Home > Flashcards > Print Preview
The flashcards below were created by user
akatherine
on FreezingBlue Flashcards. What would you like to do?

Ranking of precision
 13 very good
 45 good
 6 fair
 >6 suspect

High delusion of precision
 satellites close to each other
 inaccurate data

Low delusion of precision
 satellites to be distributed
 data more accurate

Almanac information
 Predicted orbits of the satellites by #
 Stored in the satellites, downloaded as a code into the receivers
 Takes 1015 minutes to download the data when outside
 Usually good for 2 months

Time it takes for signal to travel to the receiver
D = V x T_{Δ}

Multipath errors
 Usually comes in at a low angle
 Would likely not be used in identifying location

Color schemes
 Different from color system
 Applied in choropleth mapping

Differential correction
 · Requires 2 receivers
 · NGS (national geographic survey)
 · There is a network of points that have been accurately surveyed
 · Points defined on a map, available online
 · Usually associated with a building
 · Know the exact X, Y, & Z coordinates
 · Base station on most university campuses
 · Constantly collects data for that known location
 · Rover receiver collects unknown locations’ data
 · Difference between a known true position to the position of Rover
 · Will have a discrepancy error
 · Identifies the difference between GPS position and the true position
 · All airports have a base station
 · Locations can be downloaded

Dasymetric mapping
 Limited variables
 Related variables: relationship between the related variable and variable of interest is shown in a complex relationship
 fractional form of density

related variables
 more complex relationship with the variable shown in the choropleth map
 create a matrix breaking down the area into categories
 each field in the matrix needs to be

Tissot’s indicatrix
 Circle with a radius of 1 unit
 Plotted at intersection of latitude and longitude
 If there is an increase in the area then the circle will be shown larger, if it decreases it will be smaller
 Usually the center of the map has the least distortions
 Robinson’s projection identifies that the
 distortions are the least in the center of the map and increase the further out you go


Map uncertainty
 Probability bands
 Threedimensional draping of thematic information

Cartographic generalization
 Going from a large scale map to a smaller scale map, the small scale map includes much more detail than the large scale map
 Generalization is the change from a detailed map to a general outline on a larger scale map (more detail)
 Ex. A map of LSU will be more detailed than if looking at a map of BR where it will be displayed as a rectangle (generalized)
 Douglas and Peucker routine came up with the first algorithm to smooth a linear feature when changing the scale of a map from smaller scale to a larger scale
 Radical law: reduce the number of features when changing from a smaller scale map to a larger scale map
 Exaggeration (2 & 7): Adjust symbology to be recognized on a smaller scale (less detail)
 Displacement: a consequence of exaggeration
 Aggregation: smaller symbols can be replaced with a smaller 1 building
 Change in symbology: when scaled down

Radical Law (Töpfer & Pillewizer, 1966)
 a mathematical estimation of how many features should be maintained at smaller scales in the generalization process
 N_{f }= the number of objects at the derived scale
 N_{a} =is the number of objects on the source material
 M_{a} = scale denominator of source map
 M_{f} = scale denominator of the derived map

Douglas and Peucker routine
 Defined a formula for smoothing
 Identifying points along the line that you want to keep, which will be used to identified the smoothed line
 Iteration works with 3 most important points
 Repeat process over and over until the perpendicular distance to the anchor line is shorter than a set threshold

Iteration
 Keep first and last points, which should be connected by a straight line (anchor line)
 Find longest lines point away from the anchor line
 Then split the line at the furthest point from the anchor line and apply the process again to each section
 Define a threshold distance as to how far from the anchor line to stop detailing
 The less points the smoother the line
 The more points the less smooth the line
 Repeat process over and over until the perpendicular distance

Electromagnetic spectrum
the range of all possible frequencies of electromagnetic radiation

Properties of color
 wavelengths are measured in nanometers
 For the human eye the colors with the most contrast to each other are across from each other on the color wheel

Spectral reflectance curves
 Spectrophotometer: a device you put on an object that will identify the spectral reflectance curves
 When lights hit a white wall most of the light will be reflected, thus the color white
 On a dark surface more light is absorbed and minimal is reflected
 Hue can be identified with the dominant wave length in the graph chart
 Since saturation is not well enough understood component and therefore not used as much in mapping

Types of colors
 Additive colors mixed = white (RGB)
 Subtractive colors mixed = black (CMYK)

Color systems
 CMYK: Starts with a white background
 RGB: Starts with a black background
 CIE: (3 french words) Hue, value & saturation
 Munsell: used by geologists and archaeologists

Munsell color system
 Primary color = One capital letter
 Secondary colors = Two capital letters
 Color value = North pole to south pole
 Chroma increases by even numbers up to 14

kernel functions in CrimeStat
 Normal Popular: Uses normal distribution curve rotated around the central vertical curve
 Triangular: Uses a right triangle that is rotating around the central axis, looks like a cone
 Quartic: Popular type, uses Inverse U (parabola) rotated
 Negative exponential: Rotating hyperbole resembling a funnel
 Uniform Rectangle: rotated = cylinder

2 frequencies used for information services
 SPS: Standard Positioning Service
 PPS: Precise Positioning Service

Geodetic coordinate system
 Identifies: shape of the earth
 Ellipsoid: is the most accurate; they are different based on the region where the data is collected
 Gravimetric: varies based on the surface level
 Ex: mountains & oceans will make a difference
 h=H+N
 H: Orthometric height referenced to the GoID
 h: Geodetic height, measured from Ellipsoid
 N: Distance from Ellipsoid to Geoid Can be positive or negative

UTM system
Universal transverse Mercator grid system

NGS
 national geographic survey
 There is a network of points that have been accurately surveyed
 Points defined on a map, available online
 Usually associated with a building
 Know the exact X, Y, & Z coordinates
 Base station on most university campuses
 Constantly collects data for that known location
 Rover receiver collects unknown locations' data
  Difference between a known true position to the position of Rover
  Will have a discrepancy error
  Identifies the difference between GPS position and the true position
 All airports have a base station
 Locations can be downloaded

Mission planning data
 How many satellites available
 Delusion precision
 Each satellite has a number assigned to it, that can be identified as to its position

How does GPS work?
 It's a distance/ranging system
 Operates on the Principal of Trilateration
 Satellites transmit unique radio waves
 Receivers passively receive SV signal
 Receivers measure time for signal to reach it
 distance computed via D = V x T_{Δ}
 V = C= 300,000 km/sec (186,000 mi/sec)

Geodetic coordinate system
 Identifies shape of the earth
 Ellipsoid is the most accurate; they are different based on the region where the data is collected Gravimetric varies based on the surface level
 Ex: mountains & oceans will make a difference
 h=H+N
 H: Orthometric height referenced to the Gold h: Ellipsoldal height

Different map schemes
 Qualitative scheme
 Binary scheme
 Sequential scheme

Variations of sequential schemes
 On hue: only the hue changes
 On hue transition: changes from one color to another
 On hue steps: transitions via combined lightness and hue steps

Describe the steps of Douglas Peuker routine

Qualitative scheme with 3 hues




Diverging/Sequential scheme

Diverging/Diverging scheme

