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CoastSat_WRL
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CoastSat_WRL/coastsat/SDS_shoreline.py

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"""This module contains all the functions needed for extracting satellite-derived shorelines (SDS)
Author: Kilian Vos, Water Research Laboratory, University of New South Wales
"""
# load modules
import os
import numpy as np
import matplotlib.pyplot as plt
import pdb
# image processing modules
import skimage.filters as filters
import skimage.measure as measure
import skimage.morphology as morphology
# machine learning modules
from sklearn.externals import joblib
from shapely.geometry import LineString
# other modules
import matplotlib.patches as mpatches
import matplotlib.lines as mlines
import matplotlib.cm as cm
from matplotlib import gridspec
from pylab import ginput
import pickle
# own modules
from coastsat import SDS_tools, SDS_preprocess
np.seterr(all='ignore') # raise/ignore divisions by 0 and nans
###################################################################################################
# IMAGE CLASSIFICATION FUNCTIONS
###################################################################################################
def calculate_features(im_ms, cloud_mask, im_bool):
"""
Calculates a range of features on the image that are used for the supervised classification.
The features include spectral normalized-difference indices and standard deviation of the image.
KV WRL 2018
Arguments:
-----------
im_ms: np.array
RGB + downsampled NIR and SWIR
cloud_mask: np.array
2D cloud mask with True where cloud pixels are
im_bool: np.array
2D array of boolean indicating where on the image to calculate the features
Returns: -----------
features: np.array
matrix containing each feature (columns) calculated for all
the pixels (rows) indicated in im_bool
"""
# add all the multispectral bands
features = np.expand_dims(im_ms[im_bool,0],axis=1)
for k in range(1,im_ms.shape[2]):
feature = np.expand_dims(im_ms[im_bool,k],axis=1)
features = np.append(features, feature, axis=-1)
# NIR-G
im_NIRG = SDS_tools.nd_index(im_ms[:,:,3], im_ms[:,:,1], cloud_mask)
features = np.append(features, np.expand_dims(im_NIRG[im_bool],axis=1), axis=-1)
# SWIR-G
im_SWIRG = SDS_tools.nd_index(im_ms[:,:,4], im_ms[:,:,1], cloud_mask)
features = np.append(features, np.expand_dims(im_SWIRG[im_bool],axis=1), axis=-1)
# NIR-R
im_NIRR = SDS_tools.nd_index(im_ms[:,:,3], im_ms[:,:,2], cloud_mask)
features = np.append(features, np.expand_dims(im_NIRR[im_bool],axis=1), axis=-1)
# SWIR-NIR
im_SWIRNIR = SDS_tools.nd_index(im_ms[:,:,4], im_ms[:,:,3], cloud_mask)
features = np.append(features, np.expand_dims(im_SWIRNIR[im_bool],axis=1), axis=-1)
# B-R
im_BR = SDS_tools.nd_index(im_ms[:,:,0], im_ms[:,:,2], cloud_mask)
features = np.append(features, np.expand_dims(im_BR[im_bool],axis=1), axis=-1)
# calculate standard deviation of individual bands
for k in range(im_ms.shape[2]):
im_std = SDS_tools.image_std(im_ms[:,:,k], 1)
features = np.append(features, np.expand_dims(im_std[im_bool],axis=1), axis=-1)
# calculate standard deviation of the spectral indices
im_std = SDS_tools.image_std(im_NIRG, 1)
features = np.append(features, np.expand_dims(im_std[im_bool],axis=1), axis=-1)
im_std = SDS_tools.image_std(im_SWIRG, 1)
features = np.append(features, np.expand_dims(im_std[im_bool],axis=1), axis=-1)
im_std = SDS_tools.image_std(im_NIRR, 1)
features = np.append(features, np.expand_dims(im_std[im_bool],axis=1), axis=-1)
im_std = SDS_tools.image_std(im_SWIRNIR, 1)
features = np.append(features, np.expand_dims(im_std[im_bool],axis=1), axis=-1)
im_std = SDS_tools.image_std(im_BR, 1)
features = np.append(features, np.expand_dims(im_std[im_bool],axis=1), axis=-1)
return features
def classify_image_NN(im_ms, im_extra, cloud_mask, min_beach_area, clf):
"""
Classifies every pixel in the image in one of 4 classes:
- sand --> label = 1
- whitewater (breaking waves and swash) --> label = 2
- water --> label = 3
- other (vegetation, buildings, rocks...) --> label = 0
The classifier is a Neural Network previously trained.
