Re: [talk-au] Misaligned streets OSM or Bing wrong? - use survey mark?
On 1 September 2012 11:35, Russell Edwards wrote: > > I am still curious to know what the positional accuracy of survey markers > is meant to be, if anyone can enlighten. > > First question you have to ask is how old the survey is? Australia as a whole moves north about 7-8 cm a year (from memory), so a 12-13 year old survey has moved about a metre from the start spot. It's a moving target. Survey markers stay pretty accurate in relation to everything around them, but not necessarily in relation to some outside measuring source like GPS. But an even bigger error can be caused by using different projections. I forget which one OSM uses, but using different projections can move a given point 20m quite easily, and a survey marker may well be on a different one. Stephen ___ Talk-au mailing list Talk-au@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk-au
Re: [talk-au] Misaligned streets OSM or Bing wrong? - use survey mark?
Russell, Found this on a search. This might be your answer to average your tracks - http://wiki.openstreetmap.org/wiki/Average_tracks Sent from my iPhone On 01/09/2012, at 11:35, Russell Edwards wrote: > Thanks everyone for the replies. I have imported over 250 GPX traces from my > running log, boy does that slow JOSM down. It seems Bing may be offset but > having 100+ traces on some paths it is all just a big wide blob of grey. > Still, the blob is offset. I might try and cobble together a tool to average > them, in my non-existent spare time. Shouldn't be too hard for straight line > paths (famous last words). > > BJ - yep I would love to dive in, already have -- but would hate to spend > hours editing only to later realise I need to painstakingly go through and > fix everything I've already done! > > I am still curious to know what the positional accuracy of survey markers is > meant to be, if anyone can enlighten. > > > > On Sat, Sep 1, 2012 at 10:47 AM, Ian Sergeant wrote: > Agree with everything that Ben said. > > In addition, you may like to check the AGRI imagery. If the Bing and > AGRI imagery align exactly, chances are you have well aligned Bing > imagery. If the AGRI imagery aligns well with traces, it is easy > enough to shift the Bing background to align with AGRI, and go from > there. > > It may be an idea if you trace from bing offset, to mark that as your > source, i.e source=bing (offset). That way people coming after you > know what you've done. > > Ian. > > On 1 September 2012 09:53, Ben Johnson wrote: > > Hi Russell, > > > > Welcome aboard. Just my thoughts... > > > > For a newbie, you've made some very astute observations about the accuracy > > of the aerial imagery, so thanks for giving it the degree of thought - > > because many others just dive in and start tracing without understanding > > these subtleties. > > > > You're absolutely correct. Its quite normal for Bing (and others) to be off > > by 10m or so, but in other areas it's very accurate. It differs all over the > > place. > > > > Whatever editing tool you're using (Potlatch, JOSM, etc..), should give you > > the ability to align your background imagery. Just be aware the further you > > move away from the area you have aligned, the more likely the alignment will > > need another adjustment. > > > > JOSM allows you "bookmark" such alignments. I have a bookmark for my home > > town. But the danger of bookmarking your aerial alignment is that if Bing > > updates their imagery, your bookmarked alignment will probably no longer > > apply. Just something to keep in mind. > > > > Your known survey mark is definitely an excellent start. You can make a node > > in OSM to those exact coordinates, then align your background imagery so the > > location of the survey mark in Bing aligns to your OSM node. > > > > I would not rely on other people's OSM edits on which to base your > > alignment. You don't know how accurate or inaccurate they are. Your survey > > mark is the best way, and the GPS traces. > > > > Are you aware you can upload and share your GPS traces (in your profile > > section), and you can view all the uploaded traces while editing? This is > > great for aligning the background image. Depending where you live, you might > > have some major roads in your area which already have lots of traces. If so, > > that's great - try and find a couple of busy intersections to align and you > > should get a good alignment. > > > > Otherwise you can try walking around a block several times, or around a > > park, or around a roundabout many many times (if you see men in white coming > > to get you... Run!) Another method is to use a fixed point - and approach it > > from different angles like cross hairs to a target. > > > > As far as GPX averaging goes, I'm personally not familiar with anything that > > does this, but this list has some very talented people who can help or point > > you in the right direction. I find software averaging is not necessary > > because if you look at the traces visually you'll immediately get a very > > good idea from their density when they're all presented together (eg if you > > look at the traces on a busy dual carriageway motorway you'll very easily > > see an "average" for each carriageway). In built up areas you just need to > > be mindful of whether traces originate from cyclists, motorists, or > > pedestrians... and apply a degree of commonsense. I'm not sure if software > > can possibly distinguish between a set of traces from a roadway, and another > > set of traces from an adjacent walkway / cycleway - in such cases an average > > is meaningless. > > > > As far as tweaking other people's edits... if you're confident with your > > accuracy, I'd just do it. But if you want to take a more cautious approach > > you can contact the original editor and ask whether they mind you tweaking - > > or at least ask what method they used to position their nodes and let them > > kno
Re: [talk-au] Misaligned streets OSM or Bing wrong? - use survey mark?
