Co-registration with SNAP

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=Visualize geometric offset=
 
* Start SNAP Desktop
 
* Start SNAP Desktop
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* {{mitem|text=File --> Open Product...}} Browse and mark UAS ortho mosiacs. \geodata\uas\clip_ebee_ortho_align.tif is the master image and \geodata\uas\clip_mavic_ortho_align.tif is the slave image. {{button|text=Open}} or drag and drop marked files from Windows File Explorer into the SNAP '''Product Explorer''' tab.
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* {{mitem|text=File --> Open Product...}}. Browse for Unmanned Aerial System (UAS) ortho mosaics:
−
* Mark the slave image ''clip_mavic_ortho_align.tif'' in ToC. {{mitem|text=Raster --> Subset --> Band Subset}}. Check only '''band_1'''.
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{{typed|text=clip_ebee_ortho_align.tif}} is a reference image which is very well georeferenced. {{typed|text=clip_mavic_ortho_align.tif}} is an image with a positional offset. It needs to be registered to the reference image. {{button|text=Open}} or drag and drop marked files from Windows File Explorer into the SNAP '''Product Explorer''' tab.
 +
* Mark the reference image ''clip_ebee_ortho_align.tif'' in ToC. Right click {{mitem|text= Open RGB Image Window --> OK}}.
 +
* Mark the image to be registered ''clip_mavic_ortho_align.tif'' in ToC. Right click {{mitem|text= Open RGB Image Window --> OK}}.
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* {{mitem|text= Window --> Tile Vertically}}. Both side-by-side windows are spatially linked. Zoom in and use the {{button|text=Panning tool}} to see the offset between both images
 +
 
 +
=Split multiband to single band files=
 +
* Mark the image to be registered  ''clip_mavic_ortho_align.tif'' in ToC. {{mitem|text=Raster --> Subset --> Band Subset}}. Check exclusivly '''band_1'''.
 
[[File:snap_specify_band_subset_band_1.png|300px]]
 
[[File:snap_specify_band_subset_band_1.png|300px]]
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* Repeat this step for band_2 and band_3 creating separated single bands of the slave image .
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* Repeat this step for band_2 and band_3 creating separated single bands of the image to be registered .
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= Co-registration of single band raster files =
 
* {{mitem|text=Raster --> Geometric operations --> GeFolki Co-registration}}.
 
* {{mitem|text=Raster --> Geometric operations --> GeFolki Co-registration}}.
 
* Define I/O Parameters and Processing Parameters:
 
* Define I/O Parameters and Processing Parameters:
 
[[File:snap_gefolki_io.png|400px]] [[File:snap_gefolki_params.png|400px]]
 
[[File:snap_gefolki_io.png|400px]] [[File:snap_gefolki_params.png|400px]]
 
* Click  {{button|text=Run}}.
 
* Click  {{button|text=Run}}.
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* Repeat this step  for band_2 ('''subset_1''') and band_3 ('''subset_1'''). Adjust processing parameters for each band, accordingly.
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* Repeat this step  for band_2 ('''subset_1''') and band_3 ('''subset_2'''). Adjust processing parameters for each band, accordingly.
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* Create a stack of all coregistered single bands. {{mitem|text=Raster --> Geometric operations --> Collocation}}
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= Stack single bands to multiband file =
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* Create a stack of all coregistered single bands. {{mitem|text=Raster --> Geometric --> Collocation}}
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* Resampling Method: {{button|text=Bilinear Resampling}}
 
[[File:snap_collocation.png|400px]]
 
[[File:snap_collocation.png|400px]]
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 +
= Convert data type from float32 to uint8 =
 
* {{mitem|text=Raster --> Data Conversion --> Convert Datatype}}
 
* {{mitem|text=Raster --> Data Conversion --> Convert Datatype}}
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* Check '''Save as''' and select GeoTIFF from drop downlist
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* Check '''Save as''' and select GeoTIFF from drop downlist.
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* Target Data type: '''uint8'''
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* Scaling: '''Linear (slope and intercept)'''
 
[[File:snap_datatype_io.png|400px]] [[File:snap_datatype_params.png|400px]]
 
[[File:snap_datatype_io.png|400px]] [[File:snap_datatype_params.png|400px]]
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* Load ''clip_ebee_ortho_align.tif'', ''clip_mavic_ortho_align.tif'' and ''collocate_Cnv.tif'' into QGIS and check the geometric quality of the coregistration.  
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* Mark the coregistered image {{typed|text=collocate_cnv}} in ToC. Right click {{mitem|text= Open RGB Image Window --> OK}}. Check the geometric quality of the co-registration comparing the reference image {{typed|text=clip_ebee_ortho_align.tif}} (bottom), the image with an positional offset {{typed|text=clip_mavic_ortho_align.tif}} (middle) and the co-registered image {{typed|text=collocate_cnv.tif}} (top).
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[[File:check_collocation.png|600px]]
  
 
[[Category:SNAP Tutorial]]
 
[[Category:SNAP Tutorial]]
 
[[Category:Tutorials]]
 
[[Category:Tutorials]]

Latest revision as of 22:25, 6 November 2021

Contents

[edit] Visualize geometric offset

  • Start SNAP Desktop
  • File --> Open Product.... Browse for Unmanned Aerial System (UAS) ortho mosaics:

clip_ebee_ortho_align.tif is a reference image which is very well georeferenced. clip_mavic_ortho_align.tif is an image with a positional offset. It needs to be registered to the reference image. Open or drag and drop marked files from Windows File Explorer into the SNAP Product Explorer tab.

  • Mark the reference image clip_ebee_ortho_align.tif in ToC. Right click Open RGB Image Window --> OK.
  • Mark the image to be registered clip_mavic_ortho_align.tif in ToC. Right click Open RGB Image Window --> OK.
  • Window --> Tile Vertically. Both side-by-side windows are spatially linked. Zoom in and use the Panning tool to see the offset between both images

[edit] Split multiband to single band files

  • Mark the image to be registered clip_mavic_ortho_align.tif in ToC. Raster --> Subset --> Band Subset. Check exclusivly band_1.

Snap specify band subset band 1.png

  • Repeat this step for band_2 and band_3 creating separated single bands of the image to be registered .

[edit] Co-registration of single band raster files

  • Raster --> Geometric operations --> GeFolki Co-registration.
  • Define I/O Parameters and Processing Parameters:

Snap gefolki io.png Snap gefolki params.png

  • Click Run.
  • Repeat this step for band_2 (subset_1) and band_3 (subset_2). Adjust processing parameters for each band, accordingly.

[edit] Stack single bands to multiband file

  • Create a stack of all coregistered single bands. Raster --> Geometric --> Collocation
  • Resampling Method: Bilinear Resampling

Snap collocation.png

[edit] Convert data type from float32 to uint8

  • Raster --> Data Conversion --> Convert Datatype
  • Check Save as and select GeoTIFF from drop downlist.
  • Target Data type: uint8
  • Scaling: Linear (slope and intercept)

Snap datatype io.png Snap datatype params.png

  • Mark the coregistered image collocate_cnv in ToC. Right click Open RGB Image Window --> OK. Check the geometric quality of the co-registration comparing the reference image clip_ebee_ortho_align.tif (bottom), the image with an positional offset clip_mavic_ortho_align.tif (middle) and the co-registered image collocate_cnv.tif (top).

Check collocation.png

Retrieved from "http://wiki.awf.forst.uni-goettingen.de/wiki/index.php?title=Co-registration_with_SNAP&oldid=16458"
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