KV WRL 2018
Arguments:
-----------
im_ms: np.array
Pansharpened RGB + downsampled NIR and SWIR
im_extra:
only used for Landsat 7 and 8 where im_extra is the panchromatic band
cloud_mask: np.array
2D cloud mask with True where cloud pixels are
min_beach_area: int
minimum number of pixels that have to be connected to belong to the SAND class
clf: classifier
Returns: -----------
im_classif: np.array
2D image containing labels
im_labels: np.array of booleans
3D image containing a boolean image for each class (im_classif == label)
"""
# calculate features
vec_features = calculate_features(im_ms, cloud_mask, np.ones(cloud_mask.shape).astype(bool))
vec_features[np.isnan(vec_features)] = 1e-9 # NaN values are create when std is too close to 0
# remove NaNs and cloudy pixels
vec_cloud = cloud_mask.reshape(cloud_mask.shape[0]*cloud_mask.shape[1])
vec_nan = np.any(np.isnan(vec_features), axis=1)
vec_mask = np.logical_or(vec_cloud, vec_nan)
vec_features = vec_features[~vec_mask, :]
# classify pixels
labels = clf.predict(vec_features)
# recompose image
vec_classif = np.nan*np.ones((cloud_mask.shape[0]*cloud_mask.shape[1]))
vec_classif[~vec_mask] = labels
im_classif = vec_classif.reshape((cloud_mask.shape[0], cloud_mask.shape[1]))
# create a stack of boolean images for each label
im_sand = im_classif == 1
im_swash = im_classif == 2
im_water = im_classif == 3
# remove small patches of sand or water that could be around the image (usually noise)
im_sand = morphology.remove_small_objects(im_sand, min_size=min_beach_area, connectivity=2)
im_water = morphology.remove_small_objects(im_water, min_size=min_beach_area, connectivity=2)
im_labels = np.stack((im_sand,im_swash,im_water), axis=-1)
return im_classif, im_labels
###################################################################################################
# CONTOUR MAPPING FUNCTIONS
###################################################################################################
def find_wl_contours1(im_ndwi, cloud_mask, im_ref_buffer):
"""
Traditional method for shorelien detection.
Finds the water line by thresholding the Normalized Difference Water Index and applying
the Marching Squares Algorithm to contour the iso-value corresponding to the threshold.
KV WRL 2018
Arguments:
-----------
im_ndwi: np.ndarray
Image (2D) with the NDWI (water index)
cloud_mask: np.ndarray
2D cloud mask with True where cloud pixels are
im_ref_buffer: np.array
Binary image containing a buffer around the reference shoreline
Returns: -----------
contours_wl: list of np.arrays
contains the (row,column) coordinates of the contour lines
"""
# reshape image to vector
vec_ndwi = im_ndwi.reshape(im_ndwi.shape[0] * im_ndwi.shape[1])
vec_mask = cloud_mask.reshape(cloud_mask.shape[0] * cloud_mask.shape[1])
vec = vec_ndwi[~vec_mask]
# apply otsu's threshold
vec = vec[~np.isnan(vec)]
t_otsu = filters.threshold_otsu(vec)
# use Marching Squares algorithm to detect contours on ndwi image
im_ndwi_buffer = np.copy(im_ndwi)
im_ndwi_buffer[~im_ref_buffer] = np.nan
contours = measure.find_contours(im_ndwi_buffer, t_otsu)
# remove contours that contain NaNs (due to cloud pixels in the contour)
contours_nonans = []
for k in range(len(contours)):
if np.any(np.isnan(contours[k])):
index_nan = np.where(np.isnan(contours[k]))[0]
contours_temp = np.delete(contours[k], index_nan, axis=0)
if len(contours_temp) > 1:
contours_nonans.append(contours_temp)
else:
contours_nonans.append(contours[k])
contours = contours_nonans
return contours
def find_wl_contours2(im_ms, im_labels, cloud_mask, buffer_size, im_ref_buffer):
"""
New robust method for extracting shorelines. Incorporates the classification component to
refine the treshold and make it specific to the sand/water interface.
