Discussion moved from Talk:MassGIS
I've noticed that the MassGIS import for the town boundaries seemed to work pretty well for the inland towns. If I view, say, Arlington, MA in a view of admin boundaries like this:
I get a nice closed polygon representing the whole town boundary (you can see adjacent towns clearly too). However for coastal towns like Chelsea, MA and Winthrop, MA, the town boundary is unclear, because only a portion of the boundary was imported, but not the portions made up by a river or Boston Harbor:
It appears that what was imported was the "Massachusetts Town Survey Boundaries", which don't include the coastlines or harbor. I checked OLIVER (http://maps.massgis.state.ma.us/map_ol/oliver.php) and there is a layer called just "Massachusetts Towns" which has the boundaries. However, the boundaries do follow the coastlines, in the main. Are these the true boundaries? If so, it means that there will be areas in, say, Boston Harbor, or in rivers which aren't part of any township between adjacent towns. Is this correct, when I look at some other tools, they simply split the difference, e.g. if you visit
and zoom in and click on "Winthrop", "Boston" and "Chelsea" there are no "gaps". So what's the most correct thing to do when creating the closed polygons, should we follow the coastlines and/or rivers or split the differences? My understanding of Massachusetts was there are no incorporated areas within the state, but perhaps the Habor, and some parts of rivers are exceptions?
Either way, we should cleanup those town boundaries and I'm happy to work on them, but I wanted to get some advice on best practices here.
Thanks. -- Fiveisalive 22:01, 23 July 2012 (BST)
I did some digging the off shore county boundaries is out of date and has some of the internal boundaries wrong (for instance the red in this picture of Suffolk county.) I also found the following quote on this page
The offshore boundaries are currently being reviewed by the legal counsels of the Massachusetts Highway Department and NOAA as well as the Federal Baseline Committee. This data will not be distributed until the termination points of the offshore boundaries are approved by the Federal Baseline Committee and the Massachusetts Legislature.
But on the other hand the CZM apparently did release state offshore Boundary data for the state outline. Basically meaning we can move the state admin boundary out to see but there isn't any official data about how it relates to city/town or county areas as far as I can tell. Meaning some combination of data sources is probably the best bet, but first I'm going to try to see what kind of time frame MassGIS thinks for the new boundaries.
Thanks. --Calvin.metcalf 17:01, 21 August 2012 (BST)--
- Thanks. My understanding of Massachusetts is that all towns are contained with counties and all counties within the state (i.e. there is no unincorporated areas within a county, and presumably no area not contained within a county in the state). Since the town boundary layer from 2009:
- does include the offshore town areas, I figured it would be safe to extend the town boundaries out to sea using that Shapefile, and also move the corresponding county boundaries. I went ahead and did this, but just for Suffolk County:
- I left the state boundary where it was for the moment, figuring out that it might be better to do that after all the town boundaries were fixed, county by county. But it turns out that I got a message from massDOT (on osm, edits, contrib, heatmap, chngset com.) who said was also working on merging the county and state boundaries and then was going to move them out to sea.
- Either way is fine with me.
- Perhaps we can check whether the town boundary (from MassGIS) and the overall Mass boundary at: http://www.mass.gov/czm/mapping/czboundary.htm line up, and use that as a cross check. --Fiveisalive 22:27, 21 August 2012 (BST)
- I exported a comparison of the Shapefile for the town boundaries from here:
- and the coastal layer from here:
- the merged and exported as an image here: Fiveisalive 23:03, 21 August 2012 (BST)
- I replied below. --Calvin.metcalf 16:17, 13 September 2012 (BST)
Discussion moved from User talk:Dobratzp
town boundaries in MA?
Hi there, I noticed you've done a lot of work in listing all the relations for the towns/cities in MA (Massachusetts/Boundary Relations). Thanks! I started working on some relations recently (e.g. Brookline, and Chelsea, and an incomplete Boston). (I added the Chelsea relation to the wiki list).
