Here, geometry can be (multi)point, (multi)linestring, (multi)polygon or geometryCollection.

Parameter: preserveGeomDim

Value

Description

Default value

true

Remove degenerated geometries from the result, i.e geometries which dimension is lower than the input geometry

x

false

It is up to the client to filter degenerate geometries

Note that:

A multi-geometry will always produce a multi-geometry (eventually empty or made of a single component).

A simple geometry may produce a multi-geometry (i.e polygon with self-intersection will generally produce a multi-polygon). In this case, it is up to the client to explode multi-geometries if needed.

- Linear geometries (dim = 1): duplicate coordinates are preserved as much as possible.
- Aeral geometries (dim = 2): duplicate coordinates are generally removed due to the use of overlay operations.

Parameter: preserveDuplicateCoord

Value

Description

Default value

true

Preserve duplicate coordinates as much as possible. Generally, duplicate coordinates can be preserved for linear geometries but not for areal geometries (overlay operations used to repair polygons remove duplicate points)

x

false

All duplicated coordinates are removed

Parameter: preserveCoordDim

Value

Description

Default value

true

Preserves third and fourth ordinates

x

false

Preserves third ordinates but not fourth one

Note that the fourth dimension is not yet supported in H2GIS. So for the moment, preserveCoordDim has no impact since third ordinates (z) will always be preserved.

ST_MakeValid may add new points to node the original set of lines (especially to make polygons valid). New points just have x and y. No interpolation is performed if original geometry is in 3D or 4D.