KV WRL 2018
Arguments:
-----------
im_ms: np.array
RGB + downsampled NIR and SWIR
im_labels: np.array
3D image containing a boolean image for each class in the order (sand, swash, water)
cloud_mask: np.array
2D cloud mask with True where cloud pixels are
buffer_size: int
size of the buffer around the sandy beach over which the pixels are considered in the
thresholding algorithm.
im_ref_buffer: np.array
Binary image containing a buffer around the reference shoreline
Returns: -----------
contours_wi: list of np.arrays
contains the (row,column) coordinates of the contour lines extracted from the
NDWI (Normalized Difference Water Index) image
contours_mwi: list of np.arrays
contains the (row,column) coordinates of the contour lines extracted from the
MNDWI (Modified Normalized Difference Water Index) image
"""
nrows = cloud_mask.shape[0]
ncols = cloud_mask.shape[1]
# calculate Normalized Difference Modified Water Index (SWIR - G)
im_mwi = SDS_tools.nd_index(im_ms[:,:,4], im_ms[:,:,1], cloud_mask)
# calculate Normalized Difference Modified Water Index (NIR - G)
im_wi = SDS_tools.nd_index(im_ms[:,:,3], im_ms[:,:,1], cloud_mask)
# stack indices together
im_ind = np.stack((im_wi, im_mwi), axis=-1)
vec_ind = im_ind.reshape(nrows*ncols,2)
# reshape labels into vectors
vec_sand = im_labels[:,:,0].reshape(ncols*nrows)
vec_water = im_labels[:,:,2].reshape(ncols*nrows)
# create a buffer around the sandy beach
se = morphology.disk(buffer_size)
im_buffer = morphology.binary_dilation(im_labels[:,:,0], se)
vec_buffer = im_buffer.reshape(nrows*ncols)
# select water/sand/swash pixels that are within the buffer
int_water = vec_ind[np.logical_and(vec_buffer,vec_water),:]
int_sand = vec_ind[np.logical_and(vec_buffer,vec_sand),:]
# make sure both classes have the same number of pixels before thresholding
if len(int_water) > 0 and len(int_sand) > 0:
if np.argmin([int_sand.shape[0],int_water.shape[0]]) == 1:
int_sand = int_sand[np.random.choice(int_sand.shape[0],int_water.shape[0], replace=False),:]
else:
int_water = int_water[np.random.choice(int_water.shape[0],int_sand.shape[0], replace=False),:]
# threshold the sand/water intensities
int_all = np.append(int_water,int_sand, axis=0)
t_mwi = filters.threshold_otsu(int_all[:,0])
t_wi = filters.threshold_otsu(int_all[:,1])
# find contour with MS algorithm
im_wi_buffer = np.copy(im_wi)
im_wi_buffer[~im_ref_buffer] = np.nan
im_mwi_buffer = np.copy(im_mwi)
im_mwi_buffer[~im_ref_buffer] = np.nan
contours_wi = measure.find_contours(im_wi_buffer, t_wi)
contours_mwi = measure.find_contours(im_mwi_buffer, t_mwi)
# remove contour points that are NaNs (around clouds)
contours = contours_wi
contours_nonans = []
for k in range(len(contours)):
if np.any(np.isnan(contours[k])):
index_nan = np.where(np.isnan(contours[k]))[0]
contours_temp = np.delete(contours[k], index_nan, axis=0)
if len(contours_temp) > 1:
contours_nonans.append(contours_temp)
else:
contours_nonans.append(contours[k])
contours_wi = contours_nonans
# repeat for MNDWI contours
contours = contours_mwi
contours_nonans = []
for k in range(len(contours)):
if np.any(np.isnan(contours[k])):
index_nan = np.where(np.isnan(contours[k]))[0]
contours_temp = np.delete(contours[k], index_nan, axis=0)
if len(contours_temp) > 1:
contours_nonans.append(contours_temp)
else:
contours_nonans.append(contours[k])
contours_mwi = contours_nonans
return contours_wi, contours_mwi
###################################################################################################
# SHORELINE PROCESSING FUNCTIONS
###################################################################################################
def create_shoreline_buffer(im_shape, georef, image_epsg, pixel_size, settings):
"""
Creates a buffer around the reference shoreline. The size of the buffer is given by
settings['max_dist_ref'].