Do you have any opinions on my question on Talk:MassGIS#admin_boundaries_in_Boston_area.3F ? In particular on how to handle coastlines/rivers and town boundaries. I'm not 100% sure whether the legal boundaries include the water areas or not. MassGIS seems to suggest not, but I'm not sure how canonical that is. --Fiveisalive 20:39, 15 August 2012 (BST)
I had been working on adding/cleaning up some of the Massachusetts town boundary relations. I'll probably work on this again when the weather turns dark and cold again over the winter.
You may find portions of town boundaries with up to a dozen overlapping Ways in them due to a botched import. In that case, just delete the duplicate Ways before you add them to the Relation.
In general, I think that if a waterway=river serves as the border between two municipalities, than the Way in OSM that refers to the river should be added to the boundary relation. For towns bordering the ocean, it is a little bit trickier. According to the Relation:boundary, there should ideally be two separate relations: one for the land area of the town and one for the administrative area of the town including a certain distance out to sea. I usually just do relation for the administrative area including the portion of the town in the ocean.
To get the portions of the boundary in the ocean, I often use TIGER. I open the SHP files in Quantum GIS, convert the coordinates to WGS84, and then run the file through Shp-to-osm.jar. Then I load the OSM file as a separate layer in JOSM and I can merge portions of it.--Dobratzp 17:15, 16 August 2012 (BST)
- Thanks for your feedback. I did see that description in Relation:boundary about land vs. administrative area, but I was wondering whether the actual legal definition in Massachusetts *does* include the water regions or not? The OLIVER layer for town boundaries shows the boundaries being the water's edge (e.g. around Chelsea, MA or Winthrop, MA), but maybe the town's jurisdiction does protrude into Boston Harbor? I agree that we should use the administrative area for the relation for the time being (and do the land area maybe later once all the admin boundaries are complete). But basically is it valid to include the water areas at all in towns? e.g. I can't find any good source for the town boundary on the Boston Harbor side, if it isn't the water's edge (as shown in the OLIVER layer).
- The county boundaries as they current exist appear to include the water areas (e.g. Suffolk), and if (as I understand it), there are no areas in a county that are not also in a town, therefore there should be no space between, say Everett and Chelsea (since the boundary is the same as Suffolk/Middlesex county boundary), so in the case of town boundaries that are also county boundaries it shouldn't be too hard. However, where is the town boundary for Chelsea if it isn't the water's edge, e.g. where is the boundary between Chelsea and Boston (since they're in the same county)? --Fiveisalive 20:14, 16 August 2012 (BST)
- I guess to partially answer my own question. It appears that TIGER boundaries that you mention do have the town boundaries, and I assume that they are reasonably canonical? These do include the water areas. In the case of Boston, there's a little isthmus that extends out to sea directly to the east of Winthrop, MA. If it makes sense to you I guess I'll redo the relation for Chelsea as land_area=administrative and somehow see if I can get the TIGER data for Chelsea to get the water boundary. --Fiveisalive 20:28, 16 August 2012 (BST)
Essex County 99% done
Essex County is more or less done.
With the exception of resolving the Essex County MA/NH border area. The offshore town bounary doesn't currently line up with the MA/NH border. Not sure which is the most correct here, so I'm leaving this until we do the full MA border area, at which stage we can merge the appropriate ways/relations. --Fiveisalive 22:50, 30 August 2012 (BST)
south is mostly done
did plymouth, norfolk, barnstable, dukes county, and nantuckett, also the coastal towns and the ma boarder for them, briston is still to be done --Calvin.metcalf 21:00, 31 August 2012 (BST)
- Thanks. Looking good. I fixed up the internal town relations for the rest of Norfolk County. There were a few places where the offshore layer borders were superimposed upon the previous import from the town survey layer. I ended up deleting a few duplicate ways, hopefully all the relations hold (I checked the towns I modified, but not all of them yet).
