Class SpatialLength

Namespace

YndigoBlue.Velocity.Functions

Assembly

YndigoBlue.Velocity.dll

Represents the ST_Length spatial measurement function that computes the length of a linear geometry.

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

Inheritance

object

Function

SpatialLength

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_Length function returns the total length of a linestring or multi-linestring geometry. For polygons, it may return the perimeter. For points, typically returns 0. For Geometry types, length is in coordinate system units. For Geography types, length is calculated using spherical geometry and can be specified with a unit of measure (meters, kilometers, miles, etc.). This is useful for measuring distances, calculating route lengths, or analyzing linear features. OGC-compliant.

Return Type: Numeric (float/double). Units depend on coordinate system or specified UnitOfMeasure.

Length by Geometry Type:

Input Type	Length Result
POINT	0 (no length)
LINESTRING	Total length of the line
Multi-segment LINE	Sum of all segment lengths
POLYGON	Perimeter (sum of ring lengths)
MULTILINESTRING	Sum of all line lengths

Example Results (using test geometries):

Shape	Length (in degrees)
LN1 (vertical, 2° tall)	2.0
Diagonal line (2°×2°)	~2.83 (√8)
Multi-segment line	Sum of segment lengths
Polygon (perimeter)	Sum of all edges
PT1 (point)	0

Units of Measure: For Geography types, use UnitOfMeasure to get results in meters, kilometers, miles, or other supported units.

UnitOfMeasure	Result (Route A at -102°,37° via M at -99°,40° to B at -96°,43°, approx. 840 km)
Meter	840,000
Kilometer	840
Mile	522
Foot	2,755,906
Yard	918,635
Inch	33,070,860

Examples

Calculate the length of each road segment in the network:

var schema = manager.LoadSchema("infrastructure");
var roads = schema["roads"];

var query = new Query()
    .Select([ roads["id"], roads["name"], new Expression("segment_length", new SpatialLength(roads["path"])) ])
    .From(roads);

var results = manager.Retrieve(query);

Constructors

SpatialLength(Geometry)

Initializes a new instance of ST_Length with a geometry literal.

SpatialLength(Column)

Initializes a new instance of ST_Length with a geometry column.

SpatialLength(Column, UnitOfMeasure)

Initializes a new instance of ST_Length with a geography column and unit of measure.

SpatialLength(Function)

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

SpatialLength(Function, UnitOfMeasure)

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

SpatialLength(Geography, UnitOfMeasure)

Initializes a new instance of ST_Length with a geography literal and unit of measure.