Intro to Spatial Programming
Peter Jackson
Director, Client Solutions, Intridea Inc.
1
Friday, July 9, 2010
Agenda
• What is Spatial Programming?
• Important Spatial Terms
• Tools in the Ruby / Rails spatial stack
• How you get started
2
Friday, July 9, 2010
What is Spatial
Programming?
• Exposing physical space as a first-order
programming concept.
• Rich, built-in support for shapes, space,
and the relationship of physical objects to
one another.
Friday, July 9, 2010
Describing Objects
Spatially
• Locations on the earth
• Geometric equations
• Shapes of buildings
• Parts in an assembly (a blueprint)
• Positions of your battleships
Friday, July 9, 2010
Spatial Logic
We can use spatial techniques to answer questions
that are difficult to answer with typical object
relational data.
Friday, July 9, 2010
Spatial Logic
• Find components of a vehicle close to the
fuel line that emit heat.
• Determine which customers are in certain
census tracts
• Find competitors located within 10 miles
of “Route 95” where there is an available
billboard within 20 miles.
Friday, July 9, 2010
Important terms
6
Friday, July 9, 2010
Important terms
• GIS: Geographical
Information System
• Layers: just like the layers in
Photoshop, but they're
georeferenced.
• WMS: Web Mapping Service
• Projection: algorithm for
flatting the globe
• Geometry: the core data
type in a GIS
6
Friday, July 9, 2010
GIS
A Geographical
Information System
visually represents data
about geography.
Friday, July 9, 2010
Most widely used GIS
Friday, July 9, 2010
Most widely used GIS
Friday, July 9, 2010
Most widely used GIS
Friday, July 9, 2010
Layers
Just like in Photoshop, Spatial tools let
you layer RASTER and VECTOR data on
the screen to tell a story.
Friday, July 9, 2010
Layers
Friday, July 9, 2010
Layers
Friday, July 9, 2010
Layers
Friday, July 9, 2010
Layers
Friday, July 9, 2010
Layers
Friday, July 9, 2010
Layers
Friday, July 9, 2010
WMS
Choose the best map service for highlighting your data
OpenStreetMap
Friday, July 9, 2010
WMS
Choose the best map service for highlighting your data
NASA WorldWind / JPL
Friday, July 9, 2010
WMS
Choose the best map service for highlighting your data
Bing
Friday, July 9, 2010
WMS
Choose the best map service for highlighting your data
Private Commercial
Sources (i-Cubed)
Friday, July 9, 2010
Projection
• Method for representing the spheroid earth on a flat
surface, such as a screen or paper map. They can be:
Friday, July 9, 2010
Projection
Polar
Friday, July 9, 2010
Projection
Planar
Friday, July 9, 2010
Projection
Conic
Friday, July 9, 2010
Projection
Cylindrical
Friday, July 9, 2010
Projections are
important for Layering
+
Mercator Projection
Satellite Imagery
Friday, July 9, 2010
Braun Projection
Boundary Lines
Projections are
important for Layering
= FAIL
Friday, July 9, 2010
Projection Hints
• Roughly equivalent to SRID (System Reference ID) in the various
spatial databases
• When in doubt, try EPSG:4326 or EPSG:900913 (Google). These are
the most widely used, but there are much more accurate ones
available.
• EPSG:4326 and EPSG:4236 are similar, but have different origin
points. Dyslexia FTW.
If you really want to know more: http://spatialreference.org/
Friday, July 9, 2010
Geometry
• The basic spatial data type
• <-- Point
• Line
• Polygon
• Curve
• Multiline
• Multipolygon
• Geometry Collection
Friday, July 9, 2010
Spatial Stack
• Spatial DBMS
• PostGIS
• Oracle Spatial
• MySQL Spatial
• spatial_adapter
• GeoRuby
• OpenLayers
Friday, July 9, 2010
Spatial DBMS
• Stores GEOMETRY in your tables
• Provides spatial functions like DISTANCE()
• Implements spatial indexing, so you can
forget your High School math.
Friday, July 9, 2010
Spatial DBMS
• PostGIS ->
The best, IMHO.
• Oracle Spatial ->
Powerful, but moody
• MySQL Spatial ->
Good, but use PostGIS if you can.
