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+==================
+GeoDjango Tutorial
+==================
+Introduction
+============
+GeoDjango is an add-on for Django that turns it into a world-class geographic
+Web framework.  GeoDjango strives to make at as simple as possible to create
+geographic Web applications, like location-based services.  Some features include:
+* Django model fields for `OGC`_ geometries.
+* Extensions to Django's ORM for the querying and manipulation of spatial data.
+* Loosely-coupled, high-level Python interfaces for GIS geometry operations and
+data formats.
+* Editing of geometry fields inside the admin.
+This tutorial assumes a familiarity with Django; thus, if you're brand new to
+Django please read through the :doc:`regular tutorial </intro/tutorial01>` to introduce
+yourself with basic Django concepts.
+.. note::
+GeoDjango has special prerequisites overwhat is required by Django --
+please consult the :ref:`installation documentation <ref-gis-install>`
+for more details.
+This tutorial will guide you through the creation of a geographic Web
+application for viewing the `world borders`_. [#]_ Some of the code
+used in this tutorial is taken from and/or inspired by the `GeoDjango
+basic apps`_ project. [#]_
+.. note::
+Proceed through the tutorial sections sequentially for step-by-step
+instructions.
+.. _OGC: http://www.opengeospatial.org/
+.. _world borders: http://thematicmapping.org/downloads/world_borders.php
+.. _GeoDjango basic apps: http://code.google.com/p/geodjango-basic-apps/
+Setting Up
+==========
+Create a Spatial Database
+-------------------------
+.. note::
+MySQL and Oracle users can skip this section because spatial types
+are already built into the database.
+First, a spatial database needs to be created for our project.  If using
+PostgreSQL and PostGIS, then the following commands will
+create the database from a :ref:`spatial database template <spatialdb_template>`::
+$ createdb -T template_postgis geodjango
+.. note::
+This command must be issued by a database user that has permissions to
+create a database.  Here is an example set of commands to create such
+a user::
+$ sudo su - postgres
+$ createuser --createdb geo
+$ exit
+Replace ``geo`` to correspond to the system login user name will be
+connecting to the database.  For example, ``johndoe`` if that is the
+system user that will be running GeoDjango.
+Users of SQLite and SpatiaLite should consult the instructions on how
+to create a :ref:`SpatiaLite database <create_spatialite_db>`.
+Create GeoDjango Project
+------------------------
+Use the ``django-admin.py`` script like normal to create a ``geodjango`` project::
+$ django-admin.py startproject geodjango
+With the project initialized, now create a ``world`` Django application within
+the ``geodjango`` project::
+$ cd geodjango
+$ python manage.py startapp world
+Configure ``settings.py``
+-------------------------
+The ``geodjango`` project settings are stored in the ``settings.py`` file.  Edit
+the database connection settings appropriately::
+DATABASES = {
+'default': {
+'ENGINE': 'django.contrib.gis.db.backends.postgis',
+'NAME': 'geodjango',
+'USER': 'geo',
+}
+}
+.. note::
+These database settings are for Django 1.2 and above.
+In addition, modify the :setting:`INSTALLED_APPS` setting to include
+:mod:`django.contrib.admin`, :mod:`django.contrib.gis`,
+and ``world`` (our newly created application)::
+INSTALLED_APPS = (
+'django.contrib.auth',
+'django.contrib.contenttypes',
+'django.contrib.sessions',
+'django.contrib.sites',
+'django.contrib.admin',
+'django.contrib.gis',
+'world'
+)
+Geographic Data
+===============
+.. _worldborders:
+World Borders
+-------------
+The world borders data is available in this `zip file`__.  Create a data directory
+in the ``world`` application, download the world borders data, and unzip.
+On GNU/Linux platforms the following commands should do it::
+$ mkdir world/data
+$ cd world/data
+$ wget http://thematicmapping.org/downloads/TM_WORLD_BORDERS-0.3.zip
+$ unzip TM_WORLD_BORDERS-0.3.zip
+$ cd ../..
+The world borders ZIP file contains a set of data files collectively known as
+an `ESRI Shapefile`__, one of the most popular geospatial data formats.  When
+unzipped the world borders data set includes files with the following extensions:
+* ``.shp``: Holds the vector data for the world borders geometries.
