Precise measurements and acquisition of 3D terrain data are indispensable for construction sites and surveying work. However, conventional surveying instruments have posed many challenges, such as bulky equipment that is difficult to carry to the field and the need for advanced expertise. Recently, attempts have been made to perform 3D scanning more easily thanks to improved smartphone performance, but the GPS built into phones lacks sufficient accuracy for professional use. Enter the compact, high-precision iPhone RTK device. Used in combination with an iPhone, this device solves the problems of traditional equipment and enables anyone to easily obtain centimeter-level positioning and 3D point cloud data. This article explains the issues with conventional devices and how a compact, high-precision iPhone RTK device addresses them.

Table of Contents

• Issues with conventional equipment (complexity, lack of accuracy, weight, etc.)

• Point cloud utilization via high-precision positioning and smartphone integration (orthophoto generation, cross-section extraction, etc.)

• On-site benefits of introducing an iPhone RTK device (improved efficiency, safety, information sharing, etc.)

• FAQ

Issues with conventional equipment

First, conventional surveying instruments and measurement methods have had the following problems.

• Equipment and preparation are complicated: High-precision surveying requires multiple specialized devices, and setup and calibration on site take time. Tasks such as setting up tripods and mounting instruments or connecting cables create extra work and tend to complicate operations. For example, responding to sudden measurement needs was difficult, and in bad weather preparation could take even longer.

• Specialized knowledge and experience are required: Operating conventional equipment such as total stations or GNSS survey receivers requires specialized knowledge, and mastering them takes experience. Measurement procedures are complex, and if mistakes occur, re-measurement takes time. In recent years, the shortage of skilled technicians has worsened, and many sites must rely on personnel who are familiar with the equipment.

• Trade-off between accuracy and ease of use: Simple measurement methods (tape measures, consumer GPS units, smartphone location services, etc.) are convenient but have insufficient accuracy on the order of meters. For example, smartphone GPS can have errors of 5–10 meters, making it unusable for precise surveying. On the other hand, high-end instruments that can measure down to millimeter precision are very expensive, require large setups and skilled operators, and are not something everyone can handle easily.

• Burden of large, heavy equipment: High-precision equipment often includes heavy items such as surveying prisms, receivers, and main batteries, making transport and movement on site difficult. In mountainous or rough-terrain areas, simply carrying the equipment was strenuous. Because the equipment is large, installation in tight spaces is difficult, and transporting heavy equipment may require multiple people or vehicles. In disaster zones, transporting equipment itself became a major burden.

• Cost and limited number of units: Conventional surveying equipment is often expensive, so a company may only own a limited number of units. This leads to constraints such as “the equipment isn’t available when needed” or “it’s not feasible for each person to carry a unit,” preventing agile surveying on site. In some cases, it was necessary to rent equipment from external contractors or share units among departments and wait in line, which hindered quick responses.

As shown above, conventional methods struggled to balance accuracy and ease of use. So how can these challenges be solved? Next, let’s look at the features of a compact RTK device that can be used with an iPhone and the solutions it provides.

Point cloud utilization via high-precision positioning and smartphone integration (iPhone RTK device solution)

A new approach attracting attention for solving conventional problems is surveying using an iPhone RTK device. This involves attaching an ultra-compact RTK-GNSS receiver to an iPhone and integrating it with the smartphone’s camera and LiDAR sensor so that anyone can easily perform high-precision positioning and 3D measurements. Below are the main benefits provided by this iPhone RTK device.

Centimeter-level high-precision positioning

The standout feature of the iPhone RTK device is its positioning accuracy. The RTK (Real-Time Kinematic) method reduces the position errors of standard GPS—typically on the order of meters—to roughly a few centimeters. By using a dedicated base station or receiving high-precision correction information over the internet, real-time error-corrected positioning is possible. As a result, accurate coordinates can be obtained on site immediately, allowing confident alignment with drawings and stakeout work. Previously, achieving such high-precision positioning required surveying instruments costing tens of millions of yen, but with a compact RTK device you can achieve equivalent accuracy with a palm-sized device and a smartphone.

Intuitive operation via smartphone integration

Integration with an iPhone dramatically improves usability. Launch the dedicated app, and even those with little surveying experience can follow on-screen prompts to collect high-precision data. The app handles complex settings and calculations automatically, so no expert knowledge is required. For example, simply tapping a button at the point you want to measure records that point’s latitude, longitude, and elevation. You can also attach notes and photos, allowing the device to double as a digital field notebook. Surveying tasks that previously required skilled operators can now be performed by younger staff familiar with smartphone operations, improving overall site productivity. In fact, with only a few minutes of simple instruction, anyone can begin surveying on site.

