Source code for py_tools_ds.io.raster.reader
# -*- coding: utf-8 -*-
# py_tools_ds - A collection of geospatial data analysis tools that simplify standard
# operations when handling geospatial raster and vector data as well as projections.
#
# Copyright (C) 2016-2024
# - Daniel Scheffler (GFZ Potsdam, daniel.scheffler@gfz-potsdam.de)
# - Helmholtz Centre Potsdam - GFZ German Research Centre for Geosciences Potsdam,
# Germany (https://www.gfz-potsdam.de/)
#
# This software was developed within the context of the GeoMultiSens project funded
# by the German Federal Ministry of Education and Research
# (project grant code: 01 IS 14 010 A-C).
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# https://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
import multiprocessing
import ctypes
import numpy as np
from osgeo import gdal
from ...numeric.array import get_array_tilebounds
__author__ = "Daniel Scheffler"
shared_array = None
[docs]
def init_SharedArray_in_globals(dims: (int, int)) -> None:
rows, cols = dims
global shared_array
shared_array_base = multiprocessing.Array(ctypes.c_double, rows * cols)
shared_array = np.ctypeslib.as_array(shared_array_base.get_obj())
shared_array = shared_array.reshape(rows, cols)
[docs]
def fill_arr(argDict, def_param=shared_array):
pos = argDict.get('pos')
func = argDict.get('func2call')
args = argDict.get('func_args', [])
kwargs = argDict.get('func_kwargs', {})
(rS, rE), (cS, cE) = pos
shared_array[rS:rE + 1, cS:cE + 1] = func(*args, **kwargs)
[docs]
def gdal_read_subset(fPath, pos, bandNr):
(rS, rE), (cS, cE) = pos
with gdal.Open(fPath) as ds:
data = ds.GetRasterBand(bandNr).ReadAsArray(cS, rS, cE - cS + 1, rE - rS + 1)
return data
[docs]
def gdal_ReadAsArray_mp(fPath, bandNr, tilesize=1500):
with gdal.Open(fPath) as ds:
rows, cols = ds.RasterYSize, ds.RasterXSize
init_SharedArray_in_globals((rows, cols))
tilepos = get_array_tilebounds(array_shape=(rows, cols), tile_shape=[tilesize, tilesize])
fill_arr_argDicts = [{'pos': pos, 'func2call': gdal_read_subset, 'func_args': (fPath, pos, bandNr)} for pos in
tilepos]
with multiprocessing.Pool() as pool:
pool.map(fill_arr, fill_arr_argDicts)
pool.close()
pool.join()
return shared_array