This document discusses geographic information systems (GIS) and how to work with geospatial data using Python and related tools. It introduces common geospatial data formats like KML, GML, and GeoJSON. It also discusses storing geospatial data in spatial databases like PostGIS. The document then covers how to obtain open geospatial data from OpenStreetMap and load it into a database. It demonstrates rendering geospatial data to maps using the Mapnik library and Python. Finally, it briefly discusses tile-based map services and front-end mapping libraries like OpenLayers that can display rendered geospatial data on web maps.

1. GIS, Python and company
Igor Pochechuev
22-23 October, 2011
Kyiv, Ukraine

3. Content
● What is geometry?
geometry formats
● How to store geo data?
spatial databases
● Where we can get geo data?
● Render it!
● Demo

4. General provisions
what we got

5. Geometry
formats
● WKT, WKB
● KML, GML (xml based)
● GeoJSON (json based)
● Shapefile (ESRI open specification)
● etc.

6. Geometry
common types
● Point
(x, y)
● Line
(<point>, <point1>, <point2>, …)
● Polygon
(<line>, <line1>, <line2>, …)

7. MultiGeometry
additional types of geometry
● MultiPoint
(<point>, <point1>, <point2>, ...)
● MultiLine
(<line>, <line1>, <line2>, ...)
● MultiPolygon
(<polygon>, <polygon1>, <polygon2>, ...)

8. Database layer
storing spatial data

9. Storing data
spatial databases
● SpatiaLite (SQLite)
● MySQL
● Oracle
● PostGIS (PostgreSQL)

10. Storing data
right choice
PostGIS

11. How to get geo data?
vector data

12. Getting data
vector data
OpenStreetMap

13. OpenStreetMap
stats
● < 400 000 registered users
● ~ 1 100 000 000 nodes (points)
● 100 000 000 ways
● ~ 800 — 3 000 nodes added each day
● ~ 100 000 — 300 000 ways added each day
● More statistics:
http://wiki.openstreetmap.org/wiki/Stats

14. OpenStreetMap
downloading ...
● Download planet.osm
http://wiki.openstreetmap.org/wiki/Planet.osm
● OSM API
http://api.openstreetmap.org/api/0.6/map?bbox=11.54,48.14,11.543,48.145
● JOSM (download through desktop app)
http://wiki.openstreetmap.org/wiki/JOSM
● Third part services (GIS LAB)
http://gis-lab.info/projects/osm-export.html

15. Loading data to database

16. >wget http://wiki.openstreetmap.org/wiki/Planet.osm

17. OSM2PgSQL
loading data
● osm2pgsql
-d <db_name>
-H <db_host>
-U <db_user>
-P <db_port>
-c # create tables if needed
-s # store tmp data in database
-S osm.import.style # mapping style
-k # add tags without column to an additional hstore
-z extra_data # hstore column containing all tags that start with 'extra_data'
RU-KRS.osm # path to OSM data file

18. Rendering ...

19. Rendering
tool choosing
MapServer Mapnik

20. Mapnik
description
● Written in C++
● Python interface
● OpenStreetMap, Flickr, CloudMade use mapnik
● PostGIS, Shapefiles, GeoTIFF, OSM XML, ...
● PNG, JPG, SVG, PDF, ...

21. Mapnik
map example

22. Layers
intro

23. Mapnik
code example
import mapnik
m = mapnik.Map(600,300,"+proj=latlong +datum=WGS84")
m.background = mapnik.Color('steelblue')
r = mapnik.Rule()
r.symbols.append(mapnik.PolygonSymbolizer(mapnik.Color('#f2eff9')))
r.symbols.append(mapnik.LineSymbolizer(mapnik.Color('rgb(50%,50%,50%)'),0.1))
s = mapnik.Style()
s.rules.append(r)
m.append_style('World Style',s)

24. Mapnik
code example
import mapnik
m = mapnik.Map(600, 300, "+proj=latlong +datum=WGS84")
m.background = mapnik.Color('steelblue')
r = mapnik.Rule()
r.symbols.append(mapnik.PolygonSymbolizer(mapnik.Color('#f2eff9')))
r.symbols.append(mapnik.LineSymbolizer(mapnik.Color('rgb(50%,50%,50%)'),0.1))
s = mapnik.Style()
s.rules.append(r)
m.append_style('World Style',s)

