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I have a raster file with some data pixels around the middle and a huge amount of NODATA padding everywhere around it.

How can I crop the raster so that the extent aligns with the outermost non-NODATA pixels on all sides?

The result should be perfectly aligned to the source raster's rows and columns (so, if possible, without a vector mask layer or an extent defined in CRS units).

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  • What is the issue with a vector mask? I did a basic test with a raster with data pixels surrounded by NoData pixels, and a projected CRS. I used Raster Pixels to Polygons to create a polygon mask, and then Clip Raster By Extent with the polygon layer as a vector mask. The output layer was aligned to the source raster.
    – Tom Brennan
    Commented Mar 15, 2023 at 6:38
  • It might seem esoteric but I would be afraid of it being lossy in some circumstances due to floating point numbers etc. I want to do analysis on pixel-perfect aligned rasters, not 99.99% aligned ones.
    – bugmenot123
    Commented Mar 15, 2023 at 6:54
  • Dear two people who votes to close this, please be nice and comment on what you feel the answer is lacking.
    – bugmenot123
    Commented Mar 15, 2023 at 6:55
  • Have you seen raster grids go out of alignment before? Just trying to understand if this is a real issue or a theoretical one. Keep in mind that you can run checks on the before/after rasters to ensure that the differences are zero.
    – Tom Brennan
    Commented Mar 15, 2023 at 7:24
  • Theoretical, to be honest. Thank you!
    – bugmenot123
    Commented Mar 15, 2023 at 9:29

1 Answer 1

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Use gdal_translate https://gdal.org/programs/gdal_translate.html with -srcwin option.

-srcwin <xoff> <yoff> <xsize> <ysize>

Selects a subwindow from the source image for copying based on pixel/line location.

Offsets are counted from the top left corner. A separate challenge is to analyze the data/nodata coverage for finding the appropriate values for offsets and sizes.

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  • Thanks, this seems like the right approach.
    – bugmenot123
    Commented Apr 5, 2023 at 12:48

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