SPATIAL DATA Flashcards
What is the graticule?
Network of latitude and longitude lines on a map
Georeferencing
providing a description of where you are on the surface of the earth.
What are the equivalent words for latitude and longitude
longitude: meridian
lattitude: parralel
What is the true shape of the earth?
Roughly ellipsoid (dents and bumps due to differences in gravity)
What is a cartesian mapping system?
-A Flat Graph (UTM)
Describe UTM
Northings -0-10,000 km N -10,000 - 0 km Eastings -Starts at 500,000 - gets smaller to the west/ greater to the east
What gets distorted in projections?
- Area
- Shape
- Distance
- Direction
How many UTM zones cover BC?
5 (6 degrees each) - cannot create a full map of BC
Is BC affected by distortion on the UTM projection?
A very negligible amount
What are spatial entities?
Points - spots captured by data
Lines - roads / streams (networks when connected)
Polygons - area’s
Surfaces
What does 3d modelling refer to?
Surfaces
What does GCS refer to?
Geographic coordinate system
-refers to datum (version of lat long)
(NAD83, NAD27) WGS84 common for world
What is PCS
Projected coordinate system
- Maps are planar
- GIS draws to a planar system but it is converted from a sphere.
- UTM (only PCS studied)
What are some typical data sources?
- thematic maps (forest cover, census)
- satellite (Spot, Landsat, Quickbird)
- air photos (orthophoto)
- Field surveys (notes or GPS)
What does map scale refer to?
Ratio between the size of features on map and the size of the real world features. 1:5000 means that the real world distances are 5000 times larger than distances on that map.
