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
