Hi,
Even wrote:
However I'm not sure in which way GDAL is involved in this discussion :-)
I am preparing for the future when GDAL will have a support for WCS 2.0.1 and
it will try to read EPSG:4326 coverage data from GeoServers witch describe
coverage like this:
http://demo.geo-solutions.it/geoserver/wcs?service=WCS&version=2.0.1&request=DescribeCoverage&coverageID=nurc__Arc_Sample
I have a feeling that without a) making GDAL to interpret gridFunction or b)
Geoserver changing the way to define rectified grid (if it is possible) GDAL
will fail. If not before then at latest when it tries to read a subset of
coverage or to put the server to do server side scaling to size.
Andrea wrote:
If there is no 1:1 correspondence between geographic and raster space axis,
then I see no other way but to use Function to explicitly correlate the two.
How would you propose to proceed instead?
Perhaps with offset vectors? An example taken from “OGC GML in JPEG 2000
(GMLJP2) Encoding StandardPart 1: Core”
<gml:domainSet>
<gml:RectifiedGrid gml:id="rg0001_C0002" dimension="2"
srsName="http://www.opengis.net/def/crs/EPSG/0/4326";>
<gml:limits>
<gml:GridEnvelope>
<gml:low>1 1</gml:low>
<gml:high>3 10</gml:high>
</gml:GridEnvelope>
</gml:limits>
<gml:axisLabels>Lat Long</gml:axisLabels>
<gml:origin>
<gml:Point gml:id="P0001">
<gml:pos>9.9 9.9</gml:pos>
</gml:Point>
</gml:origin>
<gml:offsetVector>0 3.71e-005</gml:offsetVector>
<gml:offsetVector>-3.71e-005 0</gml:offsetVector>
</gml:RectifiedGrid>
I hope I have understood right when I believe that this advice means “Read data
from the JPEG 2000 file in sequence. Place the first data value to the origin
and the second one where the first offsetVector points. It is: keep the
latitude and increase the longitude by 3.71e-005 . Continue till the “high”
limit of Long axis (10). Now the first row is full. Place the 11th value where
the second offsetVector points – so decrease Lat by -3.71e-005 and keep Long at
the initial value. Fill the second row. Then one more step down and fill the
3rd row. You have finished”.
So even the grid axes are “column first – rows next” it is possible to fill the
grid by streaming from the data source that is organized as “rows first” like
JPEG 2000 or GeoTIFF. I can imagine I could demonstrate that if I had a chess
board and 64 beans, even if someone rotates the board by 90 degrees.
I must admit that I am not at all sure that I have understood it right.
Actually it is not even important for me. I just would like to see WCS to work
fluently so that all the servers and clients would understand each other.
Somehow I have hoped the OGC would support this goal by giving understandable
examples and best practice documents.
By the way, Mr Baumann told that
coverages.wg-ow...@lists.opengeospatial.org<mailto:coverages.wg-ow...@lists.opengeospatial.org>
is an open list but it does not seem to be open for everybody:
"This is an OGC member's only list. More information can be found at:
http://www.opengeospatial.org/ogc/join . If your organization is a member,
please have your organization's representative create you an OGC portal
account. Once you have an account, you may then request access to the desired
lists. If you have questions, you may send you and your company's contact
information along with an explanation to ListMaster @OpenGeospatial.org . Thank
you. OGC ListMaster"
-Jukka Rahkonen-
Lähettäjä: Andrea Aime [mailto:andrea.a...@geo-solutions.it]
Lähetetty: 10. huhtikuuta 2017 16:57
Vastaanottaja: Even Rouault <even.roua...@spatialys.com>
Kopio: Geoserver-devel <geoserver-devel@lists.sourceforge.net>;
'gdal-...@lists.osgeo.org' (gdal-...@lists.osgeo.org)
<gdal-...@lists.osgeo.org>; Peter Baumann <p.baum...@jacobs-university.de>
Aihe: Re: [Geoserver-devel] [gdal-dev] GML lat-lon coverages and
interoperability
Hi Even,
in CIS 1.1 they state:
Coverages are assumed to have a 1:1 correlation between the axis names given in
axis-Labels and gridLabels, i.e.: they shall relate pairwise, given by their
sequence position. For example, axisLabels=“Lat Long h date” and gridLabels={i
j k l} implies a correspondence of Lat with i, Long with j, h with k, and date
with l.
If there is no 1:1 correspondence between geographic and raster space axis,
then I see no other way but to use Function to explicitly correlate the two.
How would you propose to proceed instead?
Cheers
Andrea
On Mon, Apr 10, 2017 at 3:31 PM, Even Rouault
<even.roua...@spatialys.com<mailto:even.roua...@spatialys.com>> wrote:
On lundi 10 avril 2017 15:06:55 CEST Andrea Aime wrote:
> Hi,
> sorry I lost track of the subject. So, to close up, and approach where the
> envelope is reported as "lat lon" and the "i j" raster space
> axis would map pairwise, so i pointing north-wards and j east-wards, would
> be considered valid?
> E.g., if one rescaling says "i is going to be 200 pixels" it really means
> the output image will be 200 pixels tall?
IMHO, importing EPSG axis order mess in raster space would seem to be foolish
to me and cause major annoyances. Performance-wise, processing flipped rasters
with classic algorithms that process line per line would be terrible as soon as
they are large enough, since reading each line would in practice require to
read the whole raster each time.
Even
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