Lecture 3 Spatial data models and databases Flashcards
What are the two types of data models?
Raster data model and Vector data model
Name the two types of GIS features
Topological features and simple features
Define topology and its three elements
Topology is a combination of science and maths and is used to validate the geometry of vector entities.
- Adjacency
- connectivity
- enclosure
Three common rules defined in geographic object model
Attribute rule
connectivity rule
geographic rule
Define the characteristics of raster data?
It is represented by an array of cells which are arranged in rows and columns and each cell contains a value that describes the phenomena being examined.
Define Georeferencing?
Georeferencing is the process of assigning geospatial positioning information to raster data based on a defined coordinate system
Does increasing the points in a vector data model increase the quality of the image? how about increasing the grid size in a raster data model?
It does increase the quality of the image.
What is a GIS database used for?
A GIS database is used for storing attribute data
What are the two types of GIS databases? define each
Flat-file database - is used to store data in a single table structure
Relational database - is a database that groups data using common attributes found in the data set
What are the 4 types of database relationships?
One to one
One to many
Many to one
Many to many
2 Differences between relating tables and joining tables
= Joining tables physically combines tables unlike relating tables
= Joining tables has one-to-one and one-to-many relationships only while relating tables can have all relationships