KV WRL 2018
Arguments:
-----------
im_shape: np.array
size of the image (rows,columns)
georef: np.array
vector of 6 elements [Xtr, Xscale, Xshear, Ytr, Yshear, Yscale]
image_epsg: int
spatial reference system of the image from which the contours were extracted
pixel_size: int
size of the pixel in metres (15 for Landsat, 10 for Sentinel-2)
settings: dict
contains the following fields:
output_epsg: int
output spatial reference system
reference_shoreline: np.array
coordinates of the reference shoreline
max_dist_ref: int
maximum distance from the reference shoreline in metres
Returns: -----------
im_buffer: np.array
binary image, True where the buffer is, False otherwise
"""
# initialise the image buffer
im_buffer = np.ones(im_shape).astype(bool)
if 'reference_shoreline' in settings.keys():
# convert reference shoreline to pixel coordinates
ref_sl = settings['reference_shoreline']
ref_sl_conv = SDS_tools.convert_epsg(ref_sl, settings['output_epsg'],image_epsg)[:,:-1]
ref_sl_pix = SDS_tools.convert_world2pix(ref_sl_conv, georef)
ref_sl_pix_rounded = np.round(ref_sl_pix).astype(int)
# create binary image of the reference shoreline (1 where the shoreline is 0 otherwise)
im_binary = np.zeros(im_shape)
for j in range(len(ref_sl_pix_rounded)):
im_binary[ref_sl_pix_rounded[j,1], ref_sl_pix_rounded[j,0]] = 1
im_binary = im_binary.astype(bool)
# dilate the binary image to create a buffer around the reference shoreline
max_dist_ref_pixels = np.ceil(settings['max_dist_ref']/pixel_size)
se = morphology.disk(max_dist_ref_pixels)
im_buffer = morphology.binary_dilation(im_binary, se)
return im_buffer
def process_shoreline(contours, cloud_mask, georef, image_epsg, settings):
"""
Converts the contours from image coordinates to world coordinates. This function also removes
the contours that are too small to be a shoreline (based on the parameter
settings['min_length_sl'])
KV WRL 2018
Arguments:
-----------
contours: np.array or list of np.array
image contours as detected by the function find_contours
cloud_mask: np.array
2D cloud mask with True where cloud pixels are
georef: np.array
vector of 6 elements [Xtr, Xscale, Xshear, Ytr, Yshear, Yscale]
image_epsg: int
spatial reference system of the image from which the contours were extracted
settings: dict
contains the following fields:
output_epsg: int
output spatial reference system
min_length_sl: float
minimum length of shoreline perimeter to be kept (in meters)
Returns:
-----------
shoreline: np.array
array of points with the X and Y coordinates of the shoreline
"""
# convert pixel coordinates to world coordinates
contours_world = SDS_tools.convert_pix2world(contours, georef)
# convert world coordinates to desired spatial reference system
contours_epsg = SDS_tools.convert_epsg(contours_world, image_epsg, settings['output_epsg'])
# remove contours that have a perimeter < min_length_sl (provided in settings dict)
# this enables to remove the very small contours that do not correspond to the shoreline
contours_long = []
for l, wl in enumerate(contours_epsg):
coords = [(wl[k,0], wl[k,1]) for k in range(len(wl))]
a = LineString(coords) # shapely LineString structure
if a.length >= settings['min_length_sl']:
contours_long.append(wl)
# format points into np.array
x_points = np.array([])
y_points = np.array([])
for k in range(len(contours_long)):
x_points = np.append(x_points,contours_long[k][:,0])
y_points = np.append(y_points,contours_long[k][:,1])
