Spatial extract, transform, load (spatial ETL), also known as geospatial transformation and load (GTL), provides the data processing functionality of traditional

extract, transform, load In computing, extract, transform, load (ETL) is a three-phase process where data is extracted, transformed (cleaned, sanitized, scrubbed) and loaded into an output data container. The data can be collated from one or more sources and it can also ...

(ETL) software, but with a primary focus on the ability to manage spatial data (which may also be called

GIS A geographic information system (GIS) is a type of database containing geographic data (that is, descriptions of phenomena for which location is relevant), combined with software tools for managing, analyzing, and visualizing those data. In a ...

geographic Geography (from Greek: , ''geographia''. Combination of Greek words ‘Geo’ (The Earth) and ‘Graphien’ (to describe), literally "earth description") is a field of science devoted to the study of the lands, features, inhabitants, and ...

, or

map A map is a symbolic depiction emphasizing relationships between elements of some space, such as objects, regions, or themes. Many maps are static, fixed to paper or some other durable medium, while others are dynamic or interactive. Althou ...

data). A spatial ETL system may translate data directly from one format to another, or via an intermediate format; the latter being more common when transformation of the data is to be carried out.

Transform

The transformation phase of a spatial ETL process allows a variety of functions; some of these are similar to standard ETL, but some are unique to spatial data. Spatial data commonly consists of a geographic element and related attribute data; therefore spatial ETL transformations are often described as being either ''geometric transformations'' – transformation of the geographic element – or ''attribute transformations'' – transformations of the related attribute data.

Common geospatial transformations

* Reprojection: the ability to convert spatial data between one coordinate system and another. *Spatial transformations: the ability to model spatial interactions and calculate spatial predicates *Topological transformations: the ability to create topological relationships between disparate datasets *Resymbolisation: the ability to change the

cartographic Cartography (; from grc, χάρτης , "papyrus, sheet of paper, map"; and , "write") is the study and practice of making and using maps. Combining science, aesthetics and technique, cartography builds on the premise that reality (or an im ...

characteristics of a feature, such as colour or line-style *

Geocoding Address geocoding, or simply geocoding, is the process of taking a text-based description of a location, such as an address or the name of a place, and returning geographic coordinates, frequently latitude/longitude pair, to identify a locatio ...

: the ability to convert attributes of tabular data into spatial data

Additional features

Desirable features of a spatial ETL application are: *Data comparison: Ability to carry out change detection and perform incremental updates *Conflict management: Ability to manage conflicts between multiple users of the same data *Data dissemination: Ability to publish data via the internet or deliver by email regardless of source format *Semantic processing: Ability to understand the rules of different data formats to minimize user input whilst preserving meaning

Spatial ETL uses

Spatial ETL has a number of distinct uses: *

Data cleansing Data cleansing or data cleaning is the process of detecting and correcting (or removing) corrupt or inaccurate records from a record set, table, or database and refers to identifying incomplete, incorrect, inaccurate or irrelevant parts of the dat ...

: The removal of errors within a dataset * Data merging: The bringing together of multiple datasets into a common framework –

conflation Conflation is the merging of two or more sets of information, texts, ideas, opinions, etc., into one, often in error. Conflation is often misunderstood. It originally meant to fuse or blend, but has since come to mean the same as equate, treati ...

is a good example of this * Data verification: The comparison of multiple datasets for verification and quality assurance purposes *

Data conversion Data conversion is the conversion of computer data from one format to another. Throughout a computer environment, data is encoded in a variety of ways. For example, computer hardware is built on the basis of certain standards, which requires th ...

: Conversion between different data formats.

Spatial ETL – origins and history

Although ETL tools for processing non-spatial data have existed for some time, ETL tools that can manage the unique characteristics of spatial data only emerged in the early 1990s. Spatial ETL tools emerged in the

industry to enable interoperability (or the exchange of information) between the industry's diverse array of mapping applications and associated proprietary formats. However, spatial ETL tools are also becoming increasingly important in the realm of

management information system A management information system (MIS) is an information system used for decision-making, and for the coordination, control, analysis, and visualization of information in an organization. The study of the management information systems involves peo ...

s as a tool to help organizations integrate spatial data with their existing non-spatial databases, and also to leverage their spatial data assets to develop more competitive business strategies. Traditionally, GIS applications have had the ability to read or import a limited number of spatial data formats, but with few specialist ETL transformation tools; the concept being to import data then carry out step-by-step transformation or analysis within the GIS application itself. Conversely, spatial ETL does not require the user to import or view the data, and generally carries out its tasks in a single predefined process. With the push to achieve greater

interoperability Interoperability is a characteristic of a product or system to work with other products or systems. While the term was initially defined for information technology or systems engineering services to allow for information exchange, a broader defi ...

within the GIS industry, many existing GIS applications are now incorporating spatial ETL tools within their products; the

ArcGIS ArcGIS is a family of client, server and online geographic information system (GIS) software developed and maintained by Esri. ArcGIS was first released in 1999 and originally was released as ARC/INFO, a command line based GIS system for manipul ...

Data Interoperability Extension being a good example of this.

Transform

Common geospatial transformations

Additional features

Spatial ETL uses

Spatial ETL – origins and history

See also