Hi,
I am not a programmer but I can imagine that a bounding box that is expressed
in non-native projection is first re-projected into the native CRS which means
that it gets rotated and resized. Then some image data are clipped by the
envelope of the rotated BBOX and re-projected into the target system which
obviously means rotating, re-sizing and cutting out the slivers that yield from
using the rotated-enveloped BBOX for clipping while Geoserver works in the
native CRS.
It may well be that you are right but do you have any fundamental reason
against having a try with SCALESIZE/SCALEEXTENT?
-Jukka-
Lähettäjä: anna-lena.h...@bkg.bund.de [mailto:anna-lena.h...@bkg.bund.de]
Lähetetty: 11. elokuuta 2017 14:46
Vastaanottaja: andrea.a...@geo-solutions.it; Rahkonen Jukka (MML)
<jukka.rahko...@maanmittauslaitos.fi>
Kopio: geoserver-users@lists.sourceforge.net
Aihe: AW: [Geoserver-users] WCS returns wrong GeoTiffs
As far as I can interpret this, it means that in case we have OUTPUTCRS equals
SUBSETTINGCRS the extent of the image should be exactly the one requested in
SUBSET. The request coordinates aren’t transformed – the bounding box is
“fixed” and the image is filled in this extent. If you vary the dimension and
the size, then it should be possible to keep the requested extent. Am I missing
something here?
Von: andrea.a...@gmail.com<mailto:andrea.a...@gmail.com>
[mailto:andrea.a...@gmail.com] Im Auftrag von Andrea Aime
Gesendet: Freitag, 11. August 2017 12:37
An: Rahkonen Jukka (MML)
<jukka.rahko...@maanmittauslaitos.fi<mailto:jukka.rahko...@maanmittauslaitos.fi>>
Cc: Hock, Anna-Lena
<anna-lena.h...@bkg.bund.de<mailto:anna-lena.h...@bkg.bund.de>>;
geoserver-users@lists.sourceforge.net<mailto:geoserver-users@lists.sourceforge.net>
Betreff: Re: [Geoserver-users] WCS returns wrong GeoTiffs
On Fri, Aug 11, 2017 at 12:21 PM, Rahkonen Jukka (MML)
<jukka.rahko...@maanmittauslaitos.fi<mailto:jukka.rahko...@maanmittauslaitos.fi>>
wrote:
Hi,
I did not notice that reprojection happens.
Ah sorry, I thought you did not when I read you stating that the server should
keep the native resolution... which, when reprojecting,
seems a very hard thing to do, at least exactly as requested in the first mail
The GeoServer resolution is off by just 2mm, or a shift of 0.04% of the
original resolution.
Also, the two coordinate reference systems do not have the same scaling factor,
the target one has a scaling factor
of 1 and UTM32N has a scaling factor or 0.9996, so 1 meter in one is not 1
meter in the other.
Actually, guess what... 5/0.9996 -> 5.0020008, exactly the resolution computed
by GeoServer.
Can we say GeoServer is actually retaining the exact original pixel size here?
:-)
And this probably explains what should happen with extents and pixel size if
reader can interpret it (I couldn’t yet).
“The range values of the response to a successful GetCoverage request
containing an
outputCrs parameter shall be determined according to the following conceptual
evaluation model: Take the bounding box of the request’s subsetting parameter
(or the full
coverage bounding box if no subsetting was specified in the request);
re-project this
bounding box to the output CRS provided; generate the result image extent as
the smallest
bounding box around the reprojected subsetting box; fill this new image extent
with pixel
values re-projected from the coverage’s Native CRS to the output CRS in a way
that, for each
axis, the smallest distance between any two reprojected grid points is used as
offset
(including all interpolation and resampling necessary) unless specified
otherwise by further
request parameters.
Yeah, I read it as well, but could not figure out its meaning either! :-)
Regards,
Andrea Aime
==
GeoServer Professional Services from the experts! Visit http://goo.gl/it488V
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==
Ing. Andrea Aime
@geowolf
Technical Lead
GeoSolutions S.A.S.
Via di Montramito 3/A
55054 Massarosa (LU)
phone: +39 0584 962313
fax: +39 0584 1660272
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