Safe near-heavy-equipment work! Remote checks and instructions with AR heat maps

Table of contents

• What is an AR heat map?

• Challenges hidden in near-heavy-equipment work

• Benefits brought by AR heat maps

• Safe and efficient sites enabled by remote checks and instructions

• Main use cases for AR heat maps - Slope excavation - Compaction of embankments - Paving work - Land development

• Easy on-site deployment: smartphone surveying with LRTK

• FAQ

At construction sites where heavy equipment is used, it is not uncommon for workers to approach machines to perform checks or give instructions. For example, supervisors or survey technicians may work close to heavy equipment to check the slope of an excavated face or to measure the thickness and compaction of an embankment. However, “near-heavy-equipment work” always carries danger. Every year, accidents caused by contact with or being caught in heavy equipment continue to occur, making safety measures a major challenge. Attention is therefore turning to remote checks and instructions using AR heat map technology. With the power of AR (augmented reality), a new work style that allows people to avoid approaching dangerous equipment is becoming realistic. This article explains in detail, using the keyword “AR heat map,” how to improve safety and streamline quality control in heavy-equipment operations.

What is an AR heat map?

An AR heat map, in a nutshell, is a technology that visualizes the quality of as-built conditions (the shape of terrain or structures after construction) as a colored heat map and displays that map in AR over the actual site. Here, “heat map” does not mean thermal imaging that measures temperature, but rather a map that color-codes the differences between design data and actual construction results. For example, areas that are higher than the design height can be shown in red, areas that have been excavated too low in blue, and areas that match the design in green. This color display makes it easy to grasp unevenness and errors in the finished work at a glance.

Using AR (Augmented Reality) technology, the heat map information can be overlaid on the real-world view. When you point a tablet or smartphone camera at the site, a colored heat map is superimposed like a translucent layer over the actual terrain or structures. In other words, the distribution of errors you used to check on drawings can be viewed directly in correspondence with the real location. Because you can intuitively see “where and how much needs to be corrected,” quick action is possible on site. Subtle bumps and gradient deviations that were easy to overlook with paper drawings or numeric lists can be reliably detected with AR heat maps.

Challenges hidden in near-heavy-equipment work

On civil engineering and construction sites, it is necessary to check as-built conditions after heavy-equipment work (excavators, bulldozers, rollers, etc.) and to issue instructions for additional excavation or filling. However, having workers approach heavy equipment to take measurements or give instructions is extremely dangerous. Here, we summarize the challenges of conventional near-heavy-equipment work.

• Safety risks: Working around heavy equipment always carries the risk of being crushed or contacted. Especially when workers enter a slope to check gradient during slope shaping or bend down near the pavement to check finishing during paving work, sudden equipment movement or unstable footing can lead to serious accidents. In some cases at heights or on poor footing, measurements themselves had to be abandoned.

• The hassle of quality checks: With traditional methods where survey technicians measure heights and slopes point by point at each heavy-equipment work location, the process is extremely time-consuming and labor-intensive. For example, measuring heights every few meters (every few ft) after slope excavation or probing several spots with a rod after compaction of an embankment are point-based checks, so there is a risk of overlooking defective areas. On large land development sites or long roads, it is impossible to measure everything quickly, causing equipment operators to idle while waiting for results and creating inefficiencies when defects discovered later require redeployment of heavy equipment for rework.

• Communication difficulties: Traditionally, supervisors have conveyed measurement results to operators verbally or by radio, saying things like “lower it by ○ cm (○ in)” or “add a little more here.” However, matching positions on drawings with actual site locations is difficult, making it hard to accurately share “which point needs how much correction.” Even if you show an operator a paper heat map, it can be unintuitive to understand where that corresponds on the ground, so instructions may not be conveyed accurately. As a result, rework increases and it becomes difficult to completely eliminate finish variability.

Thus, near-heavy-equipment work faces various challenges in terms of safety, accuracy, and efficiency. How can AR heat maps help solve these issues?

Benefits brought by AR heat maps

By introducing AR heat maps, the following benefits can be expected in response to the above challenges.

