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213 Cards in this Set
- Front
- Back
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geocentric view
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orienting yourself with respect to the external environment
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cardinal directiosn
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N S E W
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meridian
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north south lines
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cartographic map
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graphic representation of the environment
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5 characteristics of a map
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vertical or oblique views of the env
created at a reduced scale map projection-change spherical to fit flat generalized representations symbolized representations |
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topographic map
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shows elevations and landforms
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orthophotomap
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topographic with photo superimposed
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aerial photograph
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not a map projection surface,only a photo showing scale and elevation differences
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reference map
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maps that serve as a reference library of geographic informatoin
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thematic maps
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tell an essay about a particular subject in the geospatial context
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propaganda maps
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persuasive maps that distort information
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map use
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the process of obtaining useful infomration from one or more maps to help you understand the environment and improve your mental map
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3 main activities of map use
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read
analyze interpret |
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parallels
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e to w lines
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lat and long are measured by
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the angular distance of a parallel from the equator and a meridian from the prime meridian
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Tropic of cancer and capricorn
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cancer (north hemisphere)
capricorn (southern hemisphere) where the sun is directly overhead on the summer and winter solstices |
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graticule
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arrangement of parallels and meridians
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numerical range for latitutde
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0 to 90
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numerical range for longitude
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0 to 180
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babylonian sexagesimal system
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uses degree, minutes, and seconds to pinpoint location
60 minutes a degree 60 seconds a minute |
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decimal degree system
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does not use NSEW
equation: dd+ mm/60 + ss/3600 dd = degrees mm = minutes ss = seconds |
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Where is the prime meridian located
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in greenwich, a suburb of london
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equation for centrifugal force
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m*v^2*d
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semiminor and semimajor axis
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minor - N to S axis sliced in half
major - E to W axis sliced in half |
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geodetic latitude
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angle made by the equator and a line perpendicular to the parallel of interest on the ellipsoid of the earth
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equitorial and polar radius
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equitorial - 6378.137
polar - 6356.75231 |
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geodetic longitude
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angle between the line from a point on the surface to the center of the earth to the prime meridian
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authalic sphere
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a sphere with the same SA as the reference ellipsoid being used
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statute miles vs nautical miles
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statute are used on land
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equation for converging meridians
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69.09 miles / deg. x cosine (lat)
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great circle, small circle, quadrilaterals
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great- larger circle on ellipsoid
small- when you have overlaps with another circle quadrilaterals- bound by equal lat and long |
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control points
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points on a map of known accuracy
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monument
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a fixed object established by surveyors where they know the exact location
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why do we treat the earth as smooth when it is authalic or oblate
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because the mountains and trenches are relatively small in comparison to the diameter of the earth
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rules for sig figs for if rounding with a 5
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round up for odd, for even stay the same (round down)
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rules for sig fig addition
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decimal in the place of the one with the least amount of sig figs
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scale denominator
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has a one in the numerator and the "scale denominator" in the denominator
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map scale
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tells you the relationship between distances on the map and their corresponding ground distances.
gives you an idea of how small the map is relative to real life |
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representative fraction
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ratio between the map and ground distance
shown as 1:x x = scale denominator |
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why would a scale bar be extended to the left past 0?
