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Data Day 2012_Fradkin_Intro to GIS

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Data Day 2012_Fradkin_Intro to GIS

  1. 1. Introduction to Data Mapping Barry Fradkin GIS Analyst Metropolitan Area Planning Council Friday, January 27, 2012
  2. 2. About me…
  3. 3. Data Mapping • More geographic data becoming available • See patterns that aren’t otherwise apparent • What are the properties of spatial data? • Where can we find spatial data? • How do we make maps ourselves?
  4. 4. Geographic Information Systems
  5. 5. Social Networking
  6. 6. Population Bostonography.c
  7. 7. Transportation Bostonography.c
  8. 8. Coordinate Systems • Cartesian Coordinate System • Geographic Coordinate System – Latitude and Longitude • Boston 42°21′28″N, 71°03′42″W 42.359228, -71.061515
  9. 9. Understanding Projections • Earth is roughly spherical • Maps are 2-dimensional • Distortion is inevitable
  10. 10. Types of Projections • Mercator is common • Specialized projections for smaller areas • For Massachusetts: NAD 1983 State Plane Massachusetts (m or ft.)
  11. 11. Data Models • Feature geometry can be shown in two ways: • Vector – Points, lines, polygons – Discrete objects • Raster – Grid of cells – Continuous data
  12. 12. Attributes • The information behind the geometry • Similar to Excel or Access tables • Types of attributes: – Nominal (text) – Ordinal (rank) – Interval (numeric) ID Nominal Ordinal Numeric 1 residential low 10 2 industrial high 700 3 commercial medium 14.625 4 open space very low 0.263
  13. 13. Attribute Formatting • Headers: no spaces or special characters • UPPER CASE / lower case / Sentence Case • Number format makes a difference Number Format Minimum Value Maximum Value Short integer -32,768 32,767 Long integer −2,147,483,648 2,147,483,648 Float Many digits, decimals Many digits, decimals Double More digits, decimals More digits, decimals
  14. 14. Where to find the data? • MassGIS – Office of Geographic Information – Municipalities, roads, water, land use – US Census: blocks, block groups, tracts – Air photos, elevation, impervious surface • Data tables from state and federal gov’t. – Unique IDs can be used to join to geography
  15. 15. Downloading from MassGIS
  16. 16. Compile your own data • Geocoding – Street addresses > Address Locator – Latitude/Longitude (decimal degrees) • Digitizing – Manually draw features from air photo – Georeference an existing map image • Join your own tables to existing geography
  17. 17. Displaying the Data • Data layers • Symbology – Colors – Point size – Line width • Labels – Font size – Positioning
  18. 18. Cartography • All maps should have: –North Arrow –Scale Bar –Legend –Title –Date –Source
  19. 19. Consider your audience • Make text large enough to be legible • 5 to 10% of men are colorblind • Colorbrewer.org:
  20. 20. GIS Software • Online mapping tools: – MassGIS OLIVER: http://www.mass.gov/mgis/mapping.htm – MetroBoston DataCommon: http://metrobostondatacommon.org/ – Google Maps, Google Earth, OpenStreetMap • Open Source Software – Quantum GIS, GRASS, SAGA
  21. 21. ESRI ArcGIS • ArcMap • ArcCatalog • ArcToolbox • ArcScene • ArcGlobe • Cheap non-profit license available • esri.com/nonprofit

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