Friday, July 9, 2010
Friday, July 9, 2010
:id
:abbrev
:name
1
MD
Maryland
2
PA
Pennsylvania
3
VA
Virginia
4
WV
West Virginia
:geom
Friday, July 9, 2010
:id
:route
:locality
1
95
MD
2
295
DC
3
395
DC
4
50
DC
:geom
:id
1
2
3
Friday, July 9, 2010
:first_name :last_name
Peter
Joe
John
Jackson
:location
38.91094,
-77.0327
38.91094,
Grossberg
-77.0327
Doe
41.22,
-79.01
GeoRuby
• Exposes the Geometry data types in Ruby.
• Converts ESRI Shapefile data
• Handles other interchange formats
• Does a lot of geometric magic
Friday, July 9, 2010
spatial_adapter
• Translates GEOMETRY columns in your DB
into GeoRuby::Geometry types.
• Supports :geometry columns in
migrations
Friday, July 9, 2010
spatial_adapter
If you are using PostGIS or MySQL, you can use the
stock spatial_adapter maintained by “fragility”.
If you are using Oracle Spatial, you need my fork of
spatial_adapter, which is in early beta form.
github.com/peteonrails/spatial_adapter
Friday, July 9, 2010
OpenLayers
One of many javascript visualization
libraries
Supports display of:
• Bing Maps
• Google Maps
• Yahoo Maps
• NASA Worldwind
• KML Overlays
• Your own custom imagery
Friday, July 9, 2010
OpenLayers
Friday, July 9, 2010
How it all hangs together
Friday, July 9, 2010
Visualization
Map viewer (JS Library)
Spatial
Logic
Components
Spatial
Data
Sets
KML
Friday, July 9, 2010
+
Awesome Imagery
your awesome
biz logic here
ESRI
Shapefiles
+
Your Data =
WOW
GeoRuby
spatial_adapter
PostGIS
Oracle MySQL
Spatial Spatial
Visualization
Map viewer (JS Library)
Spatial
Logic
Components
Spatial
Data
Sets
KML
Friday, July 9, 2010
+
Awesome Imagery
your awesome
biz logic here
ESRI
Shapefiles
+
Your Data =
WOW
GeoRuby
spatial_adapter
PostGIS
Oracle MySQL
Spatial Spatial
Visualization
Map viewer (JS Library)
Spatial
Logic
Components
Spatial
Data
Sets
KML
Friday, July 9, 2010
+
Awesome Imagery
your awesome
biz logic here
ESRI
Shapefiles
+
Your Data =
WOW
GeoRuby
spatial_adapter
PostGIS
Oracle MySQL
Spatial Spatial
Visualization
Map viewer (JS Library)
Spatial
Logic
Components
Spatial
Data
Sets
KML
Friday, July 9, 2010
+
Awesome Imagery
your awesome
biz logic here
ESRI
Shapefiles
+
Your Data =
WOW
GeoRuby
spatial_adapter
PostGIS
Oracle MySQL
Spatial Spatial
Visualization
Map viewer (JS Library)
Spatial
Logic
Components
Spatial
Data
Sets
KML
Friday, July 9, 2010
+
Awesome Imagery
your awesome
biz logic here
ESRI
Shapefiles
+
Your Data =
WOW
GeoRuby
spatial_adapter
PostGIS
Oracle MySQL
Spatial Spatial
How The Tools
Implement GEOMETRY
Friday, July 9, 2010
Tool
Geometry Implementation
Ruby
GeoRuby::Geometry
Oracle
MDSYS.SDO_GEOMETRY
PostGIS
Geometry and Geography
types
MySQL
GEOMETRY, POINT, LINE, etc
Getting Started
Friday, July 9, 2010
Getting Started
tar xvfz postgis-1.5.1.tar.gz
cd postgis-1.5.1
./configure
make
make install
createdb yourdatabase
createlang plpgsql yourdatabase
psql -d yourdatabase -f postgis.sql
psql -d yourdatabase -f postgis_comments.sql
psql -d yourdatabase -f spatial_ref_sys.sql
Friday, July 9, 2010
Getting Started
$ gem install GeoRuby spatial_adapter
Successfully installed GeoRuby-1.3.4
Successfully installed spatial_adapter-1.1.2
Successfully installed activesupport-2.3.8
3 gems installed
Friday, July 9, 2010
Getting Started
Now fire up IRB any try this:
Friday, July 9, 2010
>> point = Point.new(4326, false, false)
=> #<GeoRuby::SimpleFeatures::Point:0x1014ef078
@with_z=false, @x=0.0, @srid=4326, @m=0.0, @z=0.0,
@with_m=false, @y=0.0>
>> point.x = -33.56
>> point.y = 40.23
# => -33.56
# => 40.23
>> point2 = Point.new
>> point2.set_x_y_z(-35.65, 41.11, 0)
>> point.spherical_distance(point2)
=> 201598.077888077
>> point.eudclidian_distance(point2)
=> 2.26770809408971
Friday, July 9, 2010
GeoRuby does tons more than calculating
distance:
• Bounding Box
• Convert to KML
• GeoRSS
• Plays nice with spatial_adapter
Friday, July 9, 2010
What ELSE can we do ?
