# Two-dimensional domain

### From ObjectVision

In a two-dimensional domain unit each element represents the value of a cell in a two-dimensional structure.

The id of each cell consists of a coordinate with a row and a column position. in the GeoDMS the word grid is often used for a two-dimensional domain.

Most grids in GeoDMS projects are configured with an spoint value type (if the maximum value of each coordinate is 32.767) or an ipoint value type (if the maximum value for each coordinate is more than 32.767). It is advised to use value types with smaller sizes if possible and only bigger sizes if necessary.

## **Example**

The following example presents the configuration of a non-geographical grid domain, used as kernel in a potential expression:

unit<spoint> pot5km := range( spoint ,point(-int16(5),-int16(5)),point(int16(6),int16(6)) );

The pot5km configures a grid domain of 11 * 11 cells. The range function is used to define the cardinality of this domain.

## **Geographic Grid Domains**

Grids often describe a geographic area. In these cases, except from the cardinality, also how the grid relates to the earth's surface (the projection information) need to be configured for a geographic domain unit.