- Author:
- gabejackson
- Posted:
- January 27, 2010
- Language:
- Python
- Version:
- 1.1
- Score:
- 0 (after 0 ratings)
According to the KML Specification, Polygons must be oriented according to the Right-Hand Rule (Counter Clockwise orientation) for them to display correctly in Google Earth. Since not all Polygons are defined according to the Right-Hand Rule, you can use this code to orient them correctly when using GeoDjango.
Thanks goes to jbronn of #geodjango on irc.freenode.net for this!
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 | """ models.py """
from django.contrib.gis.db import models
class Airspaces(models.Model):
geom = models.PolygonField()
""" your script """
# Import your models as usual
from airspaces.models import *
# Import the GeomField from geodjango
from django.contrib.gis.db.models.sql import GeomField
# Add the custom select field for the geometry field (this needs PostGIS to work)
qs = Airspaces.objects.extra(select={'rhr' : 'ST_ForceRHR(geom)'})
# Cast the field to the GeomField type
qs.query.extra_select_fields['rhr'] = GeomField()
# Iterate over objects as usual
for airspace in qs:
# Output our counter clockwise polygon
print airspace.rhr.coords
|
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