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Re: [THREDDS #XIG-399067]: default colorScaleRange for WMS within theTDS?



On 6/2/2010 3:03 PM, Jon Blower wrote:
what does the system do if the admin doesnt set a value for that
dataset?

ncWMS scans each dataset when it's first loaded into the system and
makes a test extraction of a chunk of data from the first timestep and
first z level from each variable.  Then it finds the min and max of this
data subset, adding 10% at top and bottom.  It's far from perfect but it
at least gives a reasonable guess, which the sysadmin can override if it
turns out to be a bad choice.

If that doesn't work for any reason, ncWMS applies the default range
[-50:50].  But this doesn't happen very often.

The estimated scale ranges are persisted to the ncWMS config file so
they don't have to be recalculated when the server is rebooted.

I guess this approach would be difficult to apply in TDS, where the data
catalogs could be very big.

Jon

Seems like a possible problem is that the range of some atmos variables can vary widely depending on what z level you are at. So even a per-variable setting is not ideal.


Is it possible to use the actual min/max of the actual data used in the WMS request? Dont you have to scan that anyway?


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