Re: [Talk-ca] [Imports] Importing CanVec better?
From: Maury Markowitz [mailto:maury.markow...@gmail.com] Sent: Monday, October 15, 2012 1:28 PM To: impo...@openstreetmap.org Subject: [Imports] Importing CanVec better? Newb here, so I hope this is the right place to ask. I also posted on one of the wiki talk pages, but I didn't know if anyone goes there. I have noticed that vectors imported from the CanVec database are split at grid boundaries. This means that large objects like roads or lakes are split into multiple parts in OSM. I strongly suspect that there is a way to re-integrate these into single objects, which would greatly improve things (case in point, the cottage would no longer be on a three-part lake :-) There are five different types of ways that can be split a tile boundaries. 1. Unclosed ways, like roads. It doesn't matter if these are split, but the ends need to share nodes so that they're connected. Splitting a road doesn't change the meaning. 2. Small closed ways, like buildings. These need to be joined into one closed way. 3. Lakes. These should be joined together, either as a closed way or as a multipolygon. 4. Large forests. These do not need to be joined. In fact, they need to be split at some point to avoid having a multipolygon the size of BC. 5. Coastlines (and the coast of lakes like the great lakes). In principle these are the same as other unclosed ways, but these should only be imported with those very familiar with both the CanVec water model and OSM coastlines. As this data is automatically imported, is this the right place to discuss this? CanVec isn't automatically imported. If people aren't performing the basic checks at edges you can send them a note or ask someone else to. ___ Talk-ca mailing list Talk-ca@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk-ca
Re: [Talk-ca] [Imports] Importing CanVec better?
I started adding CanVec tile 104B to OSM using JOSM. So far I've put in the south/west quadrant. There was absolutely nothing in that area at all before. It is my first import of CanVec data so if someone has time to check, that would be great. #13460999 http://www.openstreetmap.org/browse/changeset/13460999 October 11, 2012 23:58 mattropolis_bulkhttp://www.openstreetmap.org/user/mattropolis_bulk/edits -- Matthew Buchanan -- Kamloops, BC On 15 October 2012 23:03, Paul Norman penor...@mac.com wrote: From: Maury Markowitz [mailto:maury.markow...@gmail.com] Sent: Monday, October 15, 2012 1:28 PM To: impo...@openstreetmap.org Subject: [Imports] Importing CanVec better? Newb here, so I hope this is the right place to ask. I also posted on one of the wiki talk pages, but I didn't know if anyone goes there. I have noticed that vectors imported from the CanVec database are split at grid boundaries. This means that large objects like roads or lakes are split into multiple parts in OSM. I strongly suspect that there is a way to re-integrate these into single objects, which would greatly improve things (case in point, the cottage would no longer be on a three-part lake :-) There are five different types of ways that can be split a tile boundaries. 1. Unclosed ways, like roads. It doesn't matter if these are split, but the ends need to share nodes so that they're connected. Splitting a road doesn't change the meaning. 2. Small closed ways, like buildings. These need to be joined into one closed way. 3. Lakes. These should be joined together, either as a closed way or as a multipolygon. 4. Large forests. These do not need to be joined. In fact, they need to be split at some point to avoid having a multipolygon the size of BC. 5. Coastlines (and the coast of lakes like the great lakes). In principle these are the same as other unclosed ways, but these should only be imported with those very familiar with both the CanVec water model and OSM coastlines. As this data is automatically imported, is this the right place to discuss this? CanVec isn't automatically imported. If people aren't performing the basic checks at edges you can send them a note or ask someone else to. ___ 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
Re: [Talk-ca] [Imports] Importing CanVec better?
On Mon, Oct 15, 2012 at 1:28 PM, Maury Markowitz maury.markow...@gmail.comwrote: Newb here, so I hope this is the right place to ask. I also posted on one of the wiki talk pages, but I didn't know if anyone goes there. I have noticed that vectors imported from the CanVec database are split at grid boundaries. This means that large objects like roads or lakes are split into multiple parts in OSM. I strongly suspect that there is a way to re-integrate these into single objects, which would greatly improve things (case in point, the cottage would no longer be on a three-part lake :-) As this data is automatically imported, is this the right place to discuss this? Roads I can understand. Breaking roads into manageable segments makes sense. But lakes? Can you give a link to the three part lake? Clifford ___ Talk-ca mailing list Talk-ca@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk-ca
Re: [Talk-ca] [Imports] Importing CanVec better?
On Mon, 2012-10-15 at 14:03 -0700, Clifford Snow wrote: On Mon, Oct 15, 2012 at 1:28 PM, Maury Markowitz maury.markow...@gmail.com wrote: Newb here, so I hope this is the right place to ask. I also posted on one of the wiki talk pages, but I didn't know if anyone goes there. I have noticed that vectors imported from the CanVec database are split at grid boundaries. This means that large objects like roads or lakes are split into multiple parts in OSM. I strongly suspect that there is a way to re-integrate these into single objects, which would greatly improve things (case in point, the cottage would no longer be on a three-part lake :-) For me personally, it's all by hand. download an area and start joining As this data is automatically imported, is this the right place to discuss this? I wouldn't say any import I'm doing is automated. 1 Load canvec data 2 delete roads from canvec 3 download map and merge 4 Wait for a message from someone when I mess up :-) 5 and repeat Roads I can understand. Breaking roads into manageable segments makes sense. But lakes? Can you give a link to the three part lake? http://www.openstreetmap.org/?lat=46.23lon=-79.638zoom=11layers=M Next to North Bay is multi part lake, I'm afraid to touch it see point 4 Andrew aka PurpleMustang, CanvecImports signature.asc Description: This is a digitally signed message part ___ Talk-ca mailing list Talk-ca@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk-ca
Re: [Talk-ca] [Imports] Importing CanVec better?
Three-part lakes. Canvec data is split at canvec (NTS) tile boundaries, so a lake the crosses such a boundary will be split in several pieces on those straight lines. There are other reasons to split lakes and other large objects. We split roads when the name changes, or when the highway classification changes, etc. We split lakes when they contain too many nodes. The API limits a way to less than 2000 nodes. As a practical matter, many mappers restrict ways to under 1000 nodes. Given a thousand nodes, a detailed lake boundary could require several ways. Some mappers will choose to split the ways along geographical features; here's a nice big bay; make it a way! others will just divide the lake into four roughly even-length ways. Who knows? Mappers are individuals! Then the lake is combined by a multipolygon relation. Each of the outer boundary ways become multipolygon members with 'outer roles. Island ways become multipolygon members with role = inner. Starting with a three-piece canvec lake, you might consider, rationalizing it for an OSM multipolygon. All else being the same: - Cut the loops and remove the duplicate (vertical / horizontal) NTS tile boundaries. - Check that the remaining linear ways form a loop. - Join, or sever the loop in ways of the right size. - Check and fix islands if needed. - Select all of those ways and create the new multipolygon - add the name, and other tags, etc to the multipolygon. - Set the inner and outer roles. - Check the validator to see if you've missed anything. - Cross your fingers and save. :-) - Have an experienced mapper check your work until you feel comfortable with multipolygons. :-) Bear in mind that coastlines in OSM are a special an beautiful beast. If a way is tagged as natural=coastline, then the way direction is important! Water goes on the right. Other ways don't have to follow this restriction. And several large lakes in Canada are treated as coastline, including the Great Lakes. ___ Talk-ca mailing list Talk-ca@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk-ca