Easy acquisition of 3D point cloud data

Using an iPhone RTK device, anyone can easily acquire 3D point cloud data of a site. By leveraging the iPhone’s built-in LiDAR scanner and camera, you can scan structures and terrain simply by holding up the phone and walking around. Point clouds are generated in real time as you move, much like shooting a video. Because RTK provides high-precision positional data, the captured point clouds include global coordinates, making it easy to overlay them on maps or drawings later. Traditionally, one had to set up laser scanners on tripods and measure point by point or use drone imagery followed by time-consuming photogrammetric processing. However, with an iPhone RTK device you can obtain dense, detailed point clouds just by walking around the site, enabling rapid digitalization of complex structures and large areas. For example, piping systems in industrial plants or the interior shapes of tunnels—targets that are difficult to measure manually—can be readily converted into 3D data, including areas that are hard to access by hand.

Automatic generation of orthophotos and cross-sections

The acquired point cloud data can be used not only as a 3D model but also for creating various types of drawings. With a dedicated app or cloud service, you can automatically generate orthophotos (true-top-down photographic maps) of the ground surface. This makes it possible to produce orthomosaics from the ground—a task that was traditionally done with drone surveys or aerial photography—with much less effort. You can also extract cross-sections at any desired location with a single touch. For example, you can check a road or embankment cross-section on the spot or instantly verify excavation depths and slopes. Since the point cloud can include color information, orthophotos visually resemble on-site photographs, and cross-sections can visually show strata and positions of structures. These automatic-generation functions allow you to quickly obtain surveying deliverables on site and repurpose them directly for reports. Additionally, acquired point cloud data can be uploaded to the cloud and shared with the team. Once uploaded, remote office members can instantly view the 3D point clouds and perform analyses—such as measuring distances, areas, or volumes—within a dedicated viewer. The ability to fully utilize field-acquired data in downstream processes is a major advantage.

Lightweight and compact to reduce on-site burden

As the name implies, compact, high-precision iPhone RTK devices are lightweight, compact, and highly portable. They typically weigh only a few hundred grams and are small enough to fit in a pocket even when attached to an iPhone. With an internal battery, no external power or cabling is required, so you can start using it on site without complicated preparation. Because it is easy to carry, you can take it out and measure whenever needed, reducing losses like “going back to fetch equipment” or “transporting by heavy machinery.” Its one-handed operability lets you safely perform measurements in tight scaffolding or at height. Prices are also significantly lower than those of traditional instruments, enabling field workers to carry their own surveying devices. This allows real-time data collection at the moment measurements are needed and speeds up site decision-making based on measurement results.

On-site benefits of introducing an iPhone RTK device

In summary, using an iPhone RTK device enables a new surveying style that combines “high precision,” “ease of use,” and “speed.” This yields the following on-site benefits.

• Dramatic improvement in work efficiency: Because complicated equipment setup and personnel arrangements are unnecessary, surveying time is greatly reduced. Terrain surveys that used to take half a day can be completed in tens of minutes; for example, surveying the terrain of a 50 m × 50 m plot that previously took two people half a day might be completed by one person in about an hour with an iPhone RTK device. Additionally, bringing work in-house that was previously subcontracted can reduce costs.

• Improved data accuracy and information volume: By recording the entire site as a point cloud, you obtain vastly more detailed data compared to methods that only measure a few points. Acquired data accuracy is guaranteed at the centimeter level, improving reliability for drawing checks and quantity calculations. Moreover, because there is no need to record measurement points by hand and enter them later, human recording errors can be reduced.

• Improved safety and reduced labor burden: The number of times workers must carry heavy equipment to heights or approach dangerous slopes can be reduced. LiDAR scanning from a distance makes it possible to measure areas that cannot be entered directly. For example, checking the top height of a tall bridge pier traditionally required aerial work platforms or scaffolding, but with an iPhone RTK device you can measure it safely from the ground. In addition, reducing equipment transport and long measurement sessions lowers worker fatigue and helps reduce risks such as heat stroke and accidents.

