netCDF in a mapfile

[Lowe, D (Dominic)]

Hi,

Finally got round to checking this out.
The gdalinfo -mm flag returns nan, nan. However if I do an ncdump on the
file I can see that there are  values in there too.

Are NaN values likely to cause any problems?

Dominic

gdalinfo gives:
Driver: GMT/GMT NetCDF Grid Format
Size is 1599, 1139
Coordinate System is `'
Origin = (55.983000,-27.533100)
Pixel Size = (0.00498300,-0.00433300)
Corner Coordinates:
Upper Left  (  55.9830000, -27.5331000)
Lower Left  (  55.9830000, -32.4683870)
Upper Right (  63.9508170, -27.5331000)
Lower Right (  63.9508170, -32.4683870)
Center      (  59.9669085, -30.0007435)
Band 1 Block=1599x1 Type=Float32, ColorInterp=Undefined
    Computed Min/Max=nan,nan





On Wed, 2005-01-26 at 14:24 +0000, Frank Warmerdam wrote:
> On Wed, 26 Jan 2005 11:10:32 -0000, Lowe, D (Dominic)
> <D.Lowe at rl.ac.uk> wrote:
> > Hi,
> >
> > I'm also interested in displaying netCDF (atmospheric/oceanographic)
> data.
> > So far I've got a GMT generated file 'displayed' but I can only see
> it as a
> > black rectangle. This suggests the GMT driver is working ok.
> However, any
> > type of color expression eg:
> >   COLOR
> >     # some attempt at color mapping here
> >   END
> >
> > just results in a blank image.
> >
> > Has anyone got any idea as to what a correct COLOR mapping would
> look like
> > for a GMT file?
> >
> > Sorry I haven't got the gdalinfo output available now, but I can
> send it
> > tomorrow if it helps.
>
> Dominic,
>
> First, I would encourage you to read over the MapServer 4.4 Raster
> HOWTO.  I believe it talks a bit about scaling and classification of
> raster data.
>
> But you also need to ensure that GDAL is "seeing" the proper values
> in your netCDF file.  The first way to check is to run gdalinfo with
> the
> -mm flag.  This should report the minimum and maximum of the data.
>
> If those values look OK, you should try viewing the file with a GDAL
> based viewer such as OpenEV.
>
> Assuming the values are coming through properly, you may find you
> need to control the scaling explicitly in your mapfile.  To do that
> you
> would put something like the following with a minimum and maximum
> appropriate to your data.
>
>   PROCESSING "SCALING=0,1000"
>
> Best regards,
> --
>
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> I set the clouds in motion - turn up   | Frank Warmerdam,
> warmerdam at pobox.com
> light and sound - activate the windows | http://pobox.com/~warmerdam
> and watch the world go round - Rush    | Geospatial Programmer for
> Rent
>
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