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

[Rahkonen Jukka]

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-