Spatial Operators, Dynamic Spatial Operators and Spatial Queries in DBMS
1. Spatial operators :
Spatial operators these operators are applied in geometric properties of objects.
It is then used in the physical space to capture them and the relation among them.
It is also used to perform spatial analysis.
Spatial operators are grouped into three categories :
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- Topological operators :
Topological properties do not vary when topological operations are applied, like translation or rotation.
Topological operators are hierarchically structured in many levels. The base level offers operators, ability to check for detailed topological relations between regions with a broad boundary. The higher levels offer more abstract operators that allow users to query uncertain spatial data independent of the geometric data model.
open (region), close (region), and inside (point, loop).
- Projective operators :
Projective operators, like convex hull are used to establish predicates regarding the concavity convexity of objects.
Having inside the object’s concavity.
- Metric operators :
Metric operators’s task is to provide a more accurate description of the geometry of the object. They are often used to measure the global properties of singular objects, and to measure the relative position of different objects, in terms of distance and direction.
length (of an arc) and distance (of a point to point).
2. Dynamic Spatial Operators :
Dynamic operations changes the objects upon which the operators are applied. Create, destroy, and update are the fundamental dynamic operations.
Updation of a spatial object via translate, rotate, scale up or scale down, reflect, and shear.
3. Spatial Queries :
The requests for the spatial data which requires the use of spatial operations are called Spatial Queries.
It can be divided into –
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- Range queries :
It finds all objects of a particular type that are within a given spatial area.
Finds all hospitals within the Siliguri area. A variation of this query is for a given location, find all objects within a particular distance, for example, find all banks within 5 km range.
- Nearest neighbor queries :
It Finds object of a particular type which is nearest to a given location.
Finds the nearest police station from the location of accident.
- Spatial joins or overlays :
It joins the objects of two types based on spatial condition, such as the objects which are intersecting or overlapping spatially.
Finds all Dhabas on a National Highway between two cities. It spatially joins township objects and highway object.
Finds all hotels that are within 5 kilometres of a railway station. It spatially joins railway station objects and hotels objects.
- Range queries :