Re: [talk-au] National borders (was: import of state borders?)
Hi 2012/9/18 Ian Sergeant inas66+...@gmail.com If I understand correctly, the differences should only correspond to the amount that our coastline differs from the low water mark? Are we missing parts of the true coastline, is our coastline just inaccurate do you think? Well, to me there are two major reasons for differences between the coastline in osm and the baseline used to compute the boundary: (a) osm's coastline definition as the high water mark vs. the baseline defintion as the low water mark. Obviously the difference is quite small at cliffs and increases a shallow beaches. But the biggest difference is caused by something off the coast inundated at high tide but showing at low tide - e.g. high parts of a reef. (b) Smaller bays are cut off straight. These are not included in the list of points [1], in there are only the additional larger sections. I've tried to illustrate this a bit generating an image in QGIS [2]. It combines OSM with the data from [3] to show the situation. I'd be surprised if there was any definitive low water mark data for the entire coastline. I don't know how it has been generated but I'm afraid there is one. As this directly translates into the extension of the territorial waters etc. there's quite some incentive to have it defined. Should we start with a simpler section, like NSW? This probably wouldn't really help much as it doesn't really solve the problem. Last night I have spent some time on the topic and would currently suggest the approach to simply use what's there. Use coastline from OSM and combine with the straight sections from [1]. For both a 12 nautical mile buffer can be computed in QGIS and combined. This will not be accurate as it neglects the reefs etc. But it's probably the best we can get. BTW I haven't checked yet, if there are reefs mapped in OSM. If so they could perhaps be added into the process. Michael [1] http://www.comlaw.gov.au/Details/F2006L00525 [2] https://dl.dropbox.com/u/1222615/coastline.png [3] https://www.ga.gov.au/products/servlet/controller?event=GEOCAT_DETAILScatno=63565 ___ Talk-au mailing list Talk-au@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk-au
Re: [talk-au] National borders (was: import of state borders?)
Hi, If I understand correctly, the differences should only correspond to the amount that our coastline differs from the low water mark? Are we missing parts of the true coastline, is our coastline just inaccurate do you think? I'd be surprised if there was any definitive low water mark data for the entire coastline. Should we start with a simpler section, like NSW? Ian. On 12 September 2012 23:04, Michael Krämer ohr...@gmail.com wrote: Hi, 2012/8/31 Michael Krämer ohr...@gmail.com 2012/8/31 Ian Sergeant inas66+...@gmail.com Well, I think the baseline is defined here.. http://www.comlaw.gov.au/Details/F2006L00525 I don't think we have any issues using those facts as a source. That looks great, combining this with the coastline should work. The coastline can be either drawn via osmosis from a planet extract or perhaps also from OverpassAPI. But I guess we'll have to generate all those line segments in QGIS to get the coordinate systems right. A quick update from my side on this: I'm afraid it's not as straightforward as I had assumed... I managed to generate an osm file from the points given in the proclamation [1]. This gives the straight pieces of the baseline. But the problem is that the coastline doesn't really give the right baseline for the rest (high vs. low water mark). When I checked briefly I came across some pronounced differences for example in the gulf of carpentaria. I guess it will be the same along the Great Barrier Reef. So we would have to do some guesswork to combine coastline and straight segements. BTW, it's very likely not a projection issue. I made sure by doing a check of my calculations against the data Geoscience Australia provides. Michael --- [1] https://dl.dropbox.com/u/1222615/baseline.osm ___ Talk-au mailing list Talk-au@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk-au
Re: [talk-au] National borders (was: import of state borders?)
