Thanks for the background - that explains why some things are the way they are and some of the oddities.
For connector ways, I'd estimate that 95% of them are for very small bodies of water without names or for rivers, where it does make sense to talk about the river flowing through. For the relatively rare case of a large body of water I could then revert it to sub_sea=* A typical example of a connector waterway is http://www.openstreetmap.org/browse/way/72831492 NHN had no ways tagged as waterway=river, all the rivers were tagged as waterway=stream or sub_sea=stream. An example of this is the Indian River, which was tagged as sub_sea for approximately 20 km and then was a mix of sub_sea=stream and waterway=stream for the remainder. I've found Bing's imagery in rural areas is often the same as that on the BC openmaps server and very accurately aligned, so I was planning on using Bing. Attribution will be preserved Anyways, back to the concerns about connector waterways. What would you think about if I added in with step 5 reverting sections of waterways under large lakes to sub_sea? I know that after doing all of these steps that some waterways may be mistagged, but it should be significantly fewer than currently and after simplification and joining named ways together it should be easier to go in and edit. > -----Original Message----- > From: Adam Dunn [mailto:dunna...@gmail.com] > Sent: Tuesday, February 22, 2011 9:38 AM > To: Paul Norman > Cc: Talk-CA OpenStreetMap > Subject: Re: [Talk-ca] Proposal: Cleanup of NHN ways in BC > > Right, the NHN import in the area mentioned was done by MBiker. MBiker > was a pretty big mapper for the Vancouver area. He started off doing > lots of manual edits by biking around and gps'ing, then he got involved > in the NRN road import for east GVRD, then he did NHN for the entire > watershed area (08X-something?). The problem with his NHN import was > that he bit off more than he could chew. He was going around fixing and > cleaning the NHN stuff he imported (like a good importer should do), but > he suddenly stopped working on OSM in October. I think maybe the size of > the import was too daunting for one man? > > The process used for importing NHN was different depending on how much > was being imported at once. When an entire watershed was done (which is > the case here), it was: > 1. Download NHN watershed in .osm format from Yan's server. > 2. Use one of the bulk upload scripts. > 3. Download area from OSM with JOSM and fix any issues. > > For BC non-coastal watersheds, Canvec is equal to NHN. There was an > issue with watersheds abutting against the coast, but I can't remember > if this was resolved (and a quick search through my email history turns > up nothing). > > Sam's purpose of the oneway=yes tag was twofold: to get waterflow > direction arrows to render, and to show that the flow direction was > verified (could have used a "direction_verified=yes" tag). This goes > against the standard for OSM tagging of waterways, since the direction > of the way itself implies waterflow direction. Mapnik doesn't render > flow direction, but that's a matter of the renderer, not the data, just > like Richard said. > > I don't think Sam's (or MBiker's) imports need to be wiped, since that > would mean a couple months from now someone will just do the same thing > from Canvec. Or if you are anti-import, you can delete the data, put on > some bug spray and hiking boots and go map the streams yourself. > > Now to get back to the original question. > > I disagree that connectors should be upgraded to stream. On the talk-us > list, they gave the example of a river still running through a man-made > reservoir, so upgrading to stream would be okay, but in most cases, I > don't think it would be appropriate. I think it would be incorrect to > think that Chilliwack River flows underneath Chilliwack Lake or Sweltzer > River flows through Cultus Lake. In most cases they shouldn't be > rendered, since it only makes sense to have the lake rendered. It's not > just a rendering issue though, I think connectors are logically > different from normal waterways. The purpose of the connector ways (as > far as I can think of) is for topological reasons. > It's useful to see how different streams and rivers flow through lakes, > and how they are connected to each other. We could ask, for example, > "can a fish swim from Cultus Lake to Chilliwack Lake", or "if ammonium > chloride spills into Slesse Creek, where will it end up?". > This is why the connector ways are present. You could potentially make a > script that analyzes inflowing and outflowing waterways connected to a > lake, and makes the connectors automatically, but having the connectors > there already makes it easier and verified. > > The difference between stream and river is size. Are there cases where > waterways large enough to be rivers are tagged as stream in NHN? > > Be careful when selecting the better data based on imagery. The non-NHN > waterways are probably traced from Yahoo, so using Yahoo to see which > waterway is more accurate has obvious bias towards the non-NHN way. Try > to use a third source (Bing), or look to see if there are obvious > reasons to choose one over the other (eg. if Yahoo shows a stream > redirected around new housing, then Yahoo is probably more accurate than > NHN). > > Be careful removing source tag. We still need to acknowledge > Geobase/NRCan as a source of at least part of the data. Keeping an > attribution=Geobase Canada or attribution=Natural Resources Canada > should be enough. > > Adam > > On Tue, Feb 22, 2011 at 7:43 AM, Paul Norman <penor...@mac.com> wrote: > > As an aside, the imports in the lower mainland were not done by Sam, > > but by mbiker. I'm not sure on the exact import process used for the > > NRN data. If I were to do the imports over again myself I think I'd > > use CanVec 7.0 which seems to have the same data but I haven't > evaluated it in any detail. > > > > -----Original Message----- > > From: Sam Vekemans [mailto:acrosscanadatra...@gmail.com] > > Sent: Tuesday, February 22, 2011 6:52 AM > > To: Kevin Michael Smith; Talk-CA OpenStreetMap > > Subject: Re: [Talk-ca] Proposal: Cleanup of NHN ways in BC > > > > Cool, if i knew how to edit a stylesheet i would :) So t hat's fine. > > > > > > So perhaps then it can be all changed with a bot? > > > > > > ... or is it better to simply wipe my edits? > > > > > > > > The rivers (without oneway=yes tag) is available in another api, so > > it's no big deal. > > > > > > cheers, > > Sam > > > > > > On 2/22/11, Kevin Michael Smith <smit...@draconic.ca> wrote: > >> On Tue, 2011-02-22 at 06:34 -0800, Sam Vekemans wrote: > >>> Great! Were getting somewhere.. > >>> > >>> > >>> Now lets discuss the most appropriate tag that can be used to > >>> indicate the rendering of a flow line arrow. > >> > >> It's not about tagging the rivers to say 'there should be an arrow > >> here', it's about putting 'Rivers have arrows' in the style sheet for > >> the renderer. 'Having arrows' isn't a property of the river, it's a > >> property of how we may or may not want to display it. > >> > >> -- > >> Kevin Michael Smith <smit...@draconic.ca> > >> > > > > > > -- > > Twitter: @Acrosscanada > > Blogs: http://acrosscanadatrails.posterous.com/ > > http://Acrosscanadatrails.blogspot.com > > Facebook: http://www.facebook.com/sam.vekemans > > Skype: samvekemans > > IRC: irc://irc.oftc.net #osm-ca Canadian OSM channel (an open chat > > room) @Acrosscanadatrails > > > > _______________________________________________ > > Talk-ca mailing list > > Talk-ca@openstreetmap.org > > http://lists.openstreetmap.org/listinfo/talk-ca > > > > > > _______________________________________________ > > Talk-ca mailing list > > Talk-ca@openstreetmap.org > > http://lists.openstreetmap.org/listinfo/talk-ca > > _______________________________________________ Talk-ca mailing list Talk-ca@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk-ca
