Heavy equipment is no longer necessary! Palm-sized RTK devices are transforming surveying sites

Table of Contents

• Challenges of conventional surveying methods

• What RTK surveying is

• Emergence of palm-sized RTK devices

• Features and benefits of RTK devices

• Use cases at construction and civil engineering sites

• Use in municipalities and public works

• Simple surveying with LRTK

• FAQ

Challenges of conventional surveying methods

Accurate position information is indispensable at civil engineering, construction sites, and public works. Traditionally, position surveying has been performed using total stations and large GNSS receivers, but these instruments have been large and heavy and have required significant labor to handle. For example, a total station mounted on a tripod takes time to set up and typically requires two or more operators. Conventional GNSS surveying also requires preparing both a base station (reference station) and a rover, making initial setup cumbersome. Furthermore, high-precision surveying requires experienced technicians, and the purchase and maintenance of equipment incur substantial costs. For these reasons, small- to medium-sized companies and municipalities often face barriers to adopting the latest technologies. Surveying results were also often managed on paper drawings or handwritten forms, so digitizing the data was time-consuming. Surveyors had to transcribe obtained numbers into post-processing software, creating large amounts of data entry work and increasing the risk of mistakes. In recent years, the civil engineering and construction industry has been advancing digital transformation, and initiatives such as the Ministry of Land, Infrastructure, Transport and Tourism’s “i-Construction” policy call for the use of 3D surveying and ICT technologies. However, conventional heavy equipment made it difficult to respond quickly to such changes. Especially in the BIM/CIM design era, accurate acquisition of site coordinates and integration with design data are required, and compact RTK devices meet these requirements.

• Large total stations: tripod-mounted work requiring two or more people; setup and leveling take time and manpower

• Conventional GNSS surveying: both a base station and a rover must be prepared, and installing/leveling the reference station is time-consuming

• High introduction cost: equipment and software are expensive, imposing a heavy burden on small companies and municipalities

• Requirement for expertise: surveying requires advanced knowledge and experience, making it difficult for new users

• Challenging reception environments: positioning accuracy degrades in areas with poor satellite visibility, such as under viaducts or inside tunnels

What RTK surveying is

Real-Time Kinematic (RTK) surveying is a technology that uses positioning information from GNSS satellites and two receivers—a base station and a rover—to correct position errors and obtain centimeter-level accuracy in real time. The base station is set to a known accurate coordinate, and the rover is placed at the survey point. By receiving correction information sent from the base station and performing calculations, errors that would be several meters (several ft) with standalone satellite positioning can be reduced to several centimeters or less (cm level accuracy (half-inch accuracy)). If a high-precision fixed solution (Fix) is obtained, accurate coordinates and elevations of measurement points can be acquired on-site immediately, dramatically improving the precision of civil engineering work and infrastructure maintenance. The obtained coordinates conform to public datums such as the Japanese Geodetic Datum (JGD2011), allowing direct comparison and reconciliation with design drawing coordinates. Also, by using network RTK (Ntrip) to receive correction information over the Internet, you can utilize public electronic reference point networks or VRS (Virtual Reference Station) services and obtain correction data without installing a base station. Additionally, Japan’s quasi-zenith satellite “Michibiki” provides the CLAS (Centimeter-Level Augmentation Service), which allows high-precision positioning even in environments without Internet connectivity.

• Two-device system of base station and rover: install the base station at a known point and measure position with the rover at the survey point, calculating the difference between them

• Acquisition of fixed solution (Fix): resolves phase errors in satellite signals to achieve centimeter-class accuracy (cm level accuracy (half-inch accuracy)) such as within 2 cm (0.8 in) horizontally and within 3 cm (1.2 in) vertically

• Network RTK support: obtain correction information via the Internet from public reference stations or commercial services and use the system without a local base station

• Multi-GNSS support: supports multiple satellite systems in addition to GPS, such as Michibiki, GLONASS, and Galileo, making reception more robust against changing environments

Emergence of palm-sized RTK devices

Although RTK surveying once required large equipment, recently ultra-compact RTK-GNSS receivers that work with smartphones have appeared and are revolutionizing surveying sites. These palm-sized devices weigh only a few dozen grams and can be used simply by attaching them to a smartphone. Communication is via wireless or wired connection to the phone, and a dedicated app receives positioning information in real time. As a result, tasks that once required two or more people can now be completed by a single person holding a smartphone in one hand. Equipment setup time is drastically reduced, and logistics and preparation for bringing equipment to the site are greatly simplified. Whereas smartphone GPS alone used to have errors of several meters (several ft), new RTK devices significantly improve that accuracy with the latest technology, delivering professional-grade positioning without sacrificing portability.