+* ``.shx``: Spatial index file for geometries stored in the ``.shp``.
+* ``.dbf``: Database file for holding non-geometric attribute data
+(e.g., integer and character fields).
+* ``.prj``: Contains the spatial reference information for the geographic
+data stored in the shapefile.
+__ http://thematicmapping.org/downloads/TM_WORLD_BORDERS-0.3.zip
+__ http://en.wikipedia.org/wiki/Shapefile
+Use ``ogrinfo`` to examine spatial data
+---------------------------------------
+The GDAL ``ogrinfo`` utility is excellent for examining metadata about
+shapefiles (or other vector data sources)::
+$ ogrinfo world/data/TM_WORLD_BORDERS-0.3.shp
+INFO: Open of `world/data/TM_WORLD_BORDERS-0.3.shp'
+using driver `ESRI Shapefile' successful.
+1: TM_WORLD_BORDERS-0.3 (Polygon)
+Here ``ogrinfo`` is telling us that the shapefile has one layer, and that
+layer contains polygon data.  To find out more we'll specify the layer name
+and use the ``-so`` option to get only important summary information::
+$ ogrinfo -so world/data/TM_WORLD_BORDERS-0.3.shp TM_WORLD_BORDERS-0.3
+INFO: Open of `world/data/TM_WORLD_BORDERS-0.3.shp'
+using driver `ESRI Shapefile' successful.
+Layer name: TM_WORLD_BORDERS-0.3
+Geometry: Polygon
+Feature Count: 246
+Extent: (-180.000000, -90.000000) - (180.000000, 83.623596)
+Layer SRS WKT:
+GEOGCS["GCS_WGS_1984",
+DATUM["WGS_1984",
+SPHEROID["WGS_1984",6378137.0,298.257223563]],
+PRIMEM["Greenwich",0.0],
+UNIT["Degree",0.0174532925199433]]
+FIPS: String (2.0)
+ISO2: String (2.0)
+ISO3: String (3.0)
+UN: Integer (3.0)
+NAME: String (50.0)
+AREA: Integer (7.0)
+POP2005: Integer (10.0)
+REGION: Integer (3.0)
+SUBREGION: Integer (3.0)
+LON: Real (8.3)
+LAT: Real (7.3)
+This detailed summary information tells us the number of features in the layer
+(246), the geographical extent, the spatial reference system ("SRS WKT"),
+as well as detailed information for each attribute field.  For example,
+``FIPS: String (2.0)`` indicates that there's a ``FIPS`` character field
+with a maximum length of 2; similarly, ``LON: Real (8.3)`` is a floating-point
+field that holds a maximum of 8 digits up to three decimal places.  Although
+this information may be found right on the `world borders`_ Web site, this shows
+you how to determine this information yourself when such metadata is not
+provided.
+Geographic Models
+=================
+Defining a Geographic Model
+---------------------------
+Now that we've examined our world borders data set using ``ogrinfo``, we can
+create a GeoDjango model to represent this data::
+from django.contrib.gis.db import models
+class WorldBorders(models.Model):
+# Regular Django fields corresponding to the attributes in the
+	# world borders shapefile.
+name = models.CharField(max_length=50)
+area = models.IntegerField()
+pop2005 = models.IntegerField('Population 2005')
+fips = models.CharField('FIPS Code', max_length=2)
+iso2 = models.CharField('2 Digit ISO', max_length=2)
+iso3 = models.CharField('3 Digit ISO', max_length=3)
+un = models.IntegerField('United Nations Code')
+region = models.IntegerField('Region Code')
+subregion = models.IntegerField('Sub-Region Code')
+	lon = models.FloatField()
+	lat = models.FloatField()
+	# GeoDjango-specific: a geometry field (MultiPolygonField), and
+# overriding the default manager with a GeoManager instance.
+	mpoly = models.MultiPolygonField()
+	objects = models.GeoManager()
+# So the model is pluralized correctly in the admin.
+class Meta:
+verbose_name_plural = "World Borders"
+# Returns the string representation of the model.
