Solve on-site challenges! A compact, high-precision iPhone RTK device ready to use

Precise measurement and acquisition of 3D terrain data are indispensable for construction sites and surveying work. However, traditional surveying instruments have had many issues, such as being large and difficult to carry to the site or requiring advanced specialist knowledge. Recently, attempts have been made to perform 3D scanning easily thanks to improved smartphone performance, but the GPS built into smartphones lacks the necessary accuracy for professional use. Enter the compact, high-precision iPhone RTK device. Used in combination with an iPhone, this device solves the problems of conventional instruments and enables anyone to easily obtain centimeter-level positioning (cm level accuracy (half-inch accuracy)) and 3D point cloud data. This article explains the issues with traditional equipment and how a compact, high-precision iPhone RTK device addresses them.

Table of Contents

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

• Utilizing point clouds through high-precision positioning and smartphone integration (orthophoto generation, cross-section extraction, etc.)

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

• FAQ

Issues with conventional equipment

First, the following problems have been associated with traditional surveying instruments and measurement methods.

• Equipment and preparation are complicated: High-precision surveying requires multiple dedicated instruments, and site setup and calibration take time. Setting up tripods, mounting instruments, and connecting cables add hassle and make the work cumbersome. For example, it was difficult to respond to sudden measurement needs, and in bad weather preparation could take even longer.

• Specialist knowledge and experience are required: Operating conventional instruments such as total stations or GNSS surveying equipment requires specialized knowledge and experience. Measurement procedures are complex, and when mistakes occur, re-measuring takes time. In recent years, shortages of experienced technicians have become serious, and many sites must rely on personnel familiar with the equipment.

• Trade-off between accuracy and ease of use: Simple measurement methods (tape measures, consumer GPS devices, smartphone location services) are convenient but have insufficient accuracy on the order of several meters. For example, smartphone GPS can have errors of 5-10 m (16.4-32.8 ft), making it unsuitable for precise surveying. On the other hand, high-end instruments capable of measuring down to the millimeter level are extremely expensive, require large setups and skilled operators, and are not easily handled by everyone.

• Burden of large, heavy equipment: High-precision instruments include many heavy items such as surveying prisms, receivers, and main unit batteries, making transport and on-site movement difficult. In mountainous or rough-terrain areas, merely carrying the equipment was hard labor. Because the equipment is large, installation in tight spaces is difficult, and transporting heavy gear may require multiple people or vehicles. Transporting equipment was especially burdensome in disaster sites.

• Cost and limitations on number of units: Conventional surveying instruments are often expensive, and companies may only own a limited number of units. This can mean “the equipment isn’t available when you want it” or “you can’t carry one unit per person,” preventing agile on-site surveying. In some cases, equipment must be rented from external vendors or shared among departments, causing delays and hindering rapid response.

As described above, traditional methods face difficulties in balancing accuracy and ease of use. So, how can these issues be resolved? Next, we will look at the features of compact RTK devices that can be used with iPhones and the solutions they offer.

Point cloud utilization through 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 measurement. Below we detail the main benefits this iPhone RTK device brings.

Centimeter-level high-precision positioning is possible

The biggest feature of the iPhone RTK device is positioning accuracy. The RTK (Real-Time Kinematic) method can reduce position errors that are several meters with ordinary GPS to a few centimeters. By using a dedicated base station or receiving high-precision correction information via the Internet, positioning errors can be corrected in real time. As a result, accurate coordinates can be obtained on-site immediately, allowing confident checking against drawings and stakeout work. Previously, achieving high-precision positioning required surveying instruments costing tens of millions of yen, but with a compact RTK device you can achieve comparable accuracy with a palm-sized device and a smartphone.

Intuitive operation through smartphone integration

Integration with an iPhone dramatically improves operability. Launch the dedicated app and even users with little surveying experience can follow on-screen prompts to collect high-precision data. The app handles complex settings and calculations automatically, so no specialist knowledge is required. For example, by simply tapping a button at the point you want to measure, latitude, longitude, and elevation are recorded. You can attach notes and photos, making the app function as a digital field notebook. Survey tasks that used to rely on experts can now be handled by younger staff familiar with smartphone operation, improving overall on-site productivity. In practice, after just a few minutes of simple instruction, anyone can begin surveying on site.

