The spatial extent of an analysis (or analysis extent for short) is typically a subset of the full map extent for two main reasons. First, and somewhat trivially, the set of features that make up the map may collectively represent a rather irregular shape. For example, consider a map of the 48 States that make up the continental US. The bounding box of the map extent that contains the set of States has a lot of white area in order to accommodate the aggregate shape. Second, and more importantly, the map layers input to analytical software may represent a very large area (the 48 States), but for the purposes of the current analysis we only want to include the States of the Pacific Northwest. If we select the Northwest States, and then proceed with the analysis, we have trimmed the analysis extent from 48 down to two States.
Analysis extent can be natural (e.g. watershed), or geopolitical or administrative (e.g. state).
Graphical Ontology Browser
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