contours_array = np.transpose(np.array([x_points,y_points]))
shoreline = contours_array
# now remove any shoreline points that are attached to cloud pixels
if sum(sum(cloud_mask)) > 0:
# get the coordinates of the cloud pixels
idx_cloud = np.where(cloud_mask)
idx_cloud = np.array([(idx_cloud[0][k], idx_cloud[1][k]) for k in range(len(idx_cloud[0]))])
# convert to world coordinates and same epsg as the shoreline points
coords_cloud = SDS_tools.convert_epsg(SDS_tools.convert_pix2world(idx_cloud, georef),
image_epsg, settings['output_epsg'])[:,:-1]
# only keep the shoreline points that are at least 30m from any cloud pixel
idx_keep = np.ones(len(shoreline)).astype(bool)
for k in range(len(shoreline)):
if np.any(np.linalg.norm(shoreline[k,:] - coords_cloud, axis=1) < 30):
idx_keep[k] = False
shoreline = shoreline[idx_keep]
return shoreline
def show_detection(im_ms, cloud_mask, im_labels, shoreline,image_epsg, georef,
settings, date, satname):
"""
Shows the detected shoreline to the user for visual quality control. The user can select "keep"
if the shoreline detection is correct or "skip" if it is incorrect.
KV WRL 2018
Arguments:
-----------
im_ms: np.array
RGB + downsampled NIR and SWIR
cloud_mask: np.array
2D cloud mask with True where cloud pixels are
im_labels: np.array
3D image containing a boolean image for each class in the order (sand, swash, water)
shoreline: np.array
array of points with the X and Y coordinates of the shoreline
image_epsg: int
spatial reference system of the image from which the contours were extracted
georef: np.array
vector of 6 elements [Xtr, Xscale, Xshear, Ytr, Yshear, Yscale]
settings: dict
contains the following fields:
date: string
date at which the image was taken
satname: string
indicates the satname (L5,L7,L8 or S2)
Returns:
-----------
skip_image: boolean
True if the user wants to skip the image, False otherwise.
"""
sitename = settings['inputs']['sitename']
filepath_data = settings['inputs']['filepath']
# subfolder where the .jpg file is stored if the user accepts the shoreline detection
filepath = os.path.join(filepath_data, sitename, 'jpg_files', 'detection')
im_RGB = SDS_preprocess.rescale_image_intensity(im_ms[:,:,[2,1,0]], cloud_mask, 99.9)
# compute classified image
im_class = np.copy(im_RGB)
cmap = cm.get_cmap('tab20c')
colorpalette = cmap(np.arange(0,13,1))
colours = np.zeros((3,4))
colours[0,:] = colorpalette[5]
colours[1,:] = np.array([204/255,1,1,1])
colours[2,:] = np.array([0,91/255,1,1])
for k in range(0,im_labels.shape[2]):
im_class[im_labels[:,:,k],0] = colours[k,0]
im_class[im_labels[:,:,k],1] = colours[k,1]
im_class[im_labels[:,:,k],2] = colours[k,2]
# compute MNDWI grayscale image
im_mwi = SDS_tools.nd_index(im_ms[:,:,4], im_ms[:,:,1], cloud_mask)
# transform world coordinates of shoreline into pixel coordinates
# use try/except in case there are no coordinates to be transformed (shoreline = [])
try:
sl_pix = SDS_tools.convert_world2pix(SDS_tools.convert_epsg(shoreline,
settings['output_epsg'],
image_epsg)[:,[0,1]], georef)
except:
# if try fails, just add nan into the shoreline vector so the next parts can still run
sl_pix = np.array([[np.nan, np.nan],[np.nan, np.nan]])
if plt.get_fignums():
# get open figure if it exists
fig = plt.gcf()
ax1 = fig.axes[0]
ax2 = fig.axes[1]
ax3 = fig.axes[2]
else:
# else create a new figure
fig = plt.figure()
fig.set_size_inches([12.53, 9.3])