+def __unicode__(self):
+return self.name
+Two important things to note:
+1. The ``models`` module is imported from :mod:`django.contrib.gis.db`.
+2. The model overrides its default manager with
+:class:`~django.contrib.gis.db.models.GeoManager`; this is *required*
+to perform spatial queries.
+When declaring a geometry field on your model the default spatial reference system
+is WGS84 (meaning the `SRID`__ is 4326) -- in other words, the field coordinates are in
+longitude/latitude pairs in units of degrees.  If you want the coordinate system to be
+different, then SRID of the geometry field may be customized by setting the ``srid``
+with an integer corresponding to the coordinate system of your choice.
+__ http://en.wikipedia.org/wiki/SRID
+Run ``syncdb``
+--------------
+After you've defined your model, it needs to be synced with the spatial database.
+First, let's look at the SQL that will generate the table for the ``WorldBorders``
+model::
+$ python manage.py sqlall world
+This management command should produce the following output::
+BEGIN;
+CREATE TABLE "world_worldborders" (
+"id" serial NOT NULL PRIMARY KEY,
+"name" varchar(50) NOT NULL,
+"area" integer NOT NULL,
+"pop2005" integer NOT NULL,
+"fips" varchar(2) NOT NULL,
+"iso2" varchar(2) NOT NULL,
+"iso3" varchar(3) NOT NULL,
+"un" integer NOT NULL,
+"region" integer NOT NULL,
+"subregion" integer NOT NULL,
+"lon" double precision NOT NULL,
+"lat" double precision NOT NULL
+)
+;
+SELECT AddGeometryColumn('world_worldborders', 'mpoly', 4326, 'MULTIPOLYGON', 2);
+ALTER TABLE "world_worldborders" ALTER "mpoly" SET NOT NULL;
+CREATE INDEX "world_worldborders_mpoly_id" ON "world_worldborders" USING GIST ( "mpoly" GIST_GEOMETRY_OPS );
+COMMIT;
+If satisfied, you may then create this table in the database by running the
+``syncdb`` management command::
+$ python manage.py syncdb
+Creating table world_worldborders
+Installing custom SQL for world.WorldBorders model
+The ``syncdb`` command may also prompt you to create an admin user; go ahead and
+do so (not required now, may be done at any point in the future using the
+``createsuperuser`` management command).
+Importing Spatial Data
+======================
+This section will show you how to take the data from the world borders
+shapefile and import it into GeoDjango models using the :ref:`ref-layermapping`.
+There are many different different ways to import data in to a
+spatial database -- besides the tools included within GeoDjango, you
+may also use the following to populate your spatial database:
+* `ogr2ogr`_: Command-line utility, included with GDAL, that
+supports loading a multitude of vector data formats into
+the PostGIS, MySQL, and Oracle spatial databases.
+* `shp2pgsql`_: This utility is included with PostGIS and only supports
+ESRI shapefiles.
+.. _ogr2ogr: http://www.gdal.org/ogr2ogr.html
+.. _shp2pgsql: http://postgis.refractions.net/documentation/manual-1.5/ch04.html#shp2pgsql_usage
+.. _gdalinterface:
+GDAL Interface
+--------------
+Earlier we used the the ``ogrinfo`` to explore the contents of the world borders
+shapefile.  Included within GeoDjango is an interface to GDAL's powerful OGR
+library -- in other words, you'll be able explore all the vector data sources
+that OGR supports via a Pythonic API.
