AR Heat Maps Strengthen Safety Management – Check Hazard Areas Without Contact

Table of contents

• What is an AR heat map?

• Challenges in safety management on construction sites

• Benefits of using AR heat maps

• On-site use cases for AR heat maps

• Conclusion: Easy AR adoption with LRTK simple surveying

• FAQ

Construction sites are always places where work is carried out amid hazards such as work at height, operations around heavy equipment, and handling of underground utilities. Accident prevention and safety management are the top priorities on site, but traditional methods have required considerable effort to identify and verify hazard areas. Recently, digital technology has been making inroads even into the field of safety management, and particularly noteworthy is the use of AR heat maps. By using augmented reality (AR) to display heat maps, hazard areas can be checked without physical contact, enabling more intuitive and powerful safety management. This article explains what AR heat maps are, how they work and their effects, and details the concrete benefits and use cases for strengthening on-site safety management. Finally, we introduce a modern surveying solution that makes AR heat maps easy for anyone to implement.

What is an AR heat map?

An AR heat map is a technology that visualizes various pieces of information in the real world as a color-coded “heat map” and overlays it on actual scenery through the screen of a smartphone or tablet. For example, in construction, you can express the differences between the as-built terrain or structure and the design data as a heat map, allowing you to grasp the on-site finishing status at a glance. Specifically, the completed terrain is 3D-scanned to obtain point cloud data, which is overlaid with the 3D design model; errors in height or thickness at each point are shown by color. Areas within specification are green, portions that are higher than the reference are red, and under-excavated low areas are blue—visualizing deviations by color differences. At a glance you can intuitively see “where things are higher or lower than the standard” and “which locations are out of spec.”

Traditionally, as-built quality control involved comparing measured point values on drawings to check for errors. However, numbers and drawings alone are hard to understand without expertise, and it was not easy to immediately identify problem locations on site. With AR heat maps, digital information is overlaid on live site imagery, so anyone can intuitively grasp quality and hazard locations. For example, after paving, viewing the road surface through a smartphone screen will reveal color-coded differences from the design model: areas within tolerance appear in safe colors (green/blue tones), while insufficient areas are shown in warning colors (reds). In this way, AR heat maps are a visualization tool that highlights subtle defects or risks that might be missed on conventional drawings.

Recently, the Ministry of Land, Infrastructure, Transport and Tourism has been promoting 3D measurement and surface-based as-built evaluation (heat maps) through initiatives like i-Construction, and heat-map-based quality control methods are beginning to be included in official guidelines. In other words, AR heat maps are spreading as a new standard in the era of on-site digital transformation (DX). In safety management, this AR-based “visualization” is expected to be a powerful aid for hazard prediction and work optimization.

Challenges in safety management on construction sites

No matter how careful you are, construction sites contain hidden hazards that are easy to overlook. In conventional safety management, experienced personnel patrol the site for visual inspection, or surveying teams manually measure distances and elevation differences at hazard locations to identify risks. However, this approach has several challenges.

First is increased workload and danger. Inspecting high structures requires erecting scaffolding or using aerial work platforms, which makes the work itself hazardous. Surveying on steep slopes or cliff edges carries a risk of falling, and measuring around operating heavy machinery is accompanied by the danger of accidents. When measuring many points across a large site, workers spend more time in hazardous areas, increasing the risk of accidents.

Next is manpower and time. Traditional methods using two-person teams with total stations or tape measures to measure one point at a time are very time-consuming. On large projects, it is unrealistic to check every hazard point in detail, so sampling inspections are often relied upon. As a result, oversights occur—problems tend to be found in locations that simply were not measured. It is difficult to conduct efficient safety checks with limited personnel, and in sites where labor shortages are worsening, safety management may fall behind.

Furthermore, information sharing is also challenging. Even if a hazardous location is discovered, it is not easy to communicate it to all stakeholders on the spot. Hand-drawn sketches or verbal explanations lack realism, and the severity of the hazard may not be fully shared. For inexperienced workers, numbers or abstract instructions alone make hazard recognition difficult, which can lead to human error.

