Class SpatialArea

Namespace

YndigoBlue.Velocity.Functions

Assembly

YndigoBlue.Velocity.dll

Represents the ST_Area spatial function that calculates the area of a polygon or multi-polygon geometry.

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

Inheritance

object

Function

SpatialArea

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_Area function returns the area of a geometry. For Geometry types (planar), it calculates area in coordinate system units squared. For Geography types (spherical), it calculates area on the earth's surface, optionally in specified units. Returns 0 for non-areal geometries (points, lines). Useful for land area calculations, geographic analysis, and spatial statistics. OGC-compliant.

Geometry Mode (planar, returns square coordinate units):

Shape	Area
PY0 (4°×4° square)	16.0
PY1 (0.5°×1° rectangle)	0.5
PY2 (1°×3° rectangle)	3.0
PY3 (triangle)	0.25
PY4 (2°×1.5° rectangle)	3.0
PT1, PT2 (points)	0
LN1 (linestring)	0

Geography Mode (spherical, returns square meters by default):

Shape	Area (m² default, km² with UnitOfMeasure)
PY0	~157,650,000,000 m² (~157,650 km²)
PY1	~4,900,000,000 m² (~4,900 km²)
PY2	~36,800,000,000 m² (~36,800 km²)
PY3	~3,100,000,000 m² (~3,100 km²)
PY4	~36,900,000,000 m² (~36,900 km²)
PT1, PT2, LN1	0 (non-areal geometries)

Units of Measure: For Geography types, the default unit is square meters. Use the SpatialArea(Column, UnitOfMeasure) constructor with UnitOfMeasure to specify alternative units such as square kilometers or square miles. The result is in the square of the specified linear unit (e.g., Kilometer returns km²).

UnitOfMeasure	Result (GA: -100°,39° to -97°,41°, approx. 57,000 km²)
Meter	57,000,000,000
Kilometer	57,000
Mile	22,007
Foot	613,542,300,000
Yard	68,171,370,000
Inch	88,350,120,000,000

Examples

Calculate the area of each land parcel stored as a geometry:

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

var query = new Query()
    .Select([ parcels["id"], new Expression("parcel_area", new SpatialArea(parcels["boundary"])) ])
    .From(parcels);

var results = manager.Retrieve(query);

Constructors

SpatialArea(Geometry)

Initializes a new instance of ST_Area for a geometry literal.

SpatialArea(Column)

Initializes a new instance of ST_Area for a geometry column.

SpatialArea(Column, UnitOfMeasure)

Initializes a new instance of ST_Area for a geography column with a unit of measure.

SpatialArea(Function)

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

SpatialArea(Function, UnitOfMeasure)

Initializes a new instance of ST_Area for a function result with a unit of measure.

SpatialArea(Geography, UnitOfMeasure)

Initializes a new instance of ST_Area for a geography literal with a unit of measure.