Spatial data models

Spatial data models• Raster

– exhaustive regular or irregular partitioning of space– associated with the field view– location-based

• Vector– points, lines, areas– associated with the object view– object-based

Spatial data models

Vector data models

• An object (as opposed to field or location) viewpoint of space

• represent geographic entities as discrete objects composed of points, lines, and polygons

Vector data models

• Spaghetti vector data model– each point, line, or polygon that represents a

geographic entity is stored as a record in a file that consists of that entity’s ID and a list of coordinates that define it’s location (or the coordinate space that it occupies)

Vector data models

• Spaghetti vector data model

– relationships among objects are implied

Vector data models

• Spaghetti vector data model– advantages

• simple

• efficient for display and plotting

– disadvantages• inefficient for most types of spatial analysis

Vector data models

• Vector topologic data model

– composed of points, lines, and polygons– node: a point at the intersection of two or more

lines– in addition to coordinate locations, the

topologic relationships between geometric features are explicitly recorded

Vector data models

• Vector topologic data model

Vector data models

• Vector topologic data model

Vector data models• Vector topologic data model: GBF/DIME

Vector data models

• Vector topologic data model: POLYVRT (hierarchical data structure)

Vector data models• Freeman - Hoffman chain-code for compacting vector storage

Vector data model

• TIN: Triangulated Irregular Network

Vector data model

TIN: Triangulated

Irregular Network

Vector data model• TIN: Triangulated Irregular Network

Vector data model

• Hybrid vs. integrated systems for vector data models– A hybrid system stores spatial data in one type

of data model and the attribute data in another data model that is often an existing commercial non-spatial database

– An integrated system manages both spatial and attribute data using the same data model

A

B

C

D

E

F

ID Length KeyA 5 1B 6 2C 6 2D 7 1E 9 1F 9 3

Key Name Length1 Main St. 212 Elm St. 123 Spruce St. 9