# http://pyrocko.org - GPLv3
#
# The Pyrocko Developers, 21st Century
# ---|P------/S----------~Lg----------
'''
Interface to the GSHHG (coastlines, rivers and borders) database.
The Global Self-consistent Hierarchical High-resolution Geography Database
(GSHHG) is a collection of polygons representing land, lakes, rivers and
political borders.
If the database is not already available, it will be downloaded
automatically on first use.
For more information about GSHHG, see
http://www.soest.hawaii.edu/pwessel/gshhg/.
.. note::
**If you use this dataset, please cite:**
Wessel, P., and W. H. F.
Smith, A Global Self-consistent, Hierarchical, High-resolution
Shoreline Database, J. Geophys. Res., 101, #B4, pp. 8741-8743, 1996.
'''
from __future__ import absolute_import
import logging
import io
import struct
import time
import numpy as num
from os import path
from pyrocko import config, orthodrome
from .util import get_download_callback
logger = logging.getLogger('pyrocko.dataset.gshhg')
config = config.config()
km = 1e3
micro_deg = 1e-6
def split_region_0_360(wesn):
west, east, south, north = wesn
if west < 0.:
if east <= 0:
return [(west+360., east+360., south, north)]
else:
return [(west+360., 360., south, north),
(0., east, south, north)]
else:
return [wesn]
def is_valid_bounding_box(wesn):
'''
Check if a given bounding box meets the GSHHG conventions.
:param wesn: bounding box as (west, east, south, north) in [deg]
'''
w, e, s, n = wesn
return (
w <= e
and s <= n
and -90.0 <= s <= 90.
and -90. <= n <= 90.
and -180. <= w < 360.
and -180. <= e < 360.)
def is_valid_polygon(points):
'''
Check if polygon points meet the GSHHG conventions.
:param points: Array of (lat, lon) pairs, shape (N, 2).
'''
lats = points[:, 0]
lons = points[:, 1]
return (
num.all(-90. <= lats)
and num.all(lats <= 90.)
and num.all(-180. <= lons)
and num.all(lons < 360.))
def points_in_bounding_box(points, wesn, tolerance=0.1):
'''
Check which points are contained in a given bounding box.
:param points: Array of (lat lon) pairs, shape (N, 2) [deg].
:param wesn: Region tuple (west, east, south, north) [deg]
:param tolerance: increase the size of the test bounding box by
*tolerance* [deg] on every side (Some GSHHG polygons have a too tight
bounding box).
:returns: Bool array of shape (N,).
'''
points_wrap = points.copy()
points_wrap[:, 1] %= 360.
mask = num.zeros(points_wrap.shape[0], dtype=num.bool)
for w, e, s, n in split_region_0_360(wesn):
mask = num.logical_or(
mask,
num.logical_and(
num.logical_and(
w-tolerance <= points_wrap[:, 1],
points_wrap[:, 1] <= e+tolerance),
num.logical_and(
s-tolerance <= points_wrap[:, 0],
points_wrap[:, 0] <= n+tolerance)))
return mask
def point_in_bounding_box(point, wesn, tolerance=0.1):
'''
Check whether point is contained in a given bounding box.
:param points: Array of (lat lon) pairs, shape (N, 2) [deg].
:param wesn: Region tuple (west, east, south, north) [deg]
:param tolerance: increase the size of the test bounding box by
*tolerance* [deg] on every side (Some GSHHG polygons have a too tight
bounding box).
:rtype: bool
'''
lat, lon = point
lon %= 360.
for w, e, s, n in split_region_0_360(wesn):
if (w-tolerance <= lon
and lon <= e+tolerance
and s-tolerance <= lat
and lat <= n+tolerance):
return True
return False
def bounding_boxes_overlap(wesn1, wesn2):
'''
Check whether two bounding boxes intersect.
:param wesn1, wesn2: Region tuples (west, east, south, north) [deg]
:rtype: bool
'''
for w1, e1, s1, n1 in split_region_0_360(wesn1):
for w2, e2, s2, n2 in split_region_0_360(wesn2):
if w2 <= e1 and w1 <= e2 and s2 <= n1 and s1 <= n2:
return True
return False
def is_polygon_in_bounding_box(points, wesn, tolerance=0.1):
return num.all(points_in_bounding_box(points, wesn, tolerance=tolerance))
def bounding_box_covering_points(points):
lats = points[:, 0]
lat_min, lat_max = num.min(lats), num.max(lats)
lons = points[:, 1]
lons = lons % 360.
lon_min, lon_max = num.min(lons), num.max(lons)
if lon_max - lon_min < 180.:
return lon_min, lon_max, lat_min, lat_max
lons = (lons - 180.) % 360. - 180.
lon_min, lon_max = num.min(lons), num.max(lons)
if lon_max - lon_min < 180.:
return lon_min, lon_max, lat_min, lat_max
return (-180., 180., lat_min, lat_max)
[docs]class Polygon(object):
'''
Representation of a GSHHG polygon.