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to show smaller units
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on what type of map projection will you see a variable scale bar
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mercator map projection
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what is the typical dividing point between large and small scale maps
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1:500,000
1 inch represents 500,000 inches |
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conversions that need to be known
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1 foot = 12 in
1 statute mile = 5280 ft 1 statute mile = 63,360 1 km = 100,000 centimeters |
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length of the equator in miles
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24901.46 miles
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actual scale
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the scale that you measure at any point on the map; it will differ from place to place because of geometric distortion
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principal scale
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the scale of the globe as it is reduced to its desired size
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scale factor
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actual scale / principle scale
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completeness
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ability of a map projection to show the entire earth
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continuity loss
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when a sphere is broken to be represented as a flat image. At one meridian , it will be represented twice on either edge of the map
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conformal
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when angles on the globe are preserved on the flat map
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true direction projections
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projections that preserve global directions
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azimuth
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direction from a reference point
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projection families
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planar, clyindrical, and conic
*imagine a light radiating from the earth and projecting a shadow of the landforms of the earth |
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three perspectives for planar projections
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orthographic (light source at infinity)
stereographic (light source on the surface of the globe opposite to the pooint you are looking at) gnomonic (light at center of globe) |
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tangent case projection
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the projection surface will only touch the globe at one point, or along one line (this is the case for a cone)
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secant case projection
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the projection surface intersects the globe at a small circle of tangency
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advantages to secant case
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there is less distortion
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what are tangent projections used for
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equidistant projections usually
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aspect
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location of the point or lines of tangency on the projection surface
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equitorial aspect
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when the projection line is on the equator
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transverse aspect
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used with cylindrical projections to refer to when the line of tangency is shifted 90 degrees to follow a pair of meridians
*tube turned horizontal instead of vertical |
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oblique aspect
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an aspect that is not polar, equitorial, or transverse
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orthographic projection
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shows the earth as how it looks from a distant planet
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stereographic projection
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light source from the antipodal point of the globe
usually used for polar views |
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what is a gnomic projection used for
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navigation for great circle routes
seismic and radio waves |
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Mercator map is projected how
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cylindrical conformal projection
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benefit of a mercator map
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that it is good for compass bearings
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what is the difference between a map and a cartographic map
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a map is a spatial representation of an environment, while a cartographic map is a graphic representation of an envrionment
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what makes maps popular
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convienient to use
simplify our surroundings credible strong visual impact |
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3 different types of maps
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reference, thematic, and navigation
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Ex of reference maps
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topographic map of Oregon, globe, road map
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Ex of thematic maps
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ones that will show a piece of information, such as demographic information, spread out over spatial map
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Ex of navigation map
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topographic maps, nautical charts, and aeronautical maps
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three ways to represent scale
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representative fraction
verbal scale (a sentence) scale bar |
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what is the difference between geocentric and geodetic coordinates
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geocentric is using a sphere
geodetic is using an oblate ellipsiod |
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grid coordinate system
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plane-rectangular system where the earth is projected to fit a flat surface and regularly space lat and long are used
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cartesian coordinate system
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uses x and y axis and quadrants for mapping
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What does UTM stand for
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universal transverse Mercator system
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UTM extends through what latitude
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84 N to 80 S
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How many zones are in UTM and how much longitude is in each one?
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sixty NS zones with 6 degrees long
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what is an easting?
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the E-W x coordinate in a grid coord system
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what is a northing?
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the N-S y coordinate
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false easting values
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easting = 500,000 m
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how do you report in UTM
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easting, northing, zone, hemisphere
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What does UPS stand for
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universal polar stereographic system
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UPS system
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does complete global coverage with the rectangle system as well.
has N and S zone is imposed on secant polar stereographic projection |
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UPS grid center
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2,000,000 mE 2,000,000 mN
no negative numbers |
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state plane coordinate (SPC) system
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creates grids and zones to make selling parcels of land easier
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SPC zone system
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follow state and county lines
each zone has its own central meridian uses ft instead of m |
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what is the difference between geocentric and geodetic coordinates
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geocentric is using a sphere
geodetic is using an oblate ellipsiod |
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grid coordinate system
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plane-rectangular system where the earth is projected to fit a flat surface and regularly space lat and long are used
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cartesian coordinate system
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uses x and y axis and quadrants for mapping
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What does UTM stand for
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universal transverse Mercator system
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UTM extends through what latitude
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84 N to 80 S
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gnomonic projection
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shows all great circle lines, the shortest location between two points is what is depicted on the map
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azimuth
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angular measurement on a spherical coordinate system
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rhumb lines
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lines of a constant compass heading
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straight lines on a mercator projection represent
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rhumb lines
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straight lines on a gnomonic projection represent
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great circles
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loxodromic curve
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the curve from following a rhumb line on a standard globe, spiral-like
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what way do you measure great circl azimuths
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intersections with meridians, going clockwise
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mercator projections have constant
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compass bearings
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quadrilaterals
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areas bound by the same lat and long increment
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aspect ratio of quardrilateral with increasing latitude
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aspect changes to cosine (latitude)
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SPC coordinates increase which way?
