2023-01-10 Test Flashcards
GIS
geographical information system
spatial system that creates, manages, analyzes, and maps all types of data
Raster
pixels for graphics/a format of data
vectors
another form of data/mathematical formula
scale
expressed in a ratio
ratio numbers only are useful on paper
scale bars utilized on digital images
if ratio is smaller, then the map is larger scale
large scale maps = high detail but low area
as area covered increases, errors increase
contour lines
lines on a map that indicate topographical differences
iteration culture and collaborative iteration
cite your sources
put your name (who-what-when) on map
file names with hyphens
make them editable later and post your data/layers
copyright notices
Ptopo graphs
show elevation/tophography
hills, mountains, valleys, etc
three Cs
Contrast – separate facetypes and elements that are clearly distinct (attention getting and emphasizes important elements)
Concordant – one type family without variety in shape/style/weight (harmonius but dull)
Conflicting – combination of similar typefaces but not the same (disturbing)
design is ___ for ___ ____
fundamental, communicating effectively
good lies for map making
generalizations such as cities represented as dots
bad lies for map making
chloropleth map (maps that have misleading percentages)
misleading colors (maps that lack a color series)
Tufte’s
Data vs Chartjunk
data to ink ratio matters
how much of the markings on the map actually matter/give meaning
go easy on the grid, let the data shine, not retreat
Campbell’s 6 Principles
use the space given
use normal english
watch the colors
just utilize one legend
put your name on it (who/what/when/where)
high resolution
Geodesy
precise measurement of the Earth’s shape and size
datum
reference point
given that ___, then ___
helps give more precise values
common datums
NAD27 : made in 1927, not used for new maps, utilizes Clark 1866
WGS84 : datum for GPS
types of maps
conformal, equal-area, compromise
conformal maps
conforms to shapes/preserves shape
preserves angles but not lengths
equal area maps
shapes are distorted but not that badly
preserve area measure
compromise maps
not conformal or equal-area
ex: Robinson, Winkle, Equirectangular
contrast
avoid similar elements on the same page
clarifies communication and catches eye
repetition
repeat elements throughout for organization and unity
alignment
each element must have a visual connection with another element
can help with intellectual organization to give the layout more strength
proximity
place related elements close for cohesion and organization
Earth’s Datum
ellipsoid/3D circle
projection
transferring longitude and latitude onto a plane surface
Photography History
remote sensing = photography
1854 - stereophotography
1860 - aerial photos
1914 - panorama
1930s - mass aerial photos from FDR’s new deals
post-1988 - maps become abstractions of aerials
types of photography
stereo
pano
repho
mosaic
stitched panoramas
aerial photos (3 characteristics)
heavily overlap
1: leaf on vs leaf off – representation of foliage within maps, leaf off can allow for more ground feature detail
2: vertical vs oblique – straight down or from an angle
3: orthophoto/orthorectified: corrected for use
ortho
corrected, worked on, can be used, not wobbly
DOQ
digital orthophoto quad
resolution
what you can discriminate from other things/what the smallest entity you can make out on the photo/map
measurements of resolution
pixels (ex: dots per inch [dpi])
scale (1:80,000)
smallest thing you can make out
GPS
Global Positioning System
tells you longitude and latitude
NAVSTAR GPS (1978) becomes GPS for the public
GPS was opened up to the public around the Cold War after Russia shoots down an aircraft accidentally crossing their territory
differential GPS (DGPS)
a system to correct GPS signals that utilizes reference stations nearby to correct mobile GPS receivers
helps selective availability
selective availability
intentional degradation of GPS by the government for national security reasons
Wide Area Augmentation System (WAAS)
uses differential GPS, country-size GPS scale, covers North America only
hardcopy maps
drawn/written/printed
digitizing/digital maps
process of collecting digital coordinates, usually satellite or aerial
map components: data area/pane
largest part of map, contains most of spatial data
map components: netaline
provides frame around map elements
map components: insets
contains additional elements (zoom in of part of map)
map components: map scale
ratio of distance on the map corresponding to ground distance
map components: graticule
lines on a map that represent constant longitude and latitude/set of coordinate lines
map components: grid
line of constant coordinates (doesn’t show latitude or longitude)
feature map
maps points, lines, or areas, nominal information, not ortho/to scale
chloropleth maps
quantitative information
dot density map
quantitative data, dots or other point symbols represent values
isopleth/contour maps
represents continuous surfaces
ex: rainfall, elevation, temperature
map generalizations
unavoidable approximation of real features when represented on a map
map generalizations: fused
multiple features grouped to form larger feature
map generalizations: simplified
boundary/shape details rounded off
map generalizations: displaced
offsetting feature to prevent overlap or provide distance between symbols
map generalizations: omitted
feature is omitted
map generalizations: exaggerated
larger than true size
cartography
art and technique of making maps to communicate spatial data/information
cartography: point
symbol size, unit (1/55th of an inch)
metadata
‘data about the data’
information about spatial data, required for effective use of spatial data
mercator map
useful for navigation in the past for sea
conformal cylindrical
distorts the map and does not show true size of continents
most popular projection because uses relative sizes accurately
pulls the poles and distorts areas around the poles the most
