Django snippets: Map GPX files to 3D GeoDjango Models

import os
from django.contrib.gis.utils import LayerMapping

class GPXMapping(LayerMapping):
    def __init__(self, *args, **kwargs):
        # Setting this environment variable tells OGR to use the elevation
        # attribute as the Z coordinate value on the geometries.  See:
        #  http://www.gdal.org/ogr/drv_gpx.html
        os.environ['GPX_ELE_AS_25D'] = 'YES'
        super(GPXMapping, self).__init__(*args, **kwargs)
        # Unset the environment variable, so it doesn't affect other
        # GPX DataSource objects.
        os.environ.pop('GPX_ELE_AS_25D')

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GPXMapping is a subclass of LayerMapping that imports GPX files into 3D GeoDjango models (requires Django 1.2 or SVN r11742 and higher). Here's an example of GeoDjango models for GPX points and tracks, respectively:

from django.contrib.gis.db import models

class GPXPoint(models.Model):
    timestamp = models.DateTimeField()
    point = models.PointField(dim=3)
    objects = models.GeoManager()

    def __unicode__(self):
        return unicode(self.timestamp)

class GPXTrack(models.Model):
    track = models.MultiLineStringField(dim=3)
    objects = models.GeoManager()

Assuming the above models, then GPXMapping may be used to load GPX tracks and waypoints (including elevation Z values):

track_point_mapping = {'timestamp' : 'time',
                       'point' : 'POINT',
                      }

track_mapping = {'track' : 'MULTILINESTRING'}

gpx_file = '/path/to/file.gpx'

lm = GPXMapping(GPXPoint, gpx_file, track_point_mapping, layer='track_points')
lm.save(verbose=True)

lm = GPXMapping(GPXTrack, gpx_file, track_mapping, layer='tracks')
lm.save(verbose=True)

Author:: jbronn
Posted:: November 16, 2009
Language:: Python
Django Version:: 1.1
Tags:: 3d geodjango gis gpx layermapping
Score:: 2 (after 2 ratings)

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Map GPX files to 3D GeoDjango Models

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