Glossary for Geospatial Science

  Technical vocabulary defined by MicroImages

book Glossary

color-infrared (CIR):  Color-infrared images may be collected by an electronic scanner or a camera that uses special film.  Infrared film records the photographic infrared radiation just beyond the range of human vision as red.  Normal red from the scene becomes green, and green becomes blue.  Normal blue in the scene is usually filtered out and not recorded.

Any physical or biological damage to growing plants which begins to cause a deterioration in their vigor (their water and/or chlorophyll content) causes a rapid decrease in their reflectance of photo-infrared radiation, and increases in their red reflectance.  CIR photographs show these changes much sooner and more dramatically than normal photographs or human eyesight.  Healthy, green vegetation appears in bright red, while damaged, diseased, or dying vegetation appears in shades of pink, tan, and yellow.

This knowledge was first used during the Second World War when color-infrared film was called camouflage detection film.  It provided pre-visual detection of the changes in vegetation cut or damaged by military activity and could very easily separate color-camouflage materials (like olive drab canvas) from live foliage.