A few questions about MapServer WCS

[Frank Warmerdam]

Rahkonen Jukka wrote:
> 1. Is it possible to set up a raster layer for delivering 7-band imagery in
> GeoTIFF/img formats? If it is, how?  I tried with setting "wcs_bandcount"
> "7" in the LAYER METADATA, but that lead to error message saying that band
> count can not be higher that  four. The NetCDF example I found from the use
> case document makes me think that it might be possible with some
> 'wcs_rangeset' settings.

Jukka,

I suspect the problem relates to the selection of output format.

MapServer pre-declares an output format called "GTiff" which is an RGB
(or possibly RGBA) mode output format.  It also has the mime type
"image/tiff".  I suspect you are selecting the format image/tiff via WCS
and getting that built in declaration instead of your own with the
all important "BYTE" imagemode.

My suggestion is either to use the name "GTIFF" for your outputformat
declaration (pre-empting the built in one) or select the GeoTIFF output
format by name instead of mimetype.

> 2. Does layer PROCESSING directives have any effect with WCS?  I was trying
> to select certain bands from 7-band imagery by setting for example
> PROCESSING "BANDS=7,4,2" in LAYER definitions, but I received always just
> band combination 1,2,3.  In this case I used "wcs_bandcount" "3".  In
> addition to BANDS I would like to use also LUT and RESAMPLE options with
> WCS.

I believe the bands selector is superceeded by the bands selected in the
WCS call.

Resampling types "NEAREST" and "BILINEAR" should be support via WCS
but have to be passed in via the WCS request.  I don't think you can
establish defaults in the mapfile.

I suspect the LUT operations are processed only in the image modes
other than "pure data".  That is, IMAGEMODE BYTE likely precludes their
use as things stand.  I could look at altering this if you wanted.

> 3. I have used wget for downloading from my WCS service and it works fine.
> I had installed one 'real' WCS client but it did not like my MapServer WCS
> service.  Are there some WCS clients that are known to work well with
> MapServer WCS?

wget is *my* favorite WCS client.  GDAL is also a WCS client, and should work
fairly well with MapServer.

Best regards,
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