[georss] Transport of Toponyms with GeoRSS

[Ron Lake]

Hi,

Coordinates provide part of the story.  In many problems this means
using more than one way to specify where something is. For some problems
coordinates relative to the earth's surface make sense and in many
problems that an accommodated with sufficient accuracy by a geographic
coordinate system (lat,lon).  For many other problems coordinates need
to be specified relative to some other known/identified point.  These
might be (x,y,z) relative to some origin point (e.g. corner of a room,
corner of a building) or they might be coordinates along something -
like km from a road intersection.  Now these can be expressed
(sometimes) in geographic coordinates but it may not be sufficiently
accurate, nor easy to understand.  I don't tell you my house location in
(lat,lon) not just because of accuracy issues - but also because it is
easier to understand my postal address or that I am 2 km from the
intersection of 11th and Folk Street.

Note also that coordinates are not a safe way in many cases to identify
something - since when you make data transformations the values of the
coordinates are effected by computational errors.  A small adjustment of
the coordinates might in some cases "move" the point in question so that
it is no longer inside the object of interest.

These issues are handled in GML (on which geoRSS is based) by supporting
any number of coordinate systems.  Tools can then perform coordinate
conversions as required.  In a great number of circumstances, data will
be transformed into a single coordinate system for viewing and user
interaction - so that there is a coordinate system that means something
in the users context.  For "global" problems this is typically some kind
of geographic system - for more local problems (think about navigating
inside a building) other systems are more natural and easier to relate
to.

The other key element in the story, and one that is only partly
addressed in geoRSS thus far is that of features.  Features are entities
that people relate to in a specific problem domain - so are easy to
understand - things like bridges, buildings, restaurants and parks.
Sometimes all we want to know is that we are "inside" or "near" to the
feature in question - without really knowing where it is.  At other
times we are more concerned with other properties of the thing - like
how large it is - is the road paved - what kind of food does the
restaurant have. Since geoRSS is built on GML - once create GML features
that represent these things that matter to us, along with their location
(in various coordinate systems), there size and shape and other
properties of interest.

So coordinates yes - features too.

Cheers

R

-----Original Message-----
From: georss-bounces at lists.eogeo.org
[mailto:georss-bounces at lists.eogeo.org] On Behalf Of noiv
Sent: August 17, 2006 11:38 AM
To: georss at lists.eogeo.org
Subject: Re: [georss] Transport of Toponyms with GeoRSS

I'd like to add a point from the view of a user and/or application
designer to the discussion. Years ago coordinates have been useful for
geographers and machines, (only). But since interactive maps pop up
everyday, coordinates gets a meaning for end users as well.

Now there are programs helping him to consult a map
and he easily can see where in the world a given coordinate
points to and how it belongs to himself.

I would say, the coordinates in a feed have turned from a
data element into an action element. The procedure
or problem of position a map in way the given point
is visible at best is now solved by programs for everybody.

The question is simple: What's the text on the button starting
this procedure?

Everybody is talking about Globalization, Global Warming, etc.
and there is a need for a method of linking a resource, a message
or an event to a point on this planet in an end user friendly way
And there are end users at both endings of communication.

Isn't GeoRSS the most nearest concept that
matches a solution to this challenge?

If GeoRSS will not go this way, what else do you plan?


Regards

--
Torsten Becker - ExploreOurPla.net
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