RE: OGC Ottawa TC meeting highlights

• To: "Roy Mendelssohn" <Roy.Mendelssohn@xxxxxxxx>, <Ben@xxxxxxxxxxxxxxxx>
• Subject: RE: OGC Ottawa TC meeting highlights
• From: "Ron Lake" <rlake@xxxxxxxxxxxxx>
• Date: Tue, 8 May 2007 08:58:47 -0700

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

• Follow-Ups:
  • RE: OGC Ottawa TC meeting highlights
    • From: Woolf, A (Andrew)

• References:
  • Re: OGC Ottawa TC meeting highlights
    • From: Roy Mendelssohn