+First, invoke the Django shell::
+$ python manage.py shell
+If the :ref:`worldborders` data was downloaded like earlier in the
+tutorial, then we can determine the path using Python's built-in
+``os`` module::
+>>> import os
+>>> from geodjango import world
+>>> world_shp = os.path.abspath(os.path.join(os.path.dirname(world.__file__),
+...                             'data/TM_WORLD_BORDERS-0.3.shp'))
+Now, the world borders shapefile may be opened using GeoDjango's
+:class:`~django.contrib.gis.gdal.DataSource` interface::
+>>> from django.contrib.gis.gdal import *
+>>> ds = DataSource(world_shp)
+>>> print ds
+/ ... /geodjango/world/data/TM_WORLD_BORDERS-0.3.shp (ESRI Shapefile)
+Data source objects can have different layers of geospatial features; however,
+shapefiles are only allowed to have one layer::
+>>> print len(ds)
+1
+>>> lyr = ds[0]
+>>> print lyr
+TM_WORLD_BORDERS-0.3
+You can see what the geometry type of the layer is and how many features it
+contains::
+>>> print lyr.geom_type
+Polygon
+>>> print len(lyr)
+246
+.. note::
+Unfortunately the shapefile data format does not allow for greater
+specificity with regards to geometry types.  This shapefile, like
+many others, actually includes ``MultiPolygon`` geometries in its
+features.  You need to watch out for this when creating your models
+as a GeoDjango ``PolygonField`` will not accept a ``MultiPolygon``
+type geometry -- thus a ``MultiPolygonField`` is used in our model's
+definition instead.
+The :class:`~django.contrib.gis.gdal.Layer` may also have a spatial reference
+system associated with it -- if it does, the ``srs`` attribute will return a
+:class:`~django.contrib.gis.gdal.SpatialReference` object::
+>>> srs = lyr.srs
+>>> print srs
+GEOGCS["GCS_WGS_1984",
+DATUM["WGS_1984",
+SPHEROID["WGS_1984",6378137.0,298.257223563]],
+PRIMEM["Greenwich",0.0],
+UNIT["Degree",0.0174532925199433]]
+>>> srs.proj4 # PROJ.4 representation
+'+proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs '
+Here we've noticed that the shapefile is in the popular WGS84 spatial reference
+system -- in other words, the data uses units of degrees longitude and latitude.
+In addition, shapefiles also support attribute fields that may contain
+additional data.  Here are the fields on the World Borders layer:
+>>> print lyr.fields
+['FIPS', 'ISO2', 'ISO3', 'UN', 'NAME', 'AREA', 'POP2005', 'REGION', 'SUBREGION', 'LON', 'LAT']
+Here we are examining the OGR types (e.g., whether a field is an integer or
+a string) associated with each of the fields:
+>>> [fld.__name__ for fld in lyr.field_types]
+['OFTString', 'OFTString', 'OFTString', 'OFTInteger', 'OFTString', 'OFTInteger', 'OFTInteger', 'OFTInteger', 'OFTInteger', 'OFTReal', 'OFTReal']
+You can iterate over each feature in the layer and extract information from both
+the feature's geometry (accessed via the ``geom`` attribute) as well as the
+feature's attribute fields (whose **values** are accessed via ``get()``
+method)::
+>>> for feat in lyr:
+...    print feat.get('NAME'), feat.geom.num_points
+...
+Guernsey 18
+Jersey 26
+South Georgia South Sandwich Islands 338
+Taiwan 363
+:class:`~django.contrib.gis.gdal.Layer` objects may be sliced::
+>>> lyr[0:2]
+[<django.contrib.gis.gdal.feature.Feature object at 0x2f47690>, <django.contrib.gis.gdal.feature.Feature object at 0x2f47650>]
+And individual features may be retrieved by their feature ID::
+>>> feat = lyr[234]
+>>> print feat.get('NAME')
+San Marino
+Here the boundary geometry for San Marino is extracted and looking
+exported to WKT and GeoJSON::
+>>> geom = feat.geom
+>>> print geom.wkt
+POLYGON ((12.415798 43.957954,12.450554 ...
+>>> print geom.json
+{ "type": "Polygon", "coordinates": [ [ [ 12.415798, 43.957954 ], [ 12.450554, 43.979721 ], ...