Thanks everyone for the replies. I have imported over 250 GPX traces from my running log, boy does that slow JOSM down. It seems Bing may be offset but having 100+ traces on some paths it is all just a big wide blob of grey. Still, the blob is offset. I might try and cobble together a tool to average them, in my non-existent spare time. Shouldn't be too hard for straight line paths (famous last words). BJ - yep I would love to dive in, already have -- but would hate to spend hours editing only to later realise I need to painstakingly go through and fix everything I've already done! I am still curious to know what the positional accuracy of survey markers is meant to be, if anyone can enlighten. On Sat, Sep 1, 2012 at 10:47 AM, Ian Sergeant wrote: > Agree with everything that Ben said. > > In addition, you may like to check the AGRI imagery. If the Bing and > AGRI imagery align exactly, chances are you have well aligned Bing > imagery. If the AGRI imagery aligns well with traces, it is easy > enough to shift the Bing background to align with AGRI, and go from > there. > > It may be an idea if you trace from bing offset, to mark that as your > source, i.e source=bing (offset). That way people coming after you > know what you've done. > > Ian. > > On 1 September 2012 09:53, Ben Johnson wrote: > > Hi Russell, > > > > Welcome aboard. Just my thoughts... > > > > For a newbie, you've made some very astute observations about the > accuracy > > of the aerial imagery, so thanks for giving it the degree of thought - > > because many others just dive in and start tracing without understanding > > these subtleties. > > > > You're absolutely correct. Its quite normal for Bing (and others) to be > off > > by 10m or so, but in other areas it's very accurate. It differs all over > the > > place. > > > > Whatever editing tool you're using (Potlatch, JOSM, etc..), should give > you > > the ability to align your background imagery. Just be aware the further > you > > move away from the area you have aligned, the more likely the alignment > will > > need another adjustment. > > > > JOSM allows you "bookmark" such alignments. I have a bookmark for my home > > town. But the danger of bookmarking your aerial alignment is that if Bing > > updates their imagery, your bookmarked alignment will probably no longer > > apply. Just something to keep in mind. > > > > Your known survey mark is definitely an excellent start. You can make a > node > > in OSM to those exact coordinates, then align your background imagery so > the > > location of the survey mark in Bing aligns to your OSM node. > > > > I would not rely on other people's OSM edits on which to base your > > alignment. You don't know how accurate or inaccurate they are. Your > survey > > mark is the best way, and the GPS traces. > > > > Are you aware you can upload and share your GPS traces (in your profile > > section), and you can view all the uploaded traces while editing? This is > > great for aligning the background image. Depending where you live, you > might > > have some major roads in your area which already have lots of traces. If > so, > > that's great - try and find a couple of busy intersections to align and > you > > should get a good alignment. > > > > Otherwise you can try walking around a block several times, or around a > > park, or around a roundabout many many times (if you see men in white > coming > > to get you... Run!) Another method is to use a fixed point - and > approach it > > from different angles like cross hairs to a target. > > > > As far as GPX averaging goes, I'm personally not familiar with anything > that > > does this, but this list has some very talented people who can help or > point > > you in the right direction. I find software averaging is not necessary > > because if you look at the traces visually you'll immediately get a very > > good idea from their density when they're all presented together (eg if > you > > look at the traces on a busy dual carriageway motorway you'll very easily > > see an "average" for each carriageway). In built up areas you just need > to > > be mindful of whether traces originate from cyclists, motorists, or > > pedestrians... and apply a degree of commonsense. I'm not sure if > software > > can possibly distinguish between a set of traces from a roadway, and > another > > set of traces from an adjacent walkway / cycleway - in such cases an > average > > is meaningless. > > > > As far as tweaking other people's edits... if you're confident with your > > accuracy, I'd just do it. But if you want to take a more cautious > approach > > you can contact the original editor and ask whether they mind you > tweaking - > > or at least ask what method they used to position their nodes and let > them > > know you can make it more accurate for them. Keep in mind there are many > > "inactive" users who move onto other hobbies after a while - so if you > don't > > hear back from somebody after a reasonable time,
Re: [talk-au] Misaligned streets OSM or Bing wrong? - use survey mark?
Agree with everything that Ben said. In addition, you may like to check the AGRI imagery. If the Bing and AGRI imagery align exactly, chances are you have well aligned Bing imagery. If the AGRI imagery aligns well with traces, it is easy enough to shift the Bing background to align with AGRI, and go from there. It may be an idea if you trace from bing offset, to mark that as your source, i.e source=bing (offset). That way people coming after you know what you've done. Ian. On 1 September 2012 09:53, Ben Johnson wrote: > Hi Russell, > > Welcome aboard. Just my thoughts... > > For a newbie, you've made some very astute observations about the accuracy > of the aerial imagery, so thanks for giving it the degree of thought - > because many others just dive in and start tracing without understanding > these subtleties. > > You're absolutely correct. Its quite normal for Bing (and others) to be off > by 10m or so, but in other areas it's very accurate. It differs all over the > place. > > Whatever editing tool you're using (Potlatch, JOSM, etc..), should give you > the ability to align your background imagery. Just be aware the further you > move away from the area you have aligned, the more likely the alignment will > need another adjustment. > > JOSM allows you "bookmark" such alignments. I have a bookmark for my home > town. But the danger of bookmarking your aerial alignment is that if Bing > updates their imagery, your bookmarked alignment will probably no longer > apply. Just something to keep in mind. > > Your known survey mark is definitely an excellent start. You can make a node > in OSM to those exact coordinates, then align your background imagery so the > location of the survey mark in Bing aligns to your OSM node. > > I would not rely on other people's OSM edits on which to base your > alignment. You don't know how accurate or inaccurate they are. Your survey > mark is the best way, and the GPS traces. > > Are you aware you can upload and share your GPS traces (in your profile > section), and you can view all the uploaded traces while editing? This is > great for aligning the background image. Depending where you live, you might > have some major roads in your area which already have lots of traces. If so, > that's great - try and find a couple of busy intersections to align and you > should get a good alignment. > > Otherwise you can try walking around a block several times, or around a > park, or around a roundabout many many times (if you see men in white coming > to get you... Run!) Another method is to use a fixed point - and approach it > from different angles like cross hairs to a target. > > As far as GPX averaging goes, I'm personally not familiar with anything that > does this, but this list has some very talented people who can help or point > you in the right direction. I