EXAM 1 Flashcards
define GIS
a computer-based system designed to manage and use geospacial data to solve spacial problems
how might a biologist define GIS?
a system for monitoring and mapping the spatial dynamics of species and ecosystems
Aspatial vs. Spatial Data
spatial data connects aspatial data to accurate geographical reference points, while aspatial data are the attributes.
examples of aspatial data
- temporal data (time)
- salinity
- temp
how is spatial data commonly formatted?
longitude, data
WOULD YOU WANT MAPS TO GIVE YOU DIRECTIONS IN A VECTOROR GRID? WHY
a grid because it will give you directions in a straight line
what is a line made up of?
a series of points
what is a waypoint?
HELP
tell me about longitude
- (x or y?)
- what is its datum?
- what does it run parallel to?
- x is LONG
- tells us if you are east or west of the PM
- the prime meridian is LONG (runs parallel to it)
what is a datum?
a reference point
tell me about latitude
- (x or y?)
- what is its datum?
- what does it run parallel to?
- Y has nice lats
- latitude tells us if we are north or south of the equator
- runs parallel to the equator
what is the prime meridian?
the earths zero of longitude
how are spatial data organized in a GIS?
- global or spherical coordinate system (lat/long)
- Projected Coordinate System (Universal Transverse Mercator Map Projection)
- Local Coodinate System (ex. street address)
How is spacial data categorized as?
- discrete
- continuous
- geographic area
Why do you need to update your spacial data?
landscapes are constantly changing!
what is georeferencing?
connecting a reference point (datum) to a correct location on earth
what is an ellipsoid?
it turns the 3D measurements of the earth into 2D ones
is the world a perfect sphere?
NO because
- there is elevation
- it is oval (egg shaped)
which is longer, the equator or the prime meridian?
the equator
Geoid
sea level is the reference point which then measures elevation vs bathymetry (distance below sea level)
what does the ellipsoid reference back to?
longitude and latitude
what does the geiod reference back to?
sea level
horizontal datum
geospacial scientists have brass plates spaced throughout the world to act as datum. it was last updated in 1983.
vertical datum
manage geoids
bathymetry
the distance you are below sea level
bathymetry
the distance you are below sea level
what is the difference between shapefiles and layers?
Shapefiles: a geodatabase that uses vectors to connect aspatial data with spacial data
Layers: these files are SAVE SYMBOLOGY CHANGES that are connected to the shapefile!!
can you send a layer file?
no.
if you are sending a layer file, what else do you need to send?
a shapefile.
