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Hi Roy: I think the idea of a feature "varying over one of its coordinate axes" is at best vague - since a feature in almost all cases does not have a distinguished frame of reference (for the coordinate axes). If you wish to think in this fashion, I think it would be better to think in terms of a feature which has a property (or properties) whose value is a distributed over the extent of the feature. Consider for example a road and its surface type. One might have a single property of the road - surface that takes the values (paved, gravel, dirt) - and there is only one such property for the entire road. At the other end of the spectrum one might have a surface property whose value is a function giving the distribution of the surface type as a function of distance along the road. This distribution is a coverage and the value (in this case) of the surface property. Cheers Ron
-----Original Message----- From: owner-galeon@xxxxxxxxxxxxxxxx [mailto:owner-galeon@xxxxxxxxxxxxxxxx] On Behalf Of Roy Mendelssohn Sent: May 8, 2007 8:39 AM To: Ben@xxxxxxxxxxxxxxxx Cc: Unidata GALEON Subject: Re: OGC Ottawa TC meeting highlights On Apr 30, 2007, at 8:41 AM, Ben Domenico wrote:The underlying unifying concept is that a "coverage" is in fact a special case of a "feature" and ncML-GML and CSML dialects of GML can provide the needed "wrapper."I think this is backward. I like the approach Simon Cox takes in the talk he gave at AGU last December, where a coverage is a feature that varies over one of its coordinate axes. Thus a feature is a "collapsed" coverage, not the other way around. If feature gets to be defined that broadly it loses all meaning.-Roy
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