An Introduction To Open Source GIS

An Introduction to Open Source GISAn Introduction to Open Source GIS Gavin JacksonGavin Jackson

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An Introduction To Open Source GIS

Gavin JacksonAtlas of Living Australia

CSIRO

Open Source Developers Conference 2011Canberra, Australia


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Introduction

• Not the best practice

• Coding in Perl too multidimensional for a unique maximum

• Coders of Perl too diverse for a unique maximum

• But a best practice

• Suitable for most applications


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Introduction

• Standards

• Architecture

• Databases

• Clients

• Geospatial Services

• Data / ALA Demonstration


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Standards







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OGC

• WMS – Web mapping service

• WFS – Web feature service

• WCS – Web coverage service


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Projections

• http://xkcd.com/977

• Maps a spherical surface to a 2D plane

• Area

• Shape

• Direction

• Distance/Scale


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Common Projections

• EPSG:4326 (WGS 84) lon/lat (km)

• EPSG:900913 lon/lat (m)

• GDA94/NSW Lambert EPSG:3308 (NSW)


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Formats

• ESRI Shapefile

• WKT

• KML

• GeoJSON/GeoRSS

• Raster (geotiff), ESRI Grid, ASCII Grid


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NetCDF

• Scientific Community

• Multi-Dimensional Spatial Data

– Temporal (time based)– Depth based data

• OpenDAP, THREDDS (NetCDF servers)

• THREDDS supports WMC and WCS services

• Panoply (client)


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Architecture







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Spatial Server

• OGC Services (WMS, WFS, WCS)

• CQL

• Styling

• Legend Generation

• On Click Event

• Geoserver Demo


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Thick Clients

• uDig (demo)

• World Wind (NASA)

• Google Earth


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Web Based Clients

• OpenLayers

• Google Maps (+ WMS extension)


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Thick Clients

• uDig

• World Wind (NASA)

• Google Earth


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Spatial Databases

• Capabilities

• PostGIS (demo)

• Commercial Offerings


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Spatial Services







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Geotools

• Java API

• Used by Geoserver and uDig

• Excellent workshop presented on Tuesday by Jody Garnett on Tuesday


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OGR – Simple Feature Library

• OGR is used to manipulate and work with vector based data – changing projections, converting to different types, merging shapefiles

• ogrinfo, ogr2ogr


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GDAL

• Geospatial Data Abstraction Library

• Used to manipulate and work with raster spatial data– changing projection, converting to different type, changing grid size

• gdalinfo, gdal_translate, gdalwarp …

• gdal_rasterize – convert a shapefile to a raster

• gdal_polygonize – convert a raster to a shapefile


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Geocoding

• Forward/Reverse

• Google geocoding service

• OSM (nominatim.openstreetmap.org) demo


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Spatial Metadata

• Geonetwork (OGC Client Services for the CSW implementation)


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Putting it all together (demos)







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Shapefile to web

• Quick demonstration to demonstrate:

• Shapefiles

• uDig

• PostGIS

• Geoserver

• Openlayers


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Use case – spatial.ala.org.au

• Developed by CSIRO in conjunction with a large number of data providers (Government departments, Universities, Museums, Herbaria)

• Spatial portal marries up species occurrence data with environmental layers

• Allows users to specify analysis areas and perform advanced spatial analysis functions


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Example

• Add species

• Add layer

• Add area

• Analysis tools


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Further Reading

• GIS for Web Developers - Adding where to your applications, Scott Davis, The Pragmatic Programmers LLC, 2007

• PostGIS in Action, Regina O. Obe and Leo S. Hsu, Manning, 2011

• Geoserver Tutorial (www.geoserver.org)

• UDig Tutorial (udig.refractions.net)


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URLs Visited During Talk

• http://www.openstreetmap.org/

• http://xkcd.com/977/

• http://www.gadm.org/

• http://www.naturalearthdata.com/

• http://spatial.ala.org.au

Technology

An Introduction To Open Source GIS