Class SpatialEnvelope

Namespace

YndigoBlue.Velocity.Functions

Assembly

YndigoBlue.Velocity.dll

Represents the ST_Envelope spatial analysis function that returns the bounding rectangle of a geometry.

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

Inheritance

object

Function

SpatialEnvelope

Implements

IElement

ICheckItem

IDefaultItem

IFilterItem

Remarks

Warning

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

The ST_Envelope function returns a geometry representing the minimum bounding rectangle (MBR) of the input spatial object. The envelope is always axis-aligned (parallel to coordinate system axes) and is returned as a polygon (or point/line for degenerate cases). This is the same as the bounding box. Useful for quick spatial indexing, extent calculations, or initial filtering in spatial queries. OGC-compliant.

Return Types by Input:

Input Type	Envelope Result
POINT	POINT (same as input)
Vertical/horizontal LINE	LINESTRING (degenerate)
Diagonal LINESTRING	POLYGON (bounding rectangle)
Axis-aligned POLYGON	POLYGON (same as input)
Rotated/irregular POLYGON	POLYGON (larger bounding rectangle)
MULTIPOINT	POLYGON enclosing all points

Example Results (using test geometries):

Shape	Envelope
PY0 (rectangle)	Same rectangle (already axis-aligned)
PY3 (triangle)	Bounding rectangle larger than triangle
LN1 (vertical line)	Degenerate line (width = 0)
PT1 (point)	Same point (degenerate case)
L-shape (concave)	Rectangle enclosing the L
MPT1 (multipoint)	Rectangle enclosing all points

Constructors

SpatialEnvelope(Geometry)

Initializes a new instance of ST_Envelope with a geometry literal.

SpatialEnvelope(Column)

Initializes a new instance of ST_Envelope with a spatial column.

SpatialEnvelope(Function)

Initializes a new instance of ST_Envelope for a function result (e.g., from another spatial operation).

SpatialEnvelope(Geography)

Initializes a new instance of ST_Envelope with a geography literal.