transformer_3d.py 12.9 KB
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# -*- coding: utf-8 -*-

# sensormapgeo, Transform remote sensing images between sensor and map geometry.
#
# Copyright (C) 2020  Daniel Scheffler (GFZ Potsdam, danschef@gfz-potsdam.de)
#
# This software was developed within the context of the EnMAP project supported
# by the DLR Space Administration with funds of the German Federal Ministry of
# Economic Affairs and Energy (on the basis of a decision by the German Bundestag:
# 50 EE 1529) and contributions from DLR, GFZ and OHB System AG.
#
# This program is free software: you can redistribute it and/or modify it under
# the terms of the GNU Lesser 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 Lesser General Public License for more
# details.
#
# You should have received a copy of the GNU Lesser General Public License along
# with this program.  If not, see <http://www.gnu.org/licenses/>.

"""Module to transform 3D arrays between sensor and map geometry (using band-wise Lon/Lat arrays)."""

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from typing import Union, Tuple
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import multiprocessing

import numpy as np
from py_tools_ds.geo.projection import WKT2EPSG, proj4_to_WKT
from py_tools_ds.geo.coord_trafo import get_proj4info

from .transformer_2d import SensorMapGeometryTransformer, _corner_coords_lonlat_to_extent


class SensorMapGeometryTransformer3D(object):
    def __init__(self,
                 lons: np.ndarray,
                 lats: np.ndarray,
                 resamp_alg: str = 'nearest',
                 radius_of_influence: int = 30,
                 mp_alg: str = 'auto',
                 **opts) -> None:
        """Get an instance of SensorMapGeometryTransformer.

        :param lons:    3D longitude array corresponding to the 3D sensor geometry array
        :param lats:    3D latitude array corresponding to the 3D sensor geometry array

        :Keyword Arguments:  (further documentation here: https://pyresample.readthedocs.io/en/latest/swath.html)
            - resamp_alg:           resampling algorithm ('nearest', 'bilinear', 'gauss', 'custom')
            - radius_of_influence:  <float> Cut off distance in meters (default: 30)
                                    NOTE: keyword is named 'radius' in case of bilinear resampling
            - mp_alg                multiprocessing algorithm
                                    'bands': parallelize over bands using multiprocessing lib
                                    'tiles': parallelize over tiles using OpenMP
                                    'auto': automatically choose the algorithm
            - sigmas:               <list of floats or float> [ONLY 'gauss'] List of sigmas to use for the gauss
                                    weighting of each channel 1 to k, w_k = exp(-dist^2/sigma_k^2). If only one channel
                                    is resampled sigmas is a single float value.
            - neighbours:           <int> [ONLY 'bilinear', 'gauss'] Number of neighbours to consider for each grid
                                    point when searching the closest corner points
            - epsilon:              <float> Allowed uncertainty in meters. Increasing uncertainty reduces execution time
            - weight_funcs:         <list of function objects or function object> [ONLY 'custom'] List of weight
                                    functions f(dist) to use for the weighting of each channel 1 to k. If only one
                                    channel is resampled weight_funcs is a single function object.
            - fill_value:           <int or None> Set undetermined pixels to this value (default: 0).
                                    If fill_value is None a masked array is returned with undetermined pixels masked
            - reduce_data:          <bool> Perform initial coarse reduction of source dataset in order to reduce
                                    execution time
            - nprocs:               <int>, Number of processor cores to be used
            - segments:             <int or None> Number of segments to use when resampling.
                                    If set to None an estimate will be calculated
            - with_uncert:          <bool> [ONLY 'gauss' and 'custom'] Calculate uncertainty estimates
                                    NOTE: resampling function has 3 return values instead of 1: result, stddev, count
        """
        # validation
        if lons.ndim != 3:
            raise ValueError('Expected a 3D longitude array. Received a %dD array.' % lons.ndim)
        if lats.ndim != 3:
            raise ValueError('Expected a 3D latitude array. Received a %dD array.' % lats.ndim)
        if lons.shape != lats.shape:
            raise ValueError((lons.shape, lats.shape), "'lons' and 'lats' are expected to have the same shape.")

