This topic introduces terms about HBase Ganos.
Spatio-temporal geometries in HBase Ganos include the following:
- Objects of spatio-temporal geometries
- Vector data, such as the Point, Line, and Plane features.
- Spatial data (spatial trajectory data) consists of vector data and temporal attributes.
- Operations related to objects of spatio-temporal geometries, such as spatial relation verification.
HBase Ganos supports high-performance data queries, which is based on spatio-temporal indexes. Spatio-temporal indexes are stored as rowkeys in HBase Ganos. For more information, see Create an index table.
A spatio-temporal relation describes the locations of two geometries in time and space in relation to each other. Typical spatio-temporal relations include INTERSECT, DISJOINT, OVERLAP, and CONTAIN. A geofence usually refers to the relations of the geofences of an area to an object (Point, Line, or Plane). If the object lies inside the geofences, the area contains the object. If the object lies outside the geofences, the area and object are disjoint. HBase Ganos uses Common Query Language (CQL) to define spatio-temporal relations. For more information, see Create an index table.
OGC is short for Open Geospatial Consortium. It is an international voluntary consensus standards organization. It has created a set of standards for data models and related operations. Geographic information system (GIS) vendors develop geographic information systems based on these standards to ensure that their systems can interact with spatial databases.
The SDK of HBase Ganos is based on GeoTools. GeoTools is a library that provides tools for processing geospatial data. It complies with OGC standards, and can interact with OGC standard data models and interfaces. Many geographic information systems are developed based on GeoTools. For more information, visit https://geotools.org/.
A geometry in OGC is defined as a spatial object, such as a point, a line, or a plane. A geometry only contains location information of a spatial object. It does not contain any attribute information. GeoTools provides tools for you to build geometries when you use HBase Ganos.
Simple features. A SimpleFeature contains geometries and other attributes. A trajectory point is a SimpleFeature. The SimpleFeature contains the location information of the trajectory point, temporal information, and other attributes. The temporal information is also a part of the attribute information.
CQL & ECQL
Common Query Language (CQL) is a language defined by OGC to support geospatial data queries. Extended Common Query Language (ECQL) is an extension of CQL and is more powerful than CQL. In most cases, ECQL is used to define filters by using SQL-like where clauses based on the well-known text representation. For more information, see Query spatio-temporal objects. CQL described in this user guide refers to ECQL.
Well-known text (WKT) is a text markup language defined by OGC to describe spatial objects. For example, a point can be represented by using POINT(0,0). WKT is commonly used in query statements and is much easier to read. CQL and ECQL also use WKT to describe spatial objects. For more information about WKT, visit http://www.opengeospatial.org/standards/wkt-crs.
Well-known binary (WKB) is a language defined by OGC to mark up geometries by using byte arrays. WKB data is smaller than WKT data. You can use WKT for data transmission. GeoTools provides a tool for you to transform data between WKB and WKT.