Hi I have noticed that in Devonport Tasmania the coastline has appeared with reference ABS-2006 along with an area called beach. It can be a little out so just curious what level of detail/accuracy is this and worthwhile better aligning it. Also am I correct to assume that it is the high water mark? Cheers Brett From: inas66+...@gmail.com Date: Tue, 18 Sep 2012 09:34:46 +1000 To: ohr...@gmail.com CC: talk-au@openstreetmap.org; cadmana...@live.com.au Subject: Re: [talk-au] National borders (was: import of state borders?) Hi, If I understand correctly, the differences should only correspond to the amount that our coastline differs from the low water mark? Are we missing parts of the true coastline, is our coastline just inaccurate do you think? I'd be surprised if there was any definitive low water mark data for the entire coastline. Should we start with a simpler section, like NSW? Ian. On 12 September 2012 23:04, Michael Krämer ohr...@gmail.com wrote: Hi, 2012/8/31 Michael Krämer ohr...@gmail.com 2012/8/31 Ian Sergeant inas66+...@gmail.com Well, I think the baseline is defined here.. http://www.comlaw.gov.au/Details/F2006L00525 I don't think we have any issues using those facts as a source. That looks great, combining this with the coastline should work. The coastline can be either drawn via osmosis from a planet extract or perhaps also from OverpassAPI. But I guess we'll have to generate all those line segments in QGIS to get the coordinate systems right. A quick update from my side on this: I'm afraid it's not as straightforward as I had assumed... I managed to generate an osm file from the points given in the proclamation [1]. This gives the straight pieces of the baseline. But the problem is that the coastline doesn't really give the right baseline for the rest (high vs. low water mark). When I checked briefly I came across some pronounced differences for example in the gulf of carpentaria. I guess it will be the same along the Great Barrier Reef. So we would have to do some guesswork to combine coastline and straight segements. BTW, it's very likely not a projection issue. I made sure by doing a check of my calculations against the data Geoscience Australia provides. Michael --- [1] https://dl.dropbox.com/u/1222615/baseline.osm ___ Talk-au mailing list Talk-au@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk-au ___ Talk-au mailing list Talk-au@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk-au
Re: [talk-au] National borders (was: import of state borders?)
Hi, If it is really ABS2006, then it can always be better aligned. The fact that it is still in the database when all of the ABS2006 import was removed, means that it has probably changed relative to the ABS import, and I wouldn't rely on the source tag. The convention in OSM is that coastline should be mean high water mark. In reality, it usually corresponds to the most inland area that appears to be inundated by water at some time from imagery. Some areas the beach is aligned the the coastline, and in others it extends out to sea. I can see the reasoning for making a beach an area that is exposed at lower tides, but I personally don't do it that way - I align the beach to the coastline. If you realign the coastline, remember to change the source to what you realign it to. Ian. On 18 September 2012 10:23, Brett Russell brussell...@live.com.au wrote: Hi I have noticed that in Devonport Tasmania the coastline has appeared with reference ABS-2006 along with an area called beach. It can be a little out so just curious what level of detail/accuracy is this and worthwhile better aligning it. Also am I correct to assume that it is the high water mark? Cheers Brett From: inas66+...@gmail.com Date: Tue, 18 Sep 2012 09:34:46 +1000 To: ohr...@gmail.com CC: talk-au@openstreetmap.org; cadmana...@live.com.au Subject: Re: [talk-au] National borders (was: import of state borders?) Hi, If I understand correctly, the differences should only correspond to the amount that our coastline differs from the low water mark? Are we missing parts of the true coastline, is our coastline just inaccurate do you think? I'd be surprised if there was any definitive low water mark data for the entire coastline. Should we start with a simpler section, like NSW? Ian. On 12 September 2012 23:04, Michael Krämer ohr...@gmail.com wrote: Hi, 2012/8/31 Michael Krämer ohr...@gmail.com 2012/8/31 Ian Sergeant inas66+...@gmail.com Well, I think the baseline is defined here.. http://www.comlaw.gov.au/Details/F2006L00525 I don't think we have any issues using those facts as a source. That looks great, combining this with the coastline should work. The coastline can be either drawn via osmosis from a planet extract or perhaps also from OverpassAPI. But I guess we'll have to generate all those line segments in QGIS to get the coordinate systems right. A quick update from my side on this: I'm afraid it's not as straightforward as I had assumed... I managed to generate an osm file from the points given in the proclamation [1]. This gives the straight pieces of the baseline. But the problem is that the coastline doesn't really give the right baseline for the rest (high vs. low water mark). When I checked briefly I came across some pronounced differences for example in the gulf of carpentaria. I guess it will be the same along the Great Barrier Reef. So we would have to do some guesswork to combine coastline and straight segements. BTW, it's very likely not a projection issue. I made sure by doing a check of my calculations against the data Geoscience Australia provides. Michael --- [1] https://dl.dropbox.com/u/1222615/baseline.osm ___ Talk-au mailing list Talk-au@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk-au ___ Talk-au mailing list Talk-au@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk-au
Re: [talk-au] National borders (was: import of state borders?)
