Maps and inventories should reflect what is actually on the ground. Field visits should,
therefore, be made to observe what is there in reality. Field visits for ground observation
are time-consuming and usually costly. Making observations everywhere in the entire area to be mapped is likely to take too much time. For reasons of efficiency, remote sensing data are used to extrapolate the results of a limited number of observations over the entire area being studied.
The selection of sample locations is a crucial step for cost-effective mapping. We can
use the RS images to stratify the area. To do this, we make an preliminary interpretation
of the area to be mapped based on its interpretation elements. The interpretation
units are the strata to be sampled.
During fieldwork, the locations of boundaries of the interpretation are also verified. In
addition, data is gathered about areas or features that cannot be derived from remote
sensing images.