GIS Midterm Flashcards
(31 cards)
How do you select features? (3)
- manually by table or mapview
- select by attributes
- select by location (everything inside/outside/touching)
Difference between join & relate
- A join is a means of appending a spatial layer and a data table (or two separate data tables) together based on a common attribute or field
- Table relates associate data tables without permanently appending them to the base dataset like in a Join
A GIS has the following components ______, ________, ______.
- Computer Hardware and Software
- Spatial Data from the “Real World”
- Trained People
Basic elements of vector data sets (3)
polygons
points
lines
use of census data is an example of use of _____ data
systematic collection of data
reference framework for x & y coordinates is called a ______
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difference between vector and raster data sets
raster:
satellite image, divide the area into arrays of cells and assign attributes to each cell; geographic location of each cell is implied by its position in the cell matrix. Accordingly, other than an origin poin
vector:
less complex than raster, store features as points connected by straight lines and assign attributes to the points/lines; Data can be represented at its original resolution and form without generalization
during process of representing the ‘real world’ in GIS, 2 kinds of generalization are performed. Explain the difference between the 2.
Conceptual
cartographic generalization
Explain spatial analysis method of overlaying a line and a polygon feature data set. Draw a sketch to support your explanation
- always combines attributes
- if a line and polygon combine – a line is the output feature
geomatics
gathering, storing, processing, and delivering geographic information, or spatially referenced information.
What is TIN?
Triangular Irregulated Network
- used for triangles
- describes a surface with irregular points
Continuous fields
features that exist spatially between observations (elevation, precipitation)
best displayed as raster files
Discrete objects
Individually distinguishable features that do not exist between observations (houses, roads etc.)
discrete objects can:
- overlap
- can be counted
- completely cover area under investigation
In GIS, the 4th dimension is:
measurement
x, y, z, measurement
What is GIS?
a computer based system for managing and visualizing geographic data and using this data to solve spatial problems
5 M’s of GIS
Mapping Measurement Monitoring modelling management
Components of a GIS (6parts)
Hardware Software Data Procedures People Network
2 fundamental ways to represent geography
discrete objects
continuous fields
Geographic Phenomena (3)
Discrete
fuzzy
continuous
data model
set of constructs for representing selected objects and processes for the real world on the computer digitally
why is topology important?
- to test quality of a data set
- editing productivity
- optimizing queries
Primary geographic data
sources captured specifically for use in GIS (direct measurement)
Secondary Geographic data
data reused from earlier studies or from other sources
remote sensing
technique to derive info about the physical, chemical, and biological properties of objects without physical contact
- spatial resolution
- temporal resolution
- spectral resolution