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# -*- coding: utf-8 -*- 

 

u'''Web-services-based elevations and geoid heights. 

 

Functions to obtain elevations and geoid heights thru web services, 

for (lat, lon) locations, currently limited to the U{Conterminous US 

(CONUS)<https://WikiPedia.org/wiki/Contiguous_United_States>}, see also 

module L{geoids}, module L{heights} classes and U{USGS10mElev.py 

<https://Gist.GitHub.com/pyRobShrk>}. 

 

B{macOS}: If an C{SSLCertVerificationError} occurs, especially this 

I{"[SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed: self 

"signed certificate in certificate chain ..."}, review U{this post 

<https://StackOverflow.com/questions/27835619/urllib-and-ssl-certificate 

-verify-failed-error>} for a remedy. From a Terminal window run: 

C{"/Applications/Python X.Y/Install Certificates.command"} 

''' 

 

from pygeodesy.basics import clips, ub2str 

from pygeodesy.errors import ParseError, _xkwds_get 

from pygeodesy.interns import NN, _COLONSPACE_, _elevation_, \ 

_height_, _n_a_, _no_, _SPACE_ 

from pygeodesy.lazily import _ALL_LAZY 

from pygeodesy.named import _NamedTuple 

from pygeodesy.streprs import Fmt, fstr 

from pygeodesy.units import Lat, Lon, Meter, Scalar, Str 

 

__all__ = _ALL_LAZY.elevations 

__version__ = '21.04.24' 

 

try: 

from urllib2 import urlopen # quote, urlcleanup 

from httplib import HTTPException as HTTPError 

 

except (ImportError, NameError): # Python 3+ 

from urllib.request import urlopen # urlcleanup 

# from urllib.parse import quote 

from urllib.error import HTTPError 

 

_JSON_ = 'JSON' 

_XML_ = 'XML' 

 

try: 

from json import loads as _json 

except ImportError: # PYCHOK no cover 

 

from pygeodesy.interns import _COMMA_, _QUOTE2_ 

 

def _json(ngs): 

'''(INTERNAL) Convert an NGS response in JSON to a C{dict}. 

''' 

# b'{"geoidModel": "GEOID12A", 

# "station": "UserStation", 

# "lat": 37.8816, 

# "latDms": "N375253.76000", 

# "lon": -121.9142, 

# "lonDms": "W1215451.12000", 

# "geoidHeight": -31.703, 

# "error": 0.064 

# }' 

# 

# or in case of errors: 

# 

# b'{"error": "No suitable Geoid model found for model 15" 

# }' 

d = {} 

for t in ngs.strip().lstrip('{').rstrip('}').split(_COMMA_): 

t = t.strip() 

j = t.strip(_QUOTE2_).split('": ') 

if len(j) != 2: 

raise ParseError(json=t) 

k, v = j 

try: 

v = float(v) 

except (TypeError, ValueError): 

v = Str(ub2str(v.lstrip().lstrip(_QUOTE2_)), name=k) 

d[k] = v 

return d 

 

 

def _error(fun, lat, lon, e): 

'''(INTERNAL) Format an error 

''' 

return _COLONSPACE_(Fmt.PAREN(fun.__name__, fstr((lat, lon))), e) 

 

 

def _qURL(url, timeout=2, **params): 

'''(INTERNAL) Build B{C{url}} query, get and verify response. 

''' 

if params: # build url query, don't map(quote, params)! 

p = '&'.join(Fmt.EQUAL(p, v) for p, v in params.items() if v) 

if p: 

url = NN(url, '?', p) 

u = urlopen(url, timeout=timeout) # secs 

 

s = u.getcode() 

if s != 200: # http.HTTPStatus.OK or http.client.OK 

raise IOError('code %d: %s' % (s, u.geturl())) 

 

r = u.read() 

u.close() 

# urlcleanup() 

return ub2str(r).strip() 

 

 

def _xml(tag, xml): 

'''(INTERNAL) Get a <tag>value</tag> from XML. 

''' 

# b'<?xml version="1.0" encoding="utf-8" ?> 

# <USGS_Elevation_Point_Query_Service> 

# <Elevation_Query x="-121.914200" y="37.881600"> 

# <Data_Source>3DEP 1/3 arc-second</Data_Source> 

# <Elevation>3851.03</Elevation> 

# <Units>Feet</Units> 

# </Elevation_Query> 

# </USGS_Elevation_Point_Query_Service>' 

i = xml.find(Fmt.TAG(tag)) 

if i > 0: 

i += len(tag) + 2 

j = xml.find(Fmt.TAGEND(tag), i) 

if j > i: 

return Str(xml[i:j].strip(), name=tag) 

return _no_(_XML_, Fmt.TAG(tag)) 

 

 

class Elevation2Tuple(_NamedTuple): # .elevations.py 

'''2-Tuple C{(elevation, data_source)} in C{meter} and C{str}. 

''' 

_Names_ = (_elevation_, 'data_source') 

_Units_ = ( Meter, Str) 

 

 

def elevation2(lat, lon, timeout=2.0): 

'''Get the geoid elevation at an C{NAD83} to C{NAVD88} location. 

 

@arg lat: Latitude (C{degrees}). 

@arg lon: Longitude (C{degrees}). 

@kwarg timeout: Optional, query timeout (seconds). 

 

@return: An L{Elevation2Tuple}C{(elevation, data_source)} 

or (C{None, "error"}) in case of errors. 

 

@raise ValueError: Invalid B{C{timeout}}. 

 

@note: The returned C{elevation} is C{None} if B{C{lat}} or B{C{lon}} 

is invalid or outside the C{Conterminous US (CONUS)}, 

if conversion failed or if the query timed out. The 

C{error} is the C{HTTP-, IO-, SSL-, Type-, URL-} or 

C{ValueError} as a string (C{str}). 

