Domain unit

A domain unit defines an entity that can have attributes.

The relationship between an entity and its attributes is foundational in data modeling, where the entity represents a real-world object or concept, and its attributes describe specific characteristics or properties of that entity. Essentially, attributes provide detailed information about the entity, distinguishing it from others and allowing for its analysis and understanding within a particular domain or context.

A domain unit can be:

  • Geographic, e.g. a set of countries, Nuts2 regions, or a range of raster cells.
  • Model objects, e.g. a set of houses, services, or streets.
  • Class table domain, e.g. Corine Land Cover category, EHS, Percentage_10K, often configured as domain of a reclassification table with a related brush color palette attribute.

domains and data-tables

As data is often read from external storage (database or file) as tables with rows representing different entity-members and columns representing different attributes, a domain unit can be defined as being the range of rows of such external table.

The GeoDMS supports both one-dimensional (table) and two-dimensional (raster) domains. The value-type of the domain unit defines the number of dimensions and the cardinality. The allowed unit types can be found in the CanBeDomain column of the value type table.

tiled/segmented Data

A domain unit also defined a tiling or segmentation of the related attribute data. Default segmentation for integral domains is 2^16 rows per segment; default tiling of raster domain sis 256 x 256 rows and columns per tile. Domain units can be defined with different tile of segment sizes and even with irregular tilings that don’t fully cover a rectangular bounding box, which can be convenient for highly non rectangular study areas. Only domains with unit types of more that 2 bytes (all point types, uint32, int32, uint64 or int64) can define a tiling or segmentation.


See domain-unit-example for how to configure domain units.