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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 GIS TUTORIAL 1 - Basic Workbook Longitude (meridians)

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

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

  7. Latitude and longitude Pittsburgh, PA USA 40 -80 GIS TUTORIAL 1 - Basic Workbook Coordinates

  8. Lat/Long coordinates GIS TUTORIAL 1 - Basic Workbook • 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°

  9. Lat/long coordinates GIS TUTORIAL 1 - Basic Workbook 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

  10. Mercator projection (1569) GIS TUTORIAL 1 - Basic Workbook • 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

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

  12. Robinson projection (1961) GIS TUTORIAL 1 - Basic Workbook • 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)

  13. Albers Equal Area GIS TUTORIAL 1 - Basic Workbook • 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

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

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

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

  20. State Plane coordinates GIS TUTORIAL 1 - Basic Workbook • 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)

  21. State Plane zones GIS TUTORIAL 1 - Basic Workbook • 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

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

  26. Coordinate system summary GIS TUTORIAL 1 - Basic Workbook • 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)

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

  28. GIS data sources GIS TUTORIAL 1 - Basic Workbook • 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?

  29. GIS data sources GIS TUTORIAL 1 - Basic Workbook • 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

  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 GIS TUTORIAL 1 - Basic Workbook http://www.esri.com/data/resources/geographic-data.html

  32. U.S. Census Bureau GIS TUTORIAL 1 - Basic Workbook • 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

  33. U.S. Census Bureau GIS TUTORIAL 1 - Basic Workbook • 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?

  34. Census TIGER/Line files GIS TUTORIAL 1 - Basic Workbook • 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

  35. TIGER census tracts GIS TUTORIAL 1 - Basic Workbook • 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

  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 GIS TUTORIAL 1 - Basic Workbook http://factfinder.census.gov

  45. Summary File (SF1) tables • GIS TUTORIAL 1 - Basic Workbook 45

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

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

  48. Census summary GIS TUTORIAL 1 - Basic Workbook 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

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

  50. ArcInfo coverages GIS TUTORIAL 1 - Basic Workbook Created using ESRI’s ArcInfo software Older format Set of files within a folder or directory called a workspace Files represent different types of topology or feature types

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