Domains
A domain defines the values, classes or identifiers that can be stored in a map or column. When you create a map or column, you also have to select or create a suitable domain for that map or column. When you create an attribute table for a map, the attribute table must use the same domain as the map to which the table refers; the domain provides the link between the map and the table. Further, a domain uses a certain representation which defines the graphical representation of a map, e.g. the coloring.
The four main types of domains are:
|
for data objects that contain unique identifiers (e.g. plot 1024, plot 1025) |
|
|
for data objects that contain classes (e.g. soil units: clay, sandy loam) |
|
|
for data objects that contain measured, calculated or interpolated values (e.g. height, concentration) |
|
|
for satellite images containing values between 0 and 255. |
All ILWIS data objects have a domain. One domain can be used for several data objects. For an introduction on domains, see Basic concepts : before creating maps and tables and Basic concepts : working with domains.
See also: