Streamlining Coordinate Management of Field Survey Photos with LRTK

Table of Contents

• The importance of field survey photos and coordinate management

• Challenges in managing coordinates for field survey photos

• Benefits of geotagged photos

• Utilizing high-precision positioning with RTK technology

• What is LRTK?

• Efficient coordinate management enabled by LRTK

• Simple surveying with LRTK

• FAQ

The importance of field survey photos and coordinate management

In field surveys, photos are taken in a variety of situations such as construction sites, infrastructure inspections, and disaster investigations. Photos are important materials that visually record site conditions, but it is essential to accurately know “when” and “where” they were taken. In particular, the “where” information — namely coordinates (location data) — plays a major role when linked to photos for report creation and later verification. If photos are tied to coordinates, you can display shooting locations on a map or cross-check them with other survey data, greatly improving the sharing and use of on-site information.

In recent years, digital transformation (DX) has advanced in the construction industry, and digital management of field survey data is increasingly required. Traditionally, people wrote photo numbers on paper maps by hand or organized photo locations in ledgers after shooting, but this is time-consuming and prone to errors. With the spread of digital cameras and smartphones, managing photo data by adding location information (geotags) to images is becoming common. Linking photos with coordinates for management is indispensable for field work not only for efficiency but also for accuracy and reliability.

Challenges in managing coordinates for field survey photos

However, there are several challenges in managing coordinates for field survey photos. The main issues include:

• Missing or incorrect recording of location information: If the photographer forgets to note the location on the spot or records it later from memory, inaccuracies or omissions are likely. If the coordinates associated with photos are misaligned, you may not be able to identify the site later — prompting questions like “Where exactly was this photo taken?” — which can hinder report preparation.

• Accuracy and consistency of coordinates: Position information obtained from smartphones or common GPS-enabled cameras typically has an error on the order of several meters. On large sites or in areas with similar scenery, even a few meters of offset can lead to confusing one photo for another taken in a different but similar location. Also, if photo location information is not managed in a unified coordinate system, matching it with other map data or drawings becomes difficult. For example, if photo coordinates are recorded in the World Geodetic System (WGS84) while design drawings use a different coordinate system (such as a plane rectangular coordinate system), conversion work is required to reconcile the two. Such mismatches in coordinate systems or insufficient positioning accuracy can become a significant barrier to data utilization.

• Effort required for data organization: Previously, cases were seen where people included place names in photo file names or managed correspondences between photo file names and coordinates in spreadsheets. As the number of photos increases, this method becomes cumbersome and prone to human error. Even if detailed surveys are conducted on site, if the correspondence between photos and location information is insufficient, the data cannot be fully utilized later.

In addition, in areas such as public works, including location information in photo data is becoming mandatory. The Ministry of Land, Infrastructure, Transport and Tourism’s standards for digital photo management information and electronic submission guidelines require that submitted photo data (e.g., JPEG) include accurate metadata such as shooting date/time and location information (latitude/longitude). To comply with such official standards, it is necessary to reliably manage coordinates for field photos.

Given these challenges, it is clear that field survey photo coordinate management requires a system that allows you to “record location information easily and reliably and organize it in a unified coordinate system.”

Benefits of geotagged photos

There are many benefits to adding location information (geotags) to photos and managing them. The main advantages include:

• Intuitively understanding where photos were taken: For example, if you plot geotagged photo data on mapping software, you can immediately see which photo was taken at which location. Even when dozens or hundreds of photos are taken across a large site, being able to view their distribution on a map enables efficient organization and easy checking for omissions or duplicates.

• Easier comparison over time and tracking changes: By taking photos of the same location at different times, you can accurately compare past and present photos using the location information as an anchor. In infrastructure inspections, comparing photos taken from the same spot at previous inspections allows objective assessment of deterioration over time. Knowing the coordinates ensures you can reliably reproduce “photos from the same point,” which is powerful for managing temporal changes.

• Smooth data sharing and integration: Geotagged photos can be linked with other geospatial information (maps, CAD drawings, point cloud data, etc.). Using the latitude/longitude of the shooting point, you can display the objects in the photo on a GIS or map shooting points onto design drawings. Information that is hard to convey by photos alone becomes easier to understand when overlaid on a map. Using cloud services, photos and location data taken in the field can be shared immediately with the office or stakeholders. When everyone can view photos on the same map, the speed and accuracy of information sharing improve.

• Streamlining report creation: Previously, when recording photo locations in ledgers or reports, you had to check each one manually. With geotagged photos, shooting locations can be automatically plotted on a map or output as lists from software. Digitally connecting the workflow from field records to document creation reduces the workload and shortens task time for staff.

Thus, linking photos with location information is an important part of field DX and brings benefits in both accurate recording and efficient use. However, to fully leverage the advantages of geotagged photos, the accuracy of the location information is key.

Utilizing high-precision positioning with RTK technology

RTK (Real Time Kinematic) high-precision positioning is drawing attention as a technology to improve the accuracy of photo location information. Ordinary GPS positioning can have errors of several meters, but RTK applies correction information from a reference station in real time to reduce errors to on the order of a few centimeters. This makes it possible to identify shooting locations to the centimeter level rather than just “around here.”

