Open Source GISHow we use free tools to do cool things
Martin CatalaDonald Hayward
Why Open Source?
Why Open Source?
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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?
● Still skeptical? ESRI isn't.o Python (ArcPy)o https://github.com/Esri
Why Open Source?
How we use 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)
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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
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Click to select:● OpenLayers translates the click into
(x,y)● A web API queries an indexed
PostGIS table for features intersecting the clicked coordinates
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Simplified GeoJSON Features with PostGIS:
SELECT ST_AsGeoJSON( ST_Simplify( geom, 100 ) ) FROM `table`;
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● 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.
MPO Advisory Council Map
● Open Source is cheap● Open Source is practical● Open Source is cool
Summary
Questions?