• Palm-sized, lightweight design: highly portable and easy to bring to any site

• Smartphone integration: uses the phone screen as the controller, making it intuitive compared with specialized field instruments

• Single-person operation: no need for multiple people to support large equipment; one person can complete surveying and recording

• No installation required: no tripod or large antenna needed—attach to the smartphone and start positioning

These devices are also effective at sites suffering from severe technician shortages. Recently more young people and female engineers have joined the workforce, and there is growing demand for lightweight surveying equipment that is easy for those who find heavy equipment difficult to handle. Introducing simple RTK terminals allows beginners without specialized training to learn intuitive operation, broadening the scope of surveying work.

Features and benefits of RTK devices

Small RTK terminals offer functions and usability not found in conventional equipment. The latest models improve satellite acquisition performance and provide fast reception of correction data. Smartphone apps are user-friendly and can centrally handle everything from starting positioning to data recording and attaching location information to site photos. Devices are battery-powered for long surveying sessions, and some models are dustproof and splashproof, making them reliable even in harsh outdoor environments. Using these features together significantly reduces on-site work time and procedures, enabling anyone to perform surveying tasks easily.

• Cost performance: can be introduced at lower cost than conventional equipment, making adoption easier for small sites

• Rapid positioning: with high-performance chips and the latest algorithms, multi-frequency support and satellite corrections achieve fix in a few to several tens of seconds

• High accuracy and stability: capable of high-precision positioning of about ±2 cm (±0.8 in) horizontally and ±3 cm (±1.2 in) vertically, achieving accuracy comparable to conventional equipment

• Simplified operation: positioning, recording, and photo capture can be done via a smartphone app, greatly reducing on-site data entry work

• Data integration: positioning results and photos are automatically tagged in the app or cloud and can be shared in real time with remote offices

• AR integration: smartphone AR features overlay design data on site scenes to assist alignment and inspections

• Versatility: many products support smartphones, allowing use with existing devices

• Addresses labor shortages: enables high-precision surveying with a small workforce, covering shortages of skilled personnel

• Wireless communication support: in sites without Internet, some models support wireless direct communication with a base station for corrections

• Continuous battery operation: supports long continuous use for all-day outdoor work

• Dustproof and splashproof design: rugged housings withstand harsh outdoor conditions and allow stable operation in bad weather

Use cases at construction and civil engineering sites

Palm-sized RTK devices contribute to efficiency across a variety of construction and civil engineering sites. For example, in layout work during construction preparation, a single operator can accurately mark installation positions on-site based on drawing coordinates. For as-built management, the site’s earthworks and shapes can be surveyed after construction so that accurate volumes and height information can be confirmed and recorded on the spot. In inspections of bridges and tunnels, surveying and photography are possible even at high or hard-to-access locations by simply holding up a smartphone. Acquiring 3D shapes of structures, which used to be time-consuming, has become easier, and there are increasing cases where an entire scan is completed in much less time than before. By using photogrammetry functions, GPS coordinates of the shooting location are automatically added to site photos, streamlining report creation.

• Layout and marking: enables one person to mark positions based on drawing coordinates, reducing personnel and steps

• As-built management: immediately survey post-construction terrain and structures for precise as-built verification

• Structure inspection: safely perform surveying and recording at hazardous locations such as bridges and tunnels, and easily obtain point cloud data

• Improved safety: remote surveying at dangerous locations helps ensure worker safety

• Earthwork volume calculation: compute volumes of embankments and excavations on-site to streamline as-built understanding

• Photogrammetry and recording: automatically attach positioning information to site photos to efficiently organize investigation results as geo-tagged photos

• Building construction: useful in foundations, rebar placement layout, and checking design coordinates during structural inspections

Use in municipalities and public works

Adoption of compact RTK devices is advancing in municipalities and public infrastructure management as well. They are useful for regularly inspected aging infrastructure such as water and sewage systems, bridges, dams, and agricultural facilities. For example, river embankment inspections that previously required manpower and time for shape surveys can now be conducted in a short time. In the event of a disaster, rapid surveying of terrain changes in affected areas helps grasp damage and supports restoration planning. They are also used for road pavement crack surveys and land boundary confirmation, contributing to efficiency in municipal surveying operations in general. Furthermore, they help build the foundation for municipal DX (digital transformation) by enabling creation of 3D map data and management of local disaster histories.

• Infrastructure maintenance: streamlines surveying required for regular inspections and repair planning for bridges, embankments, water and sewage systems, etc.

