[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

[THREDDS #XIG-399067]: default colorScaleRange for WMS within the TDS?



On 6/3/2010 2:45 AM, Jon Blower wrote:
> It's possible in the current setup to have the colour scale
> range automatically set to the min/max of the image, by using
> COLORSCALERANGE=auto (see
> http://www.resc.rdg.ac.uk/trac/ncWMS/wiki/WmsExtensions).
> However, this has two major disadvantages:
> 
> 1. The min/max values are not communicated back to the client,
> so the client doesn't know which values correspond with which
> colours.
> 2. In tiling WMS clients (where images are made up of
> individually-requested tiles) the colour scale range of each
> tile will be different.
> 
> Therefore ncWMS supports three ways of setting the colour scale
> range:
> 
> 1. COLORSCALERANGE=default, or no value set:  The default range
> for the variable is used.  This is useful for standard WMS
> clients that don't understand the ncWMS extensions.  The default
> legend uses the same colour scale range.
> 
> 2. COLORSCALERANGE=<min>,<max>: The client selects the colour
> scale range.  The Godiva2 client uses this to allow the user to
> customize the colour scaling.
> 
> 3. COLORSCALERANGE=auto, as above.  In practice, this is the
> least useful option as it's very difficult to generate an
> appropriate legend.
> 
> I agree that a layer's "ideal" default scale range will vary
> considerably with depth and time, but there's not much that can
> be done about this.  The best we can do is to set the narrowest
> range that is likely to encompass all the values in the variable.
> 
>> How often would one define a colourscalerange that doesn't match 
>> data_max/min?
> 
> The problem is finding data_min/max.  This isn't yet a standard CF
> attribute and is rarely, if ever, set.
> 
> Hope this helps,
> Jon


Ticket Details
===================
Ticket ID: XIG-399067
Department: Support THREDDS
Priority: Urgent
Status: Open


NOTE: All email exchanges with Unidata User Support are recorded in the Unidata inquiry tracking system and then made publicly available through the web. If you do not want to have your interactions made available in this way, you must let us know in each email you send to us.