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Open Source GIS. How we use free tools to do cool things. Martin Catala Donald Hayward. Why Open Source?. Why Open Source?. Error 999999. Why Open Source?. "Free Open Source Software" (FOSS) Free ($0) Free (-dom) Control Flexibility Quality (more eyes, more contributors) Innovation. - PowerPoint PPT Presentation
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● "Free Open Source Software" (FOSS)o Free ($0)o Free (-dom)
● Control● Flexibility● Quality (more eyes, more
contributors)● Innovation
Why Open Source?
● "Plays nice" with otherso Open Standards mean you can keep
ESRI but still get benefits from FOSSo SHP, WMS, WFS, KML, GeoJSON, etc.
● Enterprise-grade software and supporto Open Source GIS tools are not just toys
anymore (Boundless)
Why Open Source?
● It's more funo Fewer don'ts and can'tso If you can dream it, you can build ito The cool kids are doing it
Why Open Source?
● PostGIS (a spatial database system)
● QGIS (a desktop GIS application)
● OpenStreetMap● GeoServer (c.f.
ArcServer)
Our (abbreviated) Toolbox:● Python (GDAL,
Mapnik, cluster computing)
● OpenTripPlanner (Analyst Engine)
● OpenLayers, Leaflet, D3.js (Web Mapping)
Made with:● OpenLayers (web map)● PostGIS (backend, analysis)● QGIS (analysis, data management)● ArcMap (analysis)
Transit Livability Explorer
Analysis● Multi-step, often changing hands
several times (ArcGIS -> PostGIS -> QGIS -> etc.)
● Large-scale operations scripted with ArcPy, PostGIS SQL, or GDAL Python on USF Research Cluster
Transit Livability Explorer
Click to select:● OpenLayers translates the click into
(x,y)● A web API queries an indexed
PostGIS table for features intersecting the clicked coordinates
Transit Livability Explorer
Simplified GeoJSON Features with PostGIS:
SELECT ST_AsGeoJSON( ST_Simplify( geom, 100 ) ) FROM `table`;
Transit Livability Explorer
● Project constraints: o Dynamic web mapo Must work on all major browsers (even
IE)o Quick update when boundaries changeo No server-side processingo No cloud "add-ins"
MPO Advisory Council Map
First Attempt: ● GeoJSON on
OpenLayers/Leaflet/GMaps● Several layers with many features
and high-resolution boundaries● Worked fine on my computer● Client's browser crashed
MPO Advisory Council Map
Then we tried... ● Simplifying geometries
o Better, but old version of IE still choked● Rendering static images
o ArcGIS screwed up the georeferencing export
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Finally... ● Re-discovered Mapnik
o Python-based mapping libraryo Custom-made slippy tileso Accepts Shapefiles as inputo Generates 100,000+ map tiles in a few
minutes.
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