Answer: A three-dimensional surface to a two-dimensional surface
2.
Which map projection preserves the property of area
Answer: equivalent projection
3.
Which of the following best describes a datum?
A. A mathematical model that transforms a 3-dimensional shape of the Earth on to a plane
B. A mathematical model used to record position on the surface of the Erath using a rectangular grid.
C. A mathematical model used to calculate geographic coordinates
D. A mathematical model that creates a combination of latitudes and longitudes.
Answer: C
4.
Which map type can be utilized to best show population density?
Answer: Choropleth
5.
The general rule for labeling a line feature is to:
Answer: Place the name parallel to and close to the line, and follow the curvy part of the feature
Content preview
GIS
Geo-refencing: link information to the earth’s surface (take an image and assign it to certain parts of
the earth’s surface in order for the image to have geographic meaning)
Coordinate system: system used to record positions in space
Number of axes defines the dimensions of a coordinate system
Two types of coordinate systems
o Plane system: rectangular axis (Cartesian = straight lines that intersect or polar
measurements = measured by distance and angles)
o Spherical: rotation around axis
Geographic coordinate reference system:
Spherical refence: rotation around imaginary axis
Equator perpendicular to axis – northern and southern hemisphere division
Every location on the earth can be defined in terms of latitude and longitude (geographical
coordinates)
o Latitude: North-South (equator = 0)
Parallel: line of equal latitude
Great circles: when drawn will divide the earth in half
o Longitude: East-West (greenwhich = 0)
Angles to find positions are measured from the centre of the earth
The graticule:
All meridians equal length (all lines latitude parallel to equator)
o All parallels maintain the same spacing
All meridians converge at poles
Meridians and parallels intersect at right angles
Geographic coordinate system:
Analogue is measure in degrees minutes seconds (DMS) = on maps and GPS uses this
Digital is measured in decimal degrees (DD) = GIS uses this
o Conversion between the two will take place of DMS to DD
o DD = (degrees + (minutes/60) + (seconds/ 3600))
o Before the first bracket will have + or – sign dependent on what hemisphere it is
o Southern is negative and west of greenwhich
Geodesy: science that studies and measures the exact size and dimensions of the earth
There are bulges that are related to the forces present
larger at the equator due to the fact that there are central fugal forces that create the flattening
impression
Shape of the earth
Geoid: 3D shape of the earth where all the earths surface topography is removed (shape of the
earth at mean sea level
o Average gravity of the earth without any topography
o A very good approximation of the shape of the earth
Spheroid (ellipsoid): the earth revolves easterly on its axis, generating centrifugal forces,
causing a bulge in the middle and flattening at the poles.
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