#### 11.17.5.3. Functions That Create New Geometries from Existing Ones

The following sections describe functions that take geometry
values as arguments and return new geometry values.

##### 11.17.5.3.1. Geometry Functions That Produce New Geometries

Section 11.17.5.2, “`Geometry`

Functions”, discusses
several functions that construct new geometries from existing
ones. See that section for descriptions of these functions:

##### 11.17.5.3.2. Spatial Operators

OpenGIS proposes a number of other functions that can produce
geometries. They are designed to implement spatial operators.

These functions are not implemented in MySQL.

`Buffer(``g`

,`d`

)

Returns a geometry that represents all points whose
distance from the geometry value
`g`

is less than or equal to a
distance of `d`

.

`ConvexHull(``g`

)

Returns a geometry that represents the convex hull of the
geometry value `g`

.

`Difference(``g1`

,`g2`

)

Returns a geometry that represents the point set
difference of the geometry value
`g1`

with
`g2`

.

`Intersection(``g1`

,`g2`

)

Returns a geometry that represents the point set
intersection of the geometry values
`g1`

with
`g2`

.

`SymDifference(``g1`

,`g2`

)

Returns a geometry that represents the point set symmetric
difference of the geometry value
`g1`

with
`g2`

.

`Union(``g1`

,`g2`

)

Returns a geometry that represents the point set union of
the geometry values `g1`

and
`g2`

.