Streamlining with Markerless 3D Measurement: 8 Use Cases that Reduce On-site Burden

In recent years, markerless 3D measurement technologies have attracted attention in construction and civil engineering sites. Traditionally, when performing high-precision 3D surveying or scanning, it was common to install target markers or ground control points (GCPs) in advance for georeferencing. However, placing and measuring markers is time-consuming and labor-intensive, imposing a significant burden on field staff. Fortunately, recent advances—such as RTK-equipped drone surveying, SLAM-enabled laser scanners, and smartphone-integrated LiDAR—have produced many technologies that eliminate the need for marker installation. By leveraging these markerless 3D measurement methods, surveying and inspection tasks can be made more efficient and safer.

This article introduces eight practical use cases where markerless 3D measurement is beneficial on-site, from civil surveying to equipment inspection and infrastructure maintenance. We will look at the points that enable labor and time savings and examine the concrete benefits for each field task.

Table of contents

• Civil surveying: reducing control points with drone aerial photography

• Construction as-built management: visualizing construction status with point clouds

• Bridge inspection: detecting structural changes with remote 3D measurement

• Road maintenance: efficiently measuring pavements without traffic restrictions

• Plant equipment inspection: 3D recording of piping without scaffolding

• Disaster site measurement: rapidly visualizing damage

• Surveying hazardous areas and heights: acquiring data safely without contact

• Site DX: easy 3D measurement with smartphones

• Conclusion

Civil surveying: reducing control points with drone aerial photography

Extensive topographic surveys are necessary during the preparation and earthworks phases of civil engineering projects. Traditionally, many control points (ground reference points) were installed and measured one by one with surveying instruments for georeferencing. This process was indispensable for obtaining high-precision terrain models, but in forests or steep slopes, placing markers involved hazardous field entry and took substantial time.

Aerial photogrammetry using drones dramatically streamlines such civil surveying. Recent drones can be equipped with high-precision GNSS capable of RTK/PPK, enabling centimeter-level position information to be attached to each photo captured in flight (cm level accuracy (half-inch accuracy)). As a result, 3D models can be georeferenced to the required accuracy without placing numerous ground control points. For example, in one earthwork photogrammetry case, an RTK-equipped drone reportedly achieved accuracy equivalent to conventional methods even with zero control points. Installing control points can account for roughly 30% of total surveying effort in some cases, but GCP-less surveying with RTK drones can eliminate this workload entirely.

Markerless surveying via drone aerial photography also has the major advantage of allowing a single operator to complete work on large sites in a short time. Surveys that previously took a survey team several days can often be finished in a few hours with a drone. Additionally, because there is no need to force marker placement in soft ground or steep terrain, safety is improved. The orthophotos and 3D point clouds obtained make volume calculations and cross-section generation easy, greatly improving efficiency in earthwork quantity management and design review.

Construction as-built management: visualizing construction status with point clouds

3D measurement is also highly effective for construction progress and as-built (quantity) management. Traditionally, construction managers had staff measure heights and dimensions on-site at each stage and compare them with design drawings to verify quality. High-precision checks required total station measurements or manual layout with string lines and marks, and in some cases, installation of markers (stakes or markings) as measurement references.

Using point cloud data for as-built management involves 3D scanning completed structures or earthworks and comparing the point cloud with the design model or reference planes to instantly grasp construction status. For example, scanning an in-progress ground surface with a drone or ground-based laser scanner lets you visualize differences between the design surface and actual fill/cut conditions with color-coded heat maps. This immediately identifies where there is excess or deficit and where construction deviates from the design. What used to be confirmed by collecting discrete points with levels or surveys can now be intuitively understood as surfaces.

When introducing 3D scanning for as-built management, markerless measurement devices simplify practical work. There are now easy-to-use scanners ranging from iPad-mounted simple 3D scanners to high-precision mobile laser scanners, enabling point cloud acquisition without complex equipment setup or target placement. Scans can be reviewed immediately on a tablet at the site, allowing construction staff to share as-built information on the spot. The Ministry of Land, Infrastructure, Transport and Tourism’s i-Construction initiative also recommends as-built management using 3D data, and such easy point cloud measurement helps align understanding between clients and contractors. The result is reduced rework on corrective construction, improved quality assurance, and greater overall site efficiency and productivity.

Bridge inspection: detecting structural changes with remote 3D measurement

3D measurement is being used for inspection and maintenance of large structures such as bridges. Traditionally, investigating bridge health required tasks like approaching under the bridge with an aerial work platform or marking the bridge deck to measure displacement—large-scale, labor-intensive operations. For measuring distortions of piers or girders, methods sometimes involved attaching reference marks and monitoring changes over time, which required significant time and manpower.

Today, high-precision laser scanners and photogrammetry allow digital recording of a bridge’s overall shape from a distance. Scanning the underside and sides of a bridge from the ground makes it possible to accurately capture deflections and cross-sectional changes that are hard to measure with the naked eye. For long-span bridges, for example, you can correct scanner positions using GNSS at the approaches and surrounding areas while continuously capturing the underside of the girders with SLAM-enabled equipment, enabling seamless full-structure modeling. There is no need to attach reflective targets or prisms during this process because scans are automatically aligned using the structure’s own geometric features.

