The OGC SFA 1.2/SQLMM standard requires a spatial object to have an inspection property called
ST_Dimension (not to be confused with
ST_CoordDim). The standard defines this as follows:
The dimension of an
ST_Geometryvalue is less than or equal to the coordinate dimension.
This is not a useful definition for implementation. A more useful one is:
Within a traditional mathematical framework based on Euclidean geometry (Abbott, E.A., 1884, Flatland: A romance of many dimensions: OxFord, Blackwell. 100 pp.), a single point has a topological dimension of zero. Similarly, a line or curve connecting two points is one-dimensional, a plane or surface is two-dimensional, and a volume is three-dimensional (Jones, R. ...