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On 3/20/2013 6:47 AM, rhorne@xxxxxxxxxxxxxxxxx wrote:
Folks:Last year we (GOES-R Ground System) proposed a change that would allow coordinate variables to use scale_factor and add_offset (see trac item #86 with title "Allow coordinate variables to be scaled integers").We will be producing one type of product on a lat/lon grid and would like to used scale_factor and add_offset with the coordinate variables.One of these products spans the 180 degrees_east longitude (i.e. -180 degrees_east longitude) line.The implication being that the software resolving the scale factor and additive offset needs to be cognizant of the longitude coordinate variable "units".Is this an issue ? very respectfully, randy _______________________________________________ cf-satellite mailing list cf-satellite@xxxxxxxxxxxxxxxx For list information or to unsubscribe, visit: http://www.unidata.ucar.edu/mailing_lists/
Hi Randy:Once #86 is approved (which i see as a clarification) then scale/offset is fine.
An important consideration is that the coordinate values be monotonic. I would recommend that you make them really monotonic, and not constrain the values to lie between +-180 or 0-360. So if you cross the longitude seam, just keep going:
179, 180, 181, 182 ... or 358, 359, 360, 361, 362...Really, this issue is independent of scale/offset. One applies the scale/offset to get the values in the units specified, then you start thinking about the semantics.
So I dont think its the case that the "software resolving the scale factor and additive offset needs to be cognizant of the longitude coordinate variable "units"."
John
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