Assisting lookouts and park managers to accurately locate forest fires. It is a tribute to the skill of the individuals who initiated the work that produced these photographs that their product is still valuable today.
Identifying vegetation patterns. In every photograph, there are distinct patterns of vegetation. Disturbances, such as forest fires, change the vegetation patterns as trees die and new vegetation grows in its place.
Identifying landscape features. Many events occur over the course of time that may change a landscape, including human disturbance. Roads and structures are two examples that may be identifying features on a landscape.
Repeat photography. By taking an identical photograph, from the same point and in the same direction, after a period of years, change can be observed.
By working to explain what, why, how, and where we see or don’t see things, we can learn a great deal about the subjects of these photographs.
Comparing INFRARED and PANCHROMATIC film types. Most of the lookout locations contain pairs of photographs, using both infrared film and panchromatic film. Panchromatic film is a normal black-and-white film you can buy in the store; it’s what your grandparents or great grandparents used prior to the 1960s. Infrared (IR) film absorbs different wavelengths of energy than panchromatic film. On infrared film, healthy deciduous vegetation is typically very light or nearly white, while healthy coniferous vegetation reflects less IR radiation and appears in gray tones. Dead or vegetation near death appears black. On IR film, water is very dark and smooth in contrast with the surrounding land. Moist soils also appear in dark tones, while dry soils appear in lighter tones.