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moving east and north
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two ways of thinking of distance
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physical distance- a measured amount in standard unit of distance
or functional distance - distance measured at expenditure or cost, time, and energy |
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geographic mile
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represents a fraction of a degree of the earths circumference
6087.1 ft |
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knot
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velocity of one nautical mile and hour
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a meter is defined relative to what
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the speed of light
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two major ways for finding distance on large scale maps
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measure distance and compare it to a scale bar
use the representative fraction to convert the map distance to ground distance |
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how do the length of lines for distance measuring affect error
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the shorter the line, the more accurate the distance measured
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external errors
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result from the methods you use, judgements you make, calculations, etc
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internal errors
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results from the nature of the map itself. such as trying to fit a 3D world onto a 2D projection
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slope error
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the fact that most measurements are made on a flat surface when the earth is not like that in reality
the greater the slope, the greater the slop error |
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smoothing error
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maps may be smoothed by mapmakers to make lines straighter and remove irregularities
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scale variation
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no map projection maintains a constant correct scale throughout can lead to error
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disproportionate symbol error
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the size of a symbol is not proportional to its ground size (usually it is depicted larger in the proportion)
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displacement
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when features are spaced so that they don't visually run into each other, but, in fact, because of the disproportionate symbol effect, moving the objects for space distorts them from reality
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dimensional instability
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when the medium that the map is printed on changes
ex: paper can change its shape and size depending on if it is hot or cold |
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distance segments
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premeasured ground distance that is place between road intersections to give real distance
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distance insets
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double ended arrows with names of features and the distances between them
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mileage map
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routes between highlighted locations are shown as straight lines and labled with the accurate distancedist
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distance tables
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tables that identify the premeasured ground distance between a select set of locations
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route segments
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put on maps to make up for functional time, and they give the travel time between distances
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travel-time maps
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show with straight lines and how much time it takes to get between locations
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isochrones
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lines of equal travel distance time
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thinking geocentrically
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thinking in terms of geographical direction
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true north
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a geographical fixed location, the north pole of the axis of the earth's rotation
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true north reference line
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any meridian that originates from the true north
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Where is the north star
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on the handle of the little dipper
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grid north
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the northerly or zero direction indicated on the datum of the map
it does not refer to a geographical place, it is artificial |
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grid declination
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the angular difference between true north and grid north
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magnetic north
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the direction that your compass needle points to at the earth's magnetic pole
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magnetic declination
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the angular difference between true and magnetic north
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isogonic lines
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lines of constant angular distance between true and magnetic north
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agonic line
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where magnetic north and true north line up
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Compass direction systems
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compass points
azimuths bearings |
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compass points
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points indicated by arrows on the graphical face of a compass
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azimuth
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horizontal angle measured in degrees clockwise from a north reference line to a direction line
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bearings
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measured in degrees but only 0 to 90
measured either clockwise or cclockwise give reference line (NS) and orientation (EW) |
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divisions in land partitioning
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parcel
tract lot |
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plat
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maps drawn to scale to show lots in which the area has been subdivided
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metes and bounds
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a way of partitioning land based upon geographic features such as rivers, etc
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seigneuries
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parcels of land given to the elite and soliders in the french feudal system
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french long lots
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strips of land claimed along river banks. the strips were created by the owners of seigneuries, who then let everday people settle on them
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land grants
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parcels of land given to an owner before the land was given to the US
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pueblo grants
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issued to native american communities primaryily indian reservations in new mexico
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private grants
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property by the governments that could be sold by the owner and were made to individuals as a rewards for service to the government
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community grants
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land parcels that were given to groups of settlers
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donation land claim
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a 160 acre pacel that was given to settlers if they were on public land betfore the 1851 OR Wa ID treaty
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centuriation system
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a system of land partitioning first developed in roman times where land was divided into a grid and given away in parcels
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what is the foundation of the US Public Land Survey System
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the centuriation system of using grids
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initial points and PLSS
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the initial point to determine the parallel and meridian to base partitioning off of
the parallel is called the geographer's lie the meridian is called the principal meridian |
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range lines
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6 mile interval e-w marks from the initial point
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township lines
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6 mile intervals n-s marks
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township
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area bounds by 6 mi range and township lines
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rows and columns on PLSS system
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rows townships
columns ranges |
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indicating location in PLSS system
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T#(NorS), R#(EorW)
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sections
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townships divided into parcels of 640. a seciton is one unit
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correction lines
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established every 4th township to correct because meridians converge towards the north pole
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government lot
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designed when a parcel hits a body of water
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platted lots
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parcels in a platted subdivision within a section
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dominion land survey
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public land survey system to divide canada's prairie land and western provinces
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what is different about the dominion land survey in comparision to plss
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the numbering order in a section is different
range lines ID with roman numerals township lines only numbered |
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land records
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public records of who owns land
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Slope error increases with
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increasing map distance and increasing slope
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orient
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to align a map with the directions on the ground
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inspection method
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a technique of orienting maps where you do not need to know where north is
orient according to the objects that are around you, such a as road |
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compass method
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orienting by finding magnetic north
align the compass needle on the map and on the magnetic north of the actual compass |
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the difference between true north and magnetic north
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20 degrees
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distance estimation by the inspection method
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find specific features on the ground, locate them on the map. estimate your ground distance and then find your map distance
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why can it be hard to judge distance
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because of the ocular vanishing point: the point on the horizon where parallel lines appear to converge
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compass method of distance estimation
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find the angle to your object, locate the back azimuth and draw a line on the map
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resection method
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using 3 objects to triangulate your position
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what is crucial with the resection method
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keeping you and the object in your line of sight as close to 90 degrees as possible
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stadia principles
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a way of measuring distance using equipment that is based on using a constant angle to determine distance between a marker and a sighting device
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laser rangefinder
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using infrared to measure distances up to 1,000 yds
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altimeter
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measures the height above a fixed level
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intersection method
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taking angles from multiple points towards an object and plotting those to find out your location.
