CODEWITHSUNDEEP
pythonmatplotlibgeospatialdata-visualization
user186477
user186477

Reputation: 1033

Where / how to get free high resolution satellite images for geospatial data visualization with python

I want to overlay geospatial data (mostly heatmaps) on top of high resolution satellite images using python. (i am newbie, so be gentle on me ;-) )

Here is my wish list

I think google map/earth, yahoo map, bing, etc... could be potential candidates, but I am not sure how to access them easily. Code examples would be very helpful.

Any suggestions?

Upvotes: 4

Views: 12831

Answers (3)

Marc-Olivier Titeux
Marc-Olivier Titeux

Reputation: 1317

Open Street Map is a good equivalent to Google maps (which I do not know very well).

Their database increases with time. It is an open source map acquisition attempt. They are sometimes a little bit more accurate than Google maps, see the Berlin zoo example.

It has several APIs, which are read-only access: http://wiki.openstreetmap.org/wiki/XAPI.

It appears to use the REST protocol.

For the use of REST and Python, I would suggest this SO link.

Upvotes: 4

heltonbiker
heltonbiker

Reputation: 27575

Google Maps explicitly forbid using map tiles offline or caching them, but I think Microsoft Bing Maps don't say anything explicitly against it, and I guess you are not planning to use your program commercially (?)

Then, you could use this. It creates a cache, first loading a tile from memory, else fom disk, else from the internet, always caching everything to disk for reuse. Of course you'll have to figure out how to tweak it, specifically how to get the tile coordinates and zoom level you need, and for this I suggest strongly this site. Good study!

#!/usr/bin/env python
# coding: utf-8

import os
import Image
import random
import urllib
import cStringIO
import cairo
#from geofunctions import *


class TileServer(object):
    def __init__(self):
        self.imdict = {}
        self.surfdict = {}
        self.layers = 'ROADMAP'
        self.path = './'
        self.urltemplate = 'http://ecn.t{4}.tiles.virtualearth.net/tiles/{3}{5}?g=0'
        self.layerdict = {'SATELLITE': 'a', 'HYBRID': 'h', 'ROADMAP': 'r'}

    def tiletoquadkey(self, xi, yi, z):
        quadKey = ''
        for i in range(z, 0, -1):
            digit = 0
            mask = 1 << (i - 1)
            if(xi & mask) != 0:
                digit += 1
            if(yi & mask) != 0:
                digit += 2
            quadKey += str(digit)
        return quadKey

    def loadimage(self, fullname, tilekey):
        im = Image.open(fullname)
        self.imdict[tilekey] = im
        return self.imdict[tilekey]

    def tile_as_image(self, xi, yi, zoom):
        tilekey = (xi, yi, zoom)
        result = None
        try:
            result = self.imdict[tilekey]
        except:
            filename = '{}_{}_{}_{}.jpg'.format(zoom, xi, yi, self.layerdict[self.layers])
            fullname = self.path + filename
            try:
                result = self.loadimage(fullname, tilekey)
            except:
                server = random.choice(range(1,4))
                quadkey = self.tiletoquadkey(*tilekey)
                print quadkey
                url = self.urltemplate.format(xi, yi, zoom, self.layerdict[self.layers], server, quadkey)
                print "Downloading tile %s to local cache." % filename
                urllib.urlretrieve(url, fullname)
                result = self.loadimage(fullname, tilekey)
        return result

if __name__ == "__main__":
    ts = TileServer()
    im = ts.tile_as_image(5, 9, 4)
    im.show()

Upvotes: 3

Paul Fisher
Paul Fisher

Reputation: 9666

One possible source is the images from NASA World Wind. You can look at the their source to find out how they access their data sources, and do the same in your application.

Upvotes: 1

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