small GNSS receiver and a smartphone keeps initial acquisition costs lower than conventional surveying equipment. If surveying can be completed in-house, outsourcing costs can also be reduced. There is less need for equipment calibration and maintenance, contributing to lower total costs.

• Ease of learning: Intuitive smartphone app interfaces are designed to be easy to use even for staff with limited expertise. By following Japanese UI guidance and clear instructions, users can perform positioning and data collection, minimizing training time. IT-savvy younger engineers have little resistance to these tools, aiding technology transfer.

• Safety and work efficiency: Enabling small-team completion reduces the number of personnel exposed to hazardous conditions. With minimal necessary staff, fewer people are at risk while others can be allocated to different tasks. The number of survey points measured per hour increases, contributing to shorter schedules and higher productivity.

These portable, easy-to-use surveying tools are highly effective at sites requiring labor reduction and cost savings, and adoption is already beginning.

Adoption by Local Governments and Private Sector, and Disaster Response

How are these technologies actually being introduced and used in the field? Here are some examples:

• Adoption by local governments: Progressive municipalities have begun actively using on-site DX tools for disaster response and operational efficiency. For example, in Fukui City, Fukui Prefecture, a smartphone-based surveying system was introduced in 2023, and staff were able to rapidly measure locations of collapsed houses and ground deformation following an earthquake. Measurement data was shared to the cloud immediately, enabling city office personnel to grasp the situation and support recovery planning. Reports indicate that initial response could be taken without waiting for specialists, leading to reduced recovery time and cost.

• Use in private construction industry: Construction and surveying companies are also increasingly adopting DX tools that allow efficient measurement by small teams. For instance, a small construction firm incorporated smartphone surveying for in-house as-built management so site supervisors could perform measurements in a short time without outsourcing. Major general contractors have also begun trial deployments, with new workflows emerging—such as young engineers using AR-based surveying data-checking tools for quality checks.

• Effectiveness at disaster sites: As in the Fukui City example, smartphone surveying is being used for rapid post-disaster situation recording. For example, when a landslide occurs in a mountainous area, responders on site can immediately perform point-cloud surveying of the damage and share the data to the cloud. Surveys of disaster areas that previously required many people and much time have been dramatically sped up, offering a direct pathway to faster recovery.

From public institutions to private companies, adoption of on-site DX solutions is progressing. Especially in disaster response, the combination of high-accuracy GNSS and smartphones is gaining attention as a means to enable rapid information gathering and sharing.

The Significance of DX in Addressing Labor Shortages and Aging Workforce

In Japan’s construction industry, the aging of skilled workers and labor shortages are serious issues. While construction management and surveying tasks are becoming more advanced and complex, securing and training personnel to handle them cannot keep pace.

In this context, the role of simple surveying tools and on-site DX technologies that anyone can use is extremely important. If less experienced technicians can obtain high-accuracy measurement results quickly with the support of digital devices, the burden on veterans can be reduced and quality can be standardized. Also, by substituting physically demanding tasks with smartphones and lightweight devices, older skilled workers can continue to contribute their knowledge on site while reducing physical strain.

Furthermore, introducing the latest technologies on-site is attractive to younger generations and helps improve the image of the construction industry, encouraging new entrants. Digitalizing sites with tools that the smartphone generation can use without resistance contributes to securing future human resources.

Thus, on-site DX solutions do more than improve task efficiency; they serve as part of the solution to structural industry challenges. Their importance is expected to grow as they help maintain and improve productivity and safety on site.

Simple Surveying Solution Enabled by LRTK

Finally, as the culmination of the high-accuracy GNSS, smartphone, and cloud integration introduced so far, we present LRTK. LRTK is a groundbreaking smartphone surveying system developed by Refixia, a startup originating from Tokyo Institute of Technology. By simply attaching an ultra-compact RTK-GNSS receiver (weighing approximately 165 g) to an iPhone, centimeter-level positioning (half-inch accuracy) comparable to conventional surveying equipment becomes possible. In addition, a dedicated app and cloud service provide one-stop capabilities for 3D point-cloud measurement, AR-based stake-out assistance, and cloud data sharing.

With this LRTK system, the complex procedures from initial positioning setup to result sharing are greatly simplified, realizing a simple surveying solution that anyone on-site can use. Without specialized training, users can perform high-accuracy surveying by following on-screen instructions, making it easy for small contractors and municipalities to adopt—and it is already being used in various locations.

At our booth at the CSPI Expo, we will demonstrate the latest on-site DX solutions using this LRTK system. Please visit the venue to see how much high-accuracy measurement can be achieved with just one smartphone.