'''
RIVER_NOT_SET = 0
LEVELS = ['LAND', 'LAKE', 'ISLAND_IN_LAKE', 'POND_IN_ISLAND_IN_LAKE',
'ANTARCTIC_ICE_FRONT', 'ANTARCTIC_GROUNDING_LINE']
SOURCE = ['CIA_WDBII', 'WVS', 'AC']
def __init__(self, gshhg_file, offset, *attr):
'''
Initialise a GSHHG polygon
:param gshhg_file: GSHHG binary file
:type gshhg_file: str
:param offset: This polygon's offset in binary file
:type offset: int
:param attr: Polygon attributes
``(pid, npoints, _flag, west, east, south, north,
area, area_full, container, ancestor)``.
See :file:`gshhg.h` for details.
:type attr: tuple
'''
(self.pid, self.npoints, self._flag,
self.west, self.east, self.south, self.north,
self.area, self.area_full, self.container, self.ancestor) = attr
self.west *= micro_deg
self.east *= micro_deg
self.south *= micro_deg
self.north *= micro_deg
self.level_no = (self._flag & 255)
self.level = self.LEVELS[self.level_no - 1]
self.version = (self._flag >> 8) & 255
cross = (self._flag >> 16) & 3
self.greenwhich_crossed = True if cross == 1 or cross == 3 else False
self.dateline_crossed = True if cross == 2 or cross == 3 else False
self.source = self.SOURCE[(self._flag >> 24) & 1]
if self.level_no >= 5:
self.source = self.SOURCE[2]
self.river = (self._flag >> 25) & 1
scale = 10.**(self._flag >> 26)
self.area /= scale
self.area_full /= scale
self._points = None
self._file = gshhg_file
self._offset = offset
@property
def points(self):
'''
Points of the polygon.
Array of (lat, lon) pairs, shape (N, 2).
:rtype: :class:`numpy.ndarray`
'''
if self._points is None:
with open(self._file) as db:
db.seek(self._offset)
self._points = num.fromfile(
db, dtype='>i4', count=self.npoints*2)\
.astype(num.float32)\
.reshape(self.npoints, 2)
self._points = num.fliplr(self._points)
if self.level_no in (2, 4):
self._points = self._points[::-1, :]
self._points *= micro_deg
return self._points
@property
def lats(self):
return self.points[:, 0]
@property
def lons(self):
return self.points[:, 1]
def _is_level(self, level):
if self.level is self.LEVELS[level]:
return True
return False
[docs] def is_land(self):
'''
Check if the polygon is land.
:rtype: bool
'''
return self._is_level(0)
[docs] def is_lake(self):
'''
Check if the polygon is a lake.
:rtype: bool
'''
return self._is_level(1)
[docs] def is_island_in_lake(self):
'''
Check if the polygon is an island in a lake.
:rtype: bool
'''
return self._is_level(2)
[docs] def is_pond_in_island_in_lake(self):
'''
Check if the polygon is pond on an island in a lake.
:rtype: bool
'''
return self._is_level(3)
[docs] def is_antarctic_icefront(self):
'''
Check if the polygon is antarctic icefront.
:rtype: bool
'''
return self._is_level(4)
[docs] def is_antarctic_grounding_line(self):
'''
Check if the polygon is antarctic grounding line.
:rtype: bool
'''
return self._is_level(5)
[docs] def contains_point(self, point):
'''
Check if point lies in polygon.
:param point: (lat, lon) [deg]
:type point: tuple
:rtype: bool
See :py:func:`pyrocko.orthodrome.contains_points`.
'''
return bool(
self.contains_points(num.asarray(point)[num.newaxis, :])[0])
[docs] def contains_points(self, points):
'''
Check if points lie in polygon.
:param points: Array of (lat lon) pairs, shape (N, 2) [deg].
:type points: :class:`numpy.ndarray`
See :py:func:`pyrocko.orthodrome.contains_points`.
:returns: Bool array of shape (N,)
'''
mask = points_in_bounding_box(points, self.get_bounding_box())
if num.any(mask):
mask[mask] = orthodrome.contains_points(
self.points, points[mask, :])
return mask
def get_bounding_box(self):
return (self.west, self.east, self.south, self.north)
def __lt__(self, polygon):
return self.level_no < polygon.level_no
def __str__(self):
rstr = '''Polygon id: {p.pid}
-------------------
Points: {p.npoints}
Level: {p.level}
Area: {p.area} km**2
Area Full: {p.area_full} km**2
Extent: {p.west} W, {p.east} E, {p.south} S, {p.north} N
Source: {p.source}
Greenwhich crossed: {p.greenwhich_crossed}
Dateline crossed: {p.dateline_crossed}
'''.format(p=self)
return rstr
[docs]class GSHHG(object):
'''
GSHHG database access.
This class provides methods to select relevant polygons (land, lakes, etc.)
for given locations or regions. It also provides robust high-level
functions to test if the Earth is dry or wet at given coordinates.
