Lecture 3 Spatial data models and databases

Question 1

What are the two types of data models?

Answer 1

Raster data model and Vector data model

Question 2

Name the two types of GIS features

Answer 2

Topological features and simple features

Question 3

Define topology and its three elements

Answer 3

Topology is a combination of science and maths and is used to validate the geometry of vector entities.

• Adjacency
• connectivity
• enclosure

Question 4

Three common rules defined in geographic object model

Answer 4

Attribute rule
connectivity rule
geographic rule

Question 5

Define the characteristics of raster data?

Answer 5

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.

Question 6

Define Georeferencing?

Answer 6

Georeferencing is the process of assigning geospatial positioning information to raster data based on a defined coordinate system

Question 7

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?

Answer 7

It does increase the quality of the image.

Question 8

What is a GIS database used for?

Answer 8

A GIS database is used for storing attribute data

Question 9

What are the two types of GIS databases? define each

Answer 9

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

Question 10

What are the 4 types of database relationships?

Answer 10

One to one
One to many
Many to one
Many to many

Question 11

2 Differences between relating tables and joining tables

Answer 11

= 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