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GIS Lecture 5 Importing Spatial and Attribute Data

GIS Lecture 5 Importing Spatial and Attribute Data. Outline. GIS Data Sets Map Projections Coordinate Systems GIS Data Sources. GIS Data Sets. GIS Data Sets. ArcInfo Coverages ArcView Shapefiles CAD Files Aerial Photos Event Files. ArcInfo. AAT Arc Attribute Table

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GIS Lecture 5 Importing Spatial and Attribute Data

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  1. GIS Lecture 5 Importing Spatial and Attribute Data

  2. Outline • GIS Data Sets • Map Projections • Coordinate Systems • GIS Data Sources

  3. GIS Data Sets

  4. GIS Data Sets • ArcInfo Coverages • ArcView Shapefiles • CAD Files • Aerial Photos • Event Files

  5. ArcInfo

  6. AAT Arc Attribute Table ARC Arc coordinates and topology BND Coverage minimum and maximum coordinates CNT Polygon centroid table PAL Polygon topology PAT Polygon/Point Attribute Table TIC Tic coordinates and Ids DBF Database Table ArcInfo Coverages

  7. ArcINFO Coverages in ArcMap

  8. Polygon Coverages • Area and perimeter automatically calculated

  9. B E 1 2 Pine St. 733 A 734 F C Oak St. 3 4 D G Polygon Coverages Polygons share borders

  10. Line Coverages • Length automatically calculated

  11. Point Coverages

  12. ArcInfo Coverages • Advantages • Many feature types • Shared borders • Automatic Area/Perimeter/Length fields • Disadvantages • Cannot edit in ArcMap

  13. ArcInfo Export files • .e00 export exchange file • ArcCatalog translates into ArcGIS • Creates coverages

  14. ArcView Shape Files • Advantages • heads-up digitizing and editing • less storage/rapid display • can export to CAD • Disadvantages • one feature type • no area or perimeter with new shapefiles

  15. ArcView Shape Files • From 3 to 5 Files • .shp - stores feature geometry • .shx - stores index of features • .dbf - stores attribute data • .sbn and .sbx - store additional indices

  16. ArcView Shapefiles

  17. CAD Files • Why CAD Drawings? • Better Precision for Digitizing • .DWG / .DXF

  18. Adding CAD Files

  19. CAD Files in ArcMap

  20. Aerial Images • Combining Grid and Vector Maps

  21. Event Files X,Y Coordinates

  22. Event Files

  23. Event Files

  24. Map Projections

  25. Map Projections and Distortion • Map projections produce distortion in one or more spatial properties: • Shape, area, distance, and direction • Specific projections eliminate or minimize distortion

  26. Distortion Examples

  27. Mercator Projection: Distortion

  28. Robinson Projection: Distortion

  29. 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

  30. 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.

  31. Coordinate Systems

  32. Coordinate Systems • Spherical/Polar • Geographic Coordinate System • Rectangular • State Plane • UTM

  33. Geographic Coordinate System • Latitude and Longitude • Census Bureau TIGER files • Geographic • Coordinate • System Grid

  34. Longitude: Meridians

  35. Latitude: Parallels

  36. Origin • Longitude (prime meridian) 0 • Latitude (equator) 0

  37. Coordinates Pittsburgh 40 -80

  38. Pittsburgh’s Point • 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°

  39. 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*3600) = 101 feet • Length of the equator is 24,901.55 miles

  40. Rectangular Coordinate Systems State Plane Coordinates • Local Governments UTM • US Military

  41. State Plane Coordinate System • Established by the U.S. Coast and Geodetic Survey (now the National Ocean Survey) • At least one for each state • Rectangular (x,y) coordinates • 125 zones, following state and county boundaries each with its own projection: • Lambert conformal projection for zones with east-west extent • Transverse Mercatorprojection for zones with north-south extent • Cannot have zones joined to make larger regions

  42. 400 (400, 300) North (Feet) 200 (100, 200) 0 0 200 400 East (Feet) Rectangular Coordinates • Has all positive Cartesian coordinates in feet, called false eastings and false northings

  43. State Plane Coordinate Zones

  44. State Plane Coordinate Zones

  45. City of Pittsburgh as Geographic Coordinates

  46. City of Pittsburgh as State Plane Coordinates

  47. State Plane Coordinate Names • North American Datum of 1927 (NAD27) • American Datum of 1983 (NAD83) • "High Accuracy Reference Network" (HARN) • "High Precision GPS Network" (HPGN)

  48. Universal Transverse Mercator System (UTM) • Developed by the NATO in 1947 • Military grid system • Based on transverse Mercator projection • Applied to maps of the Earth's surface extending from the Equator to 84 Degrees north and 80 degrees south latitudes

  49. UTM Zones World is divided into 60 north-south zones, each covering a strip 6° wide in longitude

  50. UTM Zones in the Contiguous USA

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