Using RTK-enabled cameras or devices, you can write high-precision latitude/longitude (and in some cases height) into photo data at the time of shooting. For example, an RTK-compatible GNSS receiver built into a camera can record precise coordinates obtained at the instant the shutter is pressed as EXIF metadata. Traditionally, after taking photos you would measure point coordinates with a separate GPS device and match them to photos later, which was cumbersome. With RTK-capable devices, capture and positioning are completed in one action, greatly improving field efficiency.

High-precision location information is particularly useful where precise surveying is required. For example, in as-built verification on construction sites (checking shapes and positions after construction), if each photo’s coordinates are accurate, you can directly measure dimensions from photos or verify as-built conditions against drawings. Also, when handling multiple datasets (photos, point clouds, drawings, etc.) across a large site, having everything aligned to the same coordinate reference makes data integration smooth. It becomes easy to check photo locations on point cloud data or display photos on BIM/CIM models, enabling three-dimensional and multifaceted use of site information.

In Japan, the environment for easily utilizing RTK high-precision positioning is also being established. For instance, by using the centimeter-level augmentation service (CLAS) provided by the Quasi-Zenith Satellite System “Michibiki,” you can receive correction signals directly from satellites even in mountainous areas or remote islands without internet connection, enabling high-precision positioning. This allows stable centimeter-level positioning even in locations where setting up base stations or securing communication environments was previously difficult.

Thus, RTK technology is a trump card that dramatically improves both the accuracy and efficiency of coordinate management for field survey photos. So what tools let you easily obtain high-precision geotagged photos using RTK? One answer is the LRTK series.

What is LRTK?

LRTK is an innovative solution that combines smart devices with high-precision GNSS positioning technology to make centimeter-level positioning and recording easy for anyone. It is designed to enable precise positioning that previously required expensive, specialized surveying equipment to be performed using familiar smartphones and cameras. LRTK consists of multiple device series that can be used according to the application.

For example, using the small device LRTK Phone, which attaches to a smartphone or tablet, you can easily perform centimeter-level positioning and 3D scanning via smartphone LiDAR or photo capture (point cloud acquisition). This makes high-precision positioning, which used to be handled only by specialized surveyors, accessible to anyone on site.

There is also a device called LRTK 360 that integrates an omnidirectional camera with RTK. This device has an RTK receiver and antenna built into a 360-degree camera, allowing you to record full surrounding panoramic photos and high-precision position coordinates (latitude, longitude, height) simultaneously with a single shutter press. Traditionally, after taking 360-degree photos on site, you would measure location with a separate GPS and link them on a PC, but with LRTK 360, coordinates are tagged at the moment of shooting, greatly reducing postprocessing work.

Moreover, the LRTK concept is applied to aerial photos taken by drones and point cloud data from laser scanners. Using the LRTK cloud service, you can assign high-precision absolute coordinates to photos acquired by drone to generate 3D point cloud models, or integrate point clouds from multiple sensors with one click. This functionality is realized because LRTK’s philosophy is to acquire all data from the start in a common coordinate (global coordinate) system.

In short, LRTK is a suite of solutions for centrally managing all types of on-site data together with high-precision location information. Coordinate management of field survey photos is one of LRTK’s core strengths.

Efficient coordinate management enabled by LRTK

Let’s look at specific examples of how LRTK improves the efficiency of coordinate management for field survey photos.

On site, use LRTK-compatible devices (for example, LRTK Phone or LRTK 360) to take photos. The devices perform RTK positioning at the time of shooting and automatically write the obtained high-precision coordinates into the photo file’s EXIF information. The shooter does not need to perform special operations — by simply pressing the shutter, the photo and coordinate recording are completed. This eliminates the need to take notes or manually link photos and GPS data.

After shooting, you can immediately check photos and location information with a dedicated app on your smartphone or tablet. Opening the map screen shows the photographed images plotted as pins (markers) on the map so you can see shooting locations at a glance. Selecting a photo displays detailed information (latitude, longitude, height, shooting date/time, etc.), allowing you to double-check photo coordinates while still on site. If a shooting location is off from expectations, you can retake the photo on the spot.

Using the LRTK cloud service, you can instantly upload and back up data shot on site and share it in real time with the office or other team members. On the cloud, coordinates for each photo are organized in a database and automatically placed on a map. Flexible management and searches — such as viewing lists on a large PC screen or extracting photos from a specific location — are easy. Previously, you had to sort photos into folders or include location names in file names, but LRTK greatly reduces those tasks.

Photos acquired with LRTK can also be easily integrated with other systems. Coordinates embedded in photos (EXIF) use standard formats, so they can be imported into GIS or CAD software as needed. For example, photos can be loaded into construction management software and automatically placed on drawings, or visualized as point data with photos on a GIS. The LRTK cloud itself can integrate point cloud and drawing data with photos, allowing you to understand site conditions by comparing multiple data sources.

