Hi again,
I understand...
Perhaps an option could be using something like -lco Z_NODATA_VALUE_DST="X" to
translate NODATA from origin to this value X (NaN, 0, or whatever it may be).
The driver can offer this number instead of the own NODATA and the user can
know that the X value in destination will mean NODATA.
On the other hand, a user could also specify -lco Z_NODATA_VALUE_SRC="Y" so
that a driver can identify a value considered NODATA in the source and
translate it to the own NODATA value (or the one specified by the first
parameter (if it exists)).
Is this too complicated? Are there any repercussions that I'm not seeing?
Thanks.
De: Rahkonen Jukka <jukka.rahko...@maanmittauslaitos.fi>
Enviado el: dijous, 25 de gener de 2024 18:27
Para: Abel Pau <a....@creaf.uab.cat>; gdal-dev@lists.osgeo.org
Asunto: Re: vector NODATA for Z values?
Hi,
I think that it depends on the file format. Rather often it is set to zero but
I have seen NaN in many places. However, shapefiles explicitly denies NaN
"...Positive infinity, negative infinity, and Not-a-Number (NaN) values are not
allowed in shapefiles. Nevertheless, shapefiles support the concept of "no
data" values, but they are currently used only for measures. Any floating point
number smaller than -1038 is considered by a shapefile reader to represent a
"no data" value.
With the SQLite dialect it is possible to select the value but NaN is not
accepted.
Can be tested with
ogrinfo -dialect SQLite -sql "select CastToXYZ(ST_GeomFromText('POINT (1
2)'),3)" point.json
-Jukka Rahkonen-
Lähettäjä: gdal-dev
<gdal-dev-boun...@lists.osgeo.org<mailto:gdal-dev-boun...@lists.osgeo.org>>
Puolesta Abel Pau via gdal-dev
Lähetetty: torstai 25. tammikuuta 2024 19.07
Vastaanottaja: gdal-dev@lists.osgeo.org<mailto:gdal-dev@lists.osgeo.org>
Aihe: [gdal-dev] vector NODATA for Z values?
Hi,
there is any value in GDAL for VECTORS that indicates that a concrete value of
a Z is not known (z nodata value)?
I couldn't find it anywhere.
In MiraMon format we use one concrete number documented in our format pdf
(-1.0E+300) an in the driver it's planned to translate it to the same number. I
could translate it to the one I am asking. And the same for detecting nodata Z
and translate them to -1.0E+300 when reading another format.
Thanks!
Abel Pau Garcia
GIS developer
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