Feature classes are homogeneous collections of common features, each having the same spatial representation (such as points, lines, or polygons) and a common set of attributes (for example, a line feature class for representing road centerlines). The four most commonly used feature classes are points, lines, polygons, and annotation.
In the illustration below, these feature classes are used to represent four datasets for the same area:
- Manhole cover locations as points
- Sewer lines
- Parcel polygons
- Street name annotation
In this diagram, you might also have noted the potential requirement to model some advanced feature properties. For example, the sewer lines and manhole locations make up a storm sewer network, a system with which you can model runoff and flows. Also, note how adjacent parcels share common boundaries. Most parcel users want to maintain the integrity of shared feature boundaries in their datasets using a topology. Users often need to model such spatial relationships and behaviors in their geographic datasets. In these cases, you can extend these basic feature classes by adding a number of advanced geodatabase elements, such as topologies and utility networks.
Feature classes are created and stored in a geodatabase either as stand-alone objects or organized into a feature dataset. Feature datasets are used to spatially or thematically integrate related feature classes. The main purpose of the feature dataset is for enabling more complex behavior on your feature classes, such as the topology and utility network mentioned above.
There are four primary ways to create a new feature class:
- Using the Create Feature Class wizard
- Using the Create Feature Class geoprocessing tool
- Saving the contents of a map layer
- Converting an external data source, such as a shapefile or CAD data, into a feature class
For more details on the properties and options available when creating a new feature class, see Feature class properties.
Extending feature classes
| Use | If you want to |
|---|---|
Create a set of feature subclasses in a single feature class. Subtypes are often used to manage different behaviors on subsets of the same feature type. | |
Specify a list or range of valid values for feature class attributes. Domains help ensure the integrity of your data and are often used to enforce data classifications (such as road class, zoning codes, and land-use classifications). | |
Manage a number of key GIS workflows for data management; for example, support long transactions, historical archives, and multiuser editing. | |
Manage how coincident feature classes share their geometry. Topology allows you to create rules to enforce how features behave when they share the same location or boundary. | |
Model and analyze a complex network of systems for water, gas, electric, telecom, sewer, storm water, and other utilities. |