- Also the offshore import didn't seem to have any tags, i.e. no attribution=MassGIS or source=massgis_offshore_town_boundary_import that we discussed. I also put "boundary=administrative" on the imported ways for Essex County so that they would render as admin boundaries in Potlatch. --Fiveisalive 06:26, 2 September 2012 (BST)
- Worked on rest of Plymouth County. I created relations for all towns, however the relations for the towns that touch around Hanover, Norwell, Pembroke and Hanson are incomplete, because it looks like there are a few boundary ways missing from either the original survey point town boundary import or the coastal import that connect the towns. If you get a chance, it would be great if you could look into what happened to the missing ways. --Fiveisalive 09:20, 4 September 2012 (BST)
- yeah I only imported the ways that made up the towns that touched the coasts so some of the internal boundaries are going to be missing especially in cases where town A and town B touch and aren't coastal, but are surrounded on all sides by coastal towns
- OK, I fixed the towns around Norwell/Hanover using the offshore town boundary layer for the river boundaries, so all relations for Plymouth County should be complete. --Fiveisalive 01:23, 7 September 2012 (BST)
- -just did Bristol which completes the coasts couple things:
- -totally dropped the ball on tagging for source and import don't know how that happened, then for Bristol I tried to correct that and ended up just tagging the changeset not the ways
- -again this is just the coastal ones so we are only going to have ways for the county boarder and towns on the boarder. I did this because the internal boarders are going to be coming from a different dataset.
- -I have found the best way to deal with the dup nodes is to a couple days for mapnik to render it and then you can very easily pick the dups up on the map. The non Bristol dups should becoming obvious soon with the Bristol ones latter in the week.
- I think I finished off the rest of the town relations for Bristol County. Would appreciate a quick double-check. --Fiveisalive 22:35, 9 September 2012 (BST)
- Only thing I had to fix was the link for Easton on the wiki page, looks good. --Calvin.metcalf 13:52, 10 September 2012 (BST)
- Excellent, I had to fix one additional town in Berkshire County, but I think all town/county relations for all of MA are (or should be) complete. Hopefully others can help us double-check them all before we declare it complete. --Fiveisalive 18:35, 10 September 2012 (BST)
- the boundaries are already looking good. thanks for your help so far. --Calvin.metcalf 13:51, 4 September 2012 (BST)
Massachusetts border and CMZ?
Hi Calvin, did you have a chance to look at the this image I created here?
Now that the county/towns are fixed, I was interested in getting the MA border correct, but there appears to be areas that are withinin MA acccording to the CMZ shape file, but not within a town/county, do have an opinion on how to proceed with reconciling the two? --Fiveisalive 18:33, 10 September 2012 (BST)
I think the CMZ offshore boundaries are the definitive ones, but talking to MassGIS the boundary divided up by town isn't going to be coming out anytime soon as once the lawyers finishes arguing it out (which isn't expected soon) the legislature then has to approve it. I'm going to whip up an approximation and then we can figure out what the best solution looks like --Calvin.metcalf 14:17, 13 September 2012 (BST)
- Thanks. But it looks like even if the borders are reconciled where they are currently fairly close, but not exactly aligned, that there will still be 2 or 3 larger water regions outside the town/county that are within the MA border, i.e. state areas not within a county, e.g. if you look at the CMZ boundary there is large water region of the Bay between Provincetown and Boston that currently isn't anywhere near being within any town or county. Or would the idea be that that region is actually in a county, so the county region would have to be extended to cover it? --Fiveisalive 18:10, 13 September 2012 (BST)
- I believe yes that they would be in a Municipality, but which one I'm not sure. It's also worth noting that the CMZ also suggests some of the boarder needs to be adjusted in as well. I thought it would be easy to just divide that area in Cape Cod bay, up based on how close it was to the towns, but creating Thiessen polygons (i.e a Voronoi Diagram) from polygon input is apparently hard to do in ArcGIS or QGIS. So for now I can focus on the more cut and dry areas like Gloucester or anyplace where it needs to move in. --Calvin.metcalf 13:01, 14 September 2012 (BST)