[mapserver-users] Mapserver WCS - how to return native pixel resolution data?

[Roger André]

Hi Alexander,

Thanks for the response.  Yes, I am using a GetCoverage request that
looks like this:

http://localhost/cgi-bin/mapserv?map=/var/www/mapfiles/netCDF/netcdf.map
&SERVICE=wcs
&VERSION=1.0.0
&REQUEST=GetCoverage
&COVERAGE=elev
&CRS=EPSG:4326
&BBOX=125,50,130,55
&WIDTH=600
&HEIGHT=600
&FORMAT=image/grid

The source is a single-band image, and the data is correctly returned
as either a single-band GeoTIFF, or an ASCII Grid, depending on which
FORMAT I specify in the WCS string.

What I would like to do is eliminate the WIDTH and HEIGHT parameters
from the request, and just return whatever is available in the BBOX
area.  When I remove them from the request, I get an error that says I
either need HEIGHT and WIDTH, or RESX and RESY.  When I restructure
the command to include RESX and RESY (see below), I get an "Out of
memory" error.

http://localhost/cgi-bin/mapserv?map=/var/www/mapfiles/netCDF/netcdf.map
&SERVICE=wcs
&VERSION=1.0.0
&REQUEST=GetCoverage
&COVERAGE=elev
&CRS=EPSG:4326
&BBOX=125,50,130,55
&FORMAT=image/grid
&RESX=.033&RESY=-.033

I believe I should be able to use the pixel dimensions that are
reported back to me in a DescribeCoverage request, which show them to
be:

<gml:offsetVector>0.033333333333333 0</gml:offsetVector>
<gml:offsetVector>0 -0.033333333333333</gml:offsetVector>

Thanks for the help,

Roger
--

On Wed, Mar 18, 2009 at 6:51 PM, Alexander Petkov <greenkov at gmail.com> wrote:
> On 3/18/09, Roger André <randre at gmail.com> wrote:
>> Hi All,
>>
>>  I have a question which I'm not sure relates to the structure of a WCS
>>  request, or the setup of my WCS server.  I have a tileset of SRTM
>>  tiles that I would like to query by geographic region via WCS.  I have
>>  basic functionality working, but I can't figure out how to make a
>>  request via BBOX that only returns the actual pixels that are present
>>  in the source data.  Is this possible?  I would think that as long as
>>  I specified the matching SRS, I should be able to, but I've gotten
>>  stuck.
>
> Are you using a WCS getcoverage request to get the data? Is the source
> file a 1 band image? Is the returned data contaiining 3 bands? A
> little more information will be of help to give a good answer.
>
> You are working in the right direction by configuring your WCS to
> serve the actual data.
>
> In my case, I have 1 band palletted images, and with a getcoverage
> request  for a bounding box I got the values, but as a grayscale
> image. With some help from another user I managed to add the colormap
> info from the class directives in my map file.
>
> The following output format is what worked to add a pallette to the
> returned image:
> OUTPUTFORMAT
>   NAME "GTIFF"
>   MIMETYPE "image/tiff"
>   DRIVER "GDAL/GTiff"
>   EXTENSION "tif"
>   IMAGEMODE "PC256"
>   TRANSPARENT TRUE
>   FORMATOPTION "COMPRESS=DEFLATE"
>   FORMATOPTION "ZLEVEL=9"
>  END
>