mng = plt.get_current_fig_manager()
mng.window.showMaximized()
# according to the image shape, decide whether it is better to have the images
# in vertical subplots or horizontal subplots
if im_RGB.shape[1] > 2*im_RGB.shape[0]:
# vertical subplots
gs = gridspec.GridSpec(3, 1)
gs.update(bottom=0.03, top=0.97, left=0.03, right=0.97)
ax1 = fig.add_subplot(gs[0,0])
ax2 = fig.add_subplot(gs[1,0])
ax3 = fig.add_subplot(gs[2,0])
else:
# horizontal subplots
gs = gridspec.GridSpec(1, 3)
gs.update(bottom=0.05, top=0.95, left=0.05, right=0.95)
ax1 = fig.add_subplot(gs[0,0])
ax2 = fig.add_subplot(gs[0,1])
ax3 = fig.add_subplot(gs[0,2])
# change the color of nans to either black (0.0) or white (1.0) or somewhere in between
nan_color = 1.0
im_RGB = np.where(np.isnan(im_RGB), nan_color, im_RGB)
im_class = np.where(np.isnan(im_class), 1.0, im_class)
# create image 1 (RGB)
ax1.imshow(im_RGB)
ax1.plot(sl_pix[:,0], sl_pix[:,1], 'k.', markersize=3)
ax1.axis('off')
ax1.set_title(sitename, fontweight='bold', fontsize=16)
# create image 2 (classification)
ax2.imshow(im_class)
ax2.plot(sl_pix[:,0], sl_pix[:,1], 'k.', markersize=3)
ax2.axis('off')
orange_patch = mpatches.Patch(color=colours[0,:], label='sand')
white_patch = mpatches.Patch(color=colours[1,:], label='whitewater')
blue_patch = mpatches.Patch(color=colours[2,:], label='water')
black_line = mlines.Line2D([],[],color='k',linestyle='-', label='shoreline')
ax2.legend(handles=[orange_patch,white_patch,blue_patch, black_line],
bbox_to_anchor=(1, 0.5), fontsize=10)
ax2.set_title(date, fontweight='bold', fontsize=16)
# create image 3 (MNDWI)
ax3.imshow(im_mwi, cmap='bwr')
ax3.plot(sl_pix[:,0], sl_pix[:,1], 'k.', markersize=3)
ax3.axis('off')
ax3.set_title(satname, fontweight='bold', fontsize=16)
# additional options
# ax1.set_anchor('W')
# ax2.set_anchor('W')
# cb = plt.colorbar()
# cb.ax.tick_params(labelsize=10)
# cb.set_label('MNDWI values')
# ax3.set_anchor('W')
# if check_detection is True, let user manually accept/reject the images
skip_image = False
if settings['check_detection']:
# set a key event to accept/reject the detections (see https://stackoverflow.com/a/15033071)
# this variable needs to be immuatable so we can access it after the keypress event
key_event = {}
def press(event):
# store what key was pressed in the dictionary
key_event['pressed'] = event.key
# let the user press a key, right arrow to keep the image, left arrow to skip it
# to break the loop the user can press 'escape'
while True:
btn_keep = plt.text(1.1, 0.9, 'keep ⇨', size=12, ha="right", va="top",
transform=ax1.transAxes,
bbox=dict(boxstyle="square", ec='k',fc='w'))
btn_skip = plt.text(-0.1, 0.9, '⇦ skip', size=12, ha="left", va="top",
transform=ax1.transAxes,
bbox=dict(boxstyle="square", ec='k',fc='w'))
btn_esc = plt.text(0.5, 0, '<esc> to quit', size=12, ha="center", va="top",
transform=ax1.transAxes,
bbox=dict(boxstyle="square", ec='k',fc='w'))
plt.draw()
fig.canvas.mpl_connect('key_press_event', press)
plt.waitforbuttonpress()
# after button is pressed, remove the buttons
btn_skip.remove()
btn_keep.remove()
btn_esc.remove()
# keep/skip image according to the pressed key, 'escape' to break the loop
if key_event.get('pressed') == 'right':
skip_image = False
break
elif key_event.get('pressed') == 'left':
skip_image = True
break
elif key_event.get('pressed') == 'escape':
plt.close()
raise StopIteration('User cancelled checking shoreline detection')
