Constraints in GIS

Constraints in GIS:

Ø  Important aspects of geographic objects in GIS.

Ø  4 types of constraints:

            1.Toplogical:

ü  Deals with behavior and spatial relationship between objects.

ü  used during Insert and Update process, mostly to reduce errors and improve data quality.

            2. Semantic:

ü  Deals with the “meaning” of the spatial features.

ü  Define whether the database is valid according to semantic rules(2 buildings can’t share the same edge).

3. User-defined:

ü  Business rules of non-spatial DBMS.

ü  e.g.- a house should be located within a certain distance from a fire hydrant.

4. Temporal: it has 2 types

1. Punctual- defines an occurring of an event with a specific time. E.g. accident, earthquake….

2. Durable- description changes that occur over time. E.g. a bridge was built, maintained and demolished