• Disaster response: enables rapid surveying of affected areas after earthquakes or floods to support quick terrain restoration and to identify evacuation routes and dangerous spots

• Land and road management: streamlines land information maintenance through boundary surveying of roads, parks, and farmland, supporting municipal operations

• Land acquisition and boundary confirmation: speeds up land surveying and installation of boundary markers for public works

• GIS development support: acquired 3D data can be reflected in regional GIS for future maintenance and planning

Simple surveying with LRTK

Our LRTK terminal is a palm-sized surveying solution that meets the on-site needs described above. It consists of an ultra-compact GNSS RTK receiver that attaches to a smartphone and a dedicated app, and setup is extremely simple. Launch the smartphone app, attach the terminal, and configure base-station corrections (network RTK), and you can immediately perform positioning with centimeter-level accuracy (cm level accuracy (half-inch accuracy)). Because the large equipment and complicated preparations previously required are no longer necessary, the burden before starting work is greatly reduced. Positioning data are displayed in real time on the app and automatically saved to the cloud. For example, photos taken on site are tagged with accurate location information so you can tell at a glance where each photo was taken. By introducing LRTK, surveying tasks that used to be handled only by experts can be easily performed by construction companies and municipal site personnel.

• Preparation: attach the LRTK terminal to your smartphone and set up connection to a correction server in the dedicated app.

• Positioning: when you place the terminal at a measurement point, centimeter-level coordinates are displayed on the smartphone screen.

• Recording: acquired data are automatically recorded in the app and cloud, making it easy to share geo-tagged photos and point cloud data.

In addition, the app includes a coordinate guidance function that guides on-site surveying along points on the design plan. This makes arranging elements according to drawings easier and further improves on-site accuracy. Many construction companies and municipalities have already adopted it and reported reductions in survey man-hours and productivity gains.

The LRTK terminal also supports smartphone-built-in LiDAR sensors and drone photography, enabling easy acquisition of 3D point cloud data on site. By simply uploading the necessary photos and point cloud data to the LRTK cloud, wide-area terrain and structures can be accurately 3D modeled. This eliminates the need for expensive 3D scanners or large-scale drone surveys and allows small- to medium-sized sites to enjoy the benefits of 3D surveying.

FAQ

Q: What is an RTK device? A: An RTK device is a surveying instrument that applies GNSS satellite positioning technology and achieves centimeter-level positioning in real time by performing position corrections between a base station and a rover. Compared with conventional GPS, errors are drastically smaller, and high-precision coordinate information can be obtained instantly.

Q: How does it differ from conventional surveying instruments? A: Palm-sized RTK devices are lightweight and compact, easy to carry, and work with a smartphone to enable single-person surveying. Because they do not require setup and leveling like large instruments, preparation time is reduced and introduction is easier from a cost perspective.

Q: At what kinds of sites can it be used? A: Uses include layout and as-built management at construction sites, maintenance of bridges, roads, and facilities, terrain surveying during disasters, and GIS development for urban infrastructure. Since high-precision location information can be recorded simply by taking site photos with a smartphone, it is useful for various surveys and inspections.

Q: Can it be used without a network connection? A: If network RTK is not available, you can use the Michibiki CLAS augmentation or install a local base station and distribute corrections via radio. These methods make centimeter-level positioning possible even where communication is limited.

Q: What kind of product is the LRTK terminal? A: The LRTK terminal is our pocket-sized RTK surveying product. Attach it to a smartphone to perform high-precision positioning, and the dedicated app makes operation easy. Surveying results sync to the cloud, enabling anyone to perform high-precision surveying easily.

Q: What accuracy can be achieved? A: The latest compact RTK terminals generally achieve about 2 cm (0.8 in) horizontal and 3 cm (1.2 in) vertical accuracy. Since this level of precision is comparable to conventional large equipment, they can handle centimeter-level surveying required on-site.

Q: Can a smartphone alone perform RTK surveying? A: No. Smartphone-built-in GPS alone cannot achieve centimeter-level positioning. Positioning accuracy of a smartphone by itself is on the order of several meters (several ft), and a separate RTK device is required to utilize RTK technology. By connecting an LRTK terminal or similar device, the smartphone can function as a high-precision surveying instrument.

Q: How long is the battery operating time? A: It depends on the terminal and the smartphone specifications, but a typical compact RTK terminal can operate continuously for several hours up to about 10 hours. For long work sessions, using spare batteries or a mobile battery is recommended.

Q: Can it be used with existing smartphones? A: Most RTK devices are designed for smartphones and connect via wireless communication or USB cable. They may work with older OS versions or models, but it is recommended to check the device’s operating requirements in advance.

Q: Is RTK device setup complicated? A: Initial setup is very simple: launch the smartphone app, connect to a correction server, and attach the receiver—then you are ready. Complex calibration or adjustments typical of dedicated equipment are not required, and beginners can start operating quickly by following the manual.

Q: Is a subscription required to obtain RTK correction data? A: Using network RTK typically requires access to a commercial service or public reference stations. Public electronic reference stations are freely available, but commercial services may charge communication fees or monthly usage fees.

Q: How are surveying results managed? A: Most RTK devices integrate with dedicated apps or cloud services, allowing centralized management of obtained coordinates and photo data. Even after surveying, the office can easily refer to and analyze the data.