Hi, 2012/8/31 Michael Krämer ohr...@gmail.com 2012/8/31 Ian Sergeant inas66+...@gmail.com Well, I think the baseline is defined here.. http://www.comlaw.gov.au/Details/F2006L00525 I don't think we have any issues using those facts as a source. That looks great, combining this with the coastline should work. The coastline can be either drawn via osmosis from a planet extract or perhaps also from OverpassAPI. But I guess we'll have to generate all those line segments in QGIS to get the coordinate systems right. A quick update from my side on this: I'm afraid it's not as straightforward as I had assumed... I managed to generate an osm file from the points given in the proclamation [1]. This gives the straight pieces of the baseline. But the problem is that the coastline doesn't really give the right baseline for the rest (high vs. low water mark). When I checked briefly I came across some pronounced differences for example in the gulf of carpentaria. I guess it will be the same along the Great Barrier Reef. So we would have to do some guesswork to combine coastline and straight segements. BTW, it's very likely not a projection issue. I made sure by doing a check of my calculations against the data Geoscience Australia provides. Michael --- [1] https://dl.dropbox.com/u/1222615/baseline.osm ___ Talk-au mailing list Talk-au@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk-au
Re: [talk-au] National borders (was: import of state borders?)
2012/8/31 Ian Sergeant inas66+...@gmail.com Well, I think the baseline is defined here.. http://www.comlaw.gov.au/Details/F2006L00525 I don't think we have any issues using those facts as a source. That looks great, combining this with the coastline should work. The coastline can be either drawn via osmosis from a planet extract or perhaps also from OverpassAPI. But I guess we'll have to generate all those line segments in QGIS to get the coordinate systems right. 2012/8/31 Paul HAYDON cadmana...@live.com.au BTW, in QGIS it's Vector / Geoprocessing Tools / Buffer(s) - and I seem to recall some issue with the number/scale (read: map units), but I managed to work my way through it previously. Exactly, I remember that I somehow had to convert 12 nautical miles into fractions of degrees lat/long or so. Michael ___ Talk-au mailing list Talk-au@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk-au
Re: [talk-au] National borders (was: import of state borders?)
It has also been pointed out that having the two inner poly's of the NSW relation (ACT and Jervis Bay Territory) while having the outer border of the poly incomplete is causing mapnik and nominatim to think that both territories are in NSW. I'm presuming the algorithm being used has difficulty telling which side of a inner poly is the exempt area when the outer boundary is incomplete, even though this seems to be computable. Presumably this effect will go away when the boundary is complete. Ian. On 31 August 2012 16:06, Michael Krämer ohr...@gmail.com wrote: 2012/8/31 Ian Sergeant inas66+...@gmail.com Well, I think the baseline is defined here.. http://www.comlaw.gov.au/Details/F2006L00525 I don't think we have any issues using those facts as a source. That looks great, combining this with the coastline should work. The coastline can be either drawn via osmosis from a planet extract or perhaps also from OverpassAPI. But I guess we'll have to generate all those line segments in QGIS to get the coordinate systems right. 2012/8/31 Paul HAYDON cadmana...@live.com.au BTW, in QGIS it's Vector / Geoprocessing Tools / Buffer(s) - and I seem to recall some issue with the number/scale (read: map units), but I managed to work my way through it previously. Exactly, I remember that I somehow had to convert 12 nautical miles into fractions of degrees lat/long or so. Michael ___ Talk-au mailing list Talk-au@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk-au
[talk-au] National borders (was: import of state borders?)
