Hi Even, Thanks for such a quick fix! Really really appreciate what you've done for the GDAL community!
Zhan. On Mon, Aug 31, 2020 at 8:32 PM Even Rouault <[email protected]> wrote: > Zhan, > > > > adding back the list > > > > There was an issue in the writing code of the netCDF driver. It was > supposed supposed to copy the offset and scale settings from the source > dataset, but there was a logic error. Fixed per > > https://github.com/OSGeo/gdal/pull/2906 > > > > Even > > > > > > > Hi Even, > > > > > > Thanks a lot for your reply! Yes here in this example, scale_factor and > > > add_offset do not matter. I put them here just for demo purposes. In my > > > actual data (quite large), I'd like to use 1e-3 as scale factor but could > > > not write scale_factor into the metadata of netCDF via gdal_translate. > Even > > > if I use VRT as an intermediate file and manually add scale_factor into > the > > > VRT per band through "<MDI key="scale_factor">1e-3</MDI>". It still does > > > not work :( > > > > > > But it sounds like the implementation of the netCDF driver in GDAL has > some > > > explicit tweak of metadata items? Like you said, valid_range is > explicitly > > > discarded. Maybe scale_factor and add_offset and such are also part of > > > metadata items that the driver explicitly discards? In that case, I'll > > > stick to scale_factor=1 and add_offset=0. Not ideal though. Otherwise, > this > > > loss of metadata items for netCDF files should count as a bug to be > > > reported? > > > > > > Zhan. > > > > > > On Mon, Aug 31, 2020 at 11:06 AM Even Rouault < > [email protected]> > > > > > > wrote: > > > > On lundi 31 août 2020 00:11:54 CEST Zhan Li wrote: > > > > > Hi, when I use gdal_translate to convert a raster file (e.g., either > > > > > > > > GTiff > > > > > > > > > or VRT) into netCDF format, it always loses some important metadata > > > > > items > > > > > > > > > > such as scale_factor, add_offset and etc. What am I doing it wrong? > Can > > > > > > > > > > anyone help me to solve this problem? > > > > > > > > As scale_factor=1 and add_offset=0 in that dataset, they have no > effect, > > > > and are thus not stored when converted to GeoTIFF. > > > > > > > > > > > > > > > > valid_range is explicitly discarded from source metadata when > converting > > > > into netCDF. I'm not completely sure of the rationale for that. > > > > > > > > > > > > > > > > Even > > > > > > > > > > > > > > > > -- > > > > > > > > Spatialys - Geospatial professional services > > > > > > > > http://www.spatialys.com > > > > > > -- > > Spatialys - Geospatial professional services > > http://www.spatialys.com > -- Zhan Li <https://zhanlilz.github.io/>, 李展; Google Scholar <https://scholar.google.com/citations?user=JGNL9BoAAAAJ&hl=en>, ORCID <https://orcid.org/0000-0001-6307-5200>, Github <https://github.com/zhanlilz>, Twitter <https://twitter.com/zhanlilz>, LinkedIn <https://www.linkedin.com/in/zhanli/>
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