Choosing a classification scheme.

• Classes are always a simplification / generalization of the real world.
• Scheme choice depends on the information-extraction objective (are you counting tree crowns, or mapping land cover?).
• You can pick broad/abstract or specific/concrete classes.
• Hierarchical schemes are standard — coarse top level → refined sub-classes.
• Canonical example: Anderson (1976) land-use / land-cover system for RS data. Level I = 9 classes; Level II = 37 subclasses.