1

2# -*- coding: utf-8 -*-

3

4 u'''Web-services-based elevations and C{CONUS} geoid heights.

5

6 Functions to obtain elevations and geoid heights thru web services,

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

8 US (CONUS)<https://WikiPedia.org/wiki/Contiguous_United_States>},

9 see also modules L{pygeodesy.geoids} and L{pygeodesy.heights} and

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

11

12@see: Module L{pygeodesy.geoids} to get geoid heights from other

13 sources and for regions other than C{CONUS}.

14

15@note: If on B{macOS} an C{SSLCertVerificationError} occurs, like

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

17 self "signed certificate in certificate chain ..."}, review

18 U{this post<https://StackOverflow.com/questions/27835619/

19 urllib-and-ssl-certificate-verify-failed-error>} for a remedy.

20 From a C{Terminal} window run:

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

22'''

23

24 from pygeodesy.basics import clips, ub2str, typename

25 from pygeodesy.errors import ParseError, _xkwds_get

26# from pygeodesy.internals import typename # from .basics

27 from pygeodesy.interns import NN, _AMPERSAND_, _COLONSPACE_, _DMAIN_, \

28 _elevation_, _height_, _LCURLY_, _n_a_, \

29 _no_, _RCURLY_, _SPACE_

30 from pygeodesy.lazily import _ALL_LAZY

31 from pygeodesy.named import _NamedTuple

32 from pygeodesy.streprs import fabs, Fmt, fstr, lrstrip

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

34

35# from math import fabs # from .karney

36

37__all__ = _ALL_LAZY.elevations

38__version__ = '25.04.14'

39

40 try:

41 from urllib2 import urlopen # quote, urlcleanup

42 from httplib import HTTPException as HTTPError

43

44 except (ImportError, NameError): # Python 3+

45 from urllib.request import urlopen # urlcleanup

46 # from urllib.parse import quote

47 from urllib.error import HTTPError

48

49_JSON_ = 'JSON'

50_QUESTION_ = '?'

51_XML_ = 'XML'

52

53 try:

54 from json import loads as _json

55 except ImportError:

56

57 from pygeodesy.interns import _COMMA_, _QUOTE2_

58 _QUOTE2COLONSPACE_ = _QUOTE2_ + _COLONSPACE_

59

60 def _json(ngs):

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

62 '''

63 # b'{"geoidModel": "GEOID12A",

64 # "station": "UserStation",

65 # "lat": 37.8816,

66 # "latDms": "N375253.76000",

67 # "lon": -121.9142,

68 # "lonDms": "W1215451.12000",

69 # "geoidHeight": -31.703,

70 # "error": 0.064

71 # }'

72 #

73 # or in case of errors:

74 #

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

76 # }'

77 d = {}

78 for t in lrstrip(ngs.strip(), lrpairs={_LCURLY_: _RCURLY_}).split(_COMMA_):

79 t = t.strip()

80 j = t.strip(_QUOTE2_).split(_QUOTE2COLONSPACE_)

81 if len(j) != 2:

82 raise ParseError(json=t)

83 k, v = j

84 try:

85 v = float(v)

86 except (TypeError, ValueError):

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

88 d[k] = v

89 return d

90

91

92 def _error(fun, lat, lon, e):

93 '''(INTERNAL) Format an error

94 '''

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

96

97

98 def _qURL(url, timeout=2, **params):

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

100 '''

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

102 p = _AMPERSAND_(*(Fmt.EQUAL(p, v) for p, v in params.items() if v))

103 if p:

104 url = NN(url, _QUESTION_, p)

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

106

107 s = u.getcode()

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

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

110

111 r = u.read()

112 u.close()

113 # urlcleanup()

114 return ub2str(r).strip()

115

116

117 def _xml(tag, xml):

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

119 '''

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

121 # <USGS_Elevation_Point_Query_Service>

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

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

124 # <Elevation>3851.03</Elevation>

125 # <Units>Feet</Units>

126 # </Elevation_Query>

127 # </USGS_Elevation_Point_Query_Service>'

128 i = xml.find(Fmt.TAG(tag))

129 if i > 0:

130 i += len(tag) + 2

131 j = xml.find(Fmt.TAGEND(tag), i)

132 if j > i:

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

134 return _no_(_XML_, Fmt.TAG(tag)) # PYCHOK no cover

135

136

137 class Elevation2Tuple(_NamedTuple): # .elevations.py

138 '''2-Tuple C{(elevation, data_source)} in C{meter} and C{str}.

