This document discusses using HTML5 geolocation and GeoDjango. It provides an overview of HTML5 geolocation which allows websites to detect the user's location using inputs like GPS, WiFi networks, and IP address. It then gives a crash course in GeoDjango, describing how to store and query geographic data and features like points, lines, polygons in a Django application. It also demonstrates a sample GeoDjango application for displaying user groups on a map near a given city.

1. GeoDjango &
HTML5 Geolocation
John Paulett john@paulett.org
September 1, 2011 @johnpaulett

3. The Plan
HTML5 Geolocation
Django Crash Course
What is GeoDjango?
GeoDjango Basics
Demo Application

4. Geolocation

5. W3C Geolocation
GPS, nearby Wi-Fi networks, cell towers, IP
address
IE 9, FF 3.6, Safari 5.0, Chrome, Opera 10.6, iOS,
Android
navigator.geolocation.getCurrentPosition
navigator.geolocation.watchPosition

6. W3C Geolocation
function showMap(position) {
console.log(position);
}
navigator.geolocation.getCurrentPosition(
showMap
);

7. W3C Geolocation
{
"coords": {
"accuracy": 22000,
"altitude": null,
"altitudeAccuracy": null,
"heading": null,
"latitude": 38.631756,
"longitude": -90.24323,
"speed": null
},
"timestamp": 1314459776275
}

8. Crash Course

9. models.py
from django.db import models
class City(models.Model):
name = models.TextField()
class UserGroup(models.Model):
name = models.TextField()
city = models.ForeignKey(City)
started = models.DateField()
def join(self, user):
# add user to group

10. urls.py
urlpatterns = patterns(
url(
r'^user-groups/(?P<city_name>w+)$',
'myapp.views.user_groups'
),
)

11. views.py
def user_groups(request, city_name):
city = City.objects.get(name=city_name)
groups = UserGroup.objects.filter(city=city)
return render(request, 'user_groups.html',
{'groups': groups})

12. user_groups.html
{% extends "base.html%}
<ul>
{% for group in groups %}
<li>
{{ group.name }}
</li>
{% endfor %}
</ul>

14. What is GeoDjango?
“world-class geographic Web framework”
included in Django core
Combine existing Python & DB tools with
standard API
but first …

15. Some GIS Problems
The Earth is not a sphere!
How to store & query efficiently
Vendor implementations
Wide range of data formats
Tiger/LINE, Shapefiles, E00, OGR, GeoJSON,
WKT, EWKT, EWKB, GML, KML, OSM, GLOBE,
TIFF, ArcGrid ….

16. GeoDjango Basics

17. GeoDjango Model Fields
from django.contrib.gis.db import models
models.PointField
models.LineStringField
models.PolygonField
models.MultiPointField
models.MultiLineStringField
models.MultiPolygonField
models.GeometryCollectionField

18. Given a Set of Geo Objects
Measure & Find:
distance, area, perimeter, centroid, envelope
Edit:
transform (SRID), scale
Operations:
intersection, difference, union
Output:
geojson, gml, kml, svg
SalesRegion.objects.all().kml()

19. Geo Querying
contains, covers, crosses, disjoint, equals,
intersects, touches, left/right, distance_lt,
distance_gt …
SalesRegion.objects.filter(
poly__distance_lt=(pnt, D(mi=500))
)

20. lambdageo

21. lambdageo
http://lambdageo.ep.io
http://github.com/johnpaulett/lambdageo

22. lambdageo.ep.io
●
models.py
Admin
Views
Templates

23. Django Admin

24. GIS is Cool
Python GIS
Tile Servers, Mapnik, etc.
Data
Openstreet Maps, Census

25. lambdageo.ep.io
github.com/johnpaulett/lambdageo
john@paulett.org / @johnpaulett

26. References

27. References
Python Geospatial Development – Erik
Westra

28. References
http://geodjango.org/
http://dev.w3.org/geo/api/spec-source.html
http://src.chromium.org/viewvc/chrome/tru
nk/src/chrome/browser/geolocation/
http://caniuse.com/#search=geolocation