Geometry objects can be explicitly and implicitly cast to any character or binary type. In the case of a character type, the
geometry will be presented in EWKT format. In the case of a binary type, the geometry will be presented in WKB format. Character
and binary types can also be explicitly and implicitly cast as a geometry value. For binary values, the value must represent
a valid geometry in WKB format. For character values, the value must represent a valid geometry in either WKT or EWKT format.
If casting from WKB or WKT to a geometry value, the default value SRID of 0 is assigned to the object.
UltraLite provides a fixed set of three different reference systems that can be attributed to a column during its creation.
Individual geometry objects can be associated with any SRID value except the undefined reference system, and can only be stored
in a column associated with a matching SRID value or the undefined reference system.
The predefined reference systems are:
Undefined or "null" reference system
This is the default reference system if no SRID value is provided. It allows contained geometry values to be in any
valid reference system. This allows for "catch-all" columns that do not enforce any reference system consistency among their
Default planar reference system
Defined by specifying a SRID value of 0 during column creation, this column can contain only geometry values associated
with this reference system. The values are treated as being in 2D planar space.
WGS 84 Geodetic Reference System
Defined by specifying a SRID value of 4326 during column creation, this column can only contain geometry values associated
with this reference system. The values are treated as being on the Earth's surface and operations are applied accordingly.
A point in SRID 4326 can be stored in a column with the WGS 84 reference system or with the undefined reference system, but
not in the default planar system.
No transformations between reference systems is supported.