3D point cloud models of bridges can be overlaid over time to analyze long-term changes. Comparing an initial inspection model with a model taken several years later can quantitatively detect pier tilting or settlement. What previously relied on visual inspection or spot checks by a few instruments is now supplemented by comprehensive spatial data. Remote measurement also reduces the frequency of erecting scaffolding directly under bridges or implementing long-lasting lane closures, enhancing inspection safety and minimizing traffic impact—major benefits of non-contact 3D measurement.

Road maintenance: efficiently measuring pavements without traffic restrictions

Regular assessment of pavement condition and surrounding structures is important for road and tunnel maintenance. Traditional road surveying required workers to operate instruments on the pavement or shoulder, necessitating traffic restrictions during work. On expressways, night work and lane closures are often required, incurring considerable personnel and security costs.

Mobile mapping systems (MMS), now widely used, allow pavement and road structures to be measured while driving, using vehicle-mounted 3D laser scanners. MMS combines GPS/IMU to accurately track vehicle position without needing to place markers on the measured objects in advance. Simply driving through captures pavement irregularities, crack locations, guardrail and sign positions, and more as integrated point cloud data. As a result, broad-area road data can be acquired in a short time without imposing traffic restrictions.

One expressway reported cutting time and costs for as-built surveying by about 70% after introducing MMS. On regular roads, being able to avoid stopping daytime traffic reduces the burden on nearby residents and drivers. Dense point clouds allow precise post-processing measurements of cross slopes and rut depths, improving pavement repair planning. Tunnel measurements can also be georeferenced using relative positioning with a base station and gyro-based corrections, enabling accurate recording of wall displacements and cross-sectional shapes. In road maintenance, driving-based 3D measurement significantly enhances both efficiency and safety.

Plant equipment inspection: 3D recording of piping without scaffolding

In factory and plant equipment inspections, measuring and recording piping and equipment layouts is essential. Traditionally, understanding dimensions of complex piping networks meant measuring each pipe with a tape or creating drawings manually for clash checks. For high piping, scaffolding was erected and markings applied to measure slopes. Scaffolding installation and close-proximity measurements posed major safety and time burdens.

3D laser scanning for point cloud capture of plant equipment addresses these challenges. By mounting a fixed laser scanner on a tripod or carrying a handheld scanner and walking between pipes, you can digitally capture piping, tanks, beams, and their spatial relationships. Modern scanners can acquire millions of points at once with high-speed rotating lasers, allowing wide-area scans to be completed quickly. Even without applying marker stickers, the scanner’s precise angular and distance measurements and automatic registration of multiple scans enable continuous 3D integration of piping networks. This eliminates the traditional need to place reference marks throughout the site and later align data using those marks.

The resulting point cloud data can be used on office PCs to take measurements, generate CAD drawings, and perform clash checks with new equipment. For example, when replacing aging piping, routing for new pipes can be planned on the as-built 3D model in advance, making on-site work smoother. Compared with erecting scaffolding and measuring with tapes, this approach is far more efficient and reduces errors. Because measurement can be performed remotely even in high-temperature or hazardous areas, worker safety is also improved. Scaffolding-free 3D scanning is thus a solution that realizes both safety and productivity in plant maintenance.

Disaster site measurement: rapidly visualizing damage

At disaster sites such as landslides or floods, quick situational awareness and restoration planning are required. Immediately after a disaster, ground conditions may be unstable or there may be risks of secondary disasters, making detailed human surveying difficult. Traditionally, only limited areas could be observed from a distance, and only rough damage estimates could be made.

Markerless 3D measurement technologies are highly useful here as well. For example, flying a drone immediately after a disaster can capture wide-area damage from the air in a short time. Generating 3D models or contour maps from multiple photos makes it possible to quantify collapsed soil volumes and inundation extents. There is no need to hastily place physical markers on site—the photogrammetry software automatically aligns images using the drone’s GPS information and surrounding buildings or terrain as references. Even if GNSS errors are large, known landmarks on a map (such as building corners) can be used for post-processing adjustments, so physical markers are not required in advance.

In complex urban or indoor disaster areas, handheld 3D scanners can be used to walk through and scan damaged sections. SLAM-equipped scanners can estimate their position while capturing shapes even inside tilted buildings or piles of debris, enabling modeling of collapse zones. These methods provide disaster response headquarters with detailed visualization data in a short time. For instance, at a slope failure site, on-site volume calculations can inform emergency earth removal plans, or damage models of houses can be shared to plan safe routes for rescue teams.

Markerless 3D measurement is a powerful ally for disaster response, balancing speed and safety. It enables remote surveying of inaccessible areas while still delivering high-accuracy data, greatly supporting initial recovery work. By reducing secondary disaster risk and providing necessary information, this technology will become increasingly important.