Easy acquisition of 3D point cloud data

With an iPhone RTK device, anyone can easily capture 3D point cloud data of the site. By utilizing the iPhone’s built-in LiDAR scanner and camera, you can scan surrounding structures and terrain simply by holding up the smartphone and walking around the site. Point clouds are generated in real time as if recording video. Because RTK provides high-precision positioning information, the captured point clouds include global coordinates, making it easy to overlay them on maps or drawings later. Previously, laser scanners had to be mounted on tripods and measured point by point, or drone photos required post-processing to generate point clouds, which was labor-intensive. However, with an iPhone RTK device you can obtain dense, detailed point clouds simply by walking the site, allowing rapid digitization of complex structures and large areas. For example, piping systems in a factory plant or the interior shapes of tunnels—complex subjects that are difficult to measure manually—can be easily converted to 3D data, including areas that are hard to reach by manual measurement.

Automatic generation of orthophotos and cross-sections

The obtained point cloud data can be used not only as 3D models but also for various drawing outputs. By processing the data with dedicated apps or cloud services, you can automatically generate orthophotos (measured images viewed from directly above). This brings orthomosaic creation—traditionally done with drone or aerial photography—down to the ground level easily. You can also extract vertical cross-sections at any point from the point cloud with a single tap. For example, you can check road or embankment cross-sectional shapes on the spot or instantly verify excavation depth and slope. Since point clouds include color information, orthophotos reproduce the site visually like photos, and cross-sections can visually indicate layers or the positions of structures. These automatic generation features allow you to quickly obtain survey results on-site and reuse them directly as reporting materials. Furthermore, you can upload the captured point clouds to the cloud and share them with your team. Sending data via the Internet allows remote office members to immediately view 3D point clouds and perform analyses such as distance, area, and volume measurements on a dedicated viewer. The ability to fully utilize on-site data in downstream processes is a major advantage.

Lightweight and compact to reduce on-site burden

As the name implies, the compact, high-precision iPhone RTK device is lightweight and highly portable. It weighs only a few hundred grams and is small enough to stay pocketable when attached to an iPhone. It has an internal battery, so no external power or cabling is required, allowing immediate use on site without complicated setup. Easy to carry, you can pull it out and survey whenever needed, reducing losses such as “going back to fetch equipment” or “transporting by heavy machinery.” Its one-handed operability allows safe measurement on narrow scaffolding or at heights. Also, because its price is significantly lower than conventional instruments, individual field workers can carry their own surveying device. This enables real-time data collection at the moment measurement is needed and speeds up on-site decision-making based on measurement results.

On-site benefits of introducing an iPhone RTK device

In summary, using an iPhone RTK device realizes 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 shortened. Terrain surveys that used to take half a day can be completed in minutes in some cases. For example, a terrain survey of a 50 m square (164.0 ft square) site that previously required two people half a day could be completed by one person in about an hour with an iPhone RTK device. In addition, tasks previously outsourced to external surveyors can be brought in-house, reducing costs.

• Improved data accuracy and information content: Recording the entire site as point clouds yields vastly more detailed data than traditional methods that measure only a few points. The acquired data’s accuracy is guaranteed at the centimeter level (cm level accuracy (half-inch accuracy)), improving reliability for drawing checks and quantity calculations. Also, eliminating manual handwritten records and later input reduces human recording errors.

• Improved safety and reduced labor burden: You can reduce the number of times workers carry heavy equipment up to heights or approach dangerous slopes. Scanning with LiDAR from a distance makes it possible to measure places you cannot enter 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 safely from the ground. Moreover, reducing equipment transport and long measurement sessions reduces worker fatigue, contributing to lower risks of heatstroke 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 is accelerated. You can share measured data with stakeholders the same day and issue plan revisions or additional instructions on the spot. Digital data exchange eliminates the wait for paper drawings or reports and promotes on-site DX (digital transformation). Site personnel and office-based engineers can discuss while viewing the same data, reducing unnecessary travel and communication errors.

