Dear Julien,
Thanks for your feedback.
It is true that current syntax is somewhere in-between different
standards.
About the use of "band[]" as general syntax, it would not be
consistent with other extended filenames : we always use
"keyword=value". So, it should be something like "band=[]".
Regards,
Guillaume
On 02/25/2017 10:41 AM, Julien Radoux
wrote:
Dear Guillaume,
This would be usefull, thanks. I don't care about band or bands.
for the syntax, Python-like is nice, but then it is confusing
not to start with band 0 for the first band. maybe using []
would also make things clear. To be more "pythonic", I would
rather use bands[] with the python indices but this is probably
more difficult to parse. Also, in python, [2:4] would mean bands
with index 2 and 3 (not the 4), so this is not consistent.
To conclude, Python-like is fine, but it would be very confusing
if there are too many differences. In your example, it makes me
think of Matlab indexing, which is fine but should be stated as
such in the help (then use "end" instead of -1 for the last
band)
For the last question, I do have some home made scripts that
could benefit from band selection in the extended filename. One
application with a standard filter would be the use of Meanshift
segmentation where you only want the smoothed mean value for one
of the output bands (e.g. a NDVI band) but you want to use more
than one band as input for the mean shift segmentation.
Le vendredi 24 février 2017 17:25:37 UTC+1, Guillaume Pasero a
écrit :
Dear users,
A new feature is in development to provide an extended
filename for input band selection (see extended_band). A simple use-case is when you
have a multi-channel image, and you want to process only
the second band of this image using an OTB Application.
With this feature you could do it like this :
otbcli_MyApplication -in "my_image.tif?band=2"
-out output.tif
The current syntax (inspired by Python syntax) has already
been implemented :
- band=r1,r2,...,rn where each 'ri' is
a generic range
- A generic range can be :
- A single band index : '1' is the first band, for
negative numbers the numbering is backward ( '-1'
is the last band)
- A range of bands, using the character ':' between
optional start and end indexes :
- '3:' means the 3rd band until the last one
- ':-2' means the first band until the second
to last
- '2:4' means bands 2, 3 and 4
We would like to have your feedback on several points :
- We will likely change the keyword "band" to
plural "bands", no objection ?
- Is the syntax clear / convenient / confusing ?
- There can be a debate between 0-based and 1-based
indexing for band numbers. At the moment, it is not
uniform in OTB but we think that 1-based indexing should
be the convention exposed to the user.
- It is also possible to implement it on image writers,
would it help ? What would be your use-cases ?
Thanks for your feedback,
Guillaume
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Guillaume
PASERO
Responsable technique
Business Unit ESPACE & GeoInformation -
Département Payload Data & Applications
CS Systèmes d'Information
Parc de la Grande Plaine - 5, Rue Brindejonc des
Moulinais - BP 15872
31506 Toulouse Cedex 05 - FRANCE
+33 561 17 64 21 - [email protected] |
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Guillaume PASERO
Responsable technique
Business Unit ESPACE & GeoInformation -
Département Payload Data & Applications
CS Systèmes d'Information
Parc de la Grande Plaine - 5, Rue Brindejonc des
Moulinais - BP 15872
31506 Toulouse Cedex 05 - FRANCE
+33 561 17 64 21 - [email protected]
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