• Improved safety: The greatest advantage is that people do not need to approach heavy equipment. For example, when checking the as-built condition of a slope, required data can be obtained by scanning the site with a smartphone from a safe distance. Point cloud data obtained can be processed in the cloud to automatically create a heat map, eliminating the need for workers to climb hazardous slopes and measure with tape. Because you can give remote instructions while viewing the AR heat map, workers can maintain distance from each other, reducing the risk of contact accidents.

• Advanced quality control: As-built measurements that were previously point-based can be performed in detail as surfaces through 3D scanning. Heat maps show the distribution of errors covering the entire terrain, so areas with severe unevenness or spots at risk of settlement due to insufficient compaction can be reliably exposed. With AR display you can check on site “which part is how many cm (in) higher or lower than the design,” allowing you to intuitively grasp variations in construction accuracy. This not only improves the precision of quality inspections but also helps prevent overlooking defects.

• Immediate feedback: Using AR heat maps enables an on-site cycle of construction → measurement → judgement → correction to be completed immediately. Previously, survey teams had to take data back for inspectors to judge, then issue rework instructions later; now this can be done on the spot. For example, you can scan the finished pavement, immediately display a flatness heat map, mark high spots, and perform corrective work right away. Minimizing rework contributes significantly to shorter schedules and higher efficiency.

• Smoother communication: By visualizing the situation on site, AR heat maps make communication among stakeholders much easier. Because the colored map is projected directly onto the site, instructions like “cut this area by this much” can be shared visually. Heavy-equipment operators can also see the indicated spots at a glance through a tablet, reducing vague exchanges like “a bit around here…” and enabling precise corrective work. Clients and inspectors can also confirm as-built conditions by color without visiting the site, smoothing consensus-building.

As described above, AR heat maps provide revolutionary advantages in safety, quality, and efficiency. The next section looks at specific construction scenes where this technology can be applied, with representative examples.

Safe and efficient sites enabled by remote checks and instructions

Introducing AR heat maps is changing work styles on site. A key enabler is cloud integration that allows remote checks and instructions. Point cloud data and heat maps obtained by 3D scanning can be uploaded to the cloud and shared over the internet with all project stakeholders. For example, when a site person posts as-built data captured with an iPhone to the cloud, the site manager or client can view the latest as-built heat map on a PC or tablet in the office. They can add comments or give real-time feedback such as “can you lower this by 5 cm (2.0 in)?”

Remote attendance and remote inspection are becoming realistic, changing how site management is conducted. Inspections that used to require clients to be on site with tape measures or survey instruments may be completed online through digital data sharing and AR visualization. In the construction industry facing severe labor shortages, remote technologies reduce travel time and improve personnel efficiency. Even on sites without resident experts, experienced technicians can check data remotely and provide advice, contributing to overall skill improvement and standardization across sites.

Remote check-and-instruction environments are also effective for safety. In dangerous sites or nighttime work, remote support enables a small on-site team to receive assistance, allowing quick responses when necessary. The approach also fits post-COVID requirements for contactless and non-face-to-face work and has become a focus area for companies pursuing site DX (digital transformation).

Main use cases for AR heat maps

AR heat maps are powerful in various civil and building construction scenarios. Below are four representative cases and how the technology is used.

Slope excavation

In slope excavation and shaping for gravel extraction or road construction, surveying is essential to check the finished gradient and smoothness. Traditionally, after work, supervisors would walk around the top and bottom of the slope to measure heights and estimate slope angles, but having people enter steep slopes is dangerous and it is difficult to measure the whole face uniformly.

With AR heat maps, you can grasp the as-built condition of an entire slope in a short time. For example, once excavation is complete, you can scan the slope’s 3D shape on the spot with a drone or an iPhone LiDAR scanner. Point cloud data obtained are analyzed against the design model to generate a slope as-built heat map. Red and blue distributions make it immediately clear “which parts protrude too much” and “which parts are undercut,” and by displaying this in AR at the site, operators and supervisors can check correction points from a safe position while looking at the same screen. Because you can issue specific remote instructions like “cut a bit off this red area about ○ m (○ ft) from the slope toe,” slope shaping accuracy improves dramatically. There is no longer a need for people to climb the slope and make hazardous point-and-check gestures, enabling safe and efficient achievement of the required gradients.

