[mapserver-users] DEM

[Even Rouault]

On jeudi 29 mars 2018 16:36:34 CEST Jean-Christophe Malapert wrote:
> Hi,
> 
> I have a DEM with the following information:
> PROJCS["SimpleCylindrical Moon",
>     GEOGCS["GCS_Moon",
>         DATUM["D_Moon",
>             SPHEROID["Moon",1737400,0]],
>         PRIMEM["Reference_Meridian",0],
>         UNIT["degree",0.0174532925199433]],
>     PROJECTION["Equirectangular"],
>     PARAMETER["latitude_of_origin",0],
>     PARAMETER["central_meridian",0],
>     PARAMETER["standard_parallel_1",0],
>     PARAMETER["false_easting",0],
>     PARAMETER["false_northing",0],
>     UNIT["metre",1,
>         AUTHORITY["EPSG","9001"]]]
> Origin = (-5458203.076000000350177,2729101.538000000175089)
> Pixel Size = (118.450587586805568,-118.450587586805568)
> Metadata:
>   AREA_OR_POINT=Area
> Image Structure Metadata:
>   INTERLEAVE=BAND
> Corner Coordinates:
> Upper Left  (-5458203.076, 2729101.538) (180d 0' 0.00"W, 90d 0' 0.00"N)
> Lower Left  (-5458203.076,-2729101.538) (180d 0' 0.00"W, 90d 0' 0.00"S)
> Upper Right ( 5458203.076, 2729101.538) (180d 0' 0.00"E, 90d 0' 0.00"N)
> Lower Right ( 5458203.076,-2729101.538) (180d 0' 0.00"E, 90d 0' 0.00"S)
> Center      (   0.0000000,   0.0000000) (  0d 0' 0.01"E,  0d 0' 0.01"N)
> Band 1 Block=92160x1 Type=Int16, ColorInterp=Gray
>   NoData Value=-32768
>   Offset: 0,   Scale:0.5
> 
> From my understanding of the DEM information, each pixel value must be
> multiplied by 0.5. If I want to access to my DEM through the WCS protocol,
> how can I say to mapserver to multiply each value by 0.5 so that my client
> displays the right values ? If it is not possible, is there a way to have
> this information in the getCapabilities ?

Jean-Christophe,

You can create a VRT that will apply the scaling to raw values (ie multiply 
them by 0.5)

gdal_translate your.dem unscaled.vrt -of VRT -unscale

and serve unscaled.vrt with MapServer

If yo can spare the disk space for a full unscale copy, you can also 
gdal_translate to GeoTIFF.

Even


-- 
Spatialys - Geospatial professional services
http://www.spatialys.com