Re: [Talk-us] Underground railways, indoor mapping, and overlapping features
Almost forgot about this. clay_c and I weren't sure about this since we had two
different approaches that both seemed suspect.
I've been using layer tags where possible all along. I think there's definite
agreement there.
If I overlap nodes (or within some determinedof two differently-layered
railways or roadways, JOSM considers it an *error* of overlapping nodes.
If I have the railways or roadways share nodes, JOSM *warns* me of overlapping
ways.
Considering that routing application that might be confused by overlapping
nodes, I should definitely change the junction. With overlapping nodes, I also
have overlapping switches (which I never tagged as switches) that wouldn't be
mappable anyway.
There may come a time I have data on train track centerlines in NYC, perhaps
something highly accurate like state plane coordinates. Hopefully my FOIA
journeys are successful: I want New York to be the model of underground railway
data in OSM. (If there are any MTA insiders [or those in the transport
industry] who are familiar with mapping documents, please tell me about
documents that I can try to FOIA) I find it weird that I would have to manually
offset points when I can just plug in the state plane coordinates and my work
is done. We wouldn't necessarily be mapping for the renderer, but rather
something odd: mapping for the validator? They would be overlapping nodes
physically located at the same spot, calculated from hypothetical,
authoritative source coordinates. Proper editing of these tracks would involve
filtering out layers to work on the correct layer as needed. It's intimidating
for someone not familiar with this situation.
clay_c chose to space out rails by a whole foot, which seems rather excessive.
Spacing out can be rather weird for any editor, so hopefully people will tend
not to touch it unless they really know what they are doing. I feel like
whatever solution we choose is going to be really "weird", so we have to bite
the bullet.
I hope we settle on solution 2, ("Duplicate nodes with identical positions")
but we'll need some changes to some of the mapping validators to not throw an
error for nodes attached to ways on different layers.
--
May 16, 2020, 05:36 by m...@nguyen.cincinnati.oh.us:
> Vào lúc 10:28 2020-05-05, Michael Reichert đã viết:
>
>> Using the same nodes (like mapping to adjacent landuse polygons) breaks
>> routing because routing engines would allow trains to switch between the
>> levels. Using duplicated nodes at the same location is likely to trigger
>> quality assurance services and therefore mappers trying to "repair" it
>> by merging them. Using two identical geometries in straight sections
>> with nodes at different locations, will likely provoke the same as
>> duplicated nodes.
>>
>
> Just as a double-decker bridge requires layer tags on each deck, so would a
> double-decker subway tunnel, whether the ways are coincident or offset by
> some arbitrarily small amount. Adding layer tags, as suggested in [1], would
> likely suppress any validator warnings about coincident ways. But it's true
> that mappers could still be confused by coincident ways if editors don’t
> provide intuitive ways to navigate among them.
>
>> Regarding option 2: GraphHopper assembles its routing graph by relying
>> on the node IDs in OSM. It would not suffer from using this option but I
>> doubt that it is safe for the future. If OSM adopts to drop its 64 bit
>> node IDs in favour of the location (32 bit latitude + 32 bit longitude),
>> such cases will cause difficulties.
>>
>
> This is an intriguing notion I had not come across before. Has it ever been
> seriously considered? It seems to me that distinguishing nodes only by their
> coordinates would be tantamount to merging all coincident nodes everywhere,
> which we probably would never allow as part of a mechanical edit, much less a
> history-less database schema update. (For one thing, everyone who dislikes
> joining borders to roadways would be appalled to see just about every CDP
> boundary consistently joined that way.)
