Re: basic topology and the Data Model with geo-locations

• To: Doug Lindholm <lind@xxxxxxxx>
• Subject: Re: basic topology and the Data Model with geo-locations
• From: "From: Bill Hibbard <hibbard@xxxxxxxxxxxxxxxxx>" <billh@xxxxxxxxxxxxx>
• Date: Thu, 6 Apr 2000 17:01:03 -0500 (CDT)

Hi Doug,

> I'm partial to (time) -> ((lon, lat, alt) -> (obs)). This makes
> resampling by time or space rather convenient. VMET assumes such an
> arrangement.

Well, at any given time, the aircraft is only at one location,
so the domain sampling of ((lat, lon, alt) -> obs) would be
a SingletonSet with manifold dimension = 0.  That is, to
precisely represent the aircraft track.  So you might as
well use (time -> (lat, lon, alt, obs)).  It only takes a
few lines of code to translate between:

  (time -> (lat, lon, alt, obs))

and:

  ((lat, lon, alt) -> (time, obs))

However, if you want to graphically represent the aircraft
track as an animating streamer, then you would produce a
Field with the type you described:

  (time -> ((lon, lat, alt) -> obs))

where the domain Set of each ((lon, lat, alt) -> obs) is
a segment of the aircraft track between the current time
[i.e., domain sample of (time -> ...)] and current time
minus some constant.

> I don't want to start a religious war but I also prefer (lon,lat,alt)
> over (lat,lon,alt) because it relates directly to (x,y,z).

I originally created the system intrinsic RealTupleType
for earth location with the (lon, lat, alt) order, but by
popular demand the system now has intrinsic RealTupleTypes
for both ways.

Cheers,
Bill
----------------------------------------------------------
Bill Hibbard, SSEC, 1225 W. Dayton St., Madison, WI  53706
hibbard@xxxxxxxxxxxxxxxxx  608-263-4427  fax: 608-263-6738
http://www.ssec.wisc.edu/~billh/vis.html

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  • Re: basic topology and the Data Model with geo-locations
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  • Re: basic topology and the Data Model with geo-locations
    • From: Doug Lindholm