[Talk-us] [josm-dev] Relation editor support for north/south and east/west similar to forward/backward

Peter Davies peter.davies at crc-corp.com
Wed Nov 27 10:08:53 UTC 2013


Martijn

I, too, await your clarification for KristenK, as I'm a little confused
too.

We need to keep in mind that positive and negative GIS Linear Reference
directions (which are handy as global solutions applying everywhere in the
US at least) beginning at milepoint 0.0, usually on the southern or western
state boundary for rectangular states, are not the same as posted DOT miles
that sit on green and white pressed steel signs on the shoulder of all
Interstates and many state/US routes. DOT miles often jump and can
occasionally change directions, as route designators are altered (something
that happens quite often) and bypasses are built.  The cost of reporting
the whole route is usually prohibitive.

So GIS LRS positive and (imperfect) posted DOT miles are handy things to
keep in mind as long as we realize that there are always a few exceptions
to break our defaults.  Similarly, posted cardinal directions are fairly
rules-bound but certainly not 100%. This is why I think a good OSM solution
needs to be explicit rather than implicitly inferred from highway geometry.

Examples of state GIS definitive records are built by ESRI "Roads and
highways" (used in Indiana) and by Agile Assets (used in Idaho).  Check out
http://www.esri.com/software/arcgis/extensions/roads-and-highways

Peter


On Tue, Nov 26, 2013 at 5:24 PM, Kristen Kam <kristenk at telenav.com> wrote:

> Martijn,
>
> I want to make sure I understand what you're trying to convey to the
> group. Are you saying that If a way has a member role value of "east"
> then east will mean forward and then west (it's opposite) would mean
> backward?
>
> Example logic:
>
> ** If member role = east, node direction is eastbound would mean
> forward and backward would mean 'west'
> ** If member role = west, node direction is westbound would mean
> forward and backward would mean 'east'
> ** If member role = north, node direction is northbound would mean
> forward and backward would mean 'south'
> ** If member role = south, node direction is southbound would mean
> forward and backward would mean 'north'
>
> If the logic I stated above successfully captured with your
> suggestion, then I would like to expand on it. Why not just make the
> cardinal direction value-forward/backward value relationship a bit
> more simpler? I would like to cite Peter Davies' discussion on the
> Highway Directions in the US wiki page. He stated that milepoints
> increase as highways that trend northward or eastward--say positive
> direction. So if one is traveling south or west on a highway, the
> milepoints are decreasing--say negative direction.
>
> With this in mind, couldn't we just say that north/east = forward
> (forward movement is positive!) and west/south=backward (backward
> movement is negative!)? If we're digitizing our edges, the suggestion
> would be to set the node direction of two-way, aka single-carriageway
> roads, into a positive direction and the member roles values to north
> or east. Basically what you did for
> http://www.openstreetmap.org/browse/relation/2308411, but setting the
> single-carriageway/two-way roads to 'east' instead of 'west'.
>
> Thoughts Martijn? Others??
>
> Best,
>
> Kristen
> ---
>
> OSM Profile → http://www.openstreetmap.org/user/KristenK
>
>
> -----Original Message-----
> From: Martijn van Exel [mailto:m at rtijn.org]
> Sent: Tuesday, November 26, 2013 2:47 PM
> To: Ian Dees
> Cc: Florian Lohoff; OpenStreetMap-Josm MailConf; OSM US Talk
> Subject: Re: [Talk-us] [josm-dev] Relation editor support for
> north/south and east/west similar to forward/backward
>
> Yes, sorry for not being clearer. As Ian indicates, this is the
> *signposted cardinal direction* of a numbered road route, which does
> not change with the actual compass direction of the road. The guiding
> principle for the United States is that the odd numbered Interstates
> are north/south, and the even numbered Interstates are east/west. This
> is independent from the local compass direction. So for example, I-80
> is east-west, but runs almost north-south locally (for example here:
> http://www.openstreetmap.org/browse/way/203317481) but the sign would
> still say 'I-80 East' (or West as the case may be).
>
> So the relation between the east--west and north--south member roles
> is equivalent to the relation between forward--backward.
>
> Because the cardinal direction is commonly included on the road signs
> (see example
> http://www.aaroads.com/west/new_mexico010/bl-010_eb_at_i-010.jpg)
> this information is useful in the U.S. (and Canadian) context as a
> drop in replacement for the traditional forward / backward role
> members.
>
> Hope this clarifies somewhat!
> Martijn
>
> On Tue, Nov 26, 2013 at 2:57 PM, Ian Dees <ian.dees at gmail.com> wrote:
> > On Tue, Nov 26, 2013 at 3:51 PM, Florian Lohoff <f at zz.de> wrote:
> >>
> >> On Tue, Nov 26, 2013 at 12:30:25PM -0700, Martijn van Exel wrote:
> >> > Hi all,
> >> >
> >> > I'm new to this list so please bear with me.
> >> > The relation editor currently only parses 'forward' and 'backward'
> >> > roles when considering the visual representation in the rightmost
> >> > column. In the United States, north/south and east/west are very
> >> > common as member roles for road routes, because that is how they
> >> > are officially signposted.
> >>
> >> I would be very careful in using this. Is this really "south" e.g.
> >> 180° ? Or is it more like 99° ? Or 269° ?
> >>
> >> Most streets are not strictly on the 90° raster and signposts are
> >> only rough directions.
> >>
> >> Addings this to OSM might make it much more difficult for Data
> >> Consumers to process and interpret data.
> >
> >
> > No, these aren't compass directions. They're the directionality of the
> road.
> > For example, this way is part of the I-94 interstate going west, but a
> > compass in a car driving on it would tell the viewer they were
> > pointing
> > north:
> >
> > http://www.openstreetmap.org/browse/way/39372612
>
>
>
> --
> Martijn van Exel
> http://oegeo.wordpress.com/
> http://openstreetmap.us/
>
> _______________________________________________
> Talk-us mailing list
> Talk-us at openstreetmap.org
> https://lists.openstreetmap.org/listinfo/talk-us
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.openstreetmap.org/pipermail/talk-us/attachments/20131127/8bfc8653/attachment-0001.html>


More information about the Talk-us mailing list