>
> [1] https://lists.openstreetmap.org/pipermail/talk-us/2020-May/020015.html
>
> --
> m...@nguyen.cincinnati.oh.us
>
>
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Re: [Talk-us] Underground railways, indoor mapping, and overlapping features
Vào lúc 10:28 2020-05-05, Michael Reichert đã viết: Using the same nodes (like mapping to adjacent landuse polygons) breaks routing because routing engines would allow trains to switch between the levels. Using duplicated nodes at the same location is likely to trigger quality assurance services and therefore mappers trying to "repair" it by merging them. Using two identical geometries in straight sections with nodes at different locations, will likely provoke the same as duplicated nodes. Just as a double-decker bridge requires layer tags on each deck, so would a double-decker subway tunnel, whether the ways are coincident or offset by some arbitrarily small amount. Adding layer tags, as suggested in [1], would likely suppress any validator warnings about coincident ways. But it's true that mappers could still be confused by coincident ways if editors don’t provide intuitive ways to navigate among them. Regarding option 2: GraphHopper assembles its routing graph by relying on the node IDs in OSM. It would not suffer from using this option but I doubt that it is safe for the future. If OSM adopts to drop its 64 bit node IDs in favour of the location (32 bit latitude + 32 bit longitude), such cases will cause difficulties. This is an intriguing notion I had not come across before. Has it ever been seriously considered? It seems to me that distinguishing nodes only by their coordinates would be tantamount to merging all coincident nodes everywhere, which we probably would never allow as part of a mechanical edit, much less a history-less database schema update. (For one thing, everyone who dislikes joining borders to roadways would be appalled to see just about every CDP boundary consistently joined that way.) [1] https://lists.openstreetmap.org/pipermail/talk-us/2020-May/020015.html -- m...@nguyen.cincinnati.oh.us ___ Talk-us mailing list Talk-us@openstreetmap.org https://lists.openstreetmap.org/listinfo/talk-us
Re: [Talk-us] Underground railways, indoor mapping, and overlapping features
Hi Clay, Am 04/05/2020 um 20.15 schrieb Clay Smalley: > We've come up with some potential solutions, each of which seems to have > its own drawbacks: > > 1. Sharing nodes between levels, as in the Simple Indoor Tagging schema. > This is the approach IsStatenIsland has taken, with a working example at > the West 4th Street–Washington Square station [2]. > 2. Duplicate nodes with identical positions. > 3. Duplicate nodes, but positions scooched off-center a negligible > distance. This is how I mapped out Grand Central Terminal [3], with the > lower level mapped a foot or so away from where it should be. > > Personally, I'm leaning more towards #2. My qualm with #1 is that it adds > intersections to the two overlapping levels of railways, which I find > misleading. And with #3 I worry that I'm mapping for the renderer. I recommend option 3 and I strongly recommend not to use option 1. Examples of option 3: Dusseldorf, Germany between Steinstraße/Königsallee and Oststraße https://www.openrailwaymap.org/?lang=null=51.2230429467944=6.78480327129364=17=standard Duisburg, Germany: Hauptbahnhof and König-Heinrich-Platz https://www.openrailwaymap.org/?lang=null=51.43331030240311=6.773768663406372=16=standard Note: The operators of the tram and subway systems in Germany often uses OSM data for routing in cases where safety does not matter. Using the same nodes (like mapping to adjacent landuse polygons) breaks routing because routing engines would allow trains to switch between the levels. Using duplicated nodes at the same location is likely to trigger quality assurance services and therefore mappers trying to "repair" it by merging them. Using two identical geometries in straight sections with nodes at different locations, will likely provoke the same as duplicated nodes. Regarding option 2: GraphHopper assembles its routing graph by relying on the node IDs in OSM. It would not suffer from using this option but I doubt that it is safe for the future. If OSM adopts to drop its 64 bit node IDs in favour of the location (32 bit latitude + 32 bit longitude), such cases will cause difficulties. Best regards Michael (maintainer of a railway map style and routing engine) signature.asc Description: OpenPGP digital signature ___ Talk-us mailing list Talk-us@openstreetmap.org https://lists.openstreetmap.org/listinfo/talk-us
