Class SpatialInteriorRingN

Namespace

YndigoBlue.Velocity.Functions

Assembly

YndigoBlue.Velocity.dll

Represents the ST_InteriorRingN spatial accessor function that returns the Nth interior ring (hole) of a polygon geometry.

public class SpatialInteriorRingN : Function, ICheckItem, IDefaultItem, IFilterItem, IElement

Inheritance

object

Function

SpatialInteriorRingN

Implements

ICheckItem

IDefaultItem

IFilterItem

IElement

Remarks

Warning

Spatial functions are not available in the Community Edition of Velocity. They require the Full Edition.

The ST_InteriorRingN function returns a linestring representing the Nth interior ring (0-based index) within a polygon geometry. Interior rings represent holes or voids in the polygon. The first interior ring is at index 0. For multi-polygons or non-polygon geometries, behavior varies by database implementation. For Geometry types in planar coordinate systems, this is useful for extracting polygon holes, analyzing complex polygon structure, or topology operations. OGC-compliant.

Return Type: LineString (closed ring representing the hole boundary).

Function Call	Result
ST_InteriorRingN(polygon, 0)	First hole boundary
ST_InteriorRingN(polygon, 2)	Third hole boundary
ST_InteriorRingN(polygon_no_holes, 0)	NULL

Examples

Extract the first interior ring (hole) from each complex polygon:

var schema = manager.LoadSchema("land");
var parcels = schema["parcels"];

var query = new Query()
    .Select([ parcels["id"], new Expression("first_hole", new SpatialInteriorRingN(parcels["boundary"], new Literal<int>(1))) ])
    .From(parcels);

var results = manager.Retrieve(query);

Constructors

SpatialInteriorRingN(Geometry, int)

Initializes a new instance of ST_InteriorRingN with a polygon geometry literal and ring index.

SpatialInteriorRingN(Column, int)

Initializes a new instance of ST_InteriorRingN with a polygon geometry column and ring index.

SpatialInteriorRingN(Function, int)

Initializes a new instance of ST_InteriorRingN for a function result.

SpatialInteriorRingN(Geography, int)

Initializes a new instance of ST_InteriorRingN with a polygon geography literal and ring index.