[uf-discuss] GPX output from Geo, using Operator

[Andy Mabbett]

Mike Kaply and I have been discussing the possibility of outputting GPX
from Geos, in Operator, on a Yahoo mailing list for GPX. GPX, you may
recall, is the XML standard for GPS data (for points, trails or routes).

Here is a post which explains the fundamentals, and my reply.

The original list is:

        <http://groups.yahoo.com/group/gpsxml/>

#~#~#~#~#~#~#~#~#~#~#

Simon Slavin writes:

>On 9 Jun 2007, at 12:18am, Andy Mabbett wrote:
>
>> Suppose someone visits a web page with a list of coordinates,
>> marked up
>> using the geo microformat, such as:
>>
>>   <http://en.wikipedia.org/wiki/Manchester_Ship_Canal#Features>
>>
>> we want that person to be able to download all those points into their
>> GPS device, in a meaningful way.
>
>In GPX format, a collection of points, with nothing relating one to
>another, is a collection of waypoints.  That's the most common kind
>of GPX file you'll find.

Thank you. I think that's probably what we want, at least to start with.

What are the minimum, or optimal, properties for such a case?

>> Those coordinates may - as above - or may not - as in:
>>
>>   <http://en.wikipedia.org/wiki/List_of_impact_craters_in_South_America>
>>
>> relate to a linear feature or trail; and may be sorted geographically,
>> alphabetically, in some other way, or not at all.
>
>There are ways to express an ordered collection of points: a track or
>a route.  Conceptually, tracks are a record of where you've been,
>routes are suggestions about where you could go in the future.  So,
>for instance, you might expect to find timestamps for each point in a
>track (because someone is recording where they were and when), but
>you're unlikely to find timestamps for each point in a route (because
>you're just thinking about it, nobody might ever have travelled it yet).
>
>Both tracks and routes are simple to express in GPX format.

Thanks for explaining that subtle but important distinction. I'd not
heard of it before.

Geo does not have a facility for encoding a sequence, or a time-stamp.

It's possible to have a series of hCalendar microformats which includes
an hCard, which includes a geo - so that would allow for marking up
trails.

For sequencing without time, we could only infer that from the page,
such as the order in a list or table, or simply in the source code.

Or we could offer the user a dialogue with a set of Geos and ask them to
number, or drag them into sequence, or have a "move up/ move down"
buttons, but I would image that would be unpleasant to code and clunky
to use for long lists

>XML is so close to the XHTML used in microformats you're not going to
>have any problems learning it.  GPX format was specifically designed
>for simple communication between GPS units and mapping software made
>by different manufacturers, so it seems to fulfil that part of your
>requirements too.  I'm afraid the only manufacturer I'm very familiar
>with is Garmin, but their own import software supports GPX, and some
>of their devices even use it internally to keep track of favourites
>you've marked.
>
>I'd recommend you first download a few GPX files and look at them to
>see if you can puzzle out what's going on, then learn some XML and
>take a look at the GPX specification:
>
><http://www.topografix.com/gpx/1/1/>
>
>If you're into microformats I can't see you'll have any problem with
>GPX.

Thank you. I'll have a look, but it's really Mike's baby ;-)

-- 
Andy Mabbett
            *  Say "NO!" to compulsory UK ID Cards:  <http://www.no2id.net/>
            *  Free Our Data:  <http://www.freeourdata.org.uk>
            *  Are you using Microformats, yet: <http://microformats.org/> ?