Image fusion

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(Created page with "= Create a superimposed layer (reprojected image) = # Add the panchromatic band 8 (15m GSD) and multispectral bands (B1 – B7, 30m GSD) into QGIS using the ‘add raster laye...")
 
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= Create a superimposed layer (reprojected image) =
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Pansharpening of Sentinel-2 requires defining a 10m reference band because there is no panchromatic band as for Landsat available. The only option is a selection among the 10-m bands (2, 3, 4, or 8) or synthesis (e.g. weighted average of 10-m band). Following the latter approach, the luminance can be calculated from the Blue, Red Green and NIR band to receive a single band grey scale image.
# Add the panchromatic band 8 (15m GSD) and multispectral bands (B1 – B7, 30m GSD) into QGIS using the ‘add raster layer’ function.
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#I n the Processing Toolbox, search for Superimpose sensor.
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= Create a synthesis panchromatic band =
# In the reference input, select the band 08 file.
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# Load the input image
# Select the multispectral bands as the image to reproject.
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# Open the raster calculator and apply the following formula: Y = 0.20 * NIR(B8) 0.15 * Red(B4) + 0.58 * Green(B3) + 0.07 * Blue(B1)
# Specify the directory to save the output file and click on the ‘Run-button’.
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  [[File:rastercalc.png|200px]]
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# Define path and name for the output layer
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# Click on the ‘OK-button’.
  
 
= Create a pan-sharpened layer =
 
= Create a pan-sharpened layer =
 
# Search for Pansharpening (Bayes) algorithm in the Processing Toolbox.
 
# Search for Pansharpening (Bayes) algorithm in the Processing Toolbox.
# Select Band 08 as the Input PAN Image.
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# Select pseudo-panchromatic band as the Input PAN Image.
# Select the Superimposed layer (Reprojected image) as the InputXS Image.
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# Select the layer contain the original 20m bands as the InputXS Image.
 
# Specify the directory to save the output file and click on the ‘Run-button’.
 
# Specify the directory to save the output file and click on the ‘Run-button’.
  
 
= Compare the fused image with the original image =
 
= Compare the fused image with the original image =
In QGIS viewer by using the “Map Swipe Tool” plugin.
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[[File:no_pansharpen.png|400px]] [[File:pansharpen.png|400px]]
  
  
 
[[Category:QGIS Tutorial]]
 
[[Category:QGIS Tutorial]]

Revision as of 18:45, 16 November 2017

Pansharpening of Sentinel-2 requires defining a 10m reference band because there is no panchromatic band as for Landsat available. The only option is a selection among the 10-m bands (2, 3, 4, or 8) or synthesis (e.g. weighted average of 10-m band). Following the latter approach, the luminance can be calculated from the Blue, Red Green and NIR band to receive a single band grey scale image.

Create a synthesis panchromatic band

  1. Load the input image
  2. Open the raster calculator and apply the following formula: Y = 0.20 * NIR(B8) 0.15 * Red(B4) + 0.58 * Green(B3) + 0.07 * Blue(B1)
 Rastercalc.png
  1. Define path and name for the output layer
  2. Click on the ‘OK-button’.

Create a pan-sharpened layer

  1. Search for Pansharpening (Bayes) algorithm in the Processing Toolbox.
  2. Select pseudo-panchromatic band as the Input PAN Image.
  3. Select the layer contain the original 20m bands as the InputXS Image.
  4. Specify the directory to save the output file and click on the ‘Run-button’.

Compare the fused image with the original image

No pansharpen.png Pansharpen.png

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