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GIS Tutorial 1

GIS Tutorial 1. Lecture 5 Importing spatial and attribute data. Outline. Map projections Coordinate systems GIS data sources Vector data formats Raster data formats. Lecture 5. Map projections. Latitude and longitude. Longitude (meridians). Latitude and longitude.

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GIS Tutorial 1

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  1. GIS Tutorial 1 Lecture 5 Importing spatial and attribute data

  2. Outline • Map projections • Coordinate systems • GIS data sources • Vector data formats • Raster data formats GIS TUTORIAL 1 - Basic Workbook

  3. Lecture 5 Map projections GIS TUTORIAL 1 - Basic Workbook

  4. Latitude and longitude • Longitude (meridians) GIS TUTORIAL 1 - Basic Workbook

  5. Latitude and longitude • Latitude (parallels) GIS TUTORIAL 1 - Basic Workbook

  6. Longitude and latitude • Longitude (prime meridian) 0 • Latitude (equator) 0 GIS TUTORIAL 1 - Basic Workbook

  7. Longitude and latitude • Coordinates Pittsburgh, PA USA 40 -80 GIS TUTORIAL 1 - Basic Workbook

  8. Long/Lat coordinates • Degrees, minutes, and seconds (DMS): • 40° 26′ 2″ N latitude • -80° 0′ 58″ W longitude • Decimal degrees (DD) • 1 degree = 60 minutes, • 1 minute = 60 seconds • 40° 26′ 2″ = • 40 + 26/60 + 2/3600 = • 40 + .43333 + .00055 = • 40.434° GIS TUTORIAL 1 - Basic Workbook

  9. Long/lat coordinates Translated to distance • World circumference through the poles is 24,859.82 miles, so for latitude: • 1° = 24,859.82 / 360 = 69.1 miles • 1′ = 24,859.82 / (360 * 60) = 1.15 miles • 1″ = 24,859.82 * 5,280 / (360 * 3,600) = 101 feet • Length of the equator is 24,901.55 miles GIS TUTORIAL 1 - Basic Workbook

  10. Mercator projection (1569) • Conformal projection • Cylindrical • Parallels and meridians at right angles • Linear scale is constant in all directions around any point • Preserves angles and shapes of small objects • Distorts the size and shape of large objects • Map projection for nautical purposes GIS TUTORIAL 1 - Basic Workbook

  11. Hammer – Aitoff (1882-1889) • Equal-area • Modified azimuthal projection • Good for population density (world area) • Difficult to see some areas GIS TUTORIAL 1 - Basic Workbook

  12. Robinson projection (1961) • Pseudocylindrical • Neither equal area nor conformal • Meridians curve gently, avoiding extremes • Good compromise projection for viewing entire world • Used by Rand McNally since the 1960s and by the National Geographic Society (1988 and 1998) GIS TUTORIAL 1 - Basic Workbook

  13. Albers Equal Area • Conic projection • Scale and shape are not preserved, distortion is minimal between the standard parallels • Standard projection for British Columbia, U.S. Geological Survey, U.S. Census Bureau GIS TUTORIAL 1 - Basic Workbook

  14. Projection important • Measurements used to make important decisions • Comparing shapes, areas, distances, or directions of map features • Feature and image themes are aligned New York New York Los Angeles Los Angeles Projection: MercatorDistance: 3,124.67 miles Projection: Albers equal areaDistance: 2,455.03 miles Actual distance: 2,451 miles GIS TUTORIAL 1 - Basic Workbook

  15. Projection not important • Business applications • Not of critical importance • Concerned with the relative location of different features • On large scale maps—street maps • Distortion may be negligible • Map covers only a small part of the earth’s surface GIS TUTORIAL 1 - Basic Workbook

  16. Lecture 5 Coordinate systems GIS TUTORIAL 1 - Basic Workbook

  17. Geographic Coordinate System (GCS) • Spherical coordinates • Angles of rotation of a radius anchored at earth’s center • Latitude and longitude • Census Bureau TIGER files GIS TUTORIAL 1 - Basic Workbook

  18. U.S. Census GCS example GIS TUTORIAL 1 - Basic Workbook

  19. Rectangular coordinate system • Used for locating an intersection on a flat sheet of graph paper or a flat map • Cartesian coordinates (x,y) • State plane and UTM GIS TUTORIAL 1 - Basic Workbook

  20. State Plane coordinates • Established by the U.S. Coast and Geodetic Survey in 1930s • Originally North American Datum (NAD 1927) • More recently NAD 1983 and 1983 HARN • Used by local U.S. governments • All positive coordinates in feet (or meters) GIS TUTORIAL 1 - Basic Workbook

  21. State Plane zones • 125 zones • At least one for each state • Cannot have zones joined to make larger regions • Follow state and county boundaries • Each has its own projection: • Lambert conformal projection for zones with east-west extent • Transverse Mercator projection for zones with north-south extent GIS TUTORIAL 1 - Basic Workbook

