Contents
How are spatial relationships used in PostGIS algebra?
Spatial Relationships ¶ So far we have only used spatial functions that measure ( ST_Area, ST_Length ), serialize ( ST_GeomFromText) or deserialize ( ST_AsGML) geometries. What these functions have in common is that they only work on one geometry at a time.
How to test spatial equality of two geometries?
ST_Equals (geometry A, geometry B) tests the spatial equality of two geometries. ST_Equals returns TRUE if two geometries of the same type have identical x,y coordinate values, i.e. if the second shape is equal (identical) to the first shape.
When does ST _ Overlaps return true in PostGIS?
ST_Overlaps (geometry A, geometry B): Returns TRUE if the Geometries share space, are of the same dimension, but are not completely contained by each other. ST_Touches (geometry A, geometry B): Returns TRUE if the geometries have at least one point in common, but their interiors do not intersect.
What are the names of the functions in PostGIS?
PostGIS has begun a transition from the existing naming convention to an SQL-MM-centric convention. As a result, most of the functions that you know and love have been renamed using the standard spatial type (ST) prefix. Previous functions are still available, though are not listed in this document where updated functions are equivalent.
When does St contains in PostGIS return true?
ST_Within (geometry A , geometry B) returns TRUE if the first geometry is completely within the second geometry. ST_Within tests for the exact opposite result of ST_Contains. ST_Contains (geometry A, geometry B) returns TRUE if the second geometry is completely contained by the first geometry. 11.5. ST_Distance and ST_DWithin ¶
How to get the type of a geometry in PostGIS?
ST_BoundingDiagonal — Returns the diagonal of a geometry’s bounding box. ST_ExteriorRing — Returns a LineString representing the exterior ring of a Polygon. ST_GeometryN — Return the Nth geometry element of a geometry collection. ST_GeometryType — Returns the SQL-MM type of a geometry as text.