25. Mapnik
code example
import mapnik
m = mapnik.Map(600, 300, "+proj=latlong +datum=WGS84")
m.background = mapnik.Color('steelblue')
r = mapnik.Rule()
r.symbols.append(mapnik.PolygonSymbolizer(mapnik.Color('#f2eff9')))
r.symbols.append(mapnik.LineSymbolizer(mapnik.Color('rgb(50%,50%,50%)'), 0.1))
s = mapnik.Style()
s.rules.append(r)
m.append_style('World Style',s)

26. Mapnik
code example
import mapnik
m = mapnik.Map(600, 300, "+proj=latlong +datum=WGS84")
m.background = mapnik.Color('steelblue')
r = mapnik.Rule()
r.symbols.append(mapnik.PolygonSymbolizer(mapnik.Color('#f2eff9')))
r.symbols.append(mapnik.LineSymbolizer(mapnik.Color('rgb(50%,50%,50%)'), 0.1))
s = mapnik.Style()
s.rules.append(r)
m.append_style('World Style',s)

27. Mapnik
code example 2
lyr = mapnik.Layer('world', "+proj=latlong +datum=WGS84")
lyr.datasource = mapnik.Shapefile(file='world_borders.shp')
lyr.styles.append('World Style')
m.layers.append(lyr)
m.zoom_to_box(lyr.envelope())
mapnik.render_to_file(m,'world.png', 'png')

28. Mapnik
code example 2
lyr = mapnik.Layer('world', "+proj=latlong +datum=WGS84")
lyr.datasource = mapnik.Shapefile(file='world_borders.shp')
lyr.styles.append('World Style')
m.layers.append(lyr)
m.zoom_to_box(lyr.envelope())
mapnik.render_to_file(m,'world.png', 'png')

29. Mapnik
code example 2
lyr = mapnik.Layer('world', "+proj=latlong +datum=WGS84")
lyr.datasource = mapnik.Shapefile(file='world_borders.shp')
lyr.styles.append('World Style')
m.layers.append(lyr)
m.zoom_to_box(lyr.envelope())
mapnik.render_to_file(m,'world.png', 'png')

30. Map in browser

31. Mapnik
tile description

32. Mapnik
map services
● Tile Map Service
● Web Map Service

33. Mapnik
TMS
http: //website.com/<zoom>/<x>/<y>.png
../tiles/12/2451/1360.png

34. Mapnik
using osm scripts
● svn export http://svn.openstreetmap.org/applications/rendering/...
● ./generate_xml.py --password 'value' --host 'value' --port 'value'
--user 'value' --dbname 'value'
● MAPNIK_MAP_FILE='osm.xml' MAPNIK_TILE_DIR='tiles/'
./generate_tiles.py

35. Mapnik XML
<Map bgcolor="#b5d0d0">
<Style name="map_style">
<Rule>
<MaxScaleDenominator>[scale]</MaxScaleDenominator>
<MinScaleDenominator>[scale]</MinScaleDenominator>
<Filter>[field]='value'</Filter>
<PointSymbolizer/>
<LineSymbolizer/>
<PolygonSymbolizer/>
…
</Rule>
</Style>

36. Mapnik XML
<Layer name="misc_boundaries">
<StyleName>map_style</StyleName>
<Datasource>
<Parameter name="table">
(select way,way_area,name,boundary from polygon
where boundary='national_park') as boundary
</Parameter>
<Parameter name='dbname'>[dbname]</Parameter>
<Parameter name='host'>[host]</Parameter>
<Parameter name='user'>[user]</Parameter>
…
</Datasource>
</Layer>

37. Tile generating
./generate_tiles.py

38. Got tiles, what's next?

39. Frontend maps
choosing tool
● OpenLayers
● GeoExt
● Leaflet

40. OpenLayers
● Most powerfull
● Most used
● Large community
● OSM supported
● OSM, Google, Yahoo maps in one string
● TMS, WMS, WFS
● GML, GeoJSON, GeoRSS

41. OpenLayers

42. Show time!

43. Thanks!
Questions?