grabber.py

def landsatID(alert_date, coords, offset_days=30):
    """get the ID of the Landsat 8 image that is closest to the
    supplied alert date within the supplied GEE-formatted polygon

    """

    d = datetime.datetime.strptime(alert_date, '%Y-%m-%d')
    begin_date = d - datetime.timedelta(days=offset_days)
    poly = ee.Feature.Polygon(coords)
    coll = ee.ImageCollection('LANDSAT/LC8_L1T_TOA').filterDate(begin_date, alert_date)
    coll = coll.filterBounds(poly)

    # descending sort by acquisition time
    desc = coll.sort('system:time_start', False).limit(1)
    try:
        idx = desc.getInfo()['features'][0]['id']
    except IndexError:
        idx = None

    print idx
    return idx



def genImage(lon, lat, w, h, date):
    """Generates the pan-sharpened Landsat 8 image for the supplied
    alert and image specs

    """
    coords = createBox(lon, lat, w, h)
    image_id = landsatID(date, coords)
    if image_id:
        loc = 'LANDSAT/%s' % image_id

        input = ee.Image(loc)
        rgb = input.select("B4","B3","B2")
        pan = input.select("B8")
        sharp = hsvpan(rgb, pan)

        vis_params = {'min':0.01, 'max':0.5, 'gamma':1.2};
        visual_image = sharp.visualize(**vis_params)
        params = {'scale':30, 'crs':'EPSG:4326', 'region':str(coords)}
        url = visual_image.getThumbUrl(params)
    else:
        url = 'http://i.imgur.com/jRtVWde.png'
    return url