ESRI ArcInfo Coverage Files
ESRI ArcInfo coverage files are also known simply as coverages and, less commonly, as ADF files.
Coverages are made up of a set of files within a folder. The folder itself is the coverage name. The files roughly represent different layers, usually representing different types of topology or feature types.
>ls /data/coverage/brazilaat.adf arc.adf arx.adf bnd.adf lab.adf prj.adf tic.adf tol.adf
A folder with the name INFO
is also part of the coverage. It sits at the same hierarchical level
as the coverage folder itself. Therefore, to copy a coverage (using
regular filesystem tools), the coverage folder and the INFO folder must both be copied. The
INFO folder holds some catalog
information about the coverage:
>ls /data/coverage/infoarc0000.dat arc0001.dat arc0002.dat arc.dir arc0000.nit arc0001.nit arc0002.nit
CONNECTIONTYPE OGR must
be used. The ability to use coverages isn’t built into
MapServer.
The path to the coverage folder name is required.
The layer number is used to specify what type of features
to draw (as per the layer number from ogrinfo, but minus one).
The directory is the data source.
Layers are found within the directory.
Here’s an example that uses ogrinfo on a coverage directory:
> ogrinfo /data/coverage/brazil
INFO: Open of 'brazil'
using driver 'AVCBin' successful.
1: ARC (Line String)
2: CNT (Point)
3: LAB (Point)
4: PAL (Polygon)Here’s an example that uses ogrinfo to examine the structure of a
layer:
> ogrinfo -summary /data/coverage/brazil PAL
Had to open data source read-only.
INFO: Open of 'brazil'
using driver 'AVCBin' successful.
Layer name: PAL
Geometry: Polygon
Feature Count: 1
Extent: (1272793.274958, 795381.617050) - (1287078.382785, 807302.747284)
Layer SRS WKT:
(unknown)
ArcIds: IntegerList (0.0)
AREA: Real (18.5)
PERIMETER: Real (18.5)
F_OPER#: Integer (5.0)
F_OPER-ID: Integer (5.0)
OPER: String (2.0)
FCODE: String (10.0)