Importantly, these processes are designed to be intuitive without specialized knowledge. LRTK apps and cloud services have user-friendly interfaces for field workers, so even without knowledge of complex coordinate transformations, strict coordinate management is performed behind the scenes through the simple everyday action of taking a photo. Less-experienced technicians can avoid location-recording mistakes and produce high-quality data with LRTK, improving the reliability of field records. Experienced users can also perform advanced tasks such as combining survey drawings and point cloud data with photos with a single button, dramatically increasing data-processing efficiency.

By adopting LRTK, coordinate management for field survey photos is dramatically streamlined. From surveying to recording, data organization, sharing, and utilization, the entire workflow connects seamlessly, reducing unnecessary tasks and human errors.

Simple surveying with LRTK

LRTK’s applications extend beyond photo coordinate management. By making high-precision location information easily obtainable, it is also a powerful tool for simple surveying. For situations where you need to perform “a little surveying” on site — for example, checking the coordinates of a point or measuring the distance or elevation difference between two points — traditionally you would need surveying instruments and staff. With LRTK, however, there are many cases where a smartphone alone can substitute for specialized surveying equipment.

Using LRTK Phone, for instance, a single person can walk the site and acquire coordinates for arbitrary points and register them to the cloud on the spot. This enables immediate placement of simple features and as-built checks. Based on the acquired coordinates, plotting those points on drawings later is also smooth. The LRTK app includes a coordinate guidance function that navigates to registered coordinates, guiding users with direction and distance to a specified point. This assists tasks such as locating design coordinates on site (so-called batter-board or stakeout support), making it easy for one person to perform.

Furthermore, LRTK enables simplified execution of advanced surveying tasks such as point cloud measurement. By performing automatic continuous shooting with a smartphone camera or LiDAR and generating high-precision 3D point cloud models from photos on the LRTK cloud, workflows that previously required high-spec PCs and long processing times can be completed quickly using cloud computing power. The resulting point cloud data are already aligned to global coordinates, making integration with other survey data straightforward.

Enabling “anyone on site to perform surveying” represents a major paradigm shift. As simple surveying with LRTK spreads, some surveying tasks previously outsourced can be insourced, and staff without specialized surveying knowledge will be able to perform necessary and sufficient positioning checks with adequate accuracy. This speeds up on-site decision-making and reduces waiting times for additional surveys.

By going beyond coordinate management for field survey photos, LRTK is playing a role in the democratization of on-site surveying. Consider using LRTK to seamlessly handle both photo records and surveying to improve overall field work efficiency and accuracy.

FAQ

Q. Can I record location information with photos taken on a smartphone? A. Yes. Most smartphones and digital cameras are equipped with GPS-based location recording (geotagging), and if you enable the setting, latitude and longitude are saved in the photo at the time of shooting. However, note that built-in smartphone GPS accuracy is on the order of several meters. If approximate locations are sufficient for your field records, a smartphone is fine, but when precise location determination is important or you want to map photos accurately later, using RTK-compatible equipment (such as LRTK) will allow you to record much higher-precision location information.

Q. How accurate does location information for field survey photos need to be? A. It depends on the application. For landscape records or simple site reports, errors of several meters are often acceptable. Some sites only require rough indication of where a photo was taken. However, for construction management, detailed as-built verification, or cases where dimensions are measured from photos or photos are matched to drawings, location information with as little error as possible (centimeter-level) is desirable. In public works, submission rules may require EXIF to include location information, and if a photo carries coordinates of the wrong location, the documentation could be considered incomplete. Choose measurement methods that meet the required accuracy for your purpose.

Q. What preparations or equipment are needed to use LRTK? A. To use LRTK, you need compatible dedicated hardware and a smartphone/tablet. For LRTK Phone, for example, you attach a small RTK receiver unit to your smartphone. For LRTK 360, you use a dedicated integrated camera device. For positioning in Japan, using correction signals from Michibiki (the Quasi-Zenith Satellite System) can provide centimeter accuracy without setting up a special base station. While cloud services require internet connectivity, positioning and recording are possible offline in communication dead zones such as mountainous areas, and data synchronizes later when you go back online.

Q. Is LRTK difficult to operate? A. LRTK is designed for on-site use and is intuitive and simple to operate. The dedicated apps are available in Japanese and easy to understand; by following the guided steps you can perform positioning, shooting, and cloud saving automatically. People without positioning expertise can use it with the same ease as a smartphone camera app. Comprehensive support and manuals are also provided, so you won’t be left stranded if you get stuck. It’s designed to be stress-free even during busy fieldwork.

Q. How can the photos I take be used? A. Photos taken and recorded with LRTK have many uses. On the cloud they are mapped to a map, so you can create map-based photo lists for progress management or reporting. The embedded location information is highly versatile and can be imported into other GIS or design CAD systems to help understand site conditions. For example, inspection work often produces reports showing photo locations on maps, and construction management teams place photo shooting points on drawings to share information with stakeholders. Accumulating accurate geotagged photos in corporate databases provides valuable long-term assets for future planning and design.