find software averaging is not necessary > because if you look at the traces visually you'll immediately get a very > good idea from their density when they're all presented together (eg if you > look at the traces on a busy dual carriageway motorway you'll very easily > see an "average" for each carriageway). In built up areas you just need to > be mindful of whether traces originate from cyclists, motorists, or > pedestrians... and apply a degree of commonsense. I'm not sure if software > can possibly distinguish between a set of traces from a roadway, and another > set of traces from an adjacent walkway / cycleway - in such cases an average > is meaningless. > > As far as tweaking other people's edits... if you're confident with your > accuracy, I'd just do it. But if you want to take a more cautious approach > you can contact the original editor and ask whether they mind you tweaking - > or at least ask what method they used to position their nodes and let them > know you can make it more accurate for them. Keep in mind there are many > "inactive" users who move onto other hobbies after a while - so if you don't > hear back from somebody after a reasonable time, consider it fair game to > change it. > > Again, well done for going through this thought process, and welcome! > > BJ > > > > Sent from my iPhone > > On 01/09/2012, at 8:11, Russell Edwards wrote: > > Hello -- brand new user here, please be patient :). > > I am trying to improve OSM in my home town. I notice that many/most OSM ways > are approx 5-10 m west of where Bing has them. > > Most either have nearmap or nothing as a source. There are no GPS tracks to > download. I could make some but they're usually in (random) error by about > the same amount anyway. > > I tried to check against the coordinates given for a survey mark in town, > through http://services.land.vic.gov.au/maps/lassi.jsp (with conversion to > lat/lon with http://www.gracode.com/mapgrids.php ) ... this also had the > Bing map out by about 10 m... but southward! > > Help! Three inconsistent systems - Bing, OSM and the survey mark. Which if > any should I trust at the 1-m level? >
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 wrote: > 2012/8/31 Ian Sergeant >> >> >> 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 >> >> 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] Misaligned streets OSM or Bing wrong? - use survey mark?
The bing imagery is out. As per here: http://wiki.openstreetmap.org/wiki/Bing#Precision you need to align the bing imagery to either gps traces or source=survey or source=nearmap. Nearmap guaranteed that their imagery was within one metre, although there are some areas that are outside this. Cheers Ross On 01/09/12 08:11, Russell Edwards wrote: Hello -- brand new user here, please be patient :). I am trying to improve OSM in my home town. I notice that many/most OSM ways are approx 5-10 m west of where Bing has them. Most either have nearmap or nothing as a source. There are no GPS tracks to download. I could make some but they're usually in (random) error by about the same amount anyway. I tried to check against the coordinates given for a survey mark in town, through http://services.land.vic.gov.au/maps/lassi.jsp (with conversion to lat/lon with http://www.gracode.com/mapgrids.php ) ... this also had the Bing map out by about 10 m... but southward! Help! Three inconsistent systems - Bing, OSM and the survey mark. Which if any should I trust at the 1-m level? Is there a tool for averaging GPS tracks? There are roads I have run along dozens of times with a GPS track for every run. Maybe with averaging it could get to the 1m level of accuracy. (Yeah yeah, don't sweat the small stuff... I just can't stand seeing streets running through people's front gardens...) Thanks in advance Russell ___ 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] Misaligned streets OSM or Bing wrong? - use survey mark?