Surveying hazardous areas and heights: acquiring data safely without contact

Construction and maintenance sites often include locations where human work is risky—high places, confined spaces, or near hazardous materials. For example, building facade inspections traditionally involve sending workers up in aerial work platforms or suspended scaffolding to perform sounding tests and measurements—dangerous tasks. Slope surveys on steep terrain carry fall risks, and under-bridge surveys face traffic hazards. These hazardous measurements are precisely where non-contact 3D measurement technologies are valuable.

Photogrammetry from drones or remotely operated cameras is used for high-place inspections such as building facades or chimneys. Even where humans cannot reach, aerial imagery analysis can digitally identify crack locations and areas of tile delamination. Photogrammetry software uses the building’s structural features as markers for feature detection and stitching, so pre-marking is unnecessary. Exterior inspections can be safely conducted without scaffolding, reducing inspection costs.

Similarly, remote measurement using ground-based LiDAR is common for steep slopes and dams. Laser scanners can generate point clouds of rock surfaces from hundreds of meters (hundreds of ft) away, capturing slight surface irregularities so people don’t need to cling to slopes. Even without placing reference markers during scans, data from multiple positions can be merged later to construct a complete terrain model. In underground or enclosed spaces where toxic gases may be present, robot- or drone-mounted 3D scanners enable non-contact measurement, minimizing the need for personnel entry into hazardous zones.

Introducing 3D measurement for high, confined, or hazardous areas both ensures worker safety and improves efficiency. Areas that were previously “wanted to be measured but couldn’t be” become accessible for data capture, reducing inspection omissions and reliance on estimates. The non-contact nature increases flexibility in work planning, enabling safer procedures for infrastructure management and likely becoming a standard method going forward.

Site DX: easy 3D measurement with smartphones

The advanced 3D measurement technologies described so far may have seemed limited to specialized departments or expensive equipment. However, smartphone- and tablet-based easy 3D measurement is becoming a new trend in site DX (digital transformation). Modern smartphones include compact LiDAR sensors and excellent cameras, and with dedicated apps, anyone can scan nearby structures and generate point clouds.

For example, apps exist that create real-time 3D models of surrounding terrain and equipment simply by pointing and walking with an iPhone or iPad camera on-site. These apps apply AR (augmented reality) techniques, tracking feature points in the camera view to determine the device’s pose, enabling self-localization without special markers. Acquired point cloud data can be converted to plans or cross-sections on the spot and used to measure distances and areas, aiding immediate on-site decisions. Tasks that once required surveying expertise can now be completed in one operation by site supervisors or inspectors using smartphone measurement.

Recently, peripherals that enhance smartphone measurement accuracy have also appeared. For example, combining a high-precision GNSS receiver that attaches to a smartphone makes it possible to immediately assign geodetic coordinates (global coordinates) to scanned point clouds. This enables created 3D data to be aligned with drawing coordinate systems or maps and simplifies data integration across distant sites. Because palm-sized devices can achieve centimeter-level positioning (cm level accuracy (half-inch accuracy)), heavy surveying equipment and numerous control points are no longer necessary. The era of “one surveying device per person” is arriving, accelerating on-site DX.

Smartphone-based easy 3D measurement will continue to spread. Because familiar mobile devices enable intuitive operation, everyone from veterans to newcomers can participate in digital measurement. As a result, on-site information sharing and record keeping become more advanced in real time, improving the quality of construction management and maintenance inspections. Markerless, highly mobile smartphone measurement is changing workstyles in the construction and civil engineering industries.

Conclusion

Markerless 3D measurement technologies are key to improving efficiency and safety across a wide range of field tasks such as surveying, construction management, and infrastructure inspection. Tasks that once consumed time and manpower—like georeferencing and setting out—are being automated and simplified by labor-saving technologies, enabling limited personnel to achieve results in short timeframes. High-precision 3D data make it possible to accurately visualize site conditions for stakeholder sharing, directly reducing rework and ensuring quality. Replacing hazardous human tasks with remote methods also helps reduce the risk of occupational accidents.

That said, even when not using markers at all, it is important to follow appropriate validation procedures depending on required accuracy. For example, RTK drone surveys are recommended to verify result accuracy with a small number of check points. By skillfully combining new technologies and conventional methods, operations can balance efficiency and precision.

As site DX advances, one notable measurement tool is LRTK (an iPhone-mounted GNSS high-precision positioning device). With LRTK, a smartphone becomes a centimeter-level positional measurement terminal (cm level accuracy (half-inch accuracy)), giving absolute-coordinate reliability to convenient mobile 3D scans. Solutions that can replace high-precision reference setting at the push of a button align with the Ministry of Land, Infrastructure, Transport and Tourism’s i-Construction initiative and will greatly contribute to on-site productivity improvement. Actively adopt the latest technologies and practice smart 3D measurement without the burden of marker installation. It will dramatically improve on-site efficiency and safety and help advance your sites to the next stage.