Directory under which all the coverages and a directory called 'info' are.
coverage
The name of the coverage we want to work with
filename
The name of the file in the coverage directory that
stores the data. By default, it is called 'pal.adf'
Value
This function returns a list with two elements. The first one is
a data frame with the next fields (columns):
PolygonID
A number that identifies this polygon.
MinX
Minimum value for all the X component of the coordinates.
MinY
Minimum value for all the Y component of the coordinates.
MaxX
Maximum value for all the X component of the coordinates.
MaxY
Maximum value for all the Y component of the coordinates.
NArcs
?
The second element in the list is also a list in which each element is
composed by three arrays with information about the polygons that
are in the polygon boundary: 'Arc ID', 'From Node' and 'Adjacent Polygon'.