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Geographic Information Systems

Geographic Information Systems

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Geographic Information Systems

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  1. Geographic Information Systems TIGER Data

  2. 1 Street Unit • Street segment   - The range of addresses that run along a street from one intersection to the next intersection • Address range - The range between the lowest possible house number at one intersection and the highest possible house number at the other intersection

  3. 2 Census Units • Census tracts • Block groups • Blocks

  4. 2 (1) Census Tracts • Defined by the U.S. Census Bureau for statistical reporting of demographic, economic, and other data • The boundaries follow major streets or natural features • Population in each tract is approximately 4,000 regardless of its size • Census tracts are numbered consecutively and unique within the jurisdiction

  5. 2 Census Units • Census tracts

  6. 2 (2) Block Groups • Comprise a population of approximately 1,500 • Boundaries coterminous with census tract boundaries

  7. Block groups R Brancoto, SUNY Buffalo

  8. 2 (3) Blocks • Smallest geographic area formed by streetsegments • Coded by a 4-digit number - The first one represents the block group - The last three are consecutive and unique within a block group  

  9. Census Units .. County Block Census tract Block group

  10. 3. GBF/DIME Files • Geographic Base Files (GBF) • Dual Independent Map Encoding System (DIME)   • A data format used by the U.S. Census Bureau to encode street network and related data for the 1980 Census. • It covers only the metropolitan areas - DIME was replaced by TIGER in 1990 census

  11. 4 Vector (1) Non-Topological Structure Storing coordinates of two polygons: and Polygon x1, y1; x2,y2;x3,y3; x4,y4; x5,y5; x1,y1. Polygon x1, y1; x6,y6; x7,y7; x2,y2;x1,y1. A (x1, y1) (x1, y1) 1 2 1 2 B (x2, y2) (x2, y2) 1 2

  12. 4 Vector (2) Topological Structure Storing coordinates of two polygons: and Line 1 x1, y1; x2,y2; x3, y3; x4, y4; x5,y5; Line 2 x1, y1; x5,y5; Line 3 x5, y5; x6,y6; x7, y7; x1, y1; Polygon Line 1, Line 2 Polygon Line 2, Line 3 1 2 (x1, y1) (x1, y1) Line 1 1 Line 2 Line 3 2 (x5, y5) (x5, y5) 1 2

  13. 4. TIGER • Topologically Integrated Geographic Encoding and Referencing Files (TIGER) • Developed by the U.S. Census Bureau for 1990 census • The spatial and attribute processes were combined into one system • A single seamless data set that covers the entire country • Topologically structured

  14. TIGER Geographic Features • A combination of DIME and 1:100,000 Digital Line Graph • Uses geographic coordinate system • Two types of data: - a tabular form of demographic, social, economic statistics - a GIS form • Aggregated information is available at the block group level, few at the block level

  15. TIGER Geographic Features .. • GIS data are available as both polygon data and line data • The polygon data contain the population information in tracts, block groups, and blocks • The line data contain streets and utility lines information • The data have spatial locations, attributes, and topology

  16. TIGER ..

  17. TIGER .. • American Community Survey http://www.census.gov/acs/www/ • An ongoing statistical survey that samples a small percentage of the population every year • 1-year, 3-year, and 5-year estimates http://www.census.gov/acs/www/guidance_for_data_users/estimates/

  18. 5. Applications of TIGER Data • Address matching • Network analysis • District delineation

  19. Address Matching (line data)

  20. Address Matching ..

  21. Network Analysis Shortest path routines (line data) http://www.caliper.com/TransCAD/ApplicationModules.htm

  22. Network Analysis .. Salesperson Problem (line data) http://www.caliper.com/TransCAD/ApplicationModules.htm

  23. Network Analysis .. Location allocation (Line and polygon data) http://www.caliper.com/TransCAD/ApplicationModules.htm

  24. Districting Delineation Political redistricting (polygon data)

  25. Readings • Chapter 3

  26. http://ftp2.census.gov/geo/maps/special/HurKat/Katrina_Reference_v2.pdfhttp://ftp2.census.gov/geo/maps/special/HurKat/Katrina_Reference_v2.pdf

  27. 4. TIGER

  28. GBF/DIME Files .. http://www.geog.buffalo.edu/ncgia/gishist/DIME.html

  29. http://ftp2.census.gov/geo/maps/special/HurKat/Katrina_Pop_Density_v2.pdfhttp://ftp2.census.gov/geo/maps/special/HurKat/Katrina_Pop_Density_v2.pdf

  30. http://ftp2.census.gov/geo/maps/special/HurKat/Katrina_Housing_Units_v2.pdfhttp://ftp2.census.gov/geo/maps/special/HurKat/Katrina_Housing_Units_v2.pdf

  31. http://ftp2.census.gov/geo/maps/special/HurKat/Katrina_Poverty_Rate_v2.pdfhttp://ftp2.census.gov/geo/maps/special/HurKat/Katrina_Poverty_Rate_v2.pdf

  32. http://ftp2.census.gov/geo/maps/special/HurKat/Katrina_Pop_Under_18_v2.pdfhttp://ftp2.census.gov/geo/maps/special/HurKat/Katrina_Pop_Under_18_v2.pdf