[Tagging] simple_brunnel : one node bridge like xing highway over waterway

[Richard Z.]

On Thu, Apr 03, 2014 at 04:27:57PM -0500, John F. Eldredge wrote:
> That is my main objection as well.  This proposal is to deliberately reduce the accuracy of the data in the name of saving a few seconds of mapping time.

nonsense. This proposal is here to improve the accuracy. You do not have to use
when you have precise data about bridge position and size. On the other hand if 
your data is of the average precision (i.e. 5 meter GPS error) and you try to 
enter a 3m bridge into the database you are entering junk data. This is the
situation when less data is better because it means less junk data in effect.

Richard

> 
> 
> On April 3, 2014 12:25:46 PM CDT, "Dave F." <davefox at madasafish.com> wrote:
> > Mike
> > 
> > We should be mapping as accurately as we can within the limitations
> > (gps 
> > accuracy, aerial imagery etc) that we have. Data can always be
> > upgraded 
> > when more accurate information becomes available. This proposal is a 
> > step backwards towards inaccuracy.
> > 
> > 
> > On 02/04/2014 18:29, Mike Thompson wrote:
> > 
> > > > We aim at precision/accuracy (IMHO, at least I do),
> > > 1) How much precision/accuracy?  No real world measurement or 
> > > recording of such measurement is exactly precise/accurate. Do you
> > use 
> > > a commercial grade differential GPS when surveying?  When you are 
> > > create a way to represent a road which in reality is an arc or
> > curve, 
> > > how many nodes do you use?  You could increase your precision by 
> > > adding more nodes.
> > > 2) In general, there is a cost to increased precision (and accuracy)
> > 
> > > in terms of the survey effort, the survey equipment, the recording 
> > > effort, and the computing resources.
> > > 3) At some point the value of increased precision ceases to grow,
> > and 
> > > may even decline.
> > 
> > 
> > 
> > 
> > >
> > >
> > >
> > >
> > > On Wed, Apr 2, 2014 at 10:33 AM, Martin Koppenhoefer 
> > > <dieterdreist at gmail.com <mailto:dieterdreist at gmail.com>> wrote:
> > >
> > >
> > >     2014-04-02 18:16 GMT+02:00 Mike Thompson <miketho16 at gmail.com
> > >     <mailto:miketho16 at gmail.com>>:
> > >
> > >         > It is also a significant loss of detail because you reduce
> > >         the length of the bridge to 0
> > >         Maps are abstractions. They don't represent reality
> > precisely.
> > >
> > >
> > >
> > >
> > >     We aim at precision/accuracy (IMHO, at least I do), you can
> > always
> > >     create more abstracted maps from precise geodata, while the
> > other
> > >     way round it is not possible.
> > >
> > >           In most cases we already reduce the width of roads to 0 as
> > >         they are not represented by areas.
> > >
> > >
> > >
> > >     no, their geometric representation is a line, but their width is
> > >     (or can be) added with a tag like width and lanes, of which the
> > >     latter defaults to 2 (for non-links) if not added explicitly.
> > >
> > >
> > >          The question should be whether the value of the data is
> > >         significantly degraded if some very short bridges are
> > >         represented as nodes.
> > >
> > >
> > >
> > >     OK. Can you explain how long a "very short bridge" should be?
> > What
> > >     is the benefit of this kind of mapping style?
> > >     In this context I'd like to point out that GPS precision is not
> > >     the limit, you do not have to take 2 waypoints at the beginning
> > >     and end of the bridge and the result will become your bridge,
> > >     automatically, usually you will interpret these waypoints and
> > will
> > >     estimate the bridge length and represent it according to your
> > >     estimate, so I do not think a 3 meters long bridge will result
> > in
> > >     a 45 meters long zigzag in your mapping, just because you had
> > bad
> > >     GPS reception under the tree canopy and made a break on the
> > bridge ;-)
> > >
> > >
> > >     cheers,
> > >     Martin
> > >
> > >     _______________________________________________
> > >     Tagging mailing list
> > >     Tagging at openstreetmap.org <mailto:Tagging at openstreetmap.org>
> > >     https://lists.openstreetmap.org/listinfo/tagging
> > >
> > >
> > >
> > >
> > > _______________________________________________
> > > Tagging mailing list
> > > Tagging at openstreetmap.org
> > > https://lists.openstreetmap.org/listinfo/tagging
> > 
> > 
> > 
> > ---
> > This email is free from viruses and malware because avast! Antivirus
> > protection is active.
> > http://www.avast.com
> > 
> > 
> > ------------------------------------------------------------------------
> > 
> > _______________________________________________
> > Tagging mailing list
> > Tagging at openstreetmap.org
> > https://lists.openstreetmap.org/listinfo/tagging
> 
> -- 
> John F. Eldredge -- john at jfeldredge.com
> "Darkness cannot drive out darkness; only light can do that.  Hate cannot drive out hate; only love can do that."
> Dr. Martin Luther King, Jr.
> 
> _______________________________________________
> Tagging mailing list
> Tagging at openstreetmap.org
> https://lists.openstreetmap.org/listinfo/tagging