Re: [Talk-us] Underground railways, indoor mapping, and overlapping features
This can certainly be done using the same nodes. It's cleaner, but takes a little bit of effort. The four links below will show you a 4-story mall I mapped and most of the features use the same nodes for all four levels. Using ID, the mapping can get a bit hairy after two levels. After four levels, it's impossible to understand what's being done. However, the other links below help make it much easier to work with multi-levels. It takes practice, but it's rewarding. OSM ID: https://www.openstreetmap.org/edit#map=20/8.97655/-79.51742 OSM.cz https://openstreetmap.cz/edit/#background=""> Openlevelup (old) https://openlevelup.net/old/?lat=8.976501=-79.517537=20=0=0=1=0=0=0=0=0#20/39.75319/-105.00022 Openlevelup (new) https://openlevelup.net/?l=0#19/8.97644/-79.51786- chachafish-Original Message- From: Jack Burke Sent: May 4, 2020 8:33 PM To: talk-us@openstreetmap.org, Clay Smalley , OSM Talk US Subject: Re: [Talk-us] Underground railways, indoor mapping, and overlapping features Hi Clay. I would use the layer=* tag to reflect the various elevations of the tracks in question, and probably offset them slightly from each other to make future editing easier. -jack-- Typos courtesy of fancy auto spell technology.On May 4, 2020 2:15:07 PM EDT, Clay Smalley wrote: Hi all,Lately I've been tasking myself with mapping underground railway tracks across the US, adding features like parallel tracks, crossovers, and platforms wherever I can. My work includes the Market Street Subway in downtown San Francisco and various lines in Philadelphia. I recently began doing this work on the NYC Subway—a huge system and a daunting task. Fortunately, a local contributor (IsStatenIsland) has been working on it as well and we've had some friendly collaborative discussion.We're stumped on how to properly handle railways directly on top of each other. I've been able to avoid this issue for the most part, as it's rare in Philly (save some bits of non-revenue trackage) and the double-decker subway in San Francisco supports two railways with different gauges, making their centerlines differ by a few inches. But railways with identical centerlines are a frequent occurrence in New York, with its various configurations of local and express tracks.For example, the IRT Lexington Avenue Line (supporting 4, 5, 6, and <6> trains) between 42nd and 103rd Streets, a length of about 3 miles, was constructed as a double-decker cut-and-cover tunnel. In this case, the express tracks lie directly beneath the local tracks. Currently this segment is mapped on OSM as a single track with minimal detail [1]. How should we go about adding these details?We've come up with some potential solutions, each of which seems to have its own drawbacks:1. Sharing nodes between levels, as in the Simple Indoor Tagging schema. This is the approach IsStatenIsland has taken, with a working example at the West 4th Street–Washington Square station [2].2. Duplicate nodes with identical positions.3. Duplicate nodes, but positions scooched off-center a negligible distance. This is how I mapped out Grand Central Terminal [3], with the lower level mapped a foot or so away from where it should be. Personally, I'm leaning more towards #2. My qualm with #1 is that it adds intersections to the two overlapping levels of railways, which I find misleading. And with #3 I worry that I'm mapping for the renderer.Thoughts?-Clay[1] https://www.openstreetmap.org/way/569345492[2] https://www.openstreetmap.org/node/597928309[3] https://www.openstreetmap.org/node/7099182377 ___ Talk-us mailing list Talk-us@openstreetmap.org https://lists.openstreetmap.org/listinfo/talk-us
Re: [Talk-us] Underground railways, indoor mapping, and overlapping features
