Javier,
Le 26/10/2023 à 11:59, Javier Jimenez Shaw via gdal-dev a écrit :
Hi
Using a GeoTIFF with a single band and float values can be very useful
to show any distribution over the terrain. One typical example is DSM
(digital surface model), where the value is the elevation on every point.
Is there any standard (or accepted) metadata to say the units of those
values?
API wise in GDAL, you should use the GDALRasterBand::SetUnitType() to
set the unit
For TIFF, this will be encoded in the GDAL_METADATA TIFF tag like the
following:
<GDALMetadata>
<Item name="UNITTYPE" sample="0" role="unittype">foo</Item>
</GDALMetadata>
Regarding the value itself, it is mostly unspecified by GDAL. It could
be a good practice to suggest to use strings recognized by the "udunits"
package (when possible), like done in the netCDF CF conventions
(http://cfconventions.org/Data/cf-conventions/cf-conventions-1.10/cf-conventions.html#units)
Even
In the typical case of DSM it is usually "meter" or "foot". But it can
be something else, like "people/km2" for population, or "mm" for rain
precipitation, or "kg/ha" for agricultural yield.
Thanks
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