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Flexbrdf/hytools/topo/scsc.py
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Flexbrdf/hytools/topo/scsc.py
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# -*- 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: Adam Chlus, Zhiwei Ye, Philip Townsend.
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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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This module contains functions to apply a topographic correction (SCS+C)
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described in the following papers:
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Scott A. Soenen, Derek R. Peddle, & Craig A. Coburn (2005).
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SCS+C: A Modified Sun-Canopy-Sensor Topographic Correction in Forested Terrain.
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IEEE Transactions on Geoscience and Remote Sensing, 43(9), 2148-2159.
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https://doi.org/10.1109/TGRS.2005.852480
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Topographic correction consists of the following steps:
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1. calculate incidence angle if it is not provided
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2. estimate C-Correction value
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3. apply C-Correction value to the image data
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TODO: Rationale/ examples for using different fitting algorithms
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"""
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import numpy as np
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from .c import calc_c, get_band_samples, get_cosine_i_samples
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import ray
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from ..misc import update_topo
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from ..misc import progbar
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def calc_scsc_c1(solar_zn,slope):
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""" Calculate c1
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All input geometry units must be in radians.
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Args:
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solar_zn (numpy.ndarray): Solar zenith angle.
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slope (numpy.ndarray): Ground slope.
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Returns:
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numpy.ndarray: C1.
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"""
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# Eq 11. Soenen et al. 2005
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scsc_c1 = np.cos(solar_zn) * np.cos(slope)
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return scsc_c1
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def calc_scsc_coeffs(hy_obj,topo_dict):
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'''
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Args:
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hy_obj (TYPE): DESCRIPTION.
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Returns:
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None.
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'''
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topo_dict['coeffs'] = {}
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cosine_i = hy_obj.cosine_i()
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for band_num,band in enumerate(hy_obj.bad_bands):
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if ~band:
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band = hy_obj.get_band(band_num,mask='calc_topo')
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topo_dict['coeffs'][band_num] = calc_c(band,cosine_i[hy_obj.mask['calc_topo']],
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fit_type=topo_dict['c_fit_type'])
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hy_obj.topo = topo_dict
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def calc_scsc_coeffs_group(actors,topo_dict,group_tag):
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cosine_i_samples = ray.get([a.do.remote(get_cosine_i_samples) for a in actors])
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cosine_i_samples = np.concatenate(cosine_i_samples)
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print(f'Topo Subgroup {group_tag}')
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bad_bands = ray.get(actors[0].do.remote(lambda x: x.bad_bands))
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coeffs = {}
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for band_num,band in enumerate(bad_bands):
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if ~band:
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coeffs[band_num] = {}
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band_samples = ray.get([a.do.remote(get_band_samples,
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{'band_num':band_num}) for a in actors])
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band_samples = np.concatenate(band_samples)
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coeffs[band_num] = calc_c(band_samples,cosine_i_samples,fit_type=topo_dict['c_fit_type'])
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progbar(np.sum(~bad_bands[:band_num+1]),np.sum(~bad_bands))
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print('\n')
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#Update TOPO coeffs
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_ = ray.get([a.do.remote(update_topo,{'key':'coeffs',
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'value': coeffs}) for a in actors])
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_ = ray.get([a.do.remote(update_topo,{'key':'subgroup',
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'value': group_tag}) for a in actors])
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def apply_scsc_band(hy_obj,band,index):
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'''
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Args:
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hy_obj (TYPE): DESCRIPTION.
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band (TYPE): DESCRIPTION.
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index (TYPE): DESCRIPTION.
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Returns:
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band (TYPE): DESCRIPTION.
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'''
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c1 = np.cos(hy_obj.get_anc('slope')) * np.cos(hy_obj.get_anc('solar_zn'))
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cosine_i = hy_obj.cosine_i()
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C = hy_obj.topo['coeffs'][index]
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correction_factor = (c1 + C)/(cosine_i + C)
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band[hy_obj.mask['calc_topo']] = band[hy_obj.mask['calc_topo']] * correction_factor[hy_obj.mask['calc_topo']]
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band[~hy_obj.mask['no_data']] = hy_obj.no_data
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return band
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def apply_scsc(hy_obj,data,dimension,index):
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''' Apply SCSS correction to a slice of the data
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Args:
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hy_obj (TYPE): DESCRIPTION.
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band (TYPE): DESCRIPTION.
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index (TYPE): DESCRIPTION.
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Returns:
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band (TYPE): DESCRIPTION.
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'''
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if 'c1' not in hy_obj.ancillary.keys():
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c1 = np.cos(hy_obj.get_anc('slope')) * np.cos(hy_obj.get_anc('solar_zn'))
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hy_obj.ancillary['c1'] = c1
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if 'cosine_i' not in hy_obj.ancillary.keys():
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cosine_i = hy_obj.cosine_i()
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hy_obj.ancillary['cosine_i'] = cosine_i
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C_bands = list([int(x) for x in hy_obj.topo['coeffs'].keys()])
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C = np.array(list(hy_obj.topo['coeffs'].values()))
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#Convert to float
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data = data.astype(np.float32)
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hy_obj.topo['coeffs'] = {int(k): hy_obj.topo['coeffs'][k] for k in hy_obj.topo['coeffs']}
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if (dimension != 'band') & (dimension != 'chunk'):
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if dimension == 'line':
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#index= 3000
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#data = hy_obj.get_line(3000)
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mask = hy_obj.mask['apply_topo'][index,:]
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cosine_i = hy_obj.ancillary['cosine_i'][[index],:].T
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c1 = hy_obj.ancillary['c1'][[index],:].T
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elif dimension == 'column':
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#index= 300
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#data = hy_obj.get_column(index)
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mask = hy_obj.mask['apply_topo'][:,index]
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cosine_i = hy_obj.ancillary['cosine_i'][:,[index]]
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c1 = hy_obj.ancillary['c1'][:,[index]]
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elif dimension == 'pixels':
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#index = [[2000,2001],[200,501]]
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y,x = index
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#data = hy_obj.get_pixels(y,x)
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mask = hy_obj.mask['apply_topo'][y,x]
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cosine_i = hy_obj.ancillary['cosine_i'][[y],[x]].T
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c1 = hy_obj.ancillary['c1'][[y],[x]].T
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correction_factor = np.ones(data.shape)
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correction_factor[:,C_bands] = (c1 + C)/(cosine_i + C)
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data[mask,:] = data[mask,:]*correction_factor[mask,:]
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elif dimension == 'chunk':
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#index = 200,501,3000,3501
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x1,x2,y1,y2 = index
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#data = hy_obj.get_chunk(x1,x2,y1,y2)
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mask = hy_obj.mask['apply_topo'][y1:y2,x1:x2]
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cosine_i = hy_obj.ancillary['cosine_i'][y1:y2,x1:x2][:,:,np.newaxis]
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c1 = hy_obj.ancillary['c1'][y1:y2,x1:x2][:,:,np.newaxis]
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correction_factor = np.ones(data.shape)
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correction_factor[:,:,C_bands] = (c1 + C)/(cosine_i + C)
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data[mask,:] = data[mask,:]*correction_factor[mask,:]
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elif (dimension == 'band') and (index in hy_obj.topo['coeffs']):
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#index= 8
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#data = hy_obj.get_band(index)
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C = hy_obj.topo['coeffs'][index]
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correction_factor = (hy_obj.ancillary['c1'] + C)/(hy_obj.ancillary['cosine_i'] + C)
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data[hy_obj.mask['apply_topo']] = data[hy_obj.mask['apply_topo']] * correction_factor[hy_obj.mask['apply_topo']]
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return data
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