Source Code for Module madrona.xyquery.management.commands.loadraster

 1  import os 
 2  import sys 
 3  from osgeo import gdal 
 4  from subprocess import Popen 
 5  from django.core.management.base import BaseCommand, CommandError 
 6  from django.utils.datastructures import SortedDict 
 7  from django.contrib.gis.gdal import SpatialReference 
 8  from django.conf import settings 
 9  from madrona.xyquery.models import Raster, Layer 
10   
11  from optparse import make_option 
12   
13 -class Command(BaseCommand): 
14      option_list = BaseCommand.option_list + ( 
15          make_option('-n', '--name', dest='name', 
16              help='Raster name.'), 
17          make_option('-s', '--srs', dest='srs', 
18              help='Spatial reference system of input raster'), 
19      ) 
20      help = 'Load a shapefile into the xyquery app.' 
21      args = '[shapefile ...]' 
22   
23 -    def parse_layer(self,rast, layername, srs): 
24          ds = gdal.Open(rast) 
25          if ds is None: 
26              raise Exception("Dataset is not valid") 
27          else: 
28              rast = os.path.abspath(rast) 
29   
30          if srs: 
31              srscmdpart = "-a_srs '%s'" % srs 
32          else: 
33              srscmdpart = '' 
34              if ds.GetProjection() == '' or not ds.GetProjection(): 
35                  raise Exception("Looks like the raster doesn't have a projection defined - use --srs") 
36   
37          # Create a new layer 
38          overwrite = True 
39          if overwrite: 
40              try: 
41                  old_lyr = Layer.objects.get(name=layername) 
42                  old_lyr.delete() 
43              except: 
44                  pass 
45          the_layer = Layer(name=layername) 
46          the_layer.save() 
47   
48          # Make a vrt copy of the dataset 
49          vrtpath = os.path.abspath(os.path.join(settings.MEDIA_ROOT,"xyquery_rasters",layername + ".vrt")) 
50          command = "gdal_translate %s -of VRT '%s' '%s'" % (srscmdpart, rast, vrtpath) 
51          output = Popen(command, shell=True).communicate()[0] 
52   
53          ds = gdal.Open(vrtpath) 
54          if not ds or not os.path.exists(vrtpath): 
55              raise Exception("%s does not exist .. somthing went screwy in the gdal_translate command \n\n %s" % (vrtpath, command)) 
56          del ds 
57   
58          # Create a new raster model instance 
59          the_raster = Raster(layer=the_layer, filepath=vrtpath) 
60          the_raster.save() 
61   
62 -    def handle(self, *rast, **options): 
63          if len(rast) != 1: 
64              return "Specify the path of a single raster dataset" 
65          rast = rast[0] 
66   
67          if not os.path.exists(rast): 
68              return "%s not found; Specify the path to an existing raster file" % rast 
69   
70          srs = options.get('srs',None) 
71          layername = options.get('name',None) 
72          if not layername: 
73              layername = os.path.splitext(os.path.basename(rast))[0] 
74   
75          self.parse_layer(rast, layername, srs) 
76          return "Raster layer %s has been loaded" % layername 
77