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    Re: An essay about maps
    From: Richard B. Langley
    Date: 2010 Nov 14, 12:07 -0400

    One way to update maps, at least electronically, is though volunteered
    geographic information--getting the public to supply updates. Issues
    related to this activity are reviewed in this paper:
    -- Richard Langley
    Quoting Apache Runner :
    > Peter -
    > This is all preaching to the choir, I suppose.  Most folks on this list
    > probably know how far one can trust a map, but I do appreciate you sending
    > around the column that woman wrote.
    > I might add an addendum to the various thoughts, and even a response to her
    > essay that I suppose will never reach her, but it's something like this:
    > Consider what it takes to create a map.   You have to start with a
    > well-surveyed control network.   In the modern era, you lay on top of that
    > aerial stereo photographs to get the major topographic features.   Then you
    > have whatever local knowledge you can put on top of that to extract paths
    > that may be hidden from view in the aerial photographs.   Presumably paved
    > roads have blueprints that lay out their path relative to the control
    > network.   All of this is a lot of work.   I know some land surveyors and
    > they'll tell you how difficult it is to find some markers on the secondary
    > control networks.   Sometimes, it's a half buried bottle hidden by a bush.
    > In the particular case of the missing dirt track, washouts happen all the
    > time, and some aspects of the landscape change far faster than surveyors and
    > cartographers can keep up with it.
    > All of these are good reasons to consult the date of creation of the map and
    > the revision history.
    > Now that I think about it, I have to grab some maps myself.   Has anyone on
    > this list been to Rollright?   Know anything about astronomical alignments
    > of it (or lack thereof?).   I'm visiting there in a couple of weeks and am
    > trying to sort through the literature.   Talk about reverse engineering -
    > going back 10 years is one thing, but 4500 is quite another.
    > John H.
    > On Sun, Nov 14, 2010 at 4:39 AM, Jackie Ferrari wrote:
    >>  I have used them extensively hiking around the Highlands of Scotland.
    >> Once looking for a particular forest in which to camp, I was convinced my
    >> navigation was wrong as I could see no forest where my 1:50000 Ordnance map
    >> told me it should be. Nonetheless I kept on the path(a sheep track) and lo
    >> and behold ,there it was. A plantation of 6 inch high conifers.
    >>  However on occasion, forest tracks marked on the map are no longer there,
    >> but these have always been man made tracks, made by bulldozers for
    >> clearance. It seems the sheep tracks are more 'permanent.' !
    >> Jackie.
    >> ----- Original Message -----
    >> *From:* Apache Runner 
    >> *To:* NavList@fer3.com
    >> *Sent:* Sunday, November 14, 2010 4:07 AM
    >> *Subject:* [NavList] Re: An essay about maps
    >> Certainly, the USGS topo's are far out of date with respect to tracks -
    >> hiking and passable 4-wheel-drive routes.  I've found too many out of date
    >> instances to recount.
    >> On Sat, Nov 13, 2010 at 6:00 PM, Fred Hebard  wrote:
    >>> Are the British Ordnance Survey maps really as accurate as she claims?
    >>>  I've never seen a high resolution (<= 30') map that was 100% accurate,
    >>> where I had knowledge enough of the terrain to detect the errors.
    >>> It was rather a nice read, thanks for sharing it.
    >>> On Nov 13, 2010, at 4:43 PM, Peter Fogg wrote:
    >>> An essay for those interested in maps:
    >>>> http://www.smh.com.au/opinion/society-and-culture/road-to-nowhere-20101112-17r37.html
    >>>> You can tell the good lady is from the Big Smoke.  If she'd spent more
    >>>> time in remote places she'd have known that when you get to a place like
    >>>> Hungerford you don't just drive through it.  You stop and, first of all,
    >>>> take on fuel.  Even if your tanks are near-full - whether you'll find any
    >>>> more further on is never guaranteed, and the person selling fuel is
    >>>> potentially a good source of information about what lies ahead.  Then you
    >>>> visit the pub.  If the place is a stepping-off point to really
    >>>> remote places
    >>>> you're also expected to register with the cops.  Its just common sense
    >>>> really, but you can expect to be quizzed about how well-prepared you might
    >>>> be for the next leg, including your mapping resources.
    >>>> As you drive out from the relatively well-populated coast into the
    >>>> relatively bereft-of-people interior, you go from ignoring other motorists
    >>>> to acknowledging them.  Then when you get further out, if another vehicle
    >>>> approaches from the direction you're going then you both stop -
    >>>> blocking the
    >>>> road, but that's rarely a problem - so the drivers can have a leisurely
    >>>> chat, driver's window to driver's window, elbow to elbow, about
    >>>> the weather
    >>>> and the price of ewes and, what interests you most, what's ahead.
    >>>> In two words: local knowledge.  The good lady is dreaming with her
    >>>> whimsical insistence on mapping accuracy.  As if there was such a thing.
    >> --
    >> Keeping up with the grind
    > --
    > Keeping up with the grind
      Richard B. Langley                            E-mail: lang@unb.ca
      Geodetic Research Laboratory                  Web: http://www.unb.ca/GGE/
      Dept. of Geodesy and Geomatics Engineering    Phone:    +1 506 453-5142
      University of New Brunswick                   Fax:      +1 506 453-4943
      Fredericton, N.B., Canada  E3B 5A3
          Fredericton?  Where's that?  See: http://www.city.fredericton.nb.ca/

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