Re: [thredds] NetCDF, WMS, and auto color scale (not set by admin)

• To: "thredds@xxxxxxxxxxxxxxxx" <thredds@xxxxxxxxxxxxxxxx>
• Subject: Re: [thredds] NetCDF, WMS, and auto color scale (not set by admin)
• From: Jon Blower <j.d.blower@xxxxxxxxxxxxx>
• Date: Wed, 20 Aug 2014 18:47:45 +0000

Hi Terry,

As far as I remember THREDDS has always required setting of the default colour 
scale range by the admin. (However the standalone ncWMS could do this 
automatically, because it scans datasets during an ingestion step, which 
THREDDS does not perform.)

There is currently no way to read the default colour range from the NetCDF 
files, although a means could theoretically be invented, with “special” 
attributes. One problem is that, in a multidimensional variable, the most 
appropriate range for one z or t level may not be so appropriate for another 
value of z or t. There are other interesting issues with the behaviour of 
NetCDF attributes in aggregations (what happens if different files in the same 
aggregation have different attributes?)

How do the data providers communicate their preferences to you at the moment? 
Could you, for example, craft a script that takes their values (from a simple 
text file maybe) and inserts it appropriately into the wmsConfig.xml 
automatically?

Cheers,
Jon


> 
> 
> ----------------------------------------------------------------------
> 
> Message: 1
> Date: Wed, 20 Aug 2014 01:19:29 +0000
> From: <Terry.Rankine@xxxxxxxx>
> To: <thredds@xxxxxxxxxxxxxxxx>
> Subject: [thredds] NetCDF, WMS, and auto color scale (not set by
>       admin)
> Message-ID:
>       <918EBF4F0E40D340B213B473CCAB6B126000492D@xxxxxxxxxxxxxxxxxxxxxxxxxx>
> Content-Type: text/plain; charset="us-ascii"
> 
> Hi Guys
> 
> 
> 
> In older versions of thredds I could leave the auto color scaling for a WMS
> to thredds to take care of for me. Can I have it back - but a bit different.
> 
> 
> 
> As a system admin - I am just 'serving the data' not really understanding
> what 'sensible viewing defaults' for defaultColorScaleRange for any file in
> the directory should be. However - the data owners I interact with all have
> a 'preference' on how to color/scale their visualisations for their data
> files. 
> 
> 
> 
> Is there a way to make thredds read the netCDF file - load the variable, and
> load the visualisation range FROM THE DATA FILE - not the wmsConfig.xml -
> where I would need to explicitly set it?
> 
> 
> 
> IE - if on the elevation layer for this service:
> 
> http://vhirl-dev.csiro.au/thredds/dodsC/dem/testconvert/bathymetry_surveys_G
> A-2476_100m_version1_WGS84UTM49S_esri_grid_grid100m_GA-2476_Exmouth_100m_exm
> outh100m.nc4.html
> 
> 
> 
> I set a netcdf parameter like defaultColorScaleRange or something less
> thredds specific, max/min or something which could guide the 'lazy'
> configuration option for the data?
> 
> 
> 
> Regards
> 
> Terry 
> 
> 

• Follow-Ups:
  • Re: [thredds] NetCDF, WMS, and auto color scale (not set by admin)
    • From: Terry.Rankine