Exam 1 Flashcards
(26 cards)
What is a Datum?
A mathematical model which estimates the shape of a spheroid
Planar/azimuthal
Flat piece of paper
Cylindrical
Cylinder (up and down, around equator)
Transverse cylindrical
Cylinder (side to side, around prime meridian)
Conic
Cone
Tangent
around globe
secant
within globe
Standard Parallels
Lines where there are no distortion, where projection touches the globe. (Cylindrical and conic)
Mercator
Surface is cylindrical tangent to globe best at mapping distances and direction distortion greatest at polar regions Projection is conformal Used for navigation
Transverse Mercator
Projection is cylindrical
tangent to meridian
best at mapping distance, direction, shape, and area
Further from 15 degrees, greater distortion
Conformal
Used for mapping north south areas that are large
Lambert Conformal Conic
Projection surface is conic
secant to globe
best at distance along standard parallels
Distortion greatest away from standard parallels
Projection conformal
Used for topographic maps
Albers Equal Area
Projection surface is conic
secant to globe
Best at mapping areas
distortion greatest away from standard parallels
Robinson
Projection surface orthophanic secant to earth best at distances and directions distortion greatest at and around poles used in atlases
Geographic Coordinate system
Degrees, minutes, seconds
Not a true grid
Coordinate system for a globe
Latitude and Longitude
UTM
Universal Transverse Mercator Transverse mercator projection Tangent along meridian Earth soil into 60 zones Each zone is 6 degrees in width each zone is its own coordinate system Units are meters
State Plane Coordinate System
Each state divided into its own coordinate system
Horizontal uses Lambert conformal conic
vertical uses transverse mercator
Units are feet
Public Land Survey System
Township (North to South)
Range (East to West) lines every 6 miles from initial point
Townships = 36 sections
section = 1 mile squared
1 mile squared
640 acres
7 map elements
neat line map figure legend north arrow source block Title Scale
Nominal
Qualitative data (streams, roads, trees)
Ordinal
Differentiation by class or rank
Interval
ordinal or rank data with values
based on arbitrary scale (temperature)
Ration
Ordinal or rank data with values
based on absolute scale
zero is not arbitrary
(population, age)
Portions of EM spectrum that we use in remote sensing
the visible
the infrared
the microwave/radar