2012/8/30 Ian Sergeant inas66+...@gmail.com It looks like we've finished the NSW/Victoria border. There are probably a couple of bits I'll go back to and touch up, but otherwise looking good. Yes, I think now all land borders are completely mapped. Nice piece of work. So, what's next to complete the national/state borders? Good question, I would probably start with the national border. These maritime boundaries are rather messy, just have a look at the yellow line and the brown area in [1] or read the description there. For this I see two different methods: (a) Do the pure-OSM approach by deriving everything from the coastline with some guessing for the straight segments. (b) Try to get permission to use the official data [3] Here I would definetly favor (b) - simply because to me the only accurate definition of the baseline is the official one. But of course I don't know at all if there is a chance to get the permission to use the data in OSM. If this doesn't work we would have to work on using the coastline, somehow generate a baseline, and from there calculate the territorial waters. The piece looking most diffcult to me would be to generate the baseline, given the topography of Australia's coastline and/or looking at [1]. Any thoughts or suggestions are highly welcome! Michael --- [1] http://www.ga.gov.au/image_cache/GA3746.pdf [2] https://www.ga.gov.au/products/servlet/controller?event=GEOCAT_DETAILScatno=63565 ___ Talk-au mailing list Talk-au@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk-au
Re: [talk-au] National borders (was: import of state borders?)
Hi guys, Not sure if this will be of any help - but it can't hurt, right? I've recently used Quantum GIS (QGIS) to create a region about my GPS routes so as to capture the fuel stops (for example, within 10km of my chosen path). I would think if someone could establish the coastline as a perimeter, then it could be generated by the same means. I'm not sure what distance the territorial waters go to, but undoubtedly there's somebody more knowledgable than myself on this forum. QGIS can read OSM files, although I should think it easier to use .shp if available. Perhaps even start with one of the less detailed datasets available freely (ie. smaller scale) in order to get the information out there (presumably the boundary is more important with some inaccuracies than not existing at all - otherwise we become a part of N.Z.!!!). Anyway, I'd be happy to collaborate on this if you think it will help. Cheers, Paul. Message: 3 Date: Thu, 30 Aug 2012 08:26:51 +0200 From: Michael Kr?mer ohr...@gmail.com To: Ian Sergeant inas66+...@gmail.com, talk-au@openstreetmap.org Subject: [talk-au] National borders (was: import of state borders?) Message-ID: caduoafwwvn9w_os79spruxwg0v79gdosv1bj+rozhg1usbd...@mail.gmail.com Content-Type: text/plain; charset=iso-8859-1 2012/8/30 Ian Sergeant inas66+...@gmail.com It looks like we've finished the NSW/Victoria border. There are probably a couple of bits I'll go back to and touch up, but otherwise looking good. Yes, I think now all land borders are completely mapped. Nice piece of work. So, what's next to complete the national/state borders? Good question, I would probably start with the national border. These maritime boundaries are rather messy, just have a look at the yellow line and the brown area in [1] or read the description there. For this I see two different methods: (a) Do the pure-OSM approach by deriving everything from the coastline with some guessing for the straight segments. (b) Try to get permission to use the official data [3] Here I would definetly favor (b) - simply because to me the only accurate definition of the baseline is the official one. But of course I don't know at all if there is a chance to get the permission to use the data in OSM. If this doesn't work we would have to work on using the coastline, somehow generate a baseline, and from there calculate the territorial waters. The piece looking most diffcult to me would be to generate the baseline, given the topography of Australia's coastline and/or looking at [1]. Any thoughts or suggestions are highly welcome! Michael ___ Talk-au mailing list Talk-au@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk-au
Re: [talk-au] National borders (was: import of state borders?)
