Presentation given at Conferencia Rails 2010 http://conferenciarails.org/ Given by Javier de la Torre and Fernando Blar

1. RUBY
Javier de la Torre
GEOSPATIAL
envisioning life
CAPABILITIESIN
Fernando Blat

2. A revolution going on...
http://www.flickr.com/photos/toasty/1540997910/

3. “The future belongs to those who
understand how to use location data,
tools, and services successfully”
http://www.flickr.com/photos/crschmidt/4972140289/

4. Google Maps as a disruptive technology

5. 5
The birth of mashups

6. 6
The birth of mashups

7. 7

8. 8
The birth of mashups

9. 9
The birth of mashups

10. Twitter geolocates

11. Social media sites

12. 12
http://vimeo.com/10453518

13. Mobile geo web

14. Otrobache.com

15. Otrobache.com

16. 16
Otrobache.com v2

17. Helping to save the
world
We like to work on stories
and maps that matter

18. Crowdsourcing

19. Wikipedia
19
Wikipedia
Text

20. 20
OpenStreetMapOpenStreetMap

21. 21

22. 22

23. 23
Haiti Earthquake
http://www.flickr.com/photos/37913760@N03/4274633152/

24. 24
January 12, 2010
Peter Batty

25. 25
Imagery made available
January 13 2010

26. 26
January 14, 2010
Peter Batty

27. 27
January 26, 2010
Peter Batty

28. 28
Damage Assesment
Peter Batty

29. 29

30. 30

32. The movie

33. Data is improving!

34. Oldweather

35. 35

36. 36

37. How all this work?
http://www.satimagingcorp.com/gallery/gis-layers.html

38. A very short GIS class
POINT
LINE
POLYGON
http://en.wikipedia.org/wiki/Geographic_information_system

39. Welcome to PostGIS!

40. Based on PostgreSQL
Open Source
Very mature
Supported almost by every
GIS software

41. “Manually” create geometries
create table points (the_geom geometry, name varchar);
insert into points values ('POINT(0 0)', 'Location1');
insert into points values ('POINT(5 0)', 'Location2');
insert into points values ('POINT(0 5)', 'Location3');

42. select name, ST_AsText(the_geom),
ST_Distance(the_geom, 'POINT(5 5)') from points;
name | astext | distance
--------- + --------------
Location1 | POINT(0 0) | 7.07106
Location2 | POINT(5 0) | 5
Location3 | POINT(0 5) | 5
(3 rows)

43. More than 600 functions

44. W W W . R E F R A C T I O N S . N E T
Sample PostGIS Queries
3. Find all docks that are contained
completely within a lake, not touching a
lake bank.
SELECT a.id
FROM docks a, lakes b
WHERE a.geom && b.geom
AND ST_Relate(a.geom, b.geom, ‘ ’);
SELECT a.id
FROM docks a, lakes b
WHERE a.geom && b.geom
AND ST_Relate(a.geom, b.geom, ‘TFF ’);
SELECT a.id
FROM docks a, lakes b
WHERE a.geom && b.geom
AND ST_Relate(a.geom, b.geom, ‘TFFTFF ’);
SELECT a.id
FROM docks a, lakes b
WHERE a.geom && b.geom
AND ST_Relate(a.geom, b.geom, ‘TFFTFF212’);
SELECT a.id
FROM docks a, lakes b
WHERE a.geom && b.geom
AND ST_Relate(a.geom, b.geom, ‘TFFTFF212’);

46. What about the frontend
Google Maps Openlayers
Fusion Tables

47. Full GIS RIA on JS, HTML5...

48. Geoserver
And for rendering maps?
Fusion Tables

49. And what about Ruby?

50. In pure Ruby you can only
model data

51. Classes to represent the data

52. Export and import it from
formats such as KML, WKT, ...

53. But calculations are performed
in the storage / search engine

54. http://georuby.rubyforge.org
GeoRuby

55. Basic geometry classes:
Point, MultiPoint, LineString,
Polygon, MultiPolygon....

56. Parsers for importing data:
GeorssParser,
HexEWKBParser, EWKTParser

57. require 'rubygems'
require 'geo_ruby'
point = GeoRuby::SimpleFeatures::Point.from_lon_lat(
-3.726489543914795,
40.453423411115494
)
puts point.y
# => 40.4534234111155
puts point.x
# => -3.72648954391479
puts point.as_kml
# => => "<Point>
n<coordinates>-3.72648954391479,40.4534234111155</
coordinates>n</Point>n"
puts point.as_wkt
# => "POINT(-71 33.2)"