+``LayerMapping``
+----------------
+We're going to dive right in -- create a file called ``load.py`` inside the
+``world`` application, and insert the following::
+import os
+from django.contrib.gis.utils import LayerMapping
+from models import WorldBorders
+world_mapping = {
+'fips' : 'FIPS',
+'iso2' : 'ISO2',
+'iso3' : 'ISO3',
+'un' : 'UN',
+'name' : 'NAME',
+'area' : 'AREA',
+'pop2005' : 'POP2005',
+'region' : 'REGION',
+'subregion' : 'SUBREGION',
+'lon' : 'LON',
+'lat' : 'LAT',
+'mpoly' : 'MULTIPOLYGON',
+}
+world_shp = os.path.abspath(os.path.join(os.path.dirname(__file__), 'data/TM_WORLD_BORDERS-0.3.shp'))
+def run(verbose=True):
+lm = LayerMapping(WorldBorders, world_shp, world_mapping,
+transform=False, encoding='iso-8859-1')
+lm.save(strict=True, verbose=verbose)
+A few notes about what's going on:
+* Each key in the ``world_mapping`` dictionary corresponds to a field in the
+``WorldBorders`` model, and the value is the name of the shapefile field
+that data will be loaded from.
+* The key ``mpoly`` for the geometry field is ``MULTIPOLYGON``, the
+geometry type we wish to import as.  Even if simple polygons are encountered
+in the shapefile they will automatically be converted into collections prior
+to insertion into the database.
+* The path to the shapefile is not absolute -- in other words, if you move the
+``world`` application (with ``data`` subdirectory) to a different location,
+then the script will still work.
+* The ``transform`` keyword is set to ``False`` because the data in the
+shapefile does not need to be converted -- it's already in WGS84 (SRID=4326).
+* The ``encoding`` keyword is set to the character encoding of string values in
+the shapefile. This ensures that string values are read and saved correctly
+from their original encoding system.
+Afterwards, invoke the Django shell from the ``geodjango`` project directory::
+$ python manage.py shell
+Next, import the ``load`` module, call the ``run`` routine, and watch ``LayerMapping``
+do the work::
+>>> from world import load
+>>> load.run()
+.. _ogrinspect-intro:
+Try ``ogrinspect``
+------------------
+Now that you've seen how to define geographic models and import data with the
+:ref:`ref-layermapping`, it's possible to further automate this process with
+use of the :djadmin:`ogrinspect` management command.  The :djadmin:`ogrinspect`
+command  introspects a GDAL-supported vector data source (e.g., a shapefile) and
+generates a model definition and ``LayerMapping`` dictionary automatically.
+The general usage of the command goes as follows::
+$ python manage.py ogrinspect [options] <data_source> <model_name> [options]
+Where ``data_source`` is the path to the GDAL-supported data source and
+``model_name`` is the name to use for the model.  Command-line options may
+be used to further define how the model is generated.
+For example, the following command nearly reproduces the ``WorldBorders`` model
+and mapping dictionary created above, automatically::
+$ python manage.py ogrinspect world/data/TM_WORLD_BORDERS-0.3.shp WorldBorders --srid=4326 --mapping --multi
+A few notes about the command-line options given above:
+* The ``--srid=4326`` option sets the SRID for the geographic field.
+* The ``--mapping`` option tells ``ogrinspect`` to also generate a
+mapping dictionary for use with :class:`~django.contrib.gis.utils.LayerMapping`.
+* The ``--multi`` option is specified so that the geographic field is a
+:class:`~django.contrib.gis.db.models.MultiPolygonField` instead of just a
+:class:`~django.contrib.gis.db.models.PolygonField`.
+The command produces the following output, which may be copied
+directly into the ``models.py`` of a GeoDjango application::
+# This is an auto-generated Django model module created by ogrinspect.
+from django.contrib.gis.db import models
+class WorldBorders(models.Model):
+fips = models.CharField(max_length=2)
+iso2 = models.CharField(max_length=2)
+iso3 = models.CharField(max_length=3)
+un = models.IntegerField()
+name = models.CharField(max_length=50)
+area = models.IntegerField()
+pop2005 = models.IntegerField()
+region = models.IntegerField()
+subregion = models.IntegerField()
+lon = models.FloatField()
+lat = models.FloatField()
+geom = models.MultiPolygonField(srid=4326)
+objects = models.GeoManager()
+# Auto-generated `LayerMapping` dictionary for WorldBorders model
+worldborders_mapping = {
+'fips' : 'FIPS',
+'iso2' : 'ISO2',
+'iso3' : 'ISO3',
+'un' : 'UN',
+'name' : 'NAME',
+'area' : 'AREA',
+'pop2005' : 'POP2005',
+'region' : 'REGION',
+'subregion' : 'SUBREGION',
+'lon' : 'LON',
+'lat' : 'LAT',
+'geom' : 'MULTIPOLYGON',
+}
+Spatial Queries
+===============
+Spatial Lookups
+---------------
+GeoDjango extends the Django ORM and allows the use of spatial lookups.
