[gdal-dev] ISCE raster changes from BIL to BIP after gdal_translate

[Even Rouault]

Scott,

due to the Abstraction word in GDAL , doing a gdal_translate in the same 
format doesn't automatically applies the characteristics from the input 
dataset to the output one, because in general you translate into a 
different format, or if it is in the same format, you may apply options 
to gdal_translate that could invalidate the characteristics of the input 
dataset. So to do what you want, you need to write a specialized code.

You would need to create a CreateCopy() implementation in the ISCE 
driver that fetches from the source dataset the original scheme (it 
would have to be expose as a INTERLEAVING metadata item in the ISCE 
metadata domain for example), and uses that to force the SCHEME creation 
option.

https://github.com/OSGeo/gdal/blob/master/gdal/frmts/raw/ehdrdataset.cpp#L1811 
would probably be the closest starting point.

But you may also need the logic at 
https://github.com/OSGeo/gdal/blob/master/gdal/frmts/pds/pds4dataset.cpp#L4477 
to extract the source dataset from the in-memory VRT created by 
gdal_translate if applying for example a subsetting option.

Even


Le 24/09/2021 à 01:45, Scott Staniewicz a écrit :
> I've got a 2 band, band-interleaved-line file gendered from the ISCE 
> software. I was doing some subsetting of it with gdal_translate, and I 
> noticed that the format got changed to BIP:
>
>
>
> $ ls
> 20130719_20150427.unw  20130719_20150427.unw.vrt 
>  20130719_20150427.unw.xml
>
> $ grep -i -n3 scheme 20130719_20150427.unw.xml
> 96-        <value>2</value>
> 97-        <doc>Number of image bands.</doc>
> 98-    </property>
> 99:    <property name="scheme">
> 100-        <value>BIL</value>
> 101:        <doc>Interleaving scheme of the image.</doc>
> 102-    </property>
> 103-    <property name="width">
> 104-        <value>586</value>
>
> After running gdal_translate, the format has changed to BIP:
>
> $ gdal_translate 20130719_20150427.unw test.unw -of ISCE
> Input file size is 586, 882
> 0...10...20...30...40...50...60...70...80...90...100 - done.
> (mapping) [scott at grace gdal-translate-bug]$ grep -i -n3 scheme 
> test.unw.xml
> 11-  <property name="DATA_TYPE">
> 12-    <value>FLOAT</value>
> 13-  </property>
> 14:  <property name="SCHEME">
> 15-    <value>BIP</value>
> 16-  </property>
> 17-  <property name="BYTE_ORDER">
>
>
> I'm assuming it's related to this line for creating a dataset with 
> default BIP:
>
> https://github.com/OSGeo/gdal/blob/master/gdal/frmts/raw/iscedataset.cpp#L839 
> <https://github.com/OSGeo/gdal/blob/master/gdal/frmts/raw/iscedataset.cpp#L839>
>
> But I'm not familiar enough with the gdal_translate code to know where 
> the options are getting generated and passed here.
> Any advice on where might be a good place to fix the ISCE raster 
> generation?
>
> Thanks,
> Scott
>
>
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