89 lines
2.9 KiB
Python
89 lines
2.9 KiB
Python
# -*- coding: utf-8 -*-
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"""
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HyTools: Hyperspectral image processing library
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Copyright (C) 2021 University of Wisconsin
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Authors: Evan Greenberg.
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, version 3 of the License.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <https://www.gnu.org/licenses/>.
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"""
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import numpy as np
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from ..masks import mask_create
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def apply_hochberg_2003_correction(hy_obj, data, dimension, index):
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"""
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Glint correction algorithm following:
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Hochberg, EJ, Andréfouët, S and Tyler, MR. 2003.
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Sea surface correction of high spatial resolution Ikonos images to
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improve bottom mapping in near‐shore environments..
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IEEE Transactions on Geoscience and Remote Sensing, 41: 1724–1729.
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"""
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if 'apply_glint' not in hy_obj.mask:
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hy_obj.gen_mask(mask_create,'apply_glint',hy_obj.glint['apply_mask'])
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if hy_obj.mask['apply_glint'].sum() == 0:
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return data
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if 'hochberg_correction' not in hy_obj.ancillary:
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hy_obj.ancillary['hochberg_correction'] = (
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get_hochberg_correction(hy_obj)
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)
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if dimension == 'line':
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correction = hy_obj.ancillary['hochberg_correction'][index, :][:,np.newaxis]
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elif dimension == 'column':
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correction = hy_obj.ancillary['hochberg_correction'][:, index][np.newaxis,:]
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elif dimension == 'band':
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correction = hy_obj.ancillary['hochberg_correction']
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elif dimension == 'chunk':
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x1, x2, y1, y2 = index
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correction = hy_obj.ancillary['hochberg_correction'][y1:y2, x1:x2]
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elif dimension == 'pixels':
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y, x = index
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correction = hy_obj.ancillary['hochberg_correction'][y, x]
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return data - correction
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def get_hochberg_correction(hy_obj):
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"""
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Calculates the hochberg correction across entire image.
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Uses the NIR or SWIR wavelengths to find the amount of signal
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attributed to glint. Zeros out non-water pixels
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"""
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if isinstance(hy_obj.glint['correction_wave'],list):
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nir_swir_array = np.zeros((hy_obj.lines,hy_obj.columns))
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for wave in hy_obj.glint['correction_wave']:
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nir_swir_array+= hy_obj.get_wave(wave)
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nir_swir_array/=len(hy_obj.glint['correction_wave'])
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else:
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nir_swir_array = np.copy(hy_obj.get_wave(hy_obj.glint['correction_wave']))
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nir_swir_array[~hy_obj.mask['apply_glint']] = 0
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nir_swir_min = np.percentile(
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nir_swir_array[nir_swir_array > 0], .001
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)
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hochberg_correction = nir_swir_array - nir_swir_min
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hochberg_correction[~hy_obj.mask['apply_glint']] = 0
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return hochberg_correction
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