+Let's do an example where we find the ``WorldBorder`` model that contains
+a point.  First, fire up the management shell::
+$ python manage.py shell
+Now, define a point of interest [#]_::
+>>> pnt_wkt = 'POINT(-95.3385 29.7245)'
+The ``pnt_wkt`` string represents the point at -95.3385 degrees longitude,
+and 29.7245 degrees latitude.  The geometry is in a format known as
+Well Known Text (WKT), an open standard issued by the Open Geospatial
+Consortium (OGC). [#]_  Import the ``WorldBorders`` model, and perform
+a ``contains`` lookup using the ``pnt_wkt`` as the parameter::
+>>> from world.models import WorldBorders
+>>> qs = WorldBorders.objects.filter(mpoly__contains=pnt_wkt)
+>>> qs
+[<WorldBorders: United States>]
+Here we retrieved a ``GeoQuerySet`` that has only one model: the one
+for the United States (which is what we would expect).  Similarly,
+a :ref:`GEOS geometry object <ref-geos>` may also be used -- here the ``intersects``
+spatial lookup is combined with the ``get`` method to retrieve
+only the ``WorldBorders`` instance for San Marino instead of a queryset::
+>>> from django.contrib.gis.geos import Point
+>>> pnt = Point(12.4604, 43.9420)
+>>> sm = WorldBorders.objects.get(mpoly__intersects=pnt)
+>>> sm
+<WorldBorders: San Marino>
+The ``contains`` and ``intersects`` lookups are just a subset of what's
+available -- the :ref:`ref-gis-db-api` documentation has more.
+Automatic Spatial Transformations
+---------------------------------
+When querying the spatial database GeoDjango automatically transforms
+geometries if they're in a different coordinate system.  In the following
+example, the coordinate will be expressed in terms of `EPSG SRID 32140`__,
+a coordinate system specific to south Texas **only** and in units of
+**meters** and not degrees::
+>>> from django.contrib.gis.geos import *
+>>> pnt = Point(954158.1, 4215137.1, srid=32140)
+Note that ``pnt`` may also constructed with EWKT, an "extended" form of
+WKT that includes the SRID::
+>>> pnt = GEOSGeometry('SRID=32140;POINT(954158.1 4215137.1)')
+When using GeoDjango's ORM, it will automatically wrap geometry values
+in transformation SQL, allowing the developer to work at a higher level
+of abstraction::
+>>> qs = WorldBorders.objects.filter(mpoly__intersects=pnt)
+>>> qs.query.as_sql() # Generating the SQL
+('SELECT "world_worldborders"."id", "world_worldborders"."name", "world_worldborders"."area",
+"world_worldborders"."pop2005", "world_worldborders"."fips", "world_worldborders"."iso2",
+"world_worldborders"."iso3", "world_worldborders"."un", "world_worldborders"."region",
+"world_worldborders"."subregion", "world_worldborders"."lon", "world_worldborders"."lat",
+"world_worldborders"."mpoly" FROM "world_worldborders"
+WHERE ST_Intersects("world_worldborders"."mpoly", ST_Transform(%s, 4326))',
+(<django.contrib.gis.db.backend.postgis.adaptor.PostGISAdaptor object at 0x25641b0>,))
+>>> qs # printing evaluates the queryset
+[<WorldBorders: United States>]
+__ http://spatialreference.org/ref/epsg/32140/
+Lazy Geometries
+---------------
+Geometries come to GeoDjango in a standardized textual representation.  Upon
+access of the geometry field, GeoDjango creates a `GEOS geometry object <ref-geos>`,
+exposing powerful functionality, such as serialization properties for
+popular geospatial formats::
+>>> sm = WorldBorders.objects.get(name='San Marino')
+>>> sm.mpoly
+<MultiPolygon object at 0x24c6798>
+>>> sm.mpoly.wkt # WKT
+MULTIPOLYGON (((12.4157980000000006 43.9579540000000009, 12.4505540000000003 43.9797209999999978, ...
