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Os Percy
 

Os Percy

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    Os Percy Os Percy Presentation Transcript

    • Web Mapping with Open Source GIS Software Best practices from the PSU Experience David Percy Geospatial Data Manager, Geology Department Portland State University With gratitude to Morgan Harvey, Eric Hanson, Nate Davenport, Cris Holm, Tim Welch, and Will Garrick Funding provided by many sources, including NASA, NSF, Oregon Dept of Geology, US Geologic Survey OSCON 2007
    • Components of Open Source Web Mapping The geospatial “LAMP” stack
      • L – Linux
      • A – Apache
      • M – MySQL
      • P – PHP
      • L – Linux
      • A – Apache
      • M – MapServer
      • P – PostGIS
    • Open Source Components
      • GDAL – Raster Library
      • OGR – Vector Library
      • GD – Graphics Creation
      • Proj.4 – Coordinate Systems
      • FreeType – Nice fonts!
      • GEOS – Geometry Engine
      • Shapelib – Shapefile library
    • A closer look at the “stack”
      • Front end –
        • PHP/Mapscript with Javascript
        • PHP/Mapscript
        • Pure CGI with template substitution
      • Data in
        • PostGIS or Shapefiles for vector
        • Geotiff, ECW or JPEG2000 for raster
        • Referenced and styled by MAPFILE
      • Mapserver CGI built with all the right “includes”
      • Webserver – Apache
      • Operating system - Linux
    • The Big Choice: What front end?
      • Percy facilitates open source sessions
        • Ka-Map
        • Chameleon
        • MapBender, MapLab, FIST
      • Grad Students revolt!
        • Requirements defined
          • Pan, Zoom, Query, some AJAX
        • In a single weekend prototype developed
      • Currently used in five production systems!
    • Special features: links from each glacier to “assets” database containing airphotos, oblique photos, and satellite data used for determinig temporal change during last century.
    • Special features: links from geologic map units to map catalog, lexicon of stratigraphic names, and more detailed data on state survey servers. Oh, and the GeoWiki!
    • Special features: uses Yahoo geocoder to zoom to street address. Passed as coordinates, returned as XML to be parsed... Serves up over 10GB of imagery, with loads times ~7 seconds
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    • Components of the National Geologic Map Database geographic search: Openlayers Javascript thick client Kamap Tiling engine to pre-render the five zoom levels Mapserver Cartographic styling and rendering of maps Prototype Javascript library Perl and Oracle Database storage and retrieval
      • Querying, like a big submit button
      • Capture image pixel clicked on, x, y
      • Convert to coordinate system of data in PostGIS
      • Query PostGIS with SQL select statement
      • Return rows of any tables that intersect
    • Conclusions
      • Open Source Web Mapping is reliable and proven
      • Be careful what Open Source project you align with
        • Many projects are brilliant, but orphaned
      • ARC will continue support and development of Map-Fu, both for map interfaces and backend datastreams.
    • DEMOS
      • http://Glaciers.us
      • http://NGMDB. usgs . gov
      • http://www.oregongeology.com/sub/ogdc/
      • http://www. oregongeology . com/sub/lidar/
    • Data Streams
      • End of Monolithic Web Apps
      • Open Geospatial Consortium (OGC)‏
        • WMS
        • WFS
          • Query for capabilities
      • High Quality data streams from many sources, possibly aggregated through virtual globes, such as Google Earth, NASA WorldWind, etc