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

Martijn van Exel m at rtijn.org
Thu Nov 28 18:37:43 UTC 2013


Peter,
I think we should separate the discussion related to linear
referencing / mileposts from the cardinal direction discussion - these
are two different things really, to my mind. The notion of cardinal
direction is a relatively straightforward one, and that is already
cause for (cultural) confusion. Introducing the GIS concept of linear
referencing into this discussion I think adds to the confusion. We
should perhaps discuss that separately - I for one don't see the
immediate relation between the two, but I am happy to be proven wrong.

On Wed, Nov 27, 2013 at 3:08 AM, Peter Davies <peter.davies at crc-corp.com> wrote:
> 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
>
>



-- 
Martijn van Exel
http://oegeo.wordpress.com/
http://openstreetmap.us/



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