Hi Everyone,
I'm trying to use California wildfires 2017 - Thomas Fire analysis Sample provided in ArcGIS Python API Samples.
I have used sentinel imagery to do the same analysis but I always end up getting black imagery (All 0s). Can you please suggest where I'm doing wrong?
import arcgis
from arcgis import *
from arcgis.mapping import MapImageLayer
gis = GIS(profile="krishna_dev")
#Sentinel2
sentinel_item = gis.content.search('title:Sentinel2', 'Imagery Layer', outside_org=True)[0]
sentinel = sentinel_item.layers[0]
sentinel_item
aoi = {'spatialReference': {'latestWkid': 3857, 'wkid': 102100}, 'type': 'extent',
'xmax': 9028482.969, 'xmin': 8908018.212, 'ymax': 2478700.211, 'ymin': 2248166.133}
arcgis.env.analysis_extent = {'xmax': 9028482.969, 'xmin': 8908018.212, 'ymax': 2478700.211, 'ymin': 2248166.133,
"spatialReference":{"wkid":102100,"latestWkid":3857}}
sentinel.extent = aoi
import pandas as pd
from datetime import datetime
selected = sentinel.filter_by(where="(Category = 1)",
time=[datetime(2020, 4, 3), datetime(2020, 4, 15)],
geometry=arcgis.geometry.filters.intersects(aoi))
df = selected.query(out_fields="acquisitiondate, name, cloudcover",
order_by_fields="acquisitiondate").sdf
df['acquisitiondate'] = pd.to_datetime(df['acquisitiondate'], unit='ms')
df.tail()
prefire = sentinel.filter_by('OBJECTID in ( 10127407, 10187367)') # 2020-04-03
prefire = prefire.blend()
midfire = sentinel.filter_by('OBJECTID in (10304749, 10304746)') # 2020-04-13
midfire = midfire.blend()
from arcgis.raster.functions import *
extracted_band = extract_band(midfire, [13,12,4])
extracted_band_prefire = extract_band(prefire, [13,12,4])
nbr_prefire = band_arithmetic(prefire, "(b9 - b13) / (b9 + b13) + 2000")
nbr_postfire = band_arithmetic(midfire, "(b9 - b13) / (b9 + b13) + 2000")
nbr_diff = nbr_prefire - nbr_postfir
nbr_diff
burnt_areas = colormap(remap(nbr_diff,
input_ranges=[0.1, 0.27, # low severity
0.27, 0.44, # medium severity
0.44, 0.66, # moderate severity
0.66, 1.00], # high severity burn
output_values=[1, 2, 3, 4],
no_data_ranges=[-1, 0.1], astype='u8'),
colormap=[[4, 0xFF, 0xC3, 0], [3, 0xFA, 0x8E, 0], [2, 0xF2, 0x55, 0], [1, 0xE6, 0, 0]])
burnt_areas
Thanks,
Krish
