# Lecture 7 Intro to GIS

 What three compinents are GIS used for? space-satellitescontrol-grounduser-receiver (ex. GPS on phone) What does the space segment of GIS consist of? a constellation of 24 satellites (21 +3 operating spares)medium oribit of 12,552 miles What are the components of the control segment of GIS? they track the location and health of each satellitehealth refers to the errors and clock time on each satellitesthere are 11 stations that can be seen by at least 2 satellites Explain the user segment of GIS. The GPS receivers that are tuned to the radio frequencies from the satellitesAccuracy for regular GPS is 3 metersSelective Availability is the intentional degredation of GPS signals Explain how GPS works. There are at least 3 satellites above youA 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 What are the satellite inaccuracies for GPS? orbital biassatellite dock bias What are signal inaccuracies of GPS? Troposhperic effectsIonospheric bias This occurs when the GPS signal bounces before it reaches the antenna on the GPS receiver Multipath Error What are the characteristics of Differential GPS? requires 2 receivers (mobile and base stationcorrects its GPS positions using the base station infoErrors can be within one meter Explain the characteristics of Wide Area Augmentation System (WAAS). THey measure small variations in GPS satellies' signalsFor commercial aviationuse ground-based wide area and reference stations & geostationary WAAS satellites How are Triangulated Irregular Networks different from DEM models? base on triangle grid (not pixel grid)different sized triangles (not equal) WHat is a centroid? THe balance point or center of gravity of an AREA WHat are the two sets needed for geocoding? Address TableReference DAtabase What is the formula for the distance theorem? D= the square root of (X2-X1)2 + (Y2 -Y1)2 How do you calculate physical distance? you accumulate each straight segment WHat are some errors to measuring physical distance? Slope Errors-mountainNetwork Distance- physical distance is less than highway distanceCentroid Representation-where exactly are you measuring to?Hard Copy Seasonal Variation What are Isochrones? Lines of equal time distance What are two methods of measuring area in GIS? Grid Cell Counting MethodStrip Method How do you measure the shape index? divide the intersection by the unitif the distance is close to zero, then they are very close to each other What is the most common function distance travel times A webpage containing special scripts that dynamically add a map to the page GIS Mashup What does HTML stand for? Hyper Tect Markup Language What is the spatial regression formula? Price= weight matrices (W)*price+Sq.Ft+age+Median Income+Dist_Marta+error WHat are some basic rules to HTML? characters that denote am html tag () are referred to as angle bracketsTags usually come in pairslowercase is recommended WHat is the nearest neighbor analysis? An index to evaluate the clustering of point features What is the formula for the nearest neighbor statistic? robs / rexp WHat is spatial arrangement? the way things are placed geographically Authorbheight1 ID107771 Card SetLecture 7 Intro to GIS DescriptionIntro to MApping and GIS notes for Lectures 7 and beyond Updated2011-10-31T17:29:18Z Show Answers