else:
plt.waitforbuttonpress()
# if save_figure is True, save a .jpg under /jpg_files/detection
if settings['save_figure'] and not skip_image:
fig.savefig(os.path.join(filepath, date + '_' + satname + '.jpg'), dpi=200)
# Don't close the figure window, but remove all axes and settings, ready for next plot
for ax in fig.axes:
ax.clear()
return skip_image
def extract_shorelines(metadata, settings):
"""
Extracts shorelines from satellite images.
KV WRL 2018
Arguments:
-----------
metadata: dict
contains all the information about the satellite images that were downloaded
settings: dict
contains the following fields:
sitename: str
String containig the name of the site
cloud_mask_issue: boolean
True if there is an issue with the cloud mask and sand pixels are being masked on the images
buffer_size: int
size of the buffer (m) around the sandy beach over which the pixels are considered in the
thresholding algorithm
min_beach_area: int
minimum allowable object area (in metres^2) for the class 'sand'
cloud_thresh: float
value between 0 and 1 defining the maximum percentage of cloud cover allowed in the images
output_epsg: int
output spatial reference system as EPSG code
check_detection: boolean
True to show each invidual detection and let the user validate the mapped shoreline
Returns:
-----------
output: dict
contains the extracted shorelines and corresponding dates.
"""
sitename = settings['inputs']['sitename']
filepath_data = settings['inputs']['filepath']
# initialise output structure
output = dict([])
# create a subfolder to store the .jpg images showing the detection
filepath_jpg = os.path.join(filepath_data, sitename, 'jpg_files', 'detection')
if not os.path.exists(filepath_jpg):
os.makedirs(filepath_jpg)
# close all open figures
plt.close('all')
print('Mapping shorelines:')
# loop through satellite list
for satname in metadata.keys():
# get images
filepath = SDS_tools.get_filepath(settings['inputs'],satname)
filenames = metadata[satname]['filenames']
# initialise the output variables
output_timestamp = [] # datetime at which the image was acquired (UTC time)
output_shoreline = [] # vector of shoreline points
output_filename = [] # filename of the images from which the shorelines where derived
output_cloudcover = [] # cloud cover of the images
output_geoaccuracy = []# georeferencing accuracy of the images
output_idxkeep = [] # index that were kept during the analysis (cloudy images are skipped)
# load classifiers and
if satname in ['L5','L7','L8']:
pixel_size = 15
if settings['dark_sand']:
clf = joblib.load(os.path.join(os.getcwd(), 'classifiers', 'NN_4classes_Landsat_dark.pkl'))
else:
clf = joblib.load(os.path.join(os.getcwd(), 'classifiers', 'NN_4classes_Landsat.pkl'))
elif satname == 'S2':
pixel_size = 10
clf = joblib.load(os.path.join(os.getcwd(), 'classifiers', 'NN_4classes_S2.pkl'))
# convert settings['min_beach_area'] and settings['buffer_size'] from metres to pixels
buffer_size_pixels = np.ceil(settings['buffer_size']/pixel_size)
min_beach_area_pixels = np.ceil(settings['min_beach_area']/pixel_size**2)
# loop through the images
for i in range(len(filenames)):
print('\r%s: %d%%' % (satname,int(((i+1)/len(filenames))*100)), end='')
# get image filename
fn = SDS_tools.get_filenames(filenames[i],filepath, satname)
# preprocess image (cloud mask + pansharpening/downsampling)
im_ms, georef, cloud_mask, im_extra, im_QA, im_nodata = SDS_preprocess.preprocess_single(fn, satname, settings['cloud_mask_issue'])
