Re: [WCS.RWG] comments on the "Binary Encoding of WCS Coverages in NetCDF"

• To: Wenli Yang <yang@xxxxxxxxxxxxxxxxxxxxxxx>
• Subject: Re: [WCS.RWG] comments on the "Binary Encoding of WCS Coverages in NetCDF"
• From: John Evans <john.evans@xxxxxxxxxxxxx>
• Date: Tue, 25 Apr 2006 17:43:05 -0400

Hi Wenli,

Thanks for scrutinizing the NetCDF / WCS guide so thoroughly. I've attached my comments 
& suggested edits to what you wrote. I see that Ben has already incorporated your 
notes into the GALEON Webpage 
<http://www.unidata.ucar.edu/projects/THREDDS/GALEON/WCSnetCDFencoding.htm>; 
fortunately my edits are minor. They are in a nutshell:
1 - I usually distinguish "scalar" vs. "compound" (rather than "parametric")
2 - In the opening paragraph, it would be good to stay closer to the ISO 19123 model, where a coverage has only one 
range, which contains "records." The "19123 coverage" associates to each location in the domain a 
single "record," which may have one or more "values" in it (and each of these values may be scalar 
or compound -- though 19123 doesn't say much about that other than to say the values may have arbitrarily complex 
structure).
3 - I wonder about the typing / dimensions issue when we equate (e.g.,) an infinitely 
thin rectangle (2D) with a line segment (1D) as you do under "2) Number of axes 
(dimensions)." Can this be handled easily in NetCDF?

 - John E.

Wenli Yang wrote:

Hello,

Attached please find my comments on the "Binary Encoding of WCS Coverages in NetCDF" prepared by Ben etc. I hope that the comments can serve to clarify some WCS data model concepts and the relationship between WCS and netCDF data models. I am CCing this to the WCS RWG so that WCS expert may review, if they have time, to see if my interpretation of the WCS grid data model is correct. I feel that it will be helpful to have both GALEON and WCS groups work together on this due to conceptual difference on the data models. As I mentioned in the comments, I think that one of the most important aspects is probably to have a common understanding on the expression/use/referencing of coordinate reference system (CRS), including both geo-coordinate and array/grid coordinate.

Wenli

PS: I posted this yesterday from my GMU email but didn't get through probably because that email address was not in the GALEON list (I didn't cc to WCS WRG yesterday). I apologize if you get duplicated mail.

--
 John D. Evans, Ph.D.  <john.evans@xxxxxxxxxxxxx>
 NASA Geoscience Interoperability Office  /  GST, Inc.
 1-301-286-0803  /  1-240-542-1133

Attachment: commentOnBinaryEncodingOfWCSCoveragesInNetCDF.doc
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