Using Channel 2 (3.9 µm) Imagery in Fire Detection

  The 3.9 µm channel's strong sensitivity to sub-pixel "hot-areas" makes it very useful for fire detection.   In this 3.9 µm image, showing wildfires in Florida, darker shades represent hot pixels and lighter shades are cooler ones.   Since the response to changes in scene temperature is much larger at shorter wave lengths than at the longer ones, fires stand out even more in "difference" images, between Channel 2 and Channel 4 for instance.   These types of combined image products will be discussed in more detail in the last section of this module.