| Using Spatial Data with SAS/GIS Software |
The
GIS procedure creates and maintains the spatial databases that are used by SAS/GIS software.
A SAS/GIS spatial database consists
of
- 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
- 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 are 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 names of attribute data sets that are associated
with the map, along with definitions of how the attribute data are 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. ![[cautionend]](../common/images/cautend.gif)
Copyright 1999 by SAS Institute Inc., Cary, NC, USA. All rights reserved.
