[talk-au] Misaligned streets OSM or Bing wrong? - use survey mark?

2012-08-31 Thread Russell Edwards
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 usual

Re: [talk-au] Misaligned streets OSM or Bing wrong? - use survey mark?

2012-08-31 Thread Ben Johnson
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 a

Re: [talk-au] Misaligned streets OSM or Bing wrong? - use survey mark?

2012-08-31 Thread 4x4falcon
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

Re: [talk-au] Misaligned streets OSM or Bing wrong? - use survey mark?

2012-08-31 Thread Ian Sergeant
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, an

Re: [talk-au] Misaligned streets OSM or Bing wrong? - use survey mark?

2012-08-31 Thread Russell Edwards
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 avera

Re: [talk-au] Misaligned streets OSM or Bing wrong? - use survey mark?

2012-08-31 Thread Ben Johnson
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 l

Re: [talk-au] Misaligned streets OSM or Bing wrong? - use survey mark?

2012-08-31 Thread Stephen Hope
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 memo

Re: [talk-au] Misaligned streets OSM or Bing wrong? - use survey mark?

2012-09-01 Thread Ben Johnson
On 01/09/2012, at 16:58, Stephen Hope wrote: > 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? Austral

Re: [talk-au] Misaligned streets OSM or Bing wrong? - use survey mark?

2012-09-01 Thread Ian Sergeant
>> 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. > Can we get a definitive answer on this? I think the terminolo

Re: [talk-au] Misaligned streets OSM or Bing wrong? - use survey mark?

2012-09-01 Thread Russell Edwards
GDA94 to WGS84 is approx 45 cm from what I read but it will be affected by continental drift. GDA is fixed to points on the Australian plate so GDA coordinates will not change (much) but I guess OSM is really meant to be in WGS84. Just an update to this thread in case anyone is interested, I re-di

Re: [talk-au] Misaligned streets OSM or Bing wrong? - use survey mark?

2012-09-01 Thread 4x4falcon
On 02/09/12 10:14, Russell Edwards wrote: GDA94 to WGS84 is approx 45 cm from what I read but it will be affected by continental drift. GDA is fixed to points on the Australian plate so GDA coordinates will not change (much) but I guess OSM is really meant to be in WGS84. Just an update to this

Re: [talk-au] Misaligned streets OSM or Bing wrong? - use survey mark?

2012-09-01 Thread Ian Sergeant
On 02/09/12 12:46, 4x4falcon wrote: It's interesting that the traces from nearmap are misaligned as I said previously their guarantee was that the accuracy was within 1m. Not so interesting since we aren't using nearmap any longer, and many of the nearmap traced ways have had their accuracy

Re: [talk-au] Misaligned streets OSM or Bing wrong? - use survey mark?

2012-09-02 Thread 4x4falcon
On 01/09/12 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 m

Re: [talk-au] Misaligned streets OSM or Bing wrong? - use survey mark?

2012-09-02 Thread Russell Edwards
On Sun, Sep 2, 2012 at 1:17 PM, 4x4falcon wrote: > > Actually I have to ask also why are you tracing from bing imagery when you > have gps traces and should be adding them as source=survey > Is that not the done thing? GPS traces are usually 5-15 m in error in a random direction. Bing's pixels