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

Kristen Kam kristenk at telenav.com
Wed Nov 27 01:24:55 UTC 2013


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



More information about the josm-dev mailing list