Representing Spatial Data Flashcards
(54 cards)
Name the four different approaches to spatial analysis
Spatial data manipulation
Spatial data analysis
Spatial statistical analysis
Spatial modeling
Spatial data manipulation
The ability to input, manipulate and transform data once it has been created
Spatial data analysis
It describes datasets and explores identified patterns and processes
Spatial statistical analysis
Uses spatial statistical techniques to deduce the possibility of modeling theories and results obtained from a dataset
Spatial modeling
Predicted spatial outcomes of the investigated phenomena can form the basis of a model to determine effects of processes
Give reasons why modern methods of spatial analysis seem to be poorly represented in the tool kits provided by the typical GIS
The understanding of spatial data from a GIS view and a spatial analysis view differ.
Spatial analysis is not widely understood.
The spatial analysis perspective can sometimes obscure the advantages of GIS.
GIS data models
They are ways of dividing geographic space so that it can be represented digitally.
Discrete data
Independent numbers
Abrupt boundaries
Example of discrete data
cover-type map
Continuous data
range of numerical values
spatial gradient
Example of continuous data
elevation map
Point objects
Defined as an X,Y and Z coordinates that represents an entity on the ground.
Line objects
A connection between 2 or more points.
Area objects
A collection of connecting lines that create a polygon.
Vector data
A collection of points in geographic coordinates.
Represent objects as points, lines and polygons.
Vector data advantage
File sizes are generally small.
Quite precise in defining objects.
Store multiple attributes with each object.
Vector data disadvantages
Location of each vertex needs to stored explicitly.
Data structures are homogeneous objects.
Don’t have information about the variation within an object.
Raster data
Use regular grid to cover space.
Records an attribute value for each location of the grid cell.
Data structure is continuous.
Each location in space has a value assigned to it.
Raster data advantages
no geographic coordinates stored
data analysis is usually easy to program
discrete and continuous data
Raster data disadvantages
cell size determines the resolution
rasterization introduces data integrity
most output maps don’t conform to high-quality cartographic needs
Spatial object
Describe the world as a space made up of discrete units that have a defined spatial reference such as geographic coordinates.
Vector.
Spatial fields
Describe the world as a collection of spatial
distributions of phenomena. A spatial field is, by definition, continuous.
Raster.
Object view
Digital representation of all or part of an entity
classified into different types
instantiated by specific objects
associated behavior
Field view
spatial continuity self definition every location has a value sets of values taken together define a field can represent categorical data
