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 –
Pure CGI with template substitution
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
MapBender, MapLab, FIST
Grad Students revolt!
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
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
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.
http://NGMDB. usgs . gov
http://www. oregongeology . com/sub/lidar/
End of Monolithic Web Apps
Open Geospatial Consortium (OGC)
Query for capabilities
High Quality data streams from many sources, possibly aggregated through virtual globes, such as Google Earth, NASA WorldWind, etc