[mapserver-users] Does Mapserver WCS 1.0.0 respect OFFSITE of tileindex layer?

[Rahkonen Jukka]

Hi Armin,

Thanks a lot for you. All I had to do for getting perfect seamless
images also through WCS was to:

- Convert shapefile tileindex into .vrt with gdalbuildvrt from FWTools
2.4.2 package.  No parameters were needed, it was  enough to give a
command simply as > gdalbuildvrt M085_WMS.vrt m085_wms.shp
- Edit a mapfile to read this .vrt file instead of tileindex
        #TILEINDEX "d:/data/M085_WMS"
        DATA "d:/data/M085_WMS.vrt"

I made a ticket #3434 about this for Mapserver WCS component. I am not
sure if it is the correct. If developers think that WCS does not need to
support tileindex properly then it should be mentioned in the
documentation and this ticket belongs to Mapserver Documentation
component instead.

-Jukka Rahkonen-


Armin Burger wrote:
 
> Hello Jukka
> 
> your assumption how the the OFFSITE tag is applied for the 
> WCS output is 
> also what I would have expected it to do. I probably did not 
> notice this 
> strange behaviour since my set ups of WCS only used non-overlapping 
> tiles (for WMS I use overlapping tiles and the OFFSITE works fine).
> 
> Just an idea (I never tried it): maybe you could try to use a 
> VRT image 
> instead of the tileindex. At least since Gdal 1.7 there is the tool 
> "gdalbuildvrt" that has the options "-srcnodata" and 
> "-vrtnodata" which 
> might do what you want.
> 
> All tests I made so far with VRT images worked quite fine, they were 
> exactly treated as a single image. I don't know if the speed 
> might be a 
> bit slower, but WCS is typically slow anyway, so it should not cause 
> problems.
> 
> Greetings
> Armin
> 
> On 19/04/2010 16:10, Rahkonen Jukka wrote:
> > Frank Warmerdam wrote:
> >
> >> Jukka,
> >>
> >> Generally WCS generated geotiffs will not have a way to
> >> represent nodata
> >> in a way that a client application is likely to recognise
> >> them as nodata.
> >> By default pixels which are assigned no value from the source
> >> dataset are
> >> set to zero.
> >
> >
> > I am not sure if I could tell clearly what was my problem. 
> I will try
> > again. I have layers like this:
> >
> > LAYER
> >          NAME "M138"
> >          METADATA
> >            "wcs_label"    "M138"
> >            "OWS_EXTENT" "86000 6636000 650000 7518000"
> > 	  "WCS_RESOLUTION" "0.5 0.5"
> > 	  "WCS_SIZE" "50000 50000"
> > 	  "WCS_BANDCOUNT" "1"
> >          END
> >          STATUS ON
> >          TILEINDEX "d:/dataM138"
> >          TYPE RASTER
> >          UNITS METERS
> >          SIZEUNITS PIXELS
> >          OFFSITE 0 0 0
> >          TOLERANCE 3
> >          TOLERANCEUNITS PIXELS
> >          PROJECTION
> >            "init=epsg:3067"
> >          END
> >          DUMP TRUE
> >    END
> >
> > Tiles combined by M138_WMS.shp overlap because they are reprojected.
> > When I use this layer through WMS, having OFFSITE 0 0 0 
> makes the black
> > nodata triagles transparent and warped images make a 
> seamless mosaic.
> > Somehow I was awaiting that WCS behaves in a similar way, 
> but it does
> > not. Black nodata triangles are burned into the output image and the
> > mosaic is useless. I can get my job done by hand editing 
> WMS calls so
> > that the BBOX and WIDTH and HEIGHT give me the desired 
> pixel size, but
> > it would be a bit more simple through WCS GetCoverage and 
> ResX, ResY.
> >
> > -Jukka-
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> > mapserver-users at lists.osgeo.org
> > http://lists.osgeo.org/mailman/listinfo/mapserver-users
> >
>