NoSQL Geographic Databases: An Overview - Geographical Information Systems: Trends and Technologies - page 79

Fig. 1. OGC geometry class.
v. Analysis and Metric Functions: these functions enable to perform
some spatial analysis on the data, including:
• length(): returns the length of the geometry (linestring or
multilinestring);
• area(): returns the area of the geometry (polygon or multi-polygon);
• distance(theGeom): returns the distance between the geometries;
• buffer(distance): returns a geometry that represents all points whose
distance from this geometry is less than or equal to distance;
• convexHull(): returns the minimum convex geometry that encloses
all geometries within the set.
vi. Set functions: these functions are used to perform set oriented
functions on spatial data, including:
• intersection(theGeom): returns a geometry that represents the
intersection of the geometries;
• union(theGeom): returns a geometry that represents the union of
the geometries;