Compaction of embankments

In embankment and road filling work, it is important to compact soil to the specified density and finish to the design height and gradient. Insufficient compaction causes settlement, and deviations in fill height affect subsequent works. Traditionally, checks were made by measuring heights at random points or estimating density with plate load tests, but point information alone cannot capture the whole situation, making uniform construction management difficult.

AR heat maps allow surface-level checks of embankment height and flatness. If you scan the surface after roller compaction, a height deviation heat map relative to the design height is created. For example, if a spot is shown in red indicating “overfilled,” you can immediately instruct leveling of that area. Conversely, blue indicates “insufficient fill” and signifies the need for additional soil. Sharing color-coded information with the operator allows the team to decide on-site where the roller needs additional passes and where to add soil, enabling uniform ground without compaction variability.

Efforts are also underway to visualize differences in stiffness due to the number of roller passes or soil types on AR heat maps. By linking sensors mounted on heavy equipment or construction management systems, technologies are emerging that map “how many times each area was compacted” and display it in color in AR, making it easier to infer unseen compaction inside the ground. Thus, in embankment work, AR heat maps contribute not only to height control but also to supporting quality (density) management.

Paving work

AR heat maps are also highly useful in paving works such as roads and parking lots. In the final stage of paving, after asphalt or concrete placement, inspectors check whether surface flatness and slopes (cross slope, etc.) are within specified values. Traditionally, flatness checks rely on a 3 m (9.8 ft) straightedge, surface roughness meters, or experienced visual inspection. However, accurately measuring a wide area of pavement in a short time is difficult, and measurement itself is constrained in rain or at night.

Using AR heat maps, surface checks immediately after paving can be performed quickly and in detail. Specifically, scan the finished pavement with an iPad equipped with LiDAR or a high-precision laser scanner, and create a flatness heat map from the point cloud data. Since elevation differences on the order of a few mm (a few in) are visualized on the color map, small bumps or rutting distortions are not overlooked. By displaying this in AR on site, the entire construction team can share the finishing status. For example, you can immediately instruct “the curve before the intersection is red, indicating slight bulging—relevel it with the roller.” Even at night, the color distribution is visible on a tablet screen, making it more reliable than flashlight-based visual checks, and in rain, as long as measurement data can be taken, evaluation can be done on the spot.

Applying AR heat maps to paving work allows quality control that previously relied on flatness tests and random sampling to become real-time and full-area, greatly reducing rework and claims due to paving defects. Ultimately, this leads to improved durability and user comfort.

Land development

AR heat maps are useful on large-scale land development sites such as residential or industrial site formation. In land development, heavy equipment is used to cut and fill to shape the entire site to design heights and gradients. Surveying is essential to confirm whether the as-built condition matches the design, but it is not easy to check the entire area in detail when the construction area is vast. Traditionally, heights were checked at key points and terrain judged partly by experience.

With AR heat maps, you can manage as-built conditions over large areas as surfaces. For example, obtain a 3D model of the entire development site by drone photogrammetry or laser scanning, and create a heat map of differences from the design surface. This allows you to see in color that “only the corner on the north side of the lot is tens of centimeters (tens of inches) overfilled” or “the central part is lower than expected.” Because you can detect errors across a wide area without overlooking them, early correction of excesses and shortages in large earthworks becomes possible.

If you project the AR heat map on site, survey staff can walk the site and mark problem areas. Instead of placing flags on red areas or pointing to a bulldozer operator and saying “cut a bit here,” you can share the screen and proceed with correction work. Development sites often have blind spots with large undulations, but by using drone-acquired data you can inspect areas people cannot enter. As a result, even expansive sites can achieve efficient quality control with a minimum workforce.

Easy on-site deployment: smartphone surveying with LRTK

When you hear “state-of-the-art AR heat map technology,” you might expect expensive equipment and specialized knowledge. However, recently anyone can perform high-precision 3D surveying and AR display easily by combining a smartphone with a small device. A representative solution is called LRTK.