        self.lats = lats
        self.lons = lons
        self.resamp_alg = resamp_alg
        self.radius_of_influence = radius_of_influence
        self.opts = opts

        # define number of CPUs to use (but avoid sub-multiprocessing)
        #   -> parallelize either over bands or over image tiles
        #      bands: multiprocessing uses multiprocessing.Pool, implemented in to_map_geometry / to_sensor_geometry
        #      tiles: multiprocessing uses OpenMP implemented in pykdtree which is used by pyresample
        self.opts['nprocs'] = opts.get('nprocs', multiprocessing.cpu_count())
        self.mp_alg = ('bands' if self.lons.shape[2] >= opts['nprocs'] else 'tiles') if mp_alg == 'auto' else mp_alg

    @staticmethod
    def _to_map_geometry_2D(kwargs_dict: dict) -> Tuple[np.ndarray, tuple, str, int]:
        assert [var is not None for var in (_global_shared_lons, _global_shared_lats, _global_shared_data)]

        SMGT2D = SensorMapGeometryTransformer(lons=_global_shared_lons[:, :, kwargs_dict['band_idx']],
                                              lats=_global_shared_lats[:, :, kwargs_dict['band_idx']],
                                              resamp_alg=kwargs_dict['resamp_alg'],
                                              radius_of_influence=kwargs_dict['radius_of_influence'],
                                              **kwargs_dict['init_opts'])
        data_mapgeo, out_gt, out_prj = SMGT2D.to_map_geometry(data=_global_shared_data[:, :, kwargs_dict['band_idx']],
                                                              tgt_prj=kwargs_dict['tgt_prj'],
                                                              tgt_extent=kwargs_dict['tgt_extent'],
                                                              tgt_res=kwargs_dict['tgt_res'])

        return data_mapgeo, out_gt, out_prj, kwargs_dict['band_idx']

    def _get_common_target_extent(self, tgt_epsg):
        corner_coords_ll = [[self.lons[0, 0, :].min(), self.lats[0, 0, :].max()],  # common UL_xy
                            [self.lons[0, -1, :].max(), self.lats[0, -1, :].max()],  # common UR_xy
                            [self.lons[-1, 0, :].min(), self.lats[-1, 0, :].min()],  # common LL_xy
                            [self.lons[-1, -1, :].max(), self.lats[-1, -1, :].min()],  # common LR_xy
                            ]
        tgt_extent = _corner_coords_lonlat_to_extent(corner_coords_ll, tgt_epsg)

        return tgt_extent

    def to_map_geometry(self,
                        data: np.ndarray,
                        tgt_prj: Union[str, int],
                        tgt_extent: Tuple[float, float, float, float] = None,
                        tgt_res: Tuple = None) -> Tuple[np.ndarray, tuple, str]:
        """Transform the input sensor geometry array into map geometry.

        :param data:            3D numpy array (representing sensor geometry) to be warped to map geometry
        :param tgt_prj:         target projection (WKT or 'epsg:1234' or <EPSG_int>)
        :param tgt_extent:      extent coordinates of output map geometry array (LL_x, LL_y, UR_x, UR_y) in the tgt_prj
        :param tgt_res:         target X/Y resolution (e.g., (30, 30))
        """
        if data.ndim != 3:
            raise ValueError(data.ndim, "'data' must have 3 dimensions.")

        if data.shape != self.lons.shape:
            raise ValueError(data.shape, 'Expected a sensor geometry data array with %d rows, %d columns and %d bands.'
                             % self.lons.shape)