Hi Russell, Welcome aboard. Just my thoughts... For a newbie, you've made some very astute observations about the accuracy of the aerial imagery, so thanks for giving it the degree of thought - because many others just dive in and start tracing without understanding these subtleties. You're absolutely correct. Its quite normal for Bing (and others) to be off by 10m or so, but in other areas it's very accurate. It differs all over the place. Whatever editing tool you're using (Potlatch, JOSM, etc..), should give you the ability to align your background imagery. Just be aware the further you move away from the area you have aligned, the more likely the alignment will need another adjustment. JOSM allows you "bookmark" such alignments. I have a bookmark for my home town. But the danger of bookmarking your aerial alignment is that if Bing updates their imagery, your bookmarked alignment will probably no longer apply. Just something to keep in mind. Your known survey mark is definitely an excellent start. You can make a node in OSM to those exact coordinates, then align your background imagery so the location of the survey mark in Bing aligns to your OSM node. I would not rely on other people's OSM edits on which to base your alignment. You don't know how accurate or inaccurate they are. Your survey mark is the best way, and the GPS traces. Are you aware you can upload and share your GPS traces (in your profile section), and you can view all the uploaded traces while editing? This is great for aligning the background image. Depending where you live, you might have some major roads in your area which already have lots of traces. If so, that's great - try and find a couple of busy intersections to align and you should get a good alignment. Otherwise you can try walking around a block several times, or around a park, or around a roundabout many many times (if you see men in white coming to get you... Run!) Another method is to use a fixed point - and approach it from different angles like cross hairs to a target. As far as GPX averaging goes, I'm personally not familiar with anything that does this, but this list has some very talented people who can help or point you in the right direction. I find software averaging is not necessary because if you look at the traces visually you'll immediately get a very good idea from their density when they're all presented together (eg if you look at the traces on a busy dual carriageway motorway you'll very easily see an "average" for each carriageway). In built up areas you just need to be mindful of whether traces originate from cyclists, motorists, or pedestrians... and apply a degree of commonsense. I'm not sure if software can possibly distinguish between a set of traces from a roadway, and another set of traces from an adjacent walkway / cycleway - in such cases an average is meaningless. As far as tweaking other people's edits... if you're confident with your accuracy, I'd just do it. But if you want to take a more cautious approach you can contact the original editor and ask whether they mind you tweaking - or at least ask what method they used to position their nodes and let them know you can make it more accurate for them. Keep in mind there are many "inactive" users who move onto other hobbies after a while - so if you don't hear back from somebody after a reasonable time, consider it fair game to change it. Again, well done for going through this thought process, and welcome! BJ Sent from my iPhone On 01/09/2012, at 8:11, Russell Edwards wrote: > Hello -- brand new user here, please be patient :). > > I am trying to improve OSM in my home town. I notice that many/most OSM ways > are approx 5-10 m west of where Bing has them. > > Most either have nearmap or nothing as a source. There are no GPS tracks to > download. I could make some but they're usually in (random) error by about > the same amount anyway. > > I tried to check against the coordinates given for a survey mark in town, > through http://services.land.vic.gov.au/maps/lassi.jsp (with conversion to > lat/lon with http://www.gracode.com/mapgrids.php ) ... this also had the Bing > map out by about 10 m... but southward! > > Help! Three inconsistent systems - Bing, OSM and the survey mark. Which if > any should I trust at the 1-m level? > > Is there a tool for averaging GPS tracks? There are roads I have run along > dozens of times with a GPS track for every run. Maybe with averaging it could > get to the 1m level of accuracy. > > (Yeah yeah, don't sweat the small stuff... I just can't stand seeing streets > running through people's front gardens...) > > Thanks in advance > > Russell > > ___ > Talk-au mailing list > Talk-au@openstreetmap.org > http://lists.openstreetmap.org/listinfo/talk-au ___ Talk-au mailing list Talk-au@openstreetmap.org http:/
[talk-au] Misaligned streets OSM or Bing wrong? - use survey mark?
Hello -- brand new user here, please be patient :). I am trying to improve OSM in my home town. I notice that many/most OSM ways are approx 5-10 m west of where Bing has them. Most either have nearmap or nothing as a source. There are no GPS tracks to download. I could make some but they're usually in (random) error by about the same amount anyway. I tried to check against the coordinates given for a survey mark in town, through http://services.land.vic.gov.au/maps/lassi.jsp (with conversion to lat/lon with http://www.gracode.com/mapgrids.php ) ... this also had the Bing map out by about 10 m... but southward! Help! Three inconsistent systems - Bing, OSM and the survey mark. Which if any should I trust at the 1-m level? Is there a tool for averaging GPS tracks? There are roads I have run along dozens of times with a GPS track for every run. Maybe with averaging it could get to the 1m level of accuracy. (Yeah yeah, don't sweat the small stuff... I just can't stand seeing streets running through people's front gardens...) Thanks in advance Russell ___ Talk-au mailing list Talk-au@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk-au