 

@see: U{USGS National Map<https://NationalMap.gov/epqs>}, 

the U{FAQ<https://www.USGS.gov/faqs/what-are-projection- 

horizontal-and-vertical-datum-units-and-resolution-3dep-standard-dems>}, 

U{geoid.py<https://Gist.GitHub.com/pyRobShrk>}, module 

L{geoids}, classes L{GeoidG2012B}, L{GeoidKarney} and 

L{GeoidPGM}. 

''' 

try: 

x = _qURL('https://NED.USGS.gov/epqs/pqs.php', # 'https://NationalMap.gov/epqs/pqs.php' 

x=Lon(lon).toStr(prec=6), 

y=Lat(lat).toStr(prec=6), 

units='Meters', # 'Feet', capitalized 

output=_XML_.lower(), # _JSON_, lowercase only 

timeout=Scalar(timeout=timeout)) 

if x[:6] == '<?xml ': 

e = _xml('Elevation', x) 

try: 

e = float(e) 

if -1000000 < e < 1000000: 

return Elevation2Tuple(e, _xml('Data_Source', x)) 

e = 'non-CONUS %.2F' % (e,) 

except (TypeError, ValueError): 

pass 

else: 

e = _no_(_XML_, Fmt.QUOTE2(clips(x, limit=128, white=_SPACE_))) 

except (HTTPError, IOError, TypeError, ValueError) as x: 

e = repr(x) 

e = _error(elevation2, lat, lon, e) 

return Elevation2Tuple(None, e) 

 

 

class GeoidHeight2Tuple(_NamedTuple): # .elevations.py 

'''2-Tuple C{(height, model_name)}, geoid C{height} in C{meter} 

and C{model_name} as C{str}. 

''' 

_Names_ = (_height_, 'model_name') 

_Units_ = ( Meter, Str) 

 

 

def geoidHeight2(lat, lon, model=0, timeout=2.0): 

'''Get the C{NAVD88} geoid height at an C{NAD83} location. 

 

@arg lat: Latitude (C{degrees}). 

@arg lon: Longitude (C{degrees}). 

@kwarg model: Optional, geoid model ID (C{int}). 

@kwarg timeout: Optional, query timeout (seconds). 

 

@return: An L{GeoidHeight2Tuple}C{(height, model_name)} 

or C{(None, "error"}) in case of errors. 

 

@raise ValueError: Invalid B{C{timeout}}. 

 

@note: The returned C{height} is C{None} if B{C{lat}} or B{C{lon}} is 

invalid or outside the C{Conterminous US (CONUS)}, if the 

B{C{model}} was invalid, if conversion failed or if the 

query timed out. The C{error} is the C{HTTP-, IO-, SSL-, 

Type-, URL-} or C{ValueError} as a string (C{str}). 

 

@see: U{NOAA National Geodetic Survey 

<https://www.NGS.NOAA.gov/INFO/geodesy.shtml>}, 

U{Geoid<https://www.NGS.NOAA.gov/web_services/geoid.shtml>}, 

U{USGS10mElev.py<https://Gist.GitHub.com/pyRobShrk>}, module 

L{geoids}, classes L{GeoidG2012B}, L{GeoidKarney} and 

L{GeoidPGM}. 

''' 

try: 

j = _qURL('https://Geodesy.NOAA.gov/api/geoid/ght', 

lat=Lat(lat).toStr(prec=6), 

lon=Lon(lon).toStr(prec=6), 

model=(model if model else NN), 

timeout=Scalar(timeout=timeout)) # PYCHOK indent 

if j[:1] == '{' and j[-1:] == '}' and j.find('"error":') > 0: 

d, e = _json(j), 'geoidHeight' 

if isinstance(_xkwds_get(d, error=_n_a_), float): 

h = d.get(e, None) 

if h is not None: 

m = _xkwds_get(d, geoidModel=_n_a_) 

return GeoidHeight2Tuple(h, m) 

else: 

e = _JSON_ 

e = _no_(e, Fmt.QUOTE2(clips(j, limit=256, white=_SPACE_))) 

except (HTTPError, IOError, ParseError, TypeError, ValueError) as x: 

e = repr(x) 

e = _error(geoidHeight2, lat, lon, e) 

return GeoidHeight2Tuple(None, e) 

 

 

if __name__ == '__main__': 

 

# <https://WikiPedia.org/wiki/Mount_Diablo> 

for f in (elevation2, # (1173.79, '3DEP 1/3 arc-second') 

geoidHeight2): # (-31.699, u'GEOID12B') 

t = f(37.8816, -121.9142) 

print(_COLONSPACE_(f.__name__, t)) 

 

# **) MIT License 

# 

# Copyright (C) 2016-2021 -- mrJean1 at Gmail -- All Rights Reserved. 

# 

# Permission is hereby granted, free of charge, to any person obtaining a 

# copy of this software and associated documentation files (the "Software"), 

# to deal in the Software without restriction, including without limitation 

# the rights to use, copy, modify, merge, publish, distribute, sublicense, 

# and/or sell copies of the Software, and to permit persons to whom the 

# Software is furnished to do so, subject to the following conditions: 

# 

# The above copyright notice and this permission notice shall be included 

# in all copies or substantial portions of the Software. 

# 

# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS 

# OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 

# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL 

# THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR 

# OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, 

# ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR 

# OTHER DEALINGS IN THE SOFTWARE. 

 

# % python -m pygeodesy.elevations 

# elevation2: (1173.79, '3DEP 1/3 arc-second') 

# geoidHeight2: (-31.703, 'GEOID12B')