Thus, traditional safety management methods had issues of “time-consuming,” “dangerous,” “oversights,” and “difficult to share.” What was needed to solve these problems was a new approach that could identify hazards non-contact and in real time. Enter the AR heat map mentioned above.

Benefits of using AR heat maps

Incorporating AR heat maps into on-site safety management provides many benefits not available with conventional methods. The main advantages are summarized below.

• Intuitive identification of hazards: Color-coded heat maps make the magnitude of hazards or errors immediately apparent. From site workers to managers, anyone can understand the situation just by looking at the screen. Because “where it is safe and where it is dangerous” can be judged intuitively by color differences, accurate instructions can be given without relying on experience.

• Prevention of missed measurements: By using high-density point cloud data from drones or smartphone LiDAR to scan entire surfaces, a wide area including places that were previously difficult to measure can be checked comprehensively. Tiny distortions or localized defects that might have been missed by sampling inspections will appear as color differences on the heat map, preventing overlooked risks.

• Real-time feedback: AR heat maps provide results simply by pointing the device at the site, allowing immediate identification and correction of problem locations. For example, if part of an embankment lacks thickness, the heat map will show the deficient area in red so workers can add fill immediately. Compared to traditional methods where defects are discovered later, this minimizes rework and prevents leaving major defects that could lead to accidents.

• Easy information sharing and recordkeeping: Heat maps and point cloud data can be saved and shared as digital records. Capturing photos or videos of the AR display and sharing them with stakeholders allows managers or clients who are not on site to accurately understand the hazard status. Data stored in the cloud is useful for daily progress tracking and comparative analysis with past conditions. Remote experts can also assist with safety checks by viewing data remotely, raising team-wide safety awareness.

• Labor savings and improved safety: High-density point cloud scanning and automated analysis dramatically reduce the manpower and time required for measurement tasks. Dangerous or hard-to-access locations can be non-contact scanned remotely using lasers or LiDAR, eliminating the need for workers to enter hazardous areas and directly contributing to worker safety. Heat maps make previously difficult checks easy, reducing the need to erect scaffolding or use aerial work platforms and lowering the risk of falls or contact accidents. Shortened inspection times even during night work or under traffic restrictions reduce safety risks to the surrounding area.

As described, AR heat maps are a powerful tool that strengthens both on-site safety management and quality control. Intuitive, comprehensive checks prevent overlooked risks, and rapid correction and information sharing accelerate the PDCA cycle for accident prevention.

On-site use cases for AR heat maps

Here are some specific examples of how AR heat maps contribute to safety management on site.

Example 1: Quality checks and hazard prediction during embankment work On a road embankment project, the traditional as-built verification that had taken veteran technicians several days was replaced with an AR heat map. Using a system that combined an iPhone and RTK-capable GNSS, the as-built terrain was scanned on foot immediately after construction, and the difference from the design model was displayed as a heat map on the spot. Deficient areas appeared red on screen, so workers could immediately judge “this embankment is lacking” and add fill to correct it. They rescanned the area and confirmed it had turned blue or green, sharing that the standard was met. As a result, dangerous defects were corrected the same day, preventing risks that could have led to subsequent pavement settlement or slope collapse. The heat map images were also saved as photographic records and used in reports to the client. Because visual information is clearer than numeric reports alone, stakeholder alignment on improvements was smoother and agreement on corrective actions was easier to reach.

Example 2: Preventing accidental damage by visualizing buried utilities In infrastructure or renovation projects, buried pipes and cables are a major safety concern because they are invisible and can be accidentally damaged by excavation equipment. At one site, pre-acquired 3D data of underground utilities was projected on site using an AR heat map approach to visually “see through” the ground. A colored virtual model of the pipes appeared on the smartphone screen overlaying the ground, with visual alerts like “pipeline located ○ m (○ ft) ahead from this point.” Workers could confirm the pipe route as if they could see beneath the ground and take appropriate measures before excavation. This greatly reduced the risk of damaging buried utilities. By visualizing hidden hazards in advance, unnecessary trial excavations and overly cautious work were reduced, allowing excavation tasks to proceed safely and efficiently. The method also improved training for new workers; sharing the AR screen helped everyone grasp the presence of buried utilities, boosting team safety awareness and reducing near-miss incidents.

