Monitoring the World with Thermal Infrared Mapping

Thermal infrared (TIR) mapping captures energy in the form of longwave radiation emitted or reflected from surfaces. Unlike visible imagery, which shows how things look, thermal data reveals how warm or cool they are. While humans have measured heat for centuries, thermography became practical only after photographic technology matured in the early twentieth century, allowing temperature differences to be recorded visually.

By the 1920s, thermal imaging began to emerge as a scientific tool, and by the 1970s it had gained approval for medical applications, particularly in cancer research. Today’s thermal imaging systems either record relative temperature patterns as images or store raw digital values that can later be calibrated to precise surface temperatures. This evolution has transformed thermal infrared sensing into a powerful quantitative technology.

Over the last thirty years, thermal imaging has expanded into an impressive range of industries. It is used in professional motorsports to evaluate tire performance, in construction to identify heat loss in buildings, and by military and law enforcement agencies for nighttime operations. It also plays an important role in healthcare, infrastructure maintenance, energy production, and natural resource management. Airborne thermal data collection has further amplified these capabilities, especially as sensor quality and photogrammetric processing software have improved. Together, these advances allow large areas to be surveyed quickly and efficiently.

Below are three real-world applications where airborne thermal infrared mapping is delivering measurable value.

Monitoring River Temperature and Aquatic Health

Water temperature is one of the most influential factors governing river ecosystems. A river’s thermal regime depends on multiple variables, including air temperature, flow rate, shading from riparian vegetation, and—most critically—the source of the water itself, such as snowmelt or groundwater springs.

Carefully timed airborne TIR surveys provide a snapshot of river temperature conditions across entire watersheds. These thermal maps allow scientists, land managers, and conservation groups to identify patterns that would be impossible to observe from isolated ground measurements. The data supports planning and implementation of river restoration projects aimed at protecting fish habitat and improving ecosystem resilience.

For decades, NV5 Geospatial (through its predecessor, Watershed Sciences Inc.) has supported restoration initiatives using thermal infrared data. In the late 1990s, airborne surveys of Oregon’s John Day River revealed cold-water spring inputs essential for fish spawning and rearing. The same data helped researchers assess how riparian vegetation influences stream temperature.

Long-term monitoring along the Klamath River in Oregon and California further illustrates the value of TIR data. Three surveys conducted between 2001 and 2021 examined river segments affected by four large dams built during the twentieth century. The thermal imagery showed that dam operations had dampened natural seasonal temperature variation and created thermal stratification opposite of what occurs in free-flowing rivers. Combined with other stressors, these changes contributed to the decline of culturally and economically important salmon populations. The same datasets are now being used to model how the river may respond once dam removal restores more natural flow conditions.

Across the United States and Canada, agencies, tribal governments, and private organizations rely on TIR mapping to study rivers of all sizes. Beyond habitat analysis, thermal data has been used to locate groundwater inflows, identify fuel leaks, measure thermal discharges from power plants, and assess post-fire impacts where vegetation loss leads to warmer stream temperatures.

Unlocking Geothermal Energy Potential

While renewable energy development often centers on solar and wind, geothermal energy represents a largely untapped resource. According to estimates from the U.S. Department of Energy, less than one percent of the nation’s geothermal potential has been developed.

Traditionally, identifying geothermal resources relied on geological field surveys. Geologists searched for indicator minerals, analyzed rock formations, and interpreted topographic maps to estimate where geothermal energy might be accessible. Thermal infrared mapping now enhances this process by enabling wide-area temperature surveys that reveal subtle surface heat anomalies associated with subsurface geothermal systems.

Landscape-scale thermal maps provide a clearer picture of geothermal patterns, helping energy developers decide where to locate facilities and how to optimize production. One notable example is the Casa Diablo geothermal power plant near Mammoth Lakes, California, which draws energy from the Long Valley Caldera hydrothermal system. The area’s surface features include heat vents, gas emissions, and patches of stressed vegetation—all indicators of geothermal activity.

In 2017 and 2018, NV5 Geospatial conducted airborne TIR surveys of the Casa Diablo site for the U.S. Geological Survey and the Bureau of Land Management. These studies quantified surface temperatures while accounting for factors such as emissivity and surface area. The analyses produced estimates of radiant heat output, heat flux anomalies, and overall geothermal energy emission.

The surveys also included sections of Mammoth Creek, which flows near the facility. Future thermal monitoring will help detect any temperature changes in the creek that could signal thermal pollution or contamination associated with expanded geothermal operations.

Inspecting Bridges from the Air

The United States maintains more than 617,000 public bridges, all of which must be inspected at least every two years under the National Bridge Inspection Program. Conventional inspection methods—such as sounding, ground-penetrating radar, and vehicle-mounted thermal surveys—are effective but costly and often disruptive. In many cases, traffic must be restricted or halted during inspections.

Airborne thermal infrared mapping offers a safer and more efficient alternative. By surveying bridges from the air, inspectors can examine dozens of structures in a single flight without interrupting traffic. This approach is particularly effective for identifying near-surface defects in bridge decks.

As bridges age, steel reinforcement within the concrete corrodes and expands, creating internal stress. This leads to subsurface cracking and delamination, which worsen under repeated traffic loads. During daylight heating, these damaged areas warm faster than intact concrete, making them visible in thermal imagery.

To assess bridge conditions, NV5 collects aerial thermal data and applies advanced photogrammetric and orthorectification techniques to produce seamless, traffic-free mosaics of bridge decks. Analysts then identify and vectorize areas of delamination, allowing engineers to quantify the extent of damage as a percentage of the total deck area.

Early detection is critical. Identifying structural issues before they become severe can dramatically reduce repair costs and extend the lifespan of infrastructure.

With major investment in infrastructure repair prioritized under recent federal legislation, thermal infrared technology is expected to play an increasingly important role in evaluating bridge conditions and guiding rehabilitation efforts across the country.

Thermal infrared mapping allows us to see what is otherwise invisible—heat patterns that reveal environmental stress, structural weakness, and energy potential. As sensor technology and data processing continue to advance, TIR will remain a cornerstone of monitoring systems that protect ecosystems, infrastructure, and communities worldwide.