Class SpatialBuffer
- Namespace
- YndigoBlue.Velocity.Functions
- Assembly
- YndigoBlue.Velocity.dll
Represents the ST_Buffer spatial analysis function that creates a buffer zone around a geometry or geography.
public class SpatialBuffer : Function, IElement, ICheckItem, IDefaultItem, IFilterItem- Inheritance
-
SpatialBuffer
- Implements
Remarks
Warning
Spatial functions are not available in the Community Edition of Velocity. They require the Full Edition.
The ST_Buffer function returns a geometry or geography that represents all points within a specified distance from the input spatial object. For Geometry types (planar), the buffer distance is in coordinate system units. For Geography types (spherical), the distance can be specified with a unit of measure. Buffers are useful for proximity analysis, creating zones of influence, or spatial joins with tolerance. The resulting geometry is typically a polygon (or multi-polygon) with rounded corners. OGC-compliant.
Buffer Results by Input Type:
| Input Type | Buffer Result |
|---|---|
| POINT | Circular POLYGON centered on the point |
| LINESTRING | POLYGON with rounded ends (stadium shape) |
| POLYGON | Expanded POLYGON with rounded corners |
| MULTIPOINT | MULTIPOLYGON (circles may merge if close) |
Example Results (using test geometries, distance=0.5°):
| Shape | Buffer Result |
|---|---|
| PT1 (point) | Circular POLYGON (radius 0.5°) |
| PT2 (point) | Circular POLYGON (radius 0.5°) |
| LN1 (linestring) | POLYGON (rounded rectangle) |
| PY1 (rectangle) | Expanded POLYGON with rounded corners |
| PY3 (triangle) | Expanded POLYGON with rounded corners |
Units of Measure: For Geography types, use UnitOfMeasure to specify the buffer distance in meters, kilometers, miles, or other supported units.
Constructors
- SpatialBuffer(Geometry, float)
Initializes a new instance of ST_Buffer with a geometry literal and distance.
- SpatialBuffer(Geometry, Expression)
Initializes a new instance of ST_Buffer with a geometry literal and distance expression.
- SpatialBuffer(Column, float)
Initializes a new instance of ST_Buffer with a geometry column and distance.
- SpatialBuffer(Column, float, UnitOfMeasure)
Initializes a new instance of ST_Buffer with a geography column, distance, and unit of measure.
- SpatialBuffer(Column, Expression)
Initializes a new instance of ST_Buffer with a geometry column and distance expression.
- SpatialBuffer(Column, Expression, UnitOfMeasure)
Initializes a new instance of ST_Buffer with a geography column, distance expression, and unit of measure.
- SpatialBuffer(Function, float)
Initializes a new instance of ST_Buffer with a function result (geometry) and distance.
- SpatialBuffer(Function, float, UnitOfMeasure)
Initializes a new instance of ST_Buffer with a function result (geography), distance, and unit of measure.
- SpatialBuffer(Function, Expression)
Initializes a new instance of ST_Buffer with a function result (geometry) and distance expression.
- SpatialBuffer(Function, Expression, UnitOfMeasure)
Initializes a new instance of ST_Buffer with a function result (geography), distance expression, and unit of measure.
- SpatialBuffer(Geography, float, UnitOfMeasure)
Initializes a new instance of ST_Buffer with a geography literal, distance, and unit of measure.
- SpatialBuffer(Geography, Expression, UnitOfMeasure)
Initializes a new instance of ST_Buffer with a geography literal, distance expression, and unit of measure.