LRTK is a business-card-sized GNSS receiver that attaches to a smartphone or tablet, transforming the phone into a high-precision surveying instrument. If you combine an LiDAR-equipped device like an iPhone with LRTK, you can obtain high-precision point cloud data on site simply by pointing the device. Surveying that once required total stations or large laser scanners can now be completed with a single smartphone.

For example, if you scan a slope with LRTK and upload the data to the cloud, an as-built heat map is automatically generated. Then you just display it in AR on your smartphone screen to perform immediate on-site checks and instructions. Since RTK-GNSS allows centimeter-level positioning (half-inch-level positioning), the alignment accuracy of AR heat maps is very high, and concerns about “digital overlays appearing misaligned with reality” are minimized. You can also tap a point on the smartphone camera image to remotely obtain coordinates of that location. Being able to measure distances or confirm dimensions from a distance without going into hazardous areas helps ensure safety and improve efficiency.

Thus, smartphone surveying with LRTK dramatically lowers the barrier to AR heat map adoption. Even those without specialized surveying skills can operate intuitively and integrate it into routine site management. Data are shared in the cloud so the whole team stays up to date with site conditions. To fully reap the benefits of AR heat maps—from ensuring safety in near-heavy-equipment work to advancing quality control—consider first trying an easy-to-start smartphone surveying solution such as LRTK.

Finally, here are common questions about AR heat maps and site remoteization in a Q&A format.

FAQ

Q. What does the “heat” in AR heat map mean? Is it related to temperature? A. The “heat” in “heat map” here does not mean temperature. It refers to a visualization method that uses color gradients to indicate the magnitude or differences in data. In construction, the term “as-built heat map” is used to color-code deviations from the design; this is a diagram that shows surface elevation differences in red/blue, and it has nothing to do with heat distribution. In short, it is a color-coded error map displayed in AR for easy interpretation.

Q. What equipment and preparation are needed to use AR heat maps? A. Basically, you need devices to acquire 3D survey data and software to process and display that data. Common setups use drone photogrammetry data or point clouds obtained with LiDAR-equipped iPhones/iPads. If you compare the acquired data with the design model on a cloud service, a heat map image is generated. Then you use an AR display app on a tablet or smartphone to project it on site. For high-precision alignment, combining RTK-GNSS positioning is ideal. Recently, small GNSS receivers that attach to smartphones (e.g., LRTK) have appeared, enabling relatively easy high-precision AR implementation.

Q. Is an internet connection required on site to use it? A. An internet connection is desirable because cloud processing and data sharing proceed smoothly, but AR heat maps can still be used with ingenuity in sites without connectivity. For example, you can acquire point cloud data on site, generate the heat map later in the office via the cloud, then download it to your device for AR display back on site. There are also software options that allow you to store design data on the device beforehand and complete comparison processing offline. For RTK corrections, where mobile signals are absent, Japan’s satellite “Michibiki” augmentation (CLAS) can provide centimeter positioning without the internet. Therefore, AR heat map use is possible even where infrastructure is lacking.

Q. I’m worried about the cost of introducing AR heat maps. Is it cost-effective? A. While high-end 3D scanners and specialized software used to be necessary, operations can now center on smartphones and cloud services, making initial costs significantly lower than before. Considering the costs of repeatedly hiring survey specialists or keeping heavy equipment idle for long periods, introducing AR heat maps that enable real-time measurement and correction offers high cost-effectiveness. The economic benefits of reduced labor costs and shortened schedules are substantial, and the value of accident-free operations due to improved safety is immeasurable. Service plans are available at various scales, so it’s worth considering options that match your company’s needs.

Q. If we use AR heat maps, will traditional surveying and inspections become unnecessary? A. AR heat maps are a tool to support on-site checks and instructions; they do not completely replace traditional surveying methods or quality inspections. However, they can streamline and reduce labor for many intermediate checks and attendance inspections that were previously done manually. Final confirmations and critical inspection items will still require expert judgment, but if site self-inspections are thoroughly performed with AR heat maps beforehand, you can expect fewer reworks. In other words, the ideal is a fusion of human expertise and digital technology, and AR heat maps serve as a powerful support to take on-site work to the next level.