Building an online tool for spatial joins using open source software Karsten Vennemann Seattle

1. Building an online tool for spatial joinsusing open source software Karsten VennemannSeattle

2. Talk Overview • Who, Why and What • Tool Workflow • Definitions and Examples • Technical Background • Resources • - - - - Why this tool ? • What does it do ? • - - - - Steps to retrieve results • - - - - Tool live demo • - - - - How does it work ? • - - - - How can you build your own ? Building an online tool for spatial joins

3. Who, Why and What Why this online tool ? Why open source software ? Finding the Legal District in which a member of an organization lives is important information for many environmental voter advocacy groups. While this easily can be accomplished using commercial GIS tools, most of those Non-Profit organizations lack the resources and/or technical staff to support the use of such software. Adding Legislative District information is usually done manually.In Washington State there is the online district finder tool available: http://apps.leg.wa.gov/DistrictFinder/Default.aspx Can find single addresses Building an online tool for spatial joins

4. Who, Why and What • About this tool • Windows and Linux server platforms • based on open source software • any type of spatial join based on street address in WA state (US) and a polygon layer For simplicity we will focus on a technical overview onhow a web based tool can allow users with little or no GIS knowledge to attach legislative district information for Washington State to their membership lists. Building an online tool for spatial joins

5. Tool Workflow • Workflow for the tool can be broken up into four main parts • File upload to the server(text or Excel file containing address list via web interface) • Geocoding - Retrieval of coordinates (latitude/longitude) for the address (geocoded using 2006 Tiger line data, PHP and Perl) • Spatial Join - Matching the Legislative District information(Query onto a PostGIS Database) • 4) Transfer result information(streaming the results to the client computer text or MS Excel file) Building an online tool for spatial joins

6. Tool Workflow • Workflow for the tool can be broken up into four main parts • File upload to the server(text or Excel file via web interface ) • Geocoding - Retrieval of coordinates (latitude/longitude) for the address (geocoded using 2006 Tiger line data, PHP and Perl) • Spatial Join - Matching the Legislative District information(Query onto a PostGIS Database) • 4) Transfer result information(streaming the results to the client computer text or MS Excel file) Building an online tool for spatial joins

7. Definitions and Examples What is Geocoding ?Interpolation of real world coordinates for a given location Most geocoders use address information to interpolate (estimate) the real world position along streets using blocks and intersections as landmarks Variety of free tools available - most popular:Google and Yahoo maps API, geocoder.usAlso Tiger line geocoder for Post GIS=> Geocoder::US a Perl moduleOpen sourcecan download source code and install on your own serveruses Berkeley DB format to store Tiger data- high compression fro data - whole US Street data 750 MB (24 GB of uncompressed Tiger data) Building an online tool for spatial joins

8. Definitions and Examples What is a Spatial Join ? A spatial join operation adds information based on the geographical location of one feature to another Building an online tool for spatial joins

9. Definitions and Examples Spatial Join A spatial join operation adds information based on the geographical location of one feature to another Building an online tool for spatial joins

10. Definitions and Examples Spatial Join A spatial join operation adds information based on the geographical location of one feature to another Building an online tool for spatial joins

11. Definitions and Examples Spatial Join Building an online tool for spatial joins

12. Definitions and Examples Spatial Join Building an online tool for spatial joins

13. Definitions and Examples Live Tool Demo Building an online tool for spatial joins

14. Definitions and Examples Live Tool Demo Building an online tool for spatial joins

15. Definitions and Examples Live Tool Demo Building an online tool for spatial joins

16. Definitions and Examples Live Tool Demo Building an online tool for spatial joins

17. Definitions and Examples Live Tool Demo Building an online tool for spatial joins

18. Technical Background TechnicalOverview Building an online tool for spatial joins

19. Technical Background • Technical Overview • Text or Excel file is read with php • Get user input to select address fields • Address is concatenated and feed into the geocoder::US Perl module from within php • lat/long returned • Spatial query using lat/long results from geocoding=> in Post GIS one simple SQL query is called to retrieve the LD number • Output of results • Sample sql queries • select ndistrict from Leg_districts_2001 where Leg_districts_2001.the_geom && (setsrid((MakePoint(-122.206834, 47.611421)),4326)) and intersects (Leg_districts_2001.the_geom,setsrid((MakePoint(-122.206834, 47.611421)),4326)); • select ndistrict from Leg_districts_2001 where Leg_districts_2001.the_geom && transform(((setsrid((MakePoint(-122.206834, 47.611421)),4326))),2285) and intersects (Leg_districts_2001.the_geom,transform(((setsrid((MakePoint(-122.206834, 47.611421)),4326))),2285)); Building an online tool for spatial joins

20. Technical Background Code Building an online tool for spatial joins

21. Technical Background Perl integration for Geo::Coder::US Building an online tool for spatial joins

22. Technical Background Query in PostGIS Building an online tool for spatial joins

23. Spatial Indexes Source: “Introduction to PostGIS”, Paul Ramsey, Refractions Research Building an online tool for spatial joins

24. Technical Background • How can you build your own tool ? • Install • • Apache I or II Webserver (or IIS) • PHP (php_Perl.dll, php_pgsql.dll etc.) • Perl (5.8 or higher, geocoder::US module and several others from CPAN) • PostgreSQL • PostGIS, load polygon data • Obtain US Census Tiger Line data for states in question • Load Tiger data into BerkeleyDB (utility comes with Geo::Coder::US) • author some PHP/Perl scripts Building an online tool for spatial joins

25. Resources Open source utilities and websites Building an online tool for spatial joins

26. Resources Articles Build Your Own Geocoding Solution with Geo::Coder::US By Jason Gilmore http://www.developer.com/tech/article.php/3557171 Retrieving Map Location Coordinates By Jason Gilmore http://www.developer.com/tech/article.php/3548171 Building an online tool for spatial joins

27. Free and Open Source Software for Geospatial 2007 http://www.foss4g2007.org/ Resources Building an online tool for spatial joins

28. Resources • New local GIS user group: • “Cascadia Users of Geospatial Open Source”http://groups.google.com/group/cugos • Next meeting today April 25th, 5:30 pmIn the LizardTech offices, located near Pioneer Square: • The National Building • Suite 200 • 1008 Western Avenue • Seattle, WA 98104 Building an online tool for spatial joins