+>>> sm.mpoly.wkb # WKB (as Python binary buffer)
+<read-only buffer for 0x1fe2c70, size -1, offset 0 at 0x2564c40>
+>>> sm.mpoly.geojson # GeoJSON (requires GDAL)
+'{ "type": "MultiPolygon", "coordinates": [ [ [ [ 12.415798, 43.957954 ], [ 12.450554, 43.979721 ], ...
+This includes access to all of the advanced geometric operations provided by
+the GEOS library::
+>>> pnt = Point(12.4604, 43.9420)
+>>> sm.mpoly.contains(pnt)
+True
+>>> pnt.contains(sm.mpoly)
+False
+``GeoQuerySet`` Methods
+-----------------------
+Putting your data on the map
+============================
+Google
+------
+Geographic Admin
+----------------
+GeoDjango extends :doc:`Django's admin application </ref/contrib/admin/index>`
+to enable support for editing geometry fields.
+Basics
+^^^^^^
+GeoDjango also supplements the Django admin by allowing users to create
+and modify geometries on a JavaScript slippy map (powered by `OpenLayers`_).
+Let's dive in again -- create a file called ``admin.py`` inside the
+``world`` application, and insert the following::
+from django.contrib.gis import admin
+from models import WorldBorders
+admin.site.register(WorldBorders, admin.GeoModelAdmin)
+Next, edit your ``urls.py`` in the ``geodjango`` project folder to look
+as follows::
+from django.conf.urls.defaults import *
+from django.contrib.gis import admin
+admin.autodiscover()
+urlpatterns = patterns('',
+(r'^admin/', include(admin.site.urls)),
+)
+Start up the Django development server::
+$ python manage.py runserver
+Finally, browse to ``http://localhost:8000/admin/``, and log in with the admin
+user created after running ``syncdb``.  Browse to any of the ``WorldBorders``
+entries -- the borders may be edited by clicking on a polygon and dragging
+the vertexes to the desired position.
+.. _OpenLayers: http://openlayers.org/
+.. _Open Street Map: http://openstreetmap.org/
+.. _Vector Map Level 0: http://earth-info.nga.mil/publications/vmap0.html
+.. _Metacarta: http://metacarta.com
+.. _osmgeoadmin-intro:
+``OSMGeoAdmin``
+^^^^^^^^^^^^^^^
+With the :class:`~django.contrib.gis.admin.OSMGeoAdmin`, GeoDjango uses
+a `Open Street Map`_ layer in the admin.
+This provides more context (including street and thoroughfare details) than
+available with the :class:`~django.contrib.gis.admin.GeoModelAdmin`
+(which uses the `Vector Map Level 0`_ WMS data set hosted at `Metacarta`_).
+First, there are some important requirements and limitations:
+* :class:`~django.contrib.gis.admin.OSMGeoAdmin` requires that the
+:ref:`spherical mercator projection be added <addgoogleprojection>`
+to the to be added to the ``spatial_ref_sys`` table (PostGIS 1.3 and
+below, only).
+* The PROJ.4 datum shifting files must be installed (see the
+:ref:`PROJ.4 installation instructions <proj4>` for more details).
+If you meet these requirements, then just substitute in the ``OSMGeoAdmin``
+option class in your ``admin.py`` file::
+admin.site.register(WorldBorders, admin.OSMGeoAdmin)
+.. rubric:: Footnotes
+.. [#] Special thanks to Bjørn Sandvik of `thematicmapping.org <http://thematicmapping.org>`_ for providing and maintaining this data set.
+.. [#] GeoDjango basic apps was written by Dane Springmeyer, Josh Livni, and Christopher Schmidt.
+.. [#] Here the point is for the `University of Houston Law Center <http://www.law.uh.edu/>`_ .
+.. [#] Open Geospatial Consortium, Inc., `OpenGIS Simple Feature Specification For SQL <http://www.opengis.org/docs/99-049.pdf>`_, Document 99-049.