Example 3: Monitoring hazard zones at disaster sites After heavy rain or earthquakes, slopes prone to collapse and damaged structures must be surveyed, but entering sites at risk of secondary disasters is extremely dangerous. AR heat maps are powerful in such situations. For example, at a large landslide site, point cloud data of the collapsed terrain obtained by drone photogrammetry or ground LiDAR scanning can be compared to the stable terrain model and displayed as a heat map to show unstable areas in red. Overlaying that heat map on live tablet AR images allows identification from a safe distance of “which slope is still likely to collapse.” Because hazard areas can be understood without sending people in, recovery planning can be carried out effectively while avoiding secondary disaster risk. Moreover, disaster site data can be shared via the cloud with experts for remote advice. AR heat maps are therefore expected to be tools that visualize current conditions non-contact and support decision-making even in situations that require advanced safety management, such as disaster response and infrastructure inspection.

From these use cases, it is clear that AR heat maps are not limited to checking construction quality but have great value as a means to visualize “invisible hazards” and directly link that visualization to safety measures. By tailoring the data displayed on the heat map (height differences, stress levels, underground utility locations, flood inundation assumptions, etc.) to site conditions, the range of applications can expand further.

Conclusion: Easy AR adoption with LRTK simple surveying

Because AR heat maps are effective at strengthening safety and quality management, they are being positioned as important technologies in initiatives such as the Ministry of Land, Infrastructure, Transport and Tourism’s i-Construction and on-site DX. However, some may worry that expensive equipment or specialized knowledge are required to use them on actual sites. Finally, we introduce “LRTK simple surveying” as a solution that makes AR heat maps easy for anyone to implement.

LRTK is a surveying system that transforms a smartphone into a truly versatile surveying instrument by attaching a compact high-precision GNSS receiver to the phone. It supports RTK-GNSS (real-time kinematic positioning) and can achieve centimeter-level positioning accuracy (cm level accuracy (half-inch accuracy)), approximately horizontal ±1–2 cm (±0.4–0.8 in) and vertical ±3 cm (±1.2 in) even with a smartphone. This allows site positions to be determined with the precision that once required expensive GPS survey instruments and skilled surveyors. In addition, using the smartphone’s built-in LiDAR sensor and camera, high-density point cloud data can be obtained in a short time and immediately compared with design data to produce heat maps. On a dedicated app, the acquired point cloud and the design model are automatically matched and errors are color-coded on the spot, so you can instantly confirm as-built conditions and hazard locations with AR while on site. Because the system uses RTK correction information for positioning, the AR display has minimal positional offset and can stably overlay heat maps precisely on real objects.

Usage is simple: attach the receiver to a smartphone and walk around the site. No special skills or complex settings are required. Young staff familiar with smartphone operations can start using it after brief instruction, and even non-experts can perform high-precision AR measurements and heat map checks. In practice, the LRTK series has been introduced on sites as an easy-to-use smart construction tool, and it is valued as a solution that enables efficient and safe work with limited personnel. It aligns with the i-Construction initiatives promoted by the Ministry of Land, Infrastructure, Transport and Tourism and contributes to site digitalization and labor savings.

Sites that feel challenges in safety management or as-built control can gain great benefits by adopting this “simple surveying × AR” technology. The era in which a single smartphone can perform high-precision measurements and visualize and share hazard locations is becoming reality, reducing reliance on heavy equipment and manpower. Safety management that once depended on the intuition and experience of veterans can be transformed into work that anyone can perform with digital technology. We encourage you to consider the effects of introducing AR heat maps on your sites. By combining advanced AR technology with easy LRTK simple surveying, your construction site’s safety management can become smarter and more reliable than ever.