Hi Paul, 2012/8/31 Paul HAYDON cadmana...@live.com.au I've recently used Quantum GIS (QGIS) to create a region about my GPS routes so as to capture the fuel stops (for example, within 10km of my chosen path). I would think if someone could establish the coastline as a perimeter, then it could be generated by the same means. Yes, the offset/buffer can be calculated with QGIS. I've done this before, unfortunately I didn't take any notes at that time so I would have to find my way again. But the key problem is that the boundary is not calculated from the coastline directly. Instead of the coastline an artificial line called baseline is used (cf. [1]). Bascially this cuts off a couple of bays - (the black areas in [2]). So looking at [2] the baseline (and border) run from the northern tip of Fraser island straight west towards Bundaberg. If you would to the calculation from the coastline the border would rather have a bend to the south inbetween. That's why I personally would prefer trying to get import permission as and only use the coastline as a backup solution. I'm not sure what distance the territorial waters go to, That's the easy part: It's 12 nautical miles (from the baseline). Anyway, I'd be happy to collaborate on this if you think it will help. You're definetly welcome! Michael [1] http://wiki.openstreetmap.org/wiki/Tag:boundary%3Dmaritime [2] http://www.ga.gov.au/image_cache/GA3746.pdf ___ Talk-au mailing list Talk-au@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk-au
Re: [talk-au] National borders (was: import of state borders?)
Hey Michael, Thanks - that made for interesting reading on a subject I knew so little about. And I agree with you, that the best course of action is to obtain the data officially. But in the event of failure/refusal, I'm happy to help out. BTW, in QGIS it's Vector / Geoprocessing Tools / Buffer(s) - and I seem to recall some issue with the number/scale (read: map units), but I managed to work my way through it previously. I worked off .gpx files (my converted Magellan GPS route files), but I cannot imagine the procedure being any different as long as the data is obtained in vector format. Like you, I might need just a slight refresher :-) See how you go with the permissions, but if there's an issue with AUS not having that border we could simply apply the buffer to the coastline in the interim, could we not? Cheers,Paul. Date: Fri, 31 Aug 2012 06:43:42 +0200 Subject: Re: National borders (was: import of state borders?) From: ohr...@gmail.com To: cadmana...@live.com.au; talk-au@openstreetmap.org Hi Paul, 2012/8/31 Paul HAYDON cadmana...@live.com.au I've recently used Quantum GIS (QGIS) to create a region about my GPS routes so as to capture the fuel stops (for example, within 10km of my chosen path). I would think if someone could establish the coastline as a perimeter, then it could be generated by the same means. Yes, the offset/buffer can be calculated with QGIS. I've done this before, unfortunately I didn't take any notes at that time so I would have to find my way again. But the key problem is that the boundary is not calculated from the coastline directly. Instead of the coastline an artificial line called baseline is used (cf. [1]). Bascially this cuts off a couple of bays - (the black areas in [2]). So looking at [2] the baseline (and border) run from the northern tip of Fraser island straight west towards Bundaberg. If you would to the calculation from the coastline the border would rather have a bend to the south inbetween. That's why I personally would prefer trying to get import permission as and only use the coastline as a backup solution. I'm not sure what distance the territorial waters go to, That's the easy part: It's 12 nautical miles (from the baseline). Anyway, I'd be happy to collaborate on this if you think it will help. You're definetly welcome! Michael [1] http://wiki.openstreetmap.org/wiki/Tag:boundary%3Dmaritime [2] http://www.ga.gov.au/image_cache/GA3746.pdf ___ Talk-au mailing list Talk-au@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk-au
Re: [talk-au] National borders (was: import of state borders?)
On 31 August 2012 14:43, Michael Krämer ohr...@gmail.com wrote: But the key problem is that the boundary is not calculated from the coastline directly. Instead of the coastline an artificial line called baseline is used Well, I think the baseline is defined here.. http://www.comlaw.gov.au/Details/F2006L00525 I don't think we have any issues using those facts as a source. Ian. ___ Talk-au mailing list Talk-au@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk-au
