ST_ToMultiSurface method

Converts the geometry to a multi-surface value.

Syntax

geometry-expression.ST_ToMultiSurface()

Returns

ST_MultiSurface If the geometry-expression is of type ST_MultiSurface, returns the geometry-expression. If the geometry-expression is a geometry collection containing only surfaces, returns a multi-surface object containing the elements of the geometry-expression. If the geometry-expression is of type ST_Surface then return a multi-surface value containing one element, the geometry-expression. If the geometry-expression is the empty set, returns an empty set of type ST_MultiSurface. Otherwise, raises an exception condition.
The spatial reference system identifier of the result is the same as the spatial reference system of the geometry-expression.

Remarks

If geometry-expression is already known to be an ST_MultiSurface value, it is more efficient to use TREAT( geometry-expression AS ST_MultiSurface ) than the ST_ToMultiSurface method.

Note

By default, ST_ToMultiSurface uses the original format for a geometry, if it is available. Otherwise, the internal format is used. For more information about internal and original formats, see STORAGE FORMAT clause, CREATE SPATIAL REFERENCE SYSTEM statement.

Standards and compatibility

Example

The following example returns the result MultiSurface EMPTY.

SELECT NEW ST_GeomCollection().ST_ToMultiSurface()

The following example returns the result MultiSurface (((3 3, 8 3, 4 8, 3 3))).

SELECT Shape.ST_ToMultiSurface()
FROM SpatialShapes WHERE ShapeID = 22

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