1. Elements of image interpretation Photo or image interpretation is the process of extracting qualitative and quantitative information from a photo or image using human knowledge or experiences. Most of the time, one can recognize many features on a photo without any training. This is particularly true if you are familiar with the area in the photo. But many objects look quite different from above, and differentiating between similar objects can be difficult. For an instance, distinguishing tree species or crop types (such as wheat vs. corn) does not come easily. Interpreting features in aerial photos is a skill that takes study and practice to develop. There are eight elements/clues used in image interpretation (Figure 1). - Tone/color * lightness/darkness/color of an object - Texture - coarse or fine, such as in a corn field (distinct rows) vs. wheat field (closely-grown plants) - Shape * square, circular, irregular - Size * small to large, especially compared to known objects - Shadow - objects like buildings and trees cast shadows that indicate vertical height and shape - Pattern - many similar objects may be scattered on the landscape, such as oil wells - Site - the characteristics of the location; for example, don't expect a wetland to be in downtown Chicago - Association * an object's relation to other known objects * for example, a building at a freeway off-ramp may be a gas station based on its relative location.

1. 1. Elements of image interpretation Photo or image interpretation is the process of extracting
qualitative and quantitative information from a photo or image using human knowledge or
experiences. Most of the time, one can recognize many features on a photo without any training.
This is particularly true if you are familiar with the area in the photo. But many objects look
quite different from above, and differentiating between similar objects can be difficult. For an
instance, distinguishing tree species or crop types (such as wheat vs. corn) does not come easily.
Interpreting features in aerial photos is a skill that takes study and practice to develop. There are
eight elements/clues used in image interpretation (Figure 1). - Tone/color *
lightness/darkness/color of an object - Texture - coarse or fine, such as in a corn field (distinct
rows) vs. wheat field (closely-grown plants) - Shape * square, circular, irregular - Size * small to
large, especially compared to known objects - Shadow - objects like buildings and trees cast
shadows that indicate vertical height and shape - Pattern - many similar objects may be scattered
on the landscape, such as oil wells - Site - the characteristics of the location; for example, don't
expect a wetland to be in downtown Chicago - Association * an object's relation to other known
objects * for example, a building at a freeway off-ramp may be a gas station based on its relative
location