opposite of resection |
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trilateration method
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finding a location of a distant feature using only the distances from known locations of the feature
uses a drafting compass |
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navigation has how many parts
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2
planning your route following your route |
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Peutinger table
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A Roman simplified map that was distorted to show the road network and cities along the routes
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sounding
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depth measurement
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isobath
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bathymetric contours
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dead reckoning
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used in nautical navigation where you determine your position based on where you are now relative to your last accurate location
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what is the standard for writing coordinates/direction in nautical
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course heading first then the boat speed
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piloting
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following your route using landmarks and water depth to aid navigation
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scale on world aeronautical charts and sectional aeronautical charts and terminal charts
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1:1,000,000
1:500,000 1:250,000 |
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absolute positions
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a specific position defined by coordinates such as lat/long, utm, spc, etc
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two components of gis data
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feature - the spatail aspect
attribute - describes some characteristic of the feature |
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space trilateration
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used in GPS, where distance is measured in multiple locations based upon velocity and time of the signals to get to the location it was received
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What are the components of GPS
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a space segment, such as a satellite
user segment is the receiver that is tuned to the frequency of the space segment control segment is the set of ground montoring systems that keep track of the satellites and their health |
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where are GPS satellites positioned
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medium earth orbit
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posigrade orbit
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moving with the direction of the earth's orbit
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selective availability
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intentionally degradating the accuracy of the gps signal so that it could not be used by hostile forces
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the accuracy of a gps depends upon
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field conditions
location length of time arrangements of satellites in the sky |
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satellites and a solar day
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satellites will appear 4 min earlier than they did earlier in the day
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normal triliteration
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the method of determining relative position by the geometry of triangles
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what is a large source of error in GPS
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the clocks not being sychronized
your position can be different because the two ranges of the gps will intersect at a different time than if they were synchronized |
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elevation determiniation and gps
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gps are based off of the wgsd84 ellipsoid, which is a mathamatical model of the earth's surface.
the gps heights are based on ellipsoid approximations rather than real life |
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three sources of gps bias
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the satallites
the gps signal the receiver |
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range noise
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random error in gps
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observation noise
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white noise of other ionospheric influences
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error budget
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describes the contribution of each sourceof error to the overall eroor of the satellite range of measurement
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ionospheric effects
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what layer of the atmosphere that the satellite is in can alter the speed and direction of a signal
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receiver clock effects
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the clocks inside of gps receivers are not as effective as atomic clocks
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ephemeris bias
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error in the position of the satellite due to the earth's gravitational pull
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multipath error
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when the path of the gps bounces before it makes it to the receiver
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agonic line
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the line of zergo magnetic declination along whihc the true and magnetic north poles are aligned
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if NS utm grid lines tilt to the east...
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the mapped region lies east of the central meridian of the utm zone
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if the magnetic north line tilts east
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mapped region is west of the agonic line
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to get the back of an azimuth or bearing what should one do?
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go backwards 180 degrees
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explain how bearings are reported
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in 0 to 90 degree increments eeither W or E of North, or W or E of South
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