[GRASS-user] question on i.nightlights.intercalibration code

[Nikos Alexandris]

* Gabriel Cotlier <gabiklm01 at gmail.com> [2018-06-21 18:24:38 -0300]:

>Hello Veronica,
>
>Thanks a lot it worked!!

Dear Gabriel,

Thanks for posting details and great it works. Don't worry about the
last image, there are no coefficients for F18 and 2013. We are forced
to skip this image in any analysis.


Details

Veronica is right, and I am ignorant for so many things when it comes to Windows.

In Linux, one may use the syntax `some_command` or
$(some_command). It's a smart way to feed-in longer list of items, such
as map names in GRASS GIS. Note, the former is old-style, so best to use the $()
notation (if of interest, see
https://unix.stackexchange.com/a/5782/13011).

You might want to re-check the extent you have set, so as to
get rid of the "360 degree EW extent is exceeded by 0.999827 cells"
messages (?). Depending on how you have set your region, maybe the `-a`
option for `g.region` would help (?).

The last failing image is not a computational error. The error
message
--%<---
>ValueError: The selected model does not know about this
>combination of Satellite + Year!
--->%--
means that there are no coefficients for satellite "F18" and for the
year 2013. You may read this in
https://trac.osgeo.org/grass/browser/grass-addons/grass7/imagery/i.nightlights.intercalibration/intercalibration_coefficients.py#L99
and the referenced papers, of course.

For various reasons, I did not improve the script in
handling this situations. I just let it emit an error message. I hardly
remember having modified this message to say something like "There are
given coefficients for satellite F?? and Year ????". But I can't trace
anything in my local repository.

(
Note, there are many newer algorithms. It would be obviously great to
integrate some of them in the existing module. If a new model bases upon
a similar math formula, then it's only necessary to add:

1. a new set of coefficients in https://trac.osgeo.org/grass/browser/grass-addons/grass7/imagery/i.nightlights.intercalibration/intercalibration_coefficients.py#L38

2. a new equation in https://trac.osgeo.org/grass/browser/grass-addons/grass7/imagery/i.nightlights.intercalibration/intercalibration_equations.py#L15

3. a new subclass, for the new model, in https://trac.osgeo.org/grass/browser/grass-addons/grass7/imagery/i.nightlights.intercalibration/intercalibration_models.py

Maybe more work if there is a substantially different math logic.
)

Thanks, Nikos
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