Texture
Texture is influenced by several variables, including crown shapes, tree spacing, and tree
height. Texture interpretation as a means of identifying forest type requires knowledge of
the texture often associated with each forest type. This knowledge is acquired through
hands-on experience or the use of vegetation keys. With hands-on experience working
with aerial imagery over along period of time and through the process of trial and error,
an analyst can develop a mental catalog to relate texture in a given geographic area to a
specific forest type.
Vegetation keys have been developed through the same trial and error process but have
been documented and are available in the literature. They can be very useful in certain
instances (see Chapter 3 for examples). However, one must remember that background
knowledge of the area of interest is essential and most keys are specific to tree species,
geographic area, time of year, film type, and photoscale. When using color or color
infrared film, tone is often referred to as hue and is represented as shades of the color
image.
FM 5-33 US Army Field Manual, Terrain Analysis, p. 1-3