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

Looks like I don't know what I am talking about....

We should leverage the CF-conventions here.... not make a magical attribute
up!
http://www.unidata.ucar.edu/software/netcdf/docs/netcdf.html#Attribute-Conve
ntions

valid_min
    A scalar specifying the minimum valid value for this variable.
valid_max
    A scalar specifying the maximum valid value for this variable.

Now I understand that 'presentation is in the eye of the beholder' but
'intelligent defaults' for things may be much more useful than assuming the
default -50,50



What do others do for this problem?

Regards
Terry



-----Original Message-----
From: thredds-bounces@xxxxxxxxxxxxxxxx
[mailto:thredds-bounces@xxxxxxxxxxxxxxxx] On Behalf Of
Terry.Rankine@xxxxxxxx
Sent: Thursday, 21 August 2014 10:45 AM
To: j.d.blower@xxxxxxxxxxxxx; thredds@xxxxxxxxxxxxxxxx
Subject: [ExternalEmail] Re: [thredds] NetCDF, WMS, and auto color scale
(not set by admin)

The two workflows we have are
1. Dump the data in "this" folder heriachy/structure - it will magically
appear for you.
2. Email us and we will host it.

I cant see any issue with scripting it, but I was under the impression that
changes to the xml file would require TDS to be restarted, plus its just
another bit of data to keep in 'sync' somehow.

My desire here would be that, as an admin, I would tell the wmsConfig.xml
<location /this/path/his-data-set-*.nc>
   <layer name=elevation>
       <default color range>
          <min>$delegate[elevation.vmin]</min>
          <max>$delegate[elevation.vmax]</max>
       </default color range>
    </layer>
</location>

As an admin I would deliberately hand over the 'setting the right view
stuff' for those who could control the data production/attribution. Freeing
me from that role.

I completely understand where it is not appropriate - but I don't believe
that makes it 'inappropriate' for the simple cases.

Terry

-----Original Message-----
From: thredds-bounces@xxxxxxxxxxxxxxxx
[mailto:thredds-bounces@xxxxxxxxxxxxxxxx] On Behalf Of Jon Blower
Sent: Thursday, 21 August 2014 2:48 AM
To: thredds@xxxxxxxxxxxxxxxx
Subject: Re: [thredds] NetCDF, WMS, and auto color scale (not set by admin)

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_sur
> veys_G
> A-2476_100m_version1_WGS84UTM49S_esri_grid_grid100m_GA-2476_Exmouth_10
> 0m_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
> 
> 

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