• Real-time information sharing and decision-making: Because survey data can be shared immediately via the cloud, communication between the site and the office speeds up. Measured data can be shared with stakeholders the same day, enabling on-the-spot revisions to construction plans or issuance of additional instructions. Digital exchange of data eliminates waiting for paper drawings or reports and supports on-site digital transformation (DX). Site personnel and office engineers can review the same data together, reducing unnecessary travel and communication errors.

Thus, introducing an iPhone RTK device is an innovative solution that significantly improves on-site productivity and safety. In fact, our company offers LRTK as a compact RTK device with these capabilities. LRTK is an ultra-compact RTK-GNSS receiver designed to be mounted on an iPhone and, when used with a dedicated app, enables anyone to quickly perform the high-precision positioning and point cloud measurements described in this article. As a new tool to solve conventional challenges, we invite you to experience simple surveying on site with LRTK.

FAQ

Q: Can high-precision surveying be done with the iPhone’s LiDAR scanner alone? A: The iPhone’s built-in LiDAR scanner can easily acquire 3D models, but because positional reference is limited to the phone’s internal estimated coordinates, absolute positioning accuracy is not high. To measure buildings and terrain in an accurate coordinate system, RTK correction is needed to achieve centimeter-level accuracy. Using an iPhone RTK device adds high-precision positional information to LiDAR point clouds, producing data suitable for professional surveying.

Q: What is RTK? A: RTK (Real-Time Kinematic) is a positioning technique that adds correction information to satellite positioning like GPS to achieve higher accuracy. By combining data from a reference base station, it corrects positioning errors in real time and dramatically improves positional accuracy. GPS positioning that normally has meter-level errors can be reduced to a few centimeters or less using RTK.

Q: How large an area can be measured? A: The measurable range depends on site conditions, but the iPhone’s LiDAR can capture point clouds several meters ahead. By walking while scanning and stitching the data together, you can cover large areas. For example, even a 100 m slope can be fully recorded in detail by continuing the scan while performing periodic alignments. After acquisition, you can trim or split point clouds for processing as needed.

Q: What level of positioning accuracy can be achieved? A: Under favorable conditions, accuracies of about 1–2 cm in both horizontal and vertical directions can be expected. RTK corrections greatly reduce satellite positioning errors, making the accuracy far superior to conventional handheld GPS. However, errors may vary slightly depending on surrounding obstructions and atmospheric conditions. For instance, in urban areas surrounded by tall buildings or in dense forests where satellite signals are blocked, accuracy may degrade. Even so, it remains highly accurate compared to simple positioning methods and meets most field measurement needs.

Q: Can it be used in remote mountain areas without network coverage? A: Yes. Even in locations without network connectivity, RTK positioning is possible if the device supports reception of the high-precision augmentation signals (CLAS) broadcast by Japan’s quasi-zenith satellite Michibiki. LRTK supports CLAS reception, enabling centimeter-level positioning in mountainous or disaster-affected areas without cellular service. Where internet is available, similar accuracy can be achieved using commercial correction services or reference station data.

Q: Is specialized knowledge required to operate the device? A: No, it is designed to be usable without special expertise. The smartphone app provides an easy-to-understand user interface; simply select the item you want to measure and follow the prompts to get results. Unlike conventional instruments, complicated operations and settings are unnecessary, and beginners can start using it after a short training session.

Q: Which smartphones are supported? A: In general, recent iPhone and iPad models are supported. Models from iPhone 12 Pro onward equipped with a LiDAR scanner can fully utilize 3D point cloud acquisition. Non-LiDAR devices can still perform some surveying functions such as GNSS point positioning or photogrammetry-based measurements using photos. However, to perform high-precision point cloud scans, it is recommended to use a device with a LiDAR scanner.

Q: Can it be used in rain or indoors? A: It will operate in light rain because of water-resistant design, but heavy rain can degrade GNSS reception and LiDAR point cloud quality due to raindrop noise. Use a waterproof case as needed to protect the device. Indoors, satellite signals are not available, so RTK-based positioning cannot be performed, but LiDAR scanning itself is possible. By post-processing and merging indoor and outdoor point clouds, indoor space surveying can be supported.

Q: How long does the battery last? A: The RTK device contains a small internal battery and can perform continuous surveying for several hours on a full charge. Charging is done via USB, and it can be used while powered from a mobile battery. For long jobs, use a spare power source for peace of mind. Also note that the smartphone battery is consumed during continuous use, so it is advisable to use a mobile battery to charge the phone while surveying if necessary.