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boundary.py
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boundary.py
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#!/usr/bin/env python
# -*- coding: utf-8 -*-
# Copyright (c) 2014-2018 PyTroll community
# Author(s):
# Martin Raspaud <martin.raspaud@smhi.se>
# Adam Dybbroe <adam.dybbroe@smhi.se>
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
"""The Boundary classes.
"""
import logging
import logging.handlers
import numpy as np
from pyresample.boundary import Boundary
from pyorbital import geoloc, geoloc_instrument_definitions
logger = logging.getLogger(__name__)
class SwathBoundary(Boundary):
"""Boundaries for satellite overpasses.
"""
def get_instrument_points(self, overpass, utctime,
scans_nb, scanpoints, scan_step=1):
"""Get the boundary points for a given overpass.
"""
instrument = overpass.instrument
# logger.debug("Instrument: %s", str(instrument))
# cheating at the moment.
# scan_angle = 55.37
if instrument == "modis":
# scan_angle = 55.0
instrument = "avhrr"
elif instrument == "viirs":
# scan_angle = 55.84
instrument = "viirs"
elif instrument == "iasi":
# scan_angle = 48.3
instrument = "avhrr"
elif overpass.satellite == "noaa 16":
# scan_angle = 55.25
instrument = "avhrr"
else:
# scan_angle = 55.25
instrument = "avhrr"
instrument_fun = getattr(geoloc_instrument_definitions, instrument)
if instrument in ["olci", "avhrr", "ascat", "avhrr/3", "avhrr/2"]:
sgeom = instrument_fun(scans_nb, scanpoints)
elif instrument == 'viirs':
sgeom = instrument_fun(scans_nb, scanpoints, scan_step=scan_step)
else:
logger.warning("Instrument not tested: %s", instrument)
sgeom = instrument_fun(scans_nb)
times = sgeom.times(utctime)
pixel_pos = geoloc.compute_pixels((self.orb.tle._line1,
self.orb.tle._line2),
sgeom, times)
lons, lats, alts = geoloc.get_lonlatalt(pixel_pos, times)
del alts
return (lons.reshape(-1, len(scanpoints)),
lats.reshape(-1, len(scanpoints)))
def __init__(self, overpass, scan_step=20, frequency=100):
# compute area covered by pass
Boundary.__init__(self)
self.overpass = overpass
self.orb = overpass.orb
# compute sides
scanlength_seconds = ((overpass.falltime - overpass.risetime).seconds +
(overpass.falltime - overpass.risetime).microseconds / 1000000.0)
logger.debug("Instrument = %s", self.overpass.instrument)
if self.overpass.instrument == 'viirs':
sec_scan_duration = 1.779166667
elif self.overpass.instrument in ['avhrr', 'avhrr/3', 'avhrr/2']:
sec_scan_duration = 1./6.
elif self.overpass.instrument == 'ascat':
sec_scan_duration = 3.74747474747
else:
# Assume AVHRR!
logmsg = ("Instrument scan duration not known. Setting it to AVHRR. Instrument: ")
logger.warning(logmsg + "%s", str(self.overpass.instrument))
sec_scan_duration = 1./6.
# From pass length in seconds and the seconds for one scan derive the number of scans in the swath:
scans_nb = scanlength_seconds/sec_scan_duration
# Devide by the scan step to a reduced number of scans:
scans_nb = np.ceil(scans_nb/scan_step)
scans_nb = int(max(scans_nb, 1))
sides_lons, sides_lats = self.get_instrument_points(self.overpass,
overpass.risetime,
scans_nb,
np.array([0, self.overpass.number_of_fovs-1]),
scan_step=scan_step)
side_shape = sides_lons[::-1, 0].shape[0]
nmod = 1
if side_shape != scans_nb:
nmod = side_shape // scans_nb
logger.debug('Number of scan lines (%d) does not match number of scans (%d)',
side_shape, scans_nb)
logger.info('Take every %d th element on the sides...', nmod)
self.left_lons = sides_lons[::-1, 0][::nmod]
self.left_lats = sides_lats[::-1, 0][::nmod]
self.right_lons = sides_lons[:, 1][::nmod]
self.right_lats = sides_lats[:, 1][::nmod]
# compute bottom
maxval = self.overpass.number_of_fovs
rest = maxval % frequency
mid_range = np.arange(rest / 2, maxval, frequency)
if mid_range[0] == 0:
start_idx = 1
else:
start_idx = 0
reduced = np.hstack([0, mid_range[start_idx::], maxval - 1]).astype('int')
lons, lats = self.get_instrument_points(self.overpass,
overpass.falltime,
1,
reduced)
self.bottom_lons = lons[0][::-1]
self.bottom_lats = lats[0][::-1]
# compute top
lons, lats = self.get_instrument_points(self.overpass,
overpass.risetime,
1,
reduced)
self.top_lons = lons[0]
self.top_lats = lats[0]
def decimate(self, ratio):
l = len(self.top_lons)
start = (l % ratio) / 2
points = np.concatenate(([0], np.arange(start, l, ratio), [l - 1]))
self.top_lons = self.top_lons[points]
self.top_lats = self.top_lats[points]
self.bottom_lons = self.bottom_lons[points]
self.bottom_lats = self.bottom_lats[points]
l = len(self.right_lons)
start = (l % ratio) / 2
points = np.concatenate(([0], np.arange(start, l, ratio), [l - 1]))
self.right_lons = self.right_lons[points]
self.right_lats = self.right_lats[points]
self.left_lons = self.left_lons[points]
self.left_lats = self.left_lats[points]
def contour(self):
lons = np.concatenate((self.top_lons,
self.right_lons[1:-1],
self.bottom_lons,
self.left_lons[1:-1]))
lats = np.concatenate((self.top_lats,
self.right_lats[1:-1],
self.bottom_lats,
self.left_lats[1:-1]))
return lons, lats