Abel,
there is a subtelty:
a) If bands may have invalid pixels at different locations on different
bands, and that those bands have a different nodata value, then using
GDALRasterBand::SetNoDataValue() is the way to go.
b) If a given pixel is invalid only if its value on all bands matches
the nodata value on each band, then NODATA_VALUES should be set instead
Example with 2 bands:
- Band 1, NoData=1, pixel_1=1, pixel_2=1
- Band 2, NoData=2, pixel_1=2, pixel_2=0
In interpretation a), then pixel_1 and pixel_2 are invalid for Band 1,
and pixel_1 is invalid for Band 2
In interpretation b), then only pixel_1 is invalid (for both bands)
Le 21/05/2025 à 08:46, Abel Pau via gdal-dev a écrit :
Hello,
I am implementing a driver that allows different NODATA values for
each band in a dataset.
>From what I understand in the documentation, I should use the
|NODATA_VALUES| metadata item to document these values. However, I
don't see a clear way to indicate that a specific band has *no
NODATA* value within the tuple.
On the other hand, the documentation also suggests that
|NODATA_VALUES| is *not widely honoured*, which is not very encouraging.
Therefore, would you consider it good practice to separate bands with
different NODATA values into separate *sub*datasets instead?
Thank you very much for the clarification.
*Abel Pau Garcia
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