Lecture 7 Intro to GIS

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Lecture 7 Intro to GIS
2011-10-31 13:29:18
cartography mapping GIS

Intro to MApping and GIS notes for Lectures 7 and beyond
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  1. What three compinents are GIS used for?
    • space-satellites
    • control-ground
    • user-receiver (ex. GPS on phone)
  2. What does the space segment of GIS consist of?
    • a constellation of 24 satellites (21 +3 operating spares)
    • medium oribit of 12,552 miles
  3. What are the components of the control segment of GIS?
    • they track the location and health of each satellite
    • health refers to the errors and clock time on each satellites
    • there are 11 stations that can be seen by at least 2 satellites
  4. Explain the user segment of GIS.
    • The GPS receivers that are tuned to the radio frequencies from the satellites
    • Accuracy for regular GPS is 3 meters
    • Selective Availability is the intentional degredation of GPS signals
  5. Explain how GPS works.
    • There are at least 3 satellites above you
    • A GPS receiver and satellite clocks are precisely and continually synchronized , but there can be errors if your GPS receiver's clock is 0.1 second fast
  6. What are the satellite inaccuracies for GPS?
    • orbital bias
    • satellite dock bias
  7. What are signal inaccuracies of GPS?
    • Troposhperic effects
    • Ionospheric bias
  8. This occurs when the GPS signal bounces before it reaches the antenna on the GPS receiver
    Multipath Error
  9. What are the characteristics of Differential GPS?
    • requires 2 receivers (mobile and base station
    • corrects its GPS positions using the base station info
    • Errors can be within one meter
  10. Explain the characteristics of Wide Area Augmentation System (WAAS).
    • THey measure small variations in GPS satellies' signals
    • For commercial aviation
    • use ground-based wide area and reference stations & geostationary WAAS satellites
  11. How are Triangulated Irregular Networks different from DEM models?
    • base on triangle grid (not pixel grid)
    • different sized triangles (not equal)
  12. WHat is a centroid?
    THe balance point or center of gravity of an AREA
  13. WHat are the two sets needed for geocoding?
    • Address Table
    • Reference DAtabase
  14. What is the formula for the distance theorem?
    D= the square root of (X2-X1)2 + (Y2 -Y1)2
  15. How do you calculate physical distance?
    you accumulate each straight segment
  16. WHat are some errors to measuring physical distance?
    • Slope Errors-mountain
    • Network Distance- physical distance is less than highway distance
    • Centroid Representation-where exactly are you measuring to?
    • Hard Copy
    • Seasonal Variation
  17. What are Isochrones?
    Lines of equal time distance
  18. What are two methods of measuring area in GIS?
    • Grid Cell Counting Method
    • Strip Method
  19. How do you measure the shape index?
    • divide the intersection by the unit
    • if the distance is close to zero, then they are very close to each other
  20. What is the most common function distance
    travel times
  21. A webpage containing special scripts that dynamically add a map to the page
    GIS Mashup
  22. What does HTML stand for?
    Hyper Tect Markup Language
  23. What is the spatial regression formula?
    Price= weight matrices (W)*price+Sq.Ft+age+Median Income+Dist_Marta+error
  24. WHat are some basic rules to HTML?
    • characters that denote am html tag (<and>) are referred to as angle brackets
    • Tags usually come in pairs
    • lowercase is recommended
  25. WHat is the nearest neighbor analysis?
    An index to evaluate the clustering of point features
  26. What is the formula for the nearest neighbor statistic?
    robs / rexp
  27. WHat is spatial arrangement?
    the way things are placed geographically