Along with points, lines, and polygons, a vector layer can have a wealth of associated descriptive, or attribute, information associated with it. Attribute information is displayed in CellArrays. This is the same information that is stored in the INFO database of ArcInfo. Some attributes are automatically generated when the layer is created. Custom fields can be added to each attribute table. Attribute fields can contain numerical or character data.
The attributes for a roads layer may look similar to the example in the figure below. You can select features in the layer based on the attribute information. Likewise, when a row is selected in the attribute CellArray, that feature is highlighted in the Viewer.
Using Imported Attribute Data
When external data types are imported into ERDAS IMAGINE, only the required attribute information is imported into the attribute tables (AAT and PAT files) of the new vector layer. The rest of the attribute information is written to one of the following INFO files:
- <layer name>.ACODE—arc attribute information
- <layer name>.PCODE—polygon attribute information
- <layer name>.XCODE—point attribute information
To utilize all of this attribute information, the INFO files can be merged into the PAT and AAT files. Once this attribute information has been merged, it can be viewed in CellArrays and edited as desired. This new information can then be exported back to its original format.
The complete path of the file must be specified when establishing an INFO file name in a Viewer application, such as exporting attributes or merging attributes, as shown in the following example:
Use Show Attributes option in IMAGINE Workspace to view and manipulate vector attribute data, including merging and exporting.
See ERDAS IMAGINE Help for more information about using CellArrays.