The GIS procedure creates
and maintains the spatial databases that are used by
SAS/GIS software.
A
SAS/GIS spatial database consists of the following elements:
-
SAS data sets that contain the
coordinates and identifying information for the spatial features.
-
a spatial entry (a SAS catalog
entry of type GISSPA) that identifies which SAS data sets contain
spatial information. The spatial entry also stores the following elements:
-
composites that define how the
variables in the spatial data are used
-
names of the polygonal indexes
that define the boundaries of area layers for the map
-
a lattice hierarchy that defines
which features in the spatial data enclose or are enclosed by other
features (the relationships among the polygonal variables)
-
information about the projection
method that is used for the stored spatial data
A spatial entry alternatively
can contain references to two or more other spatial entries that have
been merged into a single spatial database.
-
a coverage entry (a SAS catalog
entry of type GISCOVER) that selects a subset of the spatial data
that is available for display in a map.
-
one or more layer entries (SAS
catalog entries of type GISLAYER) that identify features that have
common characteristics and specify how they are displayed as layers
in the map.
-
a map entry (a SAS catalog entry
of type GISMAP) that specifies which layers from a particular coverage
are included in a map. The map entry also stores the following information:
-
the names of attribute data sets
that are associated with the map, along with definitions of how the
attribute data is linked to the spatial data
-
the name of a SAS data set that
contains labels for map features
-
definitions of GIS actions that
can be performed when map features are selected
-
definitions for map legends
-
values for display and projection
options
Note: The task of creating new
SAS/GIS spatial databases from spatial data in other formats can also
be performed interactively by using the
GIS Spatial Data
Importing window or programmatically by using the
SAS/GIS
batch import process.