Hi Clay. I would use the layer=* tag to reflect the various elevations of the tracks in question, and probably offset them slightly from each other to make future editing easier. -jack -- Typos courtesy of fancy auto spell technology. On May 4, 2020 2:15:07 PM EDT, Clay Smalley wrote: >Hi all, > >Lately I've been tasking myself with mapping underground railway tracks >across the US, adding features like parallel tracks, crossovers, and >platforms wherever I can. My work includes the Market Street Subway in >downtown San Francisco and various lines in Philadelphia. I recently >began >doing this work on the NYC Subway—a huge system and a daunting task. >Fortunately, a local contributor (IsStatenIsland) has been working on >it as >well and we've had some friendly collaborative discussion. > >We're stumped on how to properly handle railways directly on top of >each >other. I've been able to avoid this issue for the most part, as it's >rare >in Philly (save some bits of non-revenue trackage) and the >double-decker >subway in San Francisco supports two railways with different gauges, >making >their centerlines differ by a few inches. But railways with identical >centerlines are a frequent occurrence in New York, with its various >configurations of local and express tracks. > >For example, the IRT Lexington Avenue Line (supporting 4, 5, 6, and <6> >trains) between 42nd and 103rd Streets, a length of about 3 miles, was >constructed as a double-decker cut-and-cover tunnel. In this case, the >express tracks lie directly beneath the local tracks. Currently this >segment is mapped on OSM as a single track with minimal detail [1]. How >should we go about adding these details? > >We've come up with some potential solutions, each of which seems to >have >its own drawbacks: > >1. Sharing nodes between levels, as in the Simple Indoor Tagging >schema. >This is the approach IsStatenIsland has taken, with a working example >at >the West 4th Street–Washington Square station [2]. >2. Duplicate nodes with identical positions. >3. Duplicate nodes, but positions scooched off-center a negligible >distance. This is how I mapped out Grand Central Terminal [3], with the >lower level mapped a foot or so away from where it should be. > >Personally, I'm leaning more towards #2. My qualm with #1 is that it >adds >intersections to the two overlapping levels of railways, which I find >misleading. And with #3 I worry that I'm mapping for the renderer. > >Thoughts? > >-Clay > >[1] https://www.openstreetmap.org/way/569345492 >[2] https://www.openstreetmap.org/node/597928309 >[3] https://www.openstreetmap.org/node/7099182377 ___ Talk-us mailing list Talk-us@openstreetmap.org https://lists.openstreetmap.org/listinfo/talk-us
[Talk-us] Underground railways, indoor mapping, and overlapping features
Hi all, Lately I've been tasking myself with mapping underground railway tracks across the US, adding features like parallel tracks, crossovers, and platforms wherever I can. My work includes the Market Street Subway in downtown San Francisco and various lines in Philadelphia. I recently began doing this work on the NYC Subway—a huge system and a daunting task. Fortunately, a local contributor (IsStatenIsland) has been working on it as well and we've had some friendly collaborative discussion. We're stumped on how to properly handle railways directly on top of each other. I've been able to avoid this issue for the most part, as it's rare in Philly (save some bits of non-revenue trackage) and the double-decker subway in San Francisco supports two railways with different gauges, making their centerlines differ by a few inches. But railways with identical centerlines are a frequent occurrence in New York, with its various configurations of local and express tracks. For example, the IRT Lexington Avenue Line (supporting 4, 5, 6, and <6> trains) between 42nd and 103rd Streets, a length of about 3 miles, was constructed as a double-decker cut-and-cover tunnel. In this case, the express tracks lie directly beneath the local tracks. Currently this segment is mapped on OSM as a single track with minimal detail [1]. How should we go about adding these details? We've come up with some potential solutions, each of which seems to have its own drawbacks: 1. Sharing nodes between levels, as in the Simple Indoor Tagging schema. This is the approach IsStatenIsland has taken, with a working example at the West 4th Street–Washington Square station [2]. 2. Duplicate nodes with identical positions. 3. Duplicate nodes, but positions scooched off-center a negligible distance. This is how I mapped out Grand Central Terminal [3], with the lower level mapped a foot or so away from where it should be. Personally, I'm leaning more towards #2. My qualm with #1 is that it adds intersections to the two overlapping levels of railways, which I find misleading. And with #3 I worry that I'm mapping for the renderer. Thoughts? -Clay [1] https://www.openstreetmap.org/way/569345492 [2] https://www.openstreetmap.org/node/597928309 [3] https://www.openstreetmap.org/node/7099182377 ___ Talk-us mailing list Talk-us@openstreetmap.org https://lists.openstreetmap.org/listinfo/talk-us