# get image spatial reference system (epsg code) from metadata dict
image_epsg = metadata[satname]['epsg'][i]
# calculate cloud cover
cloud_cover = np.divide(sum(sum(cloud_mask.astype(int))),
(cloud_mask.shape[0]*cloud_mask.shape[1]))
# skip image if cloud cover is above threshold
if cloud_cover > settings['cloud_thresh']:
continue
# classify image in 4 classes (sand, whitewater, water, other) with NN classifier
im_classif, im_labels = classify_image_NN(im_ms, im_extra, cloud_mask,
min_beach_area_pixels, clf)
# calculate a buffer around the reference shoreline (if any has been digitised)
im_ref_buffer = create_shoreline_buffer(cloud_mask.shape, georef, image_epsg,
pixel_size, settings)
# there are two options to map the contours:
# if there are pixels in the 'sand' class --> use find_wl_contours2 (enhanced)
# otherwise use find_wl_contours2 (traditional)
try: # use try/except structure for long runs
if sum(sum(im_labels[:,:,0])) == 0 :
# compute MNDWI image (SWIR-G)
im_mndwi = SDS_tools.nd_index(im_ms[:,:,4], im_ms[:,:,1], cloud_mask)
# find water contours on MNDWI grayscale image
contours_mwi = find_wl_contours1(im_mndwi, cloud_mask, im_ref_buffer)
else:
# use classification to refine threshold and extract the sand/water interface
contours_wi, contours_mwi = find_wl_contours2(im_ms, im_labels,
cloud_mask, buffer_size_pixels, im_ref_buffer)
except:
print('Could not map shoreline for this image: ' + filenames[i])
continue
# process the water contours into a shoreline
shoreline = process_shoreline(contours_mwi, cloud_mask, georef, image_epsg, settings)
# visualise the mapped shorelines, there are two options:
# if settings['check_detection'] = True, shows the detection to the user for accept/reject
# if settings['save_figure'] = True, saves a figure for each mapped shoreline
if settings['check_detection'] or settings['save_figure']:
date = filenames[i][:19]
skip_image = show_detection(im_ms, cloud_mask, im_labels, shoreline,
image_epsg, georef, settings, date, satname)
# if the user decides to skip the image, continue and do not save the mapped shoreline
if skip_image:
continue
# append to output variables
output_timestamp.append(metadata[satname]['dates'][i])
output_shoreline.append(shoreline)
output_filename.append(filenames[i])
output_cloudcover.append(cloud_cover)
output_geoaccuracy.append(metadata[satname]['acc_georef'][i])
output_idxkeep.append(i)
# create dictionnary of output
output[satname] = {
'dates': output_timestamp,
'shorelines': output_shoreline,
'filename': output_filename,
'cloud_cover': output_cloudcover,
'geoaccuracy': output_geoaccuracy,
'idx': output_idxkeep
}
print('')
# Close figure window if still open
if plt.get_fignums():
plt.close()
# change the format to have one list sorted by date with all the shorelines (easier to use)
output = SDS_tools.merge_output(output)
# save outputput structure as output.pkl
filepath = os.path.join(filepath_data, sitename)
with open(os.path.join(filepath, sitename + '_output.pkl'), 'wb') as f:
pickle.dump(output, f)
# save output into a gdb.GeoDataFrame
gdf = SDS_tools.output_to_gdf(output)
# set projection
gdf.crs = {'init':'epsg:'+str(settings['output_epsg'])}
# save as geojson
gdf.to_file(os.path.join(filepath, sitename + '_output.geojson'), driver='GeoJSON', encoding='utf-8')
return output
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