'''
gshhg_url = 'https://mirror.pyrocko.org/www.soest.hawaii.edu/pwessel/gshhg/gshhg-bin-2.3.7.zip' # noqa
_header_struct = struct.Struct('>IIIiiiiIIii')
def __init__(self, gshhg_file):
''' Initialise the database from GSHHG binary.
:param gshhg_file: Path to file
:type gshhg_file: str
:
'''
t0 = time.time()
self._file = gshhg_file
self.polygons = []
self._read_database()
logger.debug('Initialised GSHHG database from %s in [%.4f s]'
% (gshhg_file, time.time()-t0))
def _read_database(self):
with open(self._file, mode='rb') as db:
while db:
buf = db.read(self._header_struct.size)
if not buf:
break
header = self._header_struct.unpack_from(buf)
p = Polygon(
self._file,
db.tell(),
*header)
self.polygons.append(p)
offset = 8 * header[1]
db.seek(offset, io.SEEK_CUR)
@classmethod
def _get_database(cls, filename):
file = path.join(config.gshhg_dir, filename)
if not path.exists(file):
from pyrocko import util
import zipfile
archive_path = path.join(config.gshhg_dir,
path.basename(cls.gshhg_url))
util.download_file(
cls.gshhg_url, archive_path,
status_callback=get_download_callback(
'Downloading GSHHG database...'))
if not zipfile.is_zipfile(archive_path):
raise util.DownloadError('GSHHG file is corrupted!')
logger.info('Unzipping GSHHG database...')
zipf = zipfile.ZipFile(archive_path)
zipf.extractall(config.gshhg_dir)
else:
logger.debug('Using cached %s' % filename)
return file
[docs] def get_polygons_at(self, lat, lon):
'''
Get all polygons whose bounding boxes contain point.
:param lat: Latitude in [deg]
:type lat: float
:param lon: Longitude in [deg]
:type lon: float
:returns: List of :class:`~pyrocko.dataset.gshhg.Polygon`
:rtype: list
'''
rp = []
for p in self.polygons:
if point_in_bounding_box((lat, lon), p.get_bounding_box()):
rp.append(p)
return rp
[docs] def get_polygons_within(self, west, east, south, north):
'''
Get all polygons whose bounding boxes intersect with a bounding box.
:param west: Western boundary in decimal degree
:type west: float
:param east: Eastern boundary in decimal degree
:type east: float
:param north: Northern boundary in decimal degree
:type north: float
:param south: Southern boundary in decimal degree
:type south: float
:returns: List of :class:`~pyrocko.dataset.gshhg.Polygon`
:rtype: list
'''
assert is_valid_bounding_box((west, east, south, north))
rp = []
for p in self.polygons:
if bounding_boxes_overlap(
p.get_bounding_box(), (west, east, south, north)):
rp.append(p)
return rp
[docs] def is_point_on_land(self, lat, lon):
'''
Check whether a point is on land.
Lakes are considered not land.
:param lat: Latitude in [deg]
:type lat: float
:param lon: Longitude in [deg]
:type lon: float
:rtype: bool
'''
relevant_polygons = self.get_polygons_at(lat, lon)
relevant_polygons.sort()
land = False
for p in relevant_polygons:
if (p.is_land() or p.is_antarctic_grounding_line() or
p.is_island_in_lake()):
if p.contains_point((lat, lon)):
land = True
elif (p.is_lake() or p.is_antarctic_icefront() or
p.is_pond_in_island_in_lake()):
if p.contains_point((lat, lon)):
land = False
return land
[docs] def get_land_mask(self, points):
'''
Check whether given points are on land.
Lakes are considered not land.
:param points: Array of (lat, lon) pairs, shape (N, 2).
:type points: :class:`numpy.ndarray`
:return: Boolean land mask
:rtype: :class:`numpy.ndarray` of shape (N,)
'''
west, east, south, north = bounding_box_covering_points(points)
relevant_polygons = self.get_polygons_within(west, east, south, north)
relevant_polygons.sort()
mask = num.zeros(points.shape[0], dtype=num.bool)
for p in relevant_polygons:
if (p.is_land() or p.is_antarctic_grounding_line() or
p.is_island_in_lake()):
land = p.contains_points(points)
mask[land] = True
elif p.is_lake() or p.is_pond_in_island_in_lake():
water = p.contains_points(points)
mask[water] = False
return mask
[docs] @classmethod
def full(cls):
'''
Return the full-resolution GSHHG database.
'''
return cls(cls._get_database('gshhs_f.b'))
[docs] @classmethod
def high(cls):
'''
Return the high-resolution GSHHG database.
'''
return cls(cls._get_database('gshhs_h.b'))
[docs] @classmethod
def low(cls):
'''
Return the low-resolution GSHHG database.
'''
return cls(cls._get_database('gshhs_l.b'))
[docs] @classmethod
def crude(cls):
'''
Return the crude-resolution GSHHG database.
'''
return cls(cls._get_database('gshhs_c.b'))