139 '''

140 _Names_ = (_elevation_, 'data_source')

141 _Units_ = ( Meter, Str)

142

143

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

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

146

147 @arg lat: Latitude (C{degrees}).

148 @arg lon: Longitude (C{degrees}).

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

150

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

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

153

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

155

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

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

158 failed or if the query timed out. The C{"error"} is the C{HTTP-,

159 IO-, SSL-} or other C{-Error} as a string (C{str}).

160

161 @see: U{USGS Elevation Point Query Service<https://apps.NationalMap.gov/epqs/>}, the

162 U{FAQ<https://www.USGS.gov/faqs/what-are-projection-horizontal-and-vertical-

163 datum-units-and-resolution-3dep-standard-dems>}, U{geoid.py<https://Gist.GitHub.com/

164 pyRobShrk>}, module L{geoids}, classes L{GeoidG2012B}, L{GeoidKarney} and

165 L{GeoidPGM}.

166 '''

167 try: # alt 'https://NED.USGS.gov/epqs/pqs.php', 'https://epqs.NationalMap.gov/v1'

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

169 x=Lon(lon).toStr(prec=6),

170 y=Lat(lat).toStr(prec=6),

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

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

173 timeout=Scalar(timeout=timeout))

174 if x[:6] == '<?xml ':

175 e = _xml('Elevation', x)

176 try:

177 e = float(e)

178 if fabs(e) < 1e6:

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

180 e = 'non-CONUS %.2F' % (e,)

181 except (TypeError, ValueError):

182 pass

183 else: # PYCHOK no cover

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

185 except Exception as x: # (HTTPError, IOError, TypeError, ValueError)

186 e = repr(x)

187 e = _error(elevation2, lat, lon, e)

188 return Elevation2Tuple(None, e)

189

190

191 class GeoidHeight2Tuple(_NamedTuple): # .elevations.py

192 '''2-Tuple C{(height, model_name)}, geoid C{height} in C{meter}

193 and C{model_name} as C{str}.

194 '''

195 _Names_ = (_height_, 'model_name')

196 _Units_ = ( Meter, Str)

197

198

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

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

201

202 @arg lat: Latitude (C{degrees}).

203 @arg lon: Longitude (C{degrees}).

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

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

206

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

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

209

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

211

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

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

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

215 timed out. The C{"error"} is the C{HTTP-, IO-, SSL-, URL-}

216 or other C{-Error} as a string (C{str}).

217

218 @see: U{NOAA National Geodetic Survey

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

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

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

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

223 L{GeoidPGM}.

224 '''

225 try:

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

227 lat=Lat(lat).toStr(prec=6),

228 lon=Lon(lon).toStr(prec=6),

229 model=(model if model else NN),

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

231 if j[:1] == _LCURLY_ and j[-1:] == _RCURLY_ and j.find('"error":') > 0:

232 d, e = _json(j), 'geoidHeight'

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

234 h = d.get(e, None)

235 if h is not None:

236 m = _xkwds_get(d, geoidModel=_n_a_)

237 return GeoidHeight2Tuple(h, m)

238 else:

239 e = _JSON_

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

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

242 e = repr(x)

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

244 return GeoidHeight2Tuple(None, e)

245

246

247 if __name__ == _DMAIN_:

248

249 from pygeodesy import printf

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

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

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

253 t = f(37.8816, -121.9142)

254 printf(_COLONSPACE_(typename(f), t))

255

256# **) MIT License

257#

258# Copyright (C) 2016-2025 -- mrJean1 at Gmail -- All Rights Reserved.

259#

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

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

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

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

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

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

266#

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

268# in all copies or substantial portions of the Software.

269#

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

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

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

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

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

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

276# OTHER DEALINGS IN THE SOFTWARE.

277

278# % python -m pygeodesy.elevations

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

280# geoidHeight2: (-31.703, 'GEOID12B')