        # get common target extent
        tgt_epsg = WKT2EPSG(proj4_to_WKT(get_proj4info(proj=tgt_prj)))
        tgt_extent = tgt_extent or self._get_common_target_extent(tgt_epsg)

        init_opts = self.opts.copy()
        if self.mp_alg == 'bands':
            del init_opts['nprocs']  # avoid sub-multiprocessing

        args = [dict(
            resamp_alg=self.resamp_alg,
            radius_of_influence=self.radius_of_influence,
            init_opts=init_opts,
            tgt_prj=tgt_prj,
            tgt_extent=tgt_extent,
            tgt_res=tgt_res,
            band_idx=band
        ) for band in range(data.shape[2])]

        if self.opts['nprocs'] > 1 and self.mp_alg == 'bands':
            with multiprocessing.Pool(self.opts['nprocs'],
                                      initializer=_initializer,
                                      initargs=(self.lats, self.lons, data)) as pool:
                result = pool.map(self._to_map_geometry_2D, args)
        else:
            _initializer(self.lats, self.lons, data)
            result = [self._to_map_geometry_2D(argsdict) for argsdict in args]

        band_inds = list(np.array(result)[:, -1])
        data_mapgeo = np.dstack([result[band_inds.index(i)][0] for i in range(data.shape[2])])
        out_gt = result[0][1]
        out_prj = result[0][2]

        return data_mapgeo, out_gt, out_prj

    @staticmethod
    def _to_sensor_geometry_2D(kwargs_dict: dict) -> (np.ndarray, int):
        assert [var is not None for var in (_global_shared_lons, _global_shared_lats, _global_shared_data)]

        SMGT2D = SensorMapGeometryTransformer(lons=_global_shared_lons[:, :, kwargs_dict['band_idx']],
                                              lats=_global_shared_lats[:, :, kwargs_dict['band_idx']],
                                              resamp_alg=kwargs_dict['resamp_alg'],
                                              radius_of_influence=kwargs_dict['radius_of_influence'],
                                              **kwargs_dict['init_opts'])
        data_sensorgeo = SMGT2D.to_sensor_geometry(data=_global_shared_data[:, :, kwargs_dict['band_idx']],
                                                   src_prj=kwargs_dict['src_prj'],
                                                   src_extent=kwargs_dict['src_extent'])

        return data_sensorgeo, kwargs_dict['band_idx']

    def to_sensor_geometry(self,
                           data: np.ndarray,
                           src_prj: Union[str, int],
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                           src_extent: Tuple[float, float, float, float]) -> np.ndarray:
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        """Transform the input map geometry array into sensor geometry

        :param data:        3D numpy array (representing map geometry) to be warped to sensor geometry
        :param src_prj:     projection of the input map geometry array (WKT or 'epsg:1234' or <EPSG_int>)
        :param src_extent:  extent coordinates of input map geometry array (LL_x, LL_y, UR_x, UR_y) in the src_prj
        """
        if data.ndim != 3:
            raise ValueError(data.ndim, "'data' must have 3 dimensions.")

        init_opts = self.opts.copy()
        if self.mp_alg == 'bands':
            del init_opts['nprocs']  # avoid sub-multiprocessing

        args = [dict(
            resamp_alg=self.resamp_alg,
            radius_of_influence=self.radius_of_influence,
            init_opts=init_opts,
            src_prj=src_prj,
            src_extent=src_extent,
            band_idx=band
        ) for band in range(data.shape[2])]

        if self.opts['nprocs'] > 1 and self.mp_alg == 'bands':
            with multiprocessing.Pool(self.opts['nprocs'],
                                      initializer=_initializer,
                                      initargs=(self.lats, self.lons, data)) as pool:
                result = pool.map(self._to_sensor_geometry_2D, args)
        else:
            _initializer(self.lats, self.lons, data)
            result = [self._to_sensor_geometry_2D(argsdict) for argsdict in args]

        band_inds = list(np.array(result)[:, -1])
        data_sensorgeo = np.dstack([result[band_inds.index(i)][0] for i in range(data.shape[2])])

        return data_sensorgeo


_global_shared_lats = None
_global_shared_lons = None
_global_shared_data = None


def _initializer(lats, lons, data):
    """Declare global variables needed for SensorMapGeometryTransformer3D.to_map_geometry and to_sensor_geometry.

    :param lats:
    :param lons:
    :param data:
    """
    global _global_shared_lats, _global_shared_lons, _global_shared_data
    _global_shared_lats = lats
    _global_shared_lons = lons
    _global_shared_data = data