58. PostGIS adapter

59. Original:
http://rubyforge.org/projects/postgis-adapter
Improvements for
ProtectedPlanet.net
http://github.com/tokumine/postgis_adapter

60. class CreateWadusPolygons1 < ActiveRecord::Migration
def self.up
create_table :wadus_polygons do |t|
t.geometry :the_geom, :srid => 4326, :null => false
t.timestamps
end
end
def self.down
drop_table :wadus_polygons
end
end

61. class WadusPoint < ActiveRecord::Base
has_geom :the_geom => :point
end
class WadusPolygon < ActiveRecord::Base
has_geom :the_geom => :polygon
end

62. wpl = WadusPolygon.new
p1 = Point.from_lon_lat(-3.7271440029144287, 40.45342545209858)
p2 = Point.from_lon_lat(-3.725684881210327, 40.45358056663219)
p3 = Point.from_lon_lat(-3.72560977935791, 40.45302541822783)
p4 = Point.from_lon_lat(-3.7267684936523438, 40.45290295840354)
wpl.the_geom = Polygon.from_points([[p1, p2, p3, p4]])
wc = WadusPoint.new
wc.the_geom = Point.from_lon_lat(-3.726392984390259,
40.45302541822783)
wc.save
wpl.contains?(wc)

63. Where is the magic?
How the ruby library
implements those PostGIS
functions?

64. # postgis_adapter/lib/postgis_functions/class.rb
def contains(p, srid=4326)
find(:all, :conditions =>
["ST_Contains(geom, GeomFromText('POINT(#{p.x} #{p.y})',
#{srid}))"])
end

65. # Order by distance
def close_to(p, opts = {})
srid = opts.delete(:srid) || 4326
opts.merge!(:order => "ST_Distance(geom, GeomFromText
('POINT(#{p.x} #{p.y})', #{srid}))")
find(:all, opts)
end

66. http://github.com/fragility/
spatial_adapter
Spatial Adapter

67. ActiveRecord adapter that
supports MySQL spatial
extensions and PostGIS

68. Supports migrations, data
types, and geospatial indexes

69. Uses GeoRuby for data
modeling

70. http://geokit.rubyforge.org/
Geokit Ruby & Rails

71. https://github.com/andre/geokit-
gem
Gem

72. Calculate distance between
two points
Geocoding using Google,
Yahoo... geocoders
Rectangular bounds
calculations

73. Rails Plugin

74. ActiveRecord distance-based finders
IP-based location lookup utilizing
hostip.info
A before_filter helper to geocoder the
user's location based on IP address,
and retain the location in a cookie.

75. class Item < ActiveRecord::Base
acts_as_mappable :default_units => :miles,
:default_formula => :sphere,
:distance_field_name => :distance,
:lat_column_name => :lat,
:lng_column_name => :long
end

76. def close_items(limit = 10)
Item.find :all,
:origin => [lat,long],
:order => 'distance ASC',
:limit => limit,
:conditions => "id != #{self.id}"
end

77. SELECT *,
(ACOS(least(1,COS(0.688863980396179)*COS(-0.00643627778823306)
*COS(RADIANS(items.lat))*COS(RADIANS(items.long))+
COS(0.688863980396179)*SIN(-0.00643627778823306)*COS(RADIANS
(items.lat))*SIN(RADIANS(items.long))+
SIN(0.688863980396179)*SIN(RADIANS(items.lat))))*6376.77271)
AS distance FROM `items` WHERE (((items.lat>39.4600136605259 AND
items.lat<39.4779838100416 AND items.long>-0.380410723713182 AND
items.long<-0.357132382365919)) AND (
(ACOS(least(1,COS(0.688863980396179)*COS(-0.00643627778823306)
*COS(RADIANS(items.lat))*COS(RADIANS(items.long))+
COS(0.688863980396179)*SIN(-0.00643627778823306)*COS(RADIANS
(items.lat))*SIN(RADIANS(items.long))+
SIN(0.688863980396179)*SIN(RADIANS(items.lat))))*6376.77271)

78. It's great, but take care with
Active Record

80. Fusion tables gem
http://github.com/tokumine/
fusion-tables

81. ferblape@gmail.com
fernando.blat.es
THANKS
;)
@ferblape
jatorre@vizzuality.com
blog.vizzuality.com
@jatorre