FAQ

Q1. What do I need to use AR heat maps on site? A. Basically, you need an AR-capable smartphone or tablet, a high-precision GNSS receiver, and a dedicated app that can display heat maps. For example, the latest iPhones and iPads (such as the Pro series) come equipped with LiDAR sensors, so by combining them with a compact RTK-GNSS receiver you can use a handheld device as a high-precision 3D scanner and AR terminal. Prepare the design data (3D models or drawing data) and reference point coordinates in advance, then simply launch the smartphone app on site to automatically generate heat maps from the acquired point cloud data and display them in AR. You don’t need to purchase highly specialized equipment anew; the convenience of completing the workflow with a commercial smartphone and a small device is a major attraction.

Q2. Can smartphone AR displays accurately indicate hazard locations? A. Yes—if you combine high-precision positioning technology, you can achieve sufficiently reliable accuracy. Standard smartphone GPS can have errors of several meters (several ft), but using RTK-GNSS corrections can reduce errors to the order of a few centimeters. For example, in the LRTK simple surveying system, field measurements have confirmed horizontal accuracy of about 1–2 cm (0.4–0.8 in), allowing smartphone position to be corrected to a precision comparable to conventional surveying instruments. This makes it possible to overlay heat maps and virtual models on real structures almost exactly. Height differences of a few centimeters and small steps can be visually detected, helping to prevent missed hazard locations. For more rigorous verification, point cloud data obtained simultaneously with AR displays can be analyzed to perform millimeter-level precision checks.

Q3. Can AR heat maps be used for official inspections and safety reports? A. Recently, heat-map evaluation using 3D measurement data has been gaining acceptance as a method for as-built management in public works. The Ministry of Land, Infrastructure, Transport and Tourism’s guidelines include surface-based as-built management using heat maps, and demonstration projects and partial full-scale adoption are underway. Cases are already emerging in which full 3D measurement and heat map submission are required for earthwork as-built management. In the field of safety management as well, AR-based visualization of hazard locations is beginning to be used for safety training and inspections. However, when treating AR heat maps as formal safety report documents, follow the instructions of the client or supervising agency and, if necessary, export heat map diagrams to paper or submit electronic data as required. In any case, AR heat maps are being actively used on advanced sites and are likely to be incorporated into official inspection processes in the future.

Q4. Is operating AR heat maps difficult? Can young or inexperienced personnel use them? A. Operation is intuitive and not difficult. You just follow the on-screen guidance in the dedicated app and point the smartphone—similar to taking photos or playing games on a phone. Even young site staff or those unfamiliar with digital tools can master it with short training. There are cases where junior engineers accustomed to smartphone use are conducting as-built checks with AR heat maps at site with accuracy comparable to veterans. Systems like LRTK designed with a site-friendly UI allow the entire process from measurement to heat map display to be completed by following menu prompts, so no specialized surveying knowledge is required. The portability of a smartphone-and-small-device system also means you can take quick measurements whenever the need arises, making it easy for anyone on site to participate in routine safety checks.

Q5. On what kinds of sites and tasks are AR heat maps particularly effective? A. AR heat maps are useful whenever you want to check “the difference between design and as-built” on the spot in civil engineering or construction, but they are particularly effective in the following cases. First, earthworks such as road construction and land preparation over wide areas benefit greatly, since AR heat maps can manage ground elevation differences and slopes over surfaces. Localized irregularities that are easily overlooked can be detected, enabling early correction of pavement height variations and abnormal slope gradients. For structures like tunnels and dams where thickness and shape checks are critical, AR comparison with 3D design models is useful for detecting insufficient placement or deformation in concrete and preventing structural safety issues. In construction, AR is used for quality control and clash detection by verifying the position of columns and walls against BIM models or checking for interference in ceiling equipment. AR is also directly linked to safety in sites with many hidden risks such as buried utilities, or in hazardous disaster recovery sites, by enabling non-contact visualization. In short, AR heat maps offer the greatest benefits in processes where rework is costly or where safety-critical points cannot be overlooked. This technology is expected to be increasingly used as a key technology for both safety and quality on more and more sites.