Different spectral bands provide unique advantages for capturing active wildfires amidst smoke, with constantly shifting incident and environmental factors influencing the efficacy of spectral bands during each flyover of a fire.
Overwatch Imaging’s approach to this challenge involves gathering data across all spectral bands simultaneously. The company uses software to handle data processing and distribution efficiently, ensuring optimal information regardless of circumstances.
Determining the best spectral band for imaging wildfires through smoke depends on several factors, including smoke density, environmental conditions, and the specific imaging task.
Smoke absorbs visible light strongly, making visibility challenging. Generally, longer wavelengths penetrate smoke more effectively than shorter ones. Thermal bands prove particularly valuable as they capture emitted radiation that can penetrate smoke, offering clear views of fires, terrain, hotspots, and surrounding landscapes.
Mid-wave infrared (MWIR) vs long-wave infrared (LWIR)
LWIR and MWIR each offer distinct advantages for imaging through smoke. Longer wavelengths in LWIR typically penetrate smoke more effectively, providing fundamental advantages. MWIR, however, excels in detecting subtle temperature variations, making it better suited for discerning thermal differences and heat sources through smoke.
Near-infrared (NIR) vs short-wave infrared (SWIR)
SWIR, operating between 900-1700 nm, can penetrate some types of smoke and atmospheric haze that obscure visible and longer-wavelength infrared light. It can also distinguish different smoke types, such as those from fires versus industrial processes.
In certain situations, NIR (700-900 nm) can surpass SWIR in penetrating smoke and dust due to its longer wavelength and lower energy, making it less susceptible to scattering and absorption by airborne particles. NIR is also effective for assessing reflectance properties of surfaces obscured by smoke.
Advantages of Each Spectral Band
Short-wave IR
SWIR light penetrates smoke and other obscurants better than visible or near-infrared light, improving object visibility. SWIR imaging enhances object-background contrast, aiding object identification in smoky or hazy conditions, as well as accurately detecting temperature variations, useful for spotting hotspots or fires through smoke.
Middle-wave IR
MWIR cameras detect small temperature changes effectively, crucial for spotting fires or heat sources and aiding quick response to fires. MWIR light effectively penetrates smoke and obscurants better than visible light.
Long-wave IR
LWIR light penetrates smoke and dust more effectively than other spectral bands, as well as detecting temperature variations to assist rapid fire detection and response. LWIR cameras also stand out for their detailed imaging in smoky or hazy environments.
Near IR
NIR can monitor vegetation health and stress for wildfire risk assessment, whilst penetrating smoke to provide clearer images than visible light. NIR assesses moisture content in vegetation and soil, aiding fire prediction and behavior modeling.
