A layer is the visual representation of a geographic dataset in any digital map environment. Conceptually, a layer is a slice or stratum of the geographic reality in a particular area, and is more or less equivalent to a legend item on a paper map. On a road map, for example, roads, national parks, political boundaries, and rivers might be considered different layers. In ArcGIS, a layer is a reference to a data source, such as a shapefile, coverage, geodatabase feature class, or raster, that defines how the data should be symbolized on a map. Layers can also define additional properties, such as which features from the data source are included. Layers can be stored in map documents (.mxd) or saved individually as layer files (.lyr). Layers are conceptually similar to themes in ArcView 3.x.
Graphical Ontology Browser
- Click on a node to jump to the content of that node
- Pan to see the rest of the graph
- Scroll the mousewheel up and down to zoom in and out
- Rearrange the nodes in the graph by dragging a node to a different position