chap 5, 8 Flashcards
(47 cards)
5km cest combien en metre
5000m
5cm cest combien en km
500,000km
Exercise: If the graphic scale shows by measurement
that 2 cm represents 5 km, what is the RF of your map?
The RF is 1:250,000
Exercise: You have a map with a RF of 1:75,000 and
you want to draw a graphic scale representing 1 km
on it. How long should be your graphic scale in cm?
1.33 cm on your map would represent 1 km on the
ground
map projection
transforming the curve surface to a flat surface
mercator map projection
preserve shape, changes areas
equal-area map projection
preserve area, distorts shape (gall-peter projection)
Mollweide projection
minimiza shape distortions of regions of greatest interest
peters (gall-peters) projection
qual-area map, but shape not conserved, cylindrical equal-area projection, highlight the importance of the size of southern continent
the geographic coordinate system (GIS)
preserves nothing but distance
the van der grinten projection
does not preserve shape or area, but minimizes their distortions in all but polar regions
robinson projection
preserves neither area nor shape, but reduces the distortion of both
small scale
large area, more generalization, more classification
large scale
smaller area, more details
universal transverse mercator (UTM)
divided into 60 zones, each 6 degree wide
state plane coordinate system (SPCS)
used only in the united states, which is divided into over a hundred areas
geoid
more irregular than the ellipsoids but smoother than Earth’s physical surface
Graticule
imaginary network of parallels and meridians
two Coordinate systems
non-projection coordinate system and projected coordinate system
non-projected coordinate system
geographic coordinate; based on lat/long which correspond to angles at the center of the earth based on an origin and on an ellipsoid
serve for; locating precisely each earth feature
representing the earth (3D) on a map (2D)
preserves distance, but does not preserve shape or area
projected coordinate system
the mathematical transformation applied to convert a spherical coordinate system to a planar coordinate system
different types of projections based on
source of projection
projection surface
flat plane
conic
cylindrical
center of projection; contact between projection surface and ellipsoid projected (point or line)
Polar (center on a pole)
Equatorial (center on the equator)
Transverse (center to a line at 90° to this earth’s polar axis (parallel to equator)
Oblique: center on a non-specific point/line
projection preserve either
shape
area
distance/direction
most of everything
multiple media to show your map
computer monitor
black and white, on paper
color, on paper
projected
posters