OpenStreetMap and Geospatial Ruby Tim Waters sheffield ruby user group july 2015

1. OpenStreetMap
(+ other Geo/Ruby things)
Sheffield Ruby User Group
July 2015
Tim Waters
tim@geothings.net
@tim_waters

2. Live OSM
http://live.openstreetmap.fr/ https://osmlab.github.io/show-me-the-way/

3. What is OpenStreetMap?
A web project to create a free and open
map of the entire world

4. History
* Founded in the United Kingdom in 2004 by
Steve Coast
* Ordnance Survey Data was Expensive to
Use
* July 2005 the First Mapping Party Takes
Place

5. Open Data

6. http://www.ted.com/talks/view/lang/en//id/788

7. Haiti
http://vimeo.com/9182869
ito_haiti_berners_lee.mp4

8. Dude, we just use
Google.

9. The reasons not to...
Terms of Use
Copyright
Derived Works
No Data
OSM better in many areas

10. Dude, you can't trust it

11. “Wikipedia”
Fix the data
Objectiveness
Quality Control

13. Statistics
Number of users 1,045,770
Number of GPS points 3,295,708,898
Number of nodes 1,788,120,111
Number of ways 171,187,609
Active users / month 17,478
Wikipedia:
Number of pages: 29,551,074
Number of articles: 4,173,959
Active users / month 135,706

14. How do people map?

15. YOU CAN GET THE DATA

16. YOU CAN GET THE DATA
1) direct dump – planet (26G Compressed)
whole, day, hour, minute
2) API
i.e. OverPass
3) Extracts
Shapefile format
(buildings, natural, place, rail, roads, water, points, landuse)

17. Overpass API

18. TagInfo
● http://taginfo.openstreetmap.org/

20. Slide taginfo for a tag

21. Literally
More data than appears

23. More data than appears

24. Literally more data than appears
Cartography

25. Stamen - Watercolor
● http://maps.stamen.com/watercolor/#15/53.80
25/-1.5469

26. Stamen – Toner

27. Literally more data than appears
Custom Maps

34. OpenStreetMap Schema
Folksonomy: collaboratively created
created system of tagging things.
(The community creates the
OpenStreetMap tagging scheming over
time)

35. Nodes, Ways and Areas

36. OSM Stack
● Website
● API
● Editor
● Map Rendering
● Exports

37. OSM Website
Ruby on Rails
Github
openstreetmap/openstreetmap-website
All volunteers

38. Suitable tasks
● Changeset reverter, history diffs
● History bounding box improvements
● Groups of users
● Area type

39. Rosemary
● Ruby library 4 OSM
● https://github.com/sozialhelden/rosemary
require 'rosemary'
api = Rosemary::Api.new
node = api.find_way(174111099)
#<Rosemary::Way:0x000000032bab08
@nodes=[1848409287, 1848409219.... 1848409287],
@id=174111099, @version=3, @user="Paul Berry",
@timestamp=2014-03-14 14:53:49 UTC,
@changeset=21100786, @tags=
{"amenity"=>"pub", "building"=>"yes", "food"=>"yes",
"name"=>"The Red Deer", "real_ale"=>"yes"}>

40. Rosemary
client = Rosemary::BasicAuthClient.new
('osm_user_name', 'password')
api = Rosemary::Api.new(client)
changeset = api.create_changeset("Postbox on
Timothy Leary Street")
node = Rosemary::Node.new(:lat => 52.0,
:lon => 13.4)
node.add_tags({"amenity"=>"postbox"})
api.save(node, changeset)
api.close_changeset(changeset)

41. OSM Stack
● OpenHistoricalMap
● OpenGeoFiction

42. OpenHistoricalMap

43. Saeby – Denmark 18C

44. Saeby – Denmark Now

45. OpenGeoFiction

46. Other ruby geo
(GIS)
● Geos
● Gdal
● Rgeo
● Mapnik

47. GEOS
def buffer(feature, radius, min_radius=0.0)
wkb_writer = Geos::WkbWriter.new
wkb_reader = Geos::WkbReader.new
geom = wkb_reader.read_hex feature.geometry
buffer_geom = geom.buffer(radius)
if min_radius != 0.0
hole_geom = geom.buffer(min_radius)
buffer_geom = buffer_geom.difference(hole_geom)
end
feature.geometry = wkb_writer.write_hex buffer_geom
feature
end
https://github.com/dark-panda/ffi-geos
Apt-Get install libgeos-ruby

48. GDAL / OGR
● https://github.com/zhm/gdal-ruby
Gdal::Ogr.create_geometry_from_wkt('POINT (30 10)')
raster = Gdal::Gdal.open(filename)
dx = raster.RasterXSize
dy = raster.RasterYSize
x0, x_res, x_skew, y0, y_skew, y_res =
raster.get_geo_transform

49. RGeo
https://github.com/rgeo/rgeo
factory = Rgeo::Cartesian.factory
point1 = factory.point(1, 0)
point2 = factory.point(1, 4)
point3 = factory.point(­2, 0)
point4 = factory.point(­2, 4)
point2.distance(point3) # => 5.0
line_string1 = factory.line_string([point1, point2, point3])
line_string1.num_points # => 3
line_string1.point_n(0) == point1 # => true
line_string1.end_point == point3 # => true

50. PostGIS / postgres
https://github.com/rgeo/activerecord-postgis-adapter
create_table :my_spatial_table do |t|
t.column :shape1, :geometry
t.geometry :shape2
t.line_string :path, srid: 3785
t.st_point :lonlat, geographic: true
t.st_point :lonlatheight, geographic: true, has_z: true
end

51. PostGIS / postgres
record = MySpatialTable.find(1)
p = record.lonlat # Returns an RGeo::Feature::Point
puts p.x # displays the x coordinate
puts p.geometry_type.type_name # displays "Point"

52. PostGIS / postgres
bbox_polygon = Polygon.from_coordinates([bbox_coords],
4326).as_ewkt
Model.where(ST_Within(bbox_geom,
ST_GeomFromText('#{bbox_polygon}'))")

53. Ruby Mapnik :-(
https://github.com/mapnik/Ruby-Mapnik
Gem maintainer gone?
Code = old & broken
But
Mapnik = how maps are rendered from postgis from
OSM
Everyone uses it
C++ (rice)

54. map = Mapnik::Map.new do |m|
m.background = Mapnik::Color.new('#777') # A grey background
# Use the Google mercator projection
m.srs = Mapnik::Tile::DEFAULT_OUTPUT_PROJECTION
# Add a layer to the map
m.layer 'countries' do |l|
l.style do |s|
# Add a rule to the style (this one is a default rule)
s.rule do |default|
default.fill = Mapnik::Color.new('#880000')
end
end
l.srs = "+proj=latlong +datum=WGS84" # set the srs of the layer
l.datasource = Mapnik::Datasource.create :type => 'shape',
:file => "myshapefile.shp"
end
end
map.zoom_to_box(map.layers.first.envelope)
map.render_to_file('my_map.png')

55. Thanks!
@tim_waters
Leeds Ruby Thing
– last Thursday every month