def get_min_height(self, lat_ll, lon_ll, lat_ur, lon_ur):
result = {
'location_min': [],
'h_min': self.NODATA,
'counter_min': 0,
'source': self.attribution_name,
'attributions': [self.attribution]
}
if not (-90 <= lat_ll <= 90 and -180 <= lon_ll <= 180
and -90 <= lat_ur <= 90 and -180 <= lon_ur <= 180):
raise ValueError('invalid coordinates ({}, {}), ({}, {})'.format(
lat_ll, lon_ll, lat_ur, lon_ur))
# consider only correctly defined rectangle:
if lat_ll > lat_ur or lon_ll > lon_ur:
return result
try:
osgr_ll = toOsgr(eV.LatLon(lat_ll, lon_ll))
if len(osgr_ll.toStr()) == 0:
raise ValueError('not a valid OSGR coordinate')
except ValueError:
return result
try:
osgr_ur = toOsgr(eV.LatLon(lat_ur, lon_ur))
if len(osgr_ur.toStr()) == 0:
raise ValueError('not a valid OSGR coordinate')
except ValueError:
return result
file_list = {}
try:
self.create_filelist(osgr_ll, osgr_ur, file_list)
except IOError:
return result
result.update(self.check_min_files(self.filter_min_list(file_list)))
return result
def test_ll_to_osgr_to_ll():
# location on the Isles of Scilly
lat = 49.926244
lon = -6.297934
ll_orig = eV.LatLon(lat, lon)
osgr = toOsgr(ll_orig)
ll_osgr = osgr.toLatLon(eV.LatLon)
assert ll_orig.distanceTo(ll_osgr) < 1
parsed_osgr = parseOSGR(str(osgr))
ll_parsed_osgr = parsed_osgr.toLatLon(eV.LatLon)
assert ll_orig.distanceTo(ll_parsed_osgr) < 1
osgr_new = Osgr(osgr.easting, osgr.northing)
ll_osgr_new = osgr_new.toLatLon(eV.LatLon)
assert ll_orig.distanceTo(ll_osgr) < 1
def get_height(self, lat, lon):
if not (-90 <= lat <= 90 and -180 <= lon <= 180):
raise ValueError('invalid coordinates ({}, {})'.format(lat, lon))
result = {
'altitude_m': self.NODATA,
'source': self.attribution_name,
'lat': lat,
'lon': lon,
'distance_m': 0,
'attributions': [self.attribution]
}
if lat < 49.7 or lat > 62 or lon < -10 or lon > 4:
return result
try:
osgr = toOsgr(eV.LatLon(lat, lon))
if len(osgr.toStr()) == 0:
raise ValueError('not a valid OSGR coordinate')
except ValueError:
return result
# fit request to the grid
osgr = osgr_to_grid(osgr)
latlon = osgr.toLatLon(eV.LatLon)
lat_found = latlon.lat
lon_found = latlon.lon
filename = get_filename(osgr)
full_path = os.path.join(self.path, filename[:2].lower(), filename)
if not os.path.isfile(full_path):
return result
x = get_x(osgr)
y = get_y(osgr)
with open(full_path, "rb") as f:
# go to the right spot,
f.seek((y * NCOLS + x) * 4)
# read four bytes and convert them:
buf = f.read(4)
# ">f" is a four byte float
val = struct.unpack('>f', buf)[0]
result.update({
'lat_found':
round(lat_found, 6),
'lon_found':
round(lon_found, 6),
'altitude_m':
round(val, 2),
'distance_m':
round(calculate_distance(lat, lon, lat_found, lon_found), 3)
})
return result