Thus, introducing an iPhone RTK device is an innovative solution that greatly improves on-site productivity and safety. In practice, our company offers LRTK as a compact RTK device with these functions. LRTK is an ultra-compact RTK-GNSS receiver designed to be attached to an iPhone; combined with a dedicated app, it enables anyone to perform the high-precision positioning and point cloud measurements introduced in this article immediately. As a new tool that solves traditional problems, please experience simplified surveying with LRTK on your site.

FAQ

Q: Can the iPhone’s LiDAR scanner alone perform high-precision surveying? A: The iPhone’s built-in LiDAR scanner can easily capture 3D models, but its positional reference is limited to the smartphone’s internal estimated coordinates, so absolute positioning accuracy is not high. To measure buildings or terrain in an accurate coordinate system, RTK corrections are required to achieve centimeter-level accuracy (cm level accuracy (half-inch accuracy)). Using an iPhone RTK device allows high-precision position information to be added to point clouds obtained by LiDAR, producing data suitable for professional surveying.

Q: What is RTK? A: RTK (Real-Time Kinematic) is a positioning technology that improves the accuracy of satellite positioning such as GPS by adding correction information. By combining data from a reference base station, RTK corrects positioning errors in real time and dramatically improves position accuracy. GPS positioning that normally has errors on the order of meters can be reduced to a few centimeters or less using RTK.

Q: How large an area can be surveyed? A: The surveyable range depends on site conditions, but the iPhone’s LiDAR can capture point clouds several meters ahead. By walking while scanning you can stitch data together, so wide areas can be covered. For example, even a slope of about 100 m (328.1 ft) can be fully recorded in detail if you continue scanning while realigning as you go. After point cloud acquisition you can trim unnecessary parts or split the data for processing.

Q: What level of positioning accuracy can be achieved? A: Under favorable conditions, horizontal and vertical accuracies of approximately 1-2 cm (0.4-0.8 in) can be expected. RTK corrections greatly reduce satellite positioning errors, yielding far superior accuracy to conventional handheld GPS. However, accuracy can vary slightly depending on surrounding obstructions and atmospheric conditions. For example, satellite signals may be blocked in urban areas surrounded by high-rise buildings or in dense forests, reducing accuracy. Even so, accuracy is much higher than simple positioning methods and meets the needs of most on-site measurements.

Q: Can it be used in remote mountains with no network coverage? A: Yes. Even where networks are unavailable, RTK positioning is possible if the device supports high-precision augmentation signals such as Japan’s quasi-zenith satellite Michibiki CLAS. LRTK supports CLAS reception, so it can achieve centimeter-level positioning even in mountain areas or disaster sites without cellular coverage. If the Internet is available, equivalent accuracy can be achieved using private correction services or reference station data.

Q: Does operating the device require specialist knowledge? A: No, it is designed to be operable without special expertise. The smartphone app provides an easy-to-understand user interface; simply select what you want to measure and follow the instructions to get results. Complicated operations and settings typical of conventional equipment are unnecessary, and beginners can start using it after a short training session.

Q: Which smartphones are supported? A: Generally, recent iPhone and iPad models are supported. In particular, models from iPhone 12 Pro onward that include a LiDAR scanner can fully utilize 3D point cloud acquisition features. Even devices without LiDAR can use GNSS single-point positioning and some photogrammetry-based measurement functions. However, for high-precision point cloud scanning, using a LiDAR-equipped device is recommended.

Q: Can it be used in rain or indoors? A: It operates in light rain due to splash-resistant construction, but heavy rain can degrade GNSS reception and LiDAR point cloud quality due to noise from raindrops. Protect the device with a waterproof case as needed. Indoors, RTK positioning cannot be performed because satellite signals are unavailable, but LiDAR scanning itself is possible. By post-processing and merging point clouds captured both indoors and outdoors, indoor spaces can also be surveyed.

Q: How long does the battery last? A: The RTK device has a built-in small 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 by a mobile battery. For long operations, using spare power sources offers peace of mind. Also note that prolonged smartphone use drains the phone battery, so it’s advisable to charge the phone from a mobile battery as needed during surveying.