Chapter 3: Data management and processing systems Flashcards
Functional components of GIS
Data capture and preparation, data storage, data analysis, and presentation of spatial data.
Spatial Data Infrastructures (SDI)
The relevant base collection of technologies, policies and institutional arrangements that facilitate the availability and access to spatial data (i.e. arrangements between organisations, arrangements between software systems).
Geo-webservices
A geo-webservice is an online platform that allows users to access and manipulate geospatial data over the internet. It follows open standards set by organizations like the Open Geospatial Consortium (OGC) and provides a standardized way to share, integrate, and analyze geographic information.
Vector data
Vector data represents geographic features as points, lines, and polygons.
Raster data
Raster data represents geographic information as a grid of cells or pixels, where each cell contains a value representing a specific attribute or measurement. It is commonly used to store continuous data, such as satellite imagery or elevation models, and allows for detailed spatial analysis and visualization.
Advantages of raster representation
Simple data structure, simple implementation of overlays, efficient for image processing.
Disadvantages of raster representation
Less compact data structure, difficulties in representing typology, cell boundaries independent of feature boundaries.
Advantages of vector representation
Efficient representation of topology, adapts well to scale changes, allows representing networks, allows easy association with attribute data.
Disadvantages of vector representation
Complex data structure, overlay more difficult to implement, inefficient for image processing.
Maintenance of spatial data
The combined activities to keep the data set up-to-date and as supportive as possible to the user community (such as: obtaining new data, entering them into a system, replacing outdated data)
Spatial decision support systems (SDSS)
An information system composed of a database, FIS software, models, and so called knowledge engine.
Spatial data analysis
Computing new information that provides new insight from the existing, stored spatial data.
Database
A large, computerized collection of structured data.
Database management system (DBMS)
A software package that allows the user to set up, use and maintain a database.
Data model
A language that allows the definition of:
1) The structures that will be used to store the base data
2) The integrity constraints that the stored data has to obey at all moments in time
3) The computer programs used to manipulate the data
Queries
Data extraction from databases without altering it.
Relational data models
A database with a collection of relations (or tables).
Relation (table)
A collection of tuples (records) that are similarly shaped.
(Similarly shaped, i.e. single domain of values. An attribute’s domain is a (possibly infinite) set of atomic values such as the set of integer number values, the set of real number values, etc.
Tuple
An individual row or record in a database table. Each tuple records the values for the columns defined in the table.
Key (relation, tuple)
A key of a relation commprises one or more attributes. A Value of these attributes uniquely identifies a tuple.
(ESRI: An attribute or set of attributes in a database that uniquely identifies each record.)
Foreign key (relation, tuple)
An attribute or set of attributes in one table that match the primary key attributes in another table. Foreign keys and primary keys are used to join tables in a database.
Tuple selection (query, operator)
Works like a filter: it allows tuples that meet the selection condition to pass, and disallows tuples that do not meet the condition. (Wijzigt tabllen op basis van attribuutkwaliteiten (praktische zin: rijen), bijv: AreaSize > 1000.)
Attribute projection (query, operator)
Works like a tuple formatter: it passes through all tuples of the input, but reshapes each of them in the same way. (Wijzigt tabellen op basis van kolommen). This operator produces fewer attributes compared to the input relation.
Relation schema
In a relational database, the schema defines the tables, the fields in each table, the relationships between fields and tables, and the grouping of objects within the database. Schemas are generally documented in a data dictionary. A database schema provides a logical classification of database objects.
Spatial database/Geodatabase
Allows users to store, query and manipulate collections of spatial data.
