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

[Gabriel Cotlier]

Dear Markus,

Thanks a lot for the explanation.

After importing the layer F101992 I did :

r.region -a map=F101992 at PERMANENT

and I got the results as you indicated, with the new resolution message:

360 degree EW extent is exceeded by 1 cells

Nonetheless, the message of the old resolution (360 degree EW extent is
exceeded by 0.999827 cells) still appear but in the second line of the
message bellow:

Could be this indicating it changed from old to new resolution?

Thanks a lot again for your help.

Best regards,

Gabriel




On Mon, Jun 25, 2018 at 3:29 AM, Markus Metz <markus.metz.giswork at gmail.com>
wrote:

>
>
> On Mon, Jun 25, 2018 at 5:40 AM, Gabriel Cotlier <gabiklm01 at gmail.com>
> wrote:
> >
> > Hello,
> >
> > I think I have found a similar situation solved for Linux version at:
> >
> > https://trac.osgeo.org/grass/ticket/2757#comment:21
> >
> > In my case I'm using GRASS 7.4.0 in Windows 10, and when I called for
> metadata info of the layer I got the message bellow with the problem
> highlighted in yellow bellow.
> >
> > What could be happening? It would be very helpful to understand what is
> happening and how to solve importing many raster layers without this extent
> problems.
>
> The resolution is a bit wrong, it is 0.008333333300000 but should be
> 0.008333333333333, i.e. exactly 30 arc-seconds. This can be solved with the
> -a flag of r.in.gdal, or after import with r.region -a.
>
> The message
>
> > 360 degree EW extent is exceeded by 0.999827 cells
>
> will change to
>
> > 360 degree EW extent is exceeded by 1 cells
>
> but will not go away, because 360 degree EW extent is exceeded in the
> input data, the first and last column cover the same geographical area. You
> can change your current region to chop of e.g. the first column: set the
> region to the raster, then modify the current region with g.region
> w=179:59:45W -p and use this region for further processing.
>
> Markus M
>
> >
> > 360 degree EW extent is exceeded by 1.99983 cells
> >
> > (Mon Jun 25 00:30:04 2018) Command finished (0 sec)
> >
> >
> >
> >
> >
> > Virus-free. www.avg.com
> >
> > On Sun, Jun 24, 2018 at 5:09 PM, Gabriel Cotlier <gabiklm01 at gmail.com>
> wrote:
> >>
> >> Dear Vero and Markus,
> >>
> >> Thanks a lot for the guidance and help.
> >>
> >> If I understood correctly:
> >>
> >> I first have to import one layer when I select a location setting the
> coordinate system of that layer to the mapset of GRASS (at the start).
> >>
> >> Then I have to import all other layers to mapset using command
> "r.in.gdal -a"
> >>
> >> r.in.gdal -a input=C:\Users\Gabriel\Documents\layers\F121995.tif
> output=F121995
> >>
> >> Then I have to running "g.region" to set up the same extent to all
> layers as follows:
> >>
> >> g.region raster=F121995
> >>
> >> and I got the layer processed and finished but the error did not went
> way....
> >>
> >> |i Inter-satellite calibration of DMSP-OLS Nighttime Stable Lights
> >> WARNING: Operating on current region
> >>
> >> |> Calibrating average visible Digital Number values
> >> Regression coefficients: (-0.0515, 1.2293, -0.0038) | Associated R^2:
> 0.9178
> >>
> >> 360 degree EW extent is exceeded by 0.999827 cells
> >> 360 degree EW extent is exceeded by 1 cells
> >>
> >> WARNING: As requested, timestamp transferring not attempted.
> >> WARNING: No data base element files found
> >>
> >> (Sun Jun 24 17:05:31 2018) Command finished (1 min 2 sec)
>
> >>
> >> What could be doing wrong?
> >> In addition I'm doing it for one layer here, is there a way to do it
> for many layers at onces with command line or GUI dialog box?
> >>
> >> Thanks a lot again.
> >>
> >> Gabriel
> >>
> >> On Sat, Jun 23, 2018 at 6:31 AM, Markus Metz <
> markus.metz.giswork at gmail.com> wrote:
> >>>
> >>>
> >>>
> >>> On Sat, Jun 23, 2018 at 11:10 AM, Veronica Andreo <
> veroandreo at gmail.com> wrote:
> >>> >
> >>> > Hi,
> >>> >
> >>> > El sáb., 23 jun. 2018 4:35, Markus Metz <
> markus.metz.giswork at gmail.com> escribió:
> >>> >>
> >>> >>
> >>> >>
> >>> >> On Fri, Jun 22, 2018 at 10:34 PM, Veronica Andreo <
> veroandreo at gmail.com> wrote:
> >>> >> >
> >>> >> > Hi Gabriel,
> >>> >> >
> >>> >> > What you could do is import with r.in.gdal -a  that adjusts
> resolution for lat long maps [0]
> >>> >>
> >>> >> that will help to fix the resolution from 0.008333333300000 to
> 0.008333333333333, i.e. exactly 30 arc-seconds. The software used to create
> the raster data has stored the resolution with limited precision.
> >>> >
> >>> >
> >>> > Right, I overlooked this
> >>> >
> >>> >> > and then (before the intercalibration step), set the region to
> one of the imported maps with g.region raster=yourmap
> >>> >>
> >>> >> you will then get a message like
> >>> >> 360 degree EW extent is exceeded by 1 cells
> >>> >>
> >>> >> which is correct because the first and last column are duplicates.
> The cell centers cover -180, 180, and the EW extents regarding cell borders
> are E: 180:00:15E, W: 180:00:15W, grown by half a cell, i.e. 15 arc-seconds.
> >>> >
> >>> >
> >>> > So, solution is to just use the data with the extra 15 arc-seconds
> in each side?
> >>>
> >>> yes, or chop off the first or last column: set the region to the
> raster, then modify the current region with g.region w=179:59:45W -p
> >>> >
> >>> > Of I want data to fit 180/-180, would r.region mymap e=180 w=180
> help or will it change the data?
> >>>
> >>> this would modify the data because
> >>> 1) the raster will be shifted by half a cell to the east
> >>> 2) the cell size (ew resolution) will be changed
> >>>
> >>> Markus M
> >>>
> >>> >
> >>> > Vero
> >>>
> >>
> >
>
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