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ee.ImageCollection.qualityMosaic
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Composites all the images in a collection, using a quality band as a per-pixel ordering function.
Usage Returns ImageCollection. qualityMosaic (qualityBand)
Image
Argument Type Details this: collection
ImageCollection The collection to mosaic. qualityBand
String The name of the quality band in the collection.
Examples
Code Editor (JavaScript)
// The goal is to generate a best-pixel mosaic from a collection of
// Sentinel-2 images where pixel quality is based on a cloud probability score.
// The qualityMosaic() function selects the image (per-pixel) with the HIGHEST
// quality-band-score to contribute to the resulting mosaic. All bands from the
// selected image (per-pixel) associated with the HIGHEST quality-band-score
// are included in the output.
// A Sentinel-2 SR image collection (2 months of images at a specific point).
var col = ee.ImageCollection('COPERNICUS/S2_SR_HARMONIZED')
.filterBounds(ee.Geometry.Point(-103.19, 40.14))
.filterDate('2020-07-01', '2020-09-01');
// Because cloud probability ranges from 0 to 100 percent (low to high), we need
// to invert the MSK_CLDPRB band values so that low cloud probability pixels
// indicate high quality. Here, an inverting function is mapped over the
// image collection, the inverted MSK_CLDPRB band is added as a "quality" band.
col = col.map(function(img) {
var cldProb = img.select('MSK_CLDPRB');
var cldProbInv = cldProb.multiply(-1).rename('quality');
return img.addBands(cldProbInv);
});
// Image visualization settings.
var visParams = {
bands: ['B4', 'B3', 'B2'],
min: 0,
max: 4500
};
Map.setCenter(-103.19, 40.14, 9);
Map.addLayer(col, visParams, 'Collection (for series inspection)', false);
// Generate a best-pixel mosaic from the image collection.
var img = col.qualityMosaic('quality');
Map.addLayer(img, visParams, 'Best-pixel mosaic (by cloud score)');
// To build the worst-pixel mosaic, according to cloud probability, use the
// MSK_CLDPRB band as the quality band (the worst pixels have HIGHEST cloud
// probability score).
var img = col.qualityMosaic('MSK_CLDPRB');
Map.addLayer(img, visParams, 'Worst-pixel mosaic (by cloud score)', false);
Python setup
See the
Python Environment page for information on the Python API and using
geemap
for interactive development.
import ee
import geemap.core as geemap
Colab (Python)
# The goal is to generate a best-pixel mosaic from a collection of
# Sentinel-2 images where pixel quality is based on a cloud probability score.
# The qualityMosaic() function selects the image (per-pixel) with the HIGHEST
# quality-band-score to contribute to the resulting mosaic. All bands from the
# selected image (per-pixel) associated with the HIGHEST quality-band-score
# are included in the output.
# A Sentinel-2 SR image collection (2 months of images at a specific point).
col = (
ee.ImageCollection('COPERNICUS/S2_SR_HARMONIZED')
.filterBounds(ee.Geometry.Point(-103.19, 40.14))
.filterDate('2020-07-01', '2020-09-01')
)
# Because cloud probability ranges from 0 to 100 percent (low to high), we need
# to invert the MSK_CLDPRB band values so that low cloud probability pixels
# indicate high quality. Here, an inverting function is mapped over the
# image collection, the inverted MSK_CLDPRB band is added as a "quality" band.
def invertCloudProbabilityBand(img):
cldProb = img.select('MSK_CLDPRB')
cldProbInv = cldProb.multiply(-1).rename('quality')
return img.addBands(cldProbInv)
col = col.map(invertCloudProbabilityBand)
# Image visualization settings.
vis_params = {'bands': ['B4', 'B3', 'B2'], 'min': 0, 'max': 4500}
m = geemap.Map()
m.set_center(-103.19, 40.14, 9)
m.add_layer(col, vis_params, 'Collection (for series inspection)', False)
# Generate a best-pixel mosaic from the image collection.
img = col.qualityMosaic('quality')
m.add_layer(img, vis_params, 'Best-pixel mosaic (by cloud score)')
# To build the worst-pixel mosaic, according to cloud probability, use the
# MSK_CLDPRB band as the quality band (the worst pixels have HIGHEST cloud
# probability score).
img = col.qualityMosaic('MSK_CLDPRB')
m.add_layer(img, vis_params, 'Worst-pixel mosaic (by cloud score)', False)
m
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Last updated 2023-10-06 UTC.
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{"lastModified": "Last updated 2023-10-06 UTC."}
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