A lot. Let’s look:
Friday, July 9, 2010
Spatial Queries
More than just “Dots on a map”
We can answer really difficult,
meaningful questions.
26
Friday, July 9, 2010
Spatial Queries
Q: How many freshwater wells are located
within 5 miles of a chemical plant?
A: (in Oracle Spatial)
SELECT c.chemical_plant_name
FROM well_table a, chemical_plants b
WHERE sdo_within_distance (b.geom,
a.geom, 'distance=5 unit=mile') = ‘TRUE’
26
Friday, July 9, 2010
Using PostGIS, spatial_adapter, and
GeoRuby, your Rails app could do this:
Friday, July 9, 2010
class CreateWells< ActiveRecord::Migration
def self.up
create_table :wells do |t|
t.references :customer
t.geometry :location
end
end
# <= spatial_adapter magic.
def self.down
drop_table :wells
end
end
# More spatial adapter magic
add_index :wells, :location, :spatial => true
Friday, July 9, 2010
class Well < ActiveRecord::Base
def self.find_by_proximity(km)
# This example uses Oracle syntax
find(:all, :joins => :chemical_plant,
:conditions => [“sdo_within_distance (chemical_plants.geom,
wells.geom, 'distance=? unit=km') = ‘TRUE’”, km])
end
end
class WellController < ApplicationController
def index
@wells = Well.find_by_proximity(params[:buffer])
end
end
Friday, July 9, 2010
Adding the View
<script src="../OpenLayers.js"></script>
<script type="text/javascript">
var map, layer;
function init(){
map = new OpenLayers.Map('map', {maxResolution:'auto'});
map.addControl(new OpenLayers.Control.LayerSwitcher());
layer = new OpenLayers.Layer.WMS( "OpenLayers WMS",
"http://labs.metacarta.com/wms/vmap0", {layers: 'basic'} );
map.addLayer(layer);
map.setCenter(new OpenLayers.LonLat(0, 0), 0);
var newl = new OpenLayers.Layer.Markers( 'POIs');
map.addLayer(newl);
}
</script>
Friday, July 9, 2010
Getting Started
Summary
• Install Spatial DBMS
• Install GeoRuby and spatial_adapter
• Use OpenLayers or some other JS library
• Start thinking spatially!
Friday, July 9, 2010
Friday, July 9, 2010
Agenda
• What is Spatial Programming?
• Important Spatial Terms
• Tools in the Ruby / Rails spatial stack
• How you get started
33
Friday, July 9, 2010
License
Creative Commons Attribution 3.0 Unported
You are free:
1. to Share — to copy, distribute and transmit the work
2. to Remix — to adapt the work
Attribution — You must attribute this work to Peter Jackson (with link). If you want to remix or redistribute
the work, including for your own personal or commercial use with no redistribution, please be sure that the
prior sentence remains intact.
THIS IS NOT A SHARE-ALIKE LICENSE. YOU MAY MAKE CHANGES TO THIS WORK AND KEEP
THEM FOR YOUR OWN USE, COMMERCIAL OR PERSONAL.
http://creativecommons.org/licenses/by/3.0/
Friday, July 9, 2010