The State of Open Geo Hacking
Facilitated by Evan Henshaw-Plath, protest.net
Evan will reprise his ever-popular sessions on geo hacking, offering his thoughts on what's new and cool and then opening the floor up for questions and discussion.
There are two kinds of computer geography folks GIS and Online 3 years ago was the "pushpins on maps era" GIS thought that was stupid b/c it was missing polygons, etc.
TIGER/line = Govt. map data from the census bureau for streets and rivers that's used as a basis for US Street maps
For optimization, tile images are used. Everyblock uses their own tiles
Modest Maps Open source mapping system in flash under bsd license
MSNBC Hurricane tracker built on Modest Maps
Mailing List: GeoWanking
- GeoRSS, GeoAtom, GeoJSON - good for a feed of points and also shapes, but not necc complex shapes.
- KML - supported by GoogleEarth, OpenLayers, Geo
Can also take an existing feed and extract geographic information from it through something like Yahoo! Pipes.
HealthCity of LA has lots of data that they make available for overlaying various information (i.e. asthma rates vs. income vs. avg commute time to work)
Alternatives to Google Maps
- OpenLayers for the front (rendering of the mapstuff) and MapServer/GeoServer for back end
OpenSource Map Stack Drupal article here
- Openlayers for the front interface
- TileCache between Manik and openLayers
- mapnik for rendering the tiles
- Tiger/Line for Govt. street data
- Open Street Map an opensource project to drive around and take a picture of every street in the world with Wiki-like capabilities - Cool part about this is that you can write back instead of just always reading
- Andrew Turner's blog (a neographer)
- Beyond Google Maps a presentation by Andrew Turner
- Apps For Democracy DC GeoData contest
- Rabble's del.icio.us geo links
Discussion on how to determine where an address is within a polygon
- Walkscore.com shows you how walkable your neighborhood is
- pgRouting for route data
Geocoders convert addresses into lat/long (often us specific) Google and Yahoo! offer them. GeoCode.us, GeoCode.ca
When storing goespatial data in and RDBMS there is a separate datatype for that data. The best open source database for geospatial data is PostGIS, which is an extension for PostgreSQL
2 fields - geographic information systems (gis) (cartographers), self taught hackers (have taken and restructured the world)
geowankers - mailinglist of geo hackers
from gis to crappy maps like mapblast
australian company that was eaten by google, then launched google maps. not an open platform initially, but people started reverse engineering, using.
pushpins on maps became really easy. all the gis community thought that was stupid, wanted polygons, etc.
gis - information related to geospatial features - elevation in area as a field, attributes of an area (i.e. population)
portland housing authority - level of income and green space - map layers - see correlation of these two factors
things to figure out - map data, points, lines, polygons. attach all sorts of data to points, lines, polygons
tigerline - used as a baseline for building maps
optimizations that make it more complicated. google stores tiles, loads images as you zoom around.
everyblock - rendering their own -
archaic maps of london
ilovemountains.org - maps of coal mining country that show 1970 view and current view. also
georrs, geojson - rss with additional info -
if you don't have the geo info and have a feed, you can run the feed thru yahoo pipes and have it find geo info and then display on a map.
for the basic stuff, georss is enough.
item in a feed can have a list of points -
KML - defacto standard, can drop it into openlayers. not as supported on the desktop GML - scarier
maps are not things we watch, it is things we create. we can expose data...
LA ngo - healthycity.org. obtained lots of data, some open, some they purchased. can overlay all sorts of data on a map.
geocommons mapmaker - can take a snapshot of collection of data and publish it out as a new map.
twitter data was used to do this. clear that it represented a certain
dc had an open project - that shows all sorts of data.
geocommons - attempt to collect huge data set
barrier to mapping - developing large enough dataset so you can start
guardian.co.uk/uk/interactive/2008/nov19/bnp - adding overlay of income would give
californiadancenetwork.org - want to see this overlayed with racist
search for msnbc hurricane maps - stamen design, in sf mission - have their own platform (flash based)
britekite - location twitter - social network update kind of thing that include geo info. probably 40 of them.
search for modest maps - oakland transit data - took pdf and turned into tiles
chicago transit data - available to google but
openlayers - open source - initial design is ugly - you do have full css control
national atlas, us govt,
openstreetsmap - attempt to geomap the world - wiki type approach to
beijing - poorly mapped on google, really well mapped on openstreetmaps
styling openstreetmap data - have to do it on the level you render the tiles. mapnik is one tool to do that.
if you want to make a map that does not look like google, changethe style. also, allows you to emphasize info that is not roads.
bike paths and bike fatalities? nyc has crash dat maps, although proprietary with data. real heat maps.
hillmaps in sf also really great.
giving directions - another level of complexities. what direction the street goes in. attribute data is attached to streets. openstreet maps has those attributes. you can redo the routing. google now has car, walk and public transit
mapping people into congressional districts - egocode address, CONTAINS query to find out in which polygon. challenging because of things like
storing geographic data in relational databases. store lat and latitude in a geospatial
best opensource database to store data is postgis
mysql spatial extensions work kinda well. can't talk about the shape, just the rectangle.
for stuff as precise as congressional districts you need to use postgis
biggest trick - 4 sided polygon is 5 points, not 4. it has to go back to the beginning.
fireeagle - built for yahoo - collects info from cellphone
land trust accredation mapping - clustering icons for when many points overlay
slideshare.net/ andrew turner slide presentation
- geocodr.net -
onion video thing with slippy map
mountain biking site - ride with gps units, gathering data that will be shareable
geobabble - take gps data and put it into any format you can think of
flicker approach - zipcodes people do not know, visual approach to gathering geo data
pgrouting.postlbs.org - ridethecity.com lbs- location based services