  22. State Plane zones GIS TUTORIAL 1 - Basic Workbook

  23. State Plane zones GIS TUTORIAL 1 - Basic Workbook

  24. Pittsburgh neighborhoods as state plane coordinates GIS TUTORIAL 1 - Basic Workbook

  25. Universal Transverse Mercator (UTM) • Rectangular coordinate system • Used by U.S. military • Covers entire world • Metric coordinates • Longitude zones are 6° wide • Latitude zones are 8° high GIS TUTORIAL 1 - Basic Workbook

  26. Coordinate system summary • Geographic coordinate system • U.S. Census • State plane coordinate system • Local governments • U.S. military • Projections defined in ArcCatalog or ArcMap (.prj) files • First file added in a map document sets the projection (others will adjust to it as long as they have a .prj file) GIS TUTORIAL 1 - Basic Workbook

  27. Lecture 5 GIS Data sources GIS TUTORIAL 1 - Basic Workbook

  28. GIS data sources • ESRI • U.S. Census • USGS and other government sources • GDT Dynamap/2000 U.S. Street Data • Engineering companies • land surveys, aerial photos, CAD drawings • University Web sites (e.g. Penn State’s PASDA) • Others? GIS TUTORIAL 1 - Basic Workbook

  29. GIS data sources • 30+ million Internet search results • type “GIS data download” or “population China .e00 • add the name of the state, county, or city to the search GIS TUTORIAL 1 - Basic Workbook

  30. GIS departments Web sites • Washington, D.C. • dcgis.dc.gov/  • Chicago, IL • www.cityofchicago.org/gis • Austin, TX • Tip: Search by county name (Travis County, Texas) • http://www.ci.austin.tx.us/development/ • ftp://ftp.ci.austin.tx.us/GIS-Data/Regional/coa_gis.html GIS TUTORIAL 1 - Basic Workbook

  31. ESRI’s Web site • http://www.esri.com/data/resources/geographic-data.html GIS TUTORIAL 1 - Basic Workbook

  32. U.S. Census Bureau • Started building a map infrastructure in the late 1970s and early 1980s • Census mapping needs were twofold: • To assign census employees to areas of responsibility, covering the entire country and its possessions • To report and display census tabulations by area, officials determined that the smallest area needed for these purposes is a city block or its equivalent GIS TUTORIAL 1 - Basic Workbook

  33. U.S. Census Bureau • Compiles all line features used to create a block layer for the entire country • Map features smaller than are the responsibility of local governments • deeded land parcels • buildings • street curbs • parking lots • others? GIS TUTORIAL 1 - Basic Workbook

  34. Census TIGER/Line files • Topologically Integrated Geographic Encoding and Referencing files • Census Bureau’s product for digital mapping of the U.S. • Available for the entire U.S. and its possessions • Include the following geographic features • roads and street centerlines • railroads • rivers • lakes • census statistical boundaries GIS TUTORIAL 1 - Basic Workbook

  35. TIGER census tracts • Statistical boundary (below county level) • between 1,000 and 8,000 people (in general) • 1,700 housing units or 4,000 people • homogeneous population characteristics (economic status and living conditions) • normally follow visible features • may follow governmental unit boundaries and other nonvisible features • more than 60,000 census tracts in Census 2000 GIS TUTORIAL 1 - Basic Workbook

  36. PA tracts GIS TUTORIAL 1 - Basic Workbook

  37. Allegheny County tracts GIS TUTORIAL 1 - Basic Workbook

  38. City Pittsburgh tracts GIS TUTORIAL 1 - Basic Workbook

  39. TIGER census block groups • Subdivision of a census tract • 400 housing units, with a minimum of 250 and a maximum of 550 housing units • Follow clearly visible features such as roads, rivers, and railroads GIS TUTORIAL 1 - Basic Workbook

  40. Census block groups GIS TUTORIAL 1 - Basic Workbook 40

  41. TIGER census blocks • Smallest geographic area for which the Census Bureau collects and tabulates decennial census information • Visible boundaries • street • road • stream • Shoreline • Nonvisible boundaries • county, city, neighborhood boundary • property line GIS TUTORIAL 1 - Basic Workbook 41

  42. Census blocks GIS TUTORIAL 1 - Basic Workbook 42

  43. Other TIGER layers GIS TUTORIAL 1 - Basic Workbook

  44. U.S. Census Bureau data tables • http://factfinder.census.gov GIS TUTORIAL 1 - Basic Workbook

  45. Geospatial Website for U.S.: geodata.gov GIS TUTORIAL 1 - Basic Workbook

  46. Summary File (SF1) tables GIS TUTORIAL 1 - Basic Workbook 46

  47. Summary File (SF3) tables GIS TUTORIAL 1 - Basic Workbook

  48. SF tables comparisons SF1 • Population • Age • Sex • Race • Housing units • FFH SF3 • Income • Educational attainment • Citizenship • Transportation • Detailed housing GIS TUTORIAL 1 - Basic Workbook

  49. Census summary • Shapefiles downloaded from www.census.gov or www.esri.com • Data tables downloaded from American Factfinder http://factfinder.census.gov • Data joins needed to join SF1 or SF3 to shapefiles GIS TUTORIAL 1 - Basic Workbook

  50. Lecture 5 Vector data formats GIS TUTORIAL 1 - Basic Workbook

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