Re: [OSM-talk] Defective GPS trace

On Sun, Jan 3, 2010 at 9:17 AM, Jean-Marc Liotier wrote: > Steve Bennett wrote: > >> I'm even tempted to draw a massive straight line between several >> towns to indicate roads that I know exist but that I haven't >> surveyed. Would this offend a lot of people here? > > That would be using a map a

Re: [OSM-talk] Defective GPS trace

On Sun, Jan 3, 2010 at 10:17 AM, Jean-Marc Liotier wrote: > That would be using a map as an item in a to-do list. It would look ugly > to me and I doubt that many people would support that use. Better keep > the todo list separate - in another layer if you want it represented > geographically. >

Re: [OSM-talk] Defective GPS trace

2010/1/3 Steve Bennett : > completely missing way. I'm even tempted to draw a massive straight line > between several towns to indicate roads that I know exist but that I haven't > surveyed. Would this offend a lot of people here? I've done this, I knew a road ran between 2 towns but wasn't on OSM

Re: [OSM-talk] Defective GPS trace

Steve Bennett wrote: > On Sat, Jan 2, 2010 at 3:40 AM, Craig Wallace wrote: > > But I'd still agree with Shaun - a single GPS trace is not really > accurate enough for adding ways to OSM IMO. > > Hmmm...is there consensus on this view? My approach so far has been "any > information that i

Re: [OSM-talk] Defective GPS trace

On Sat, Jan 2, 2010 at 3:40 AM, Craig Wallace wrote: > But I'd still agree with Shaun - a single GPS trace is not really > accurate enough for adding ways to OSM IMO. > Hmmm...is there consensus on this view? My approach so far has been "any information that is approximately correct is better th

Re: [OSM-talk] Defective GPS trace

Martin Koppenhoefer schrieb: > while this might help in the case your devices calculations/capabilities > create the offset, this is still no help in the case of atmospheric > interferences. True, but it does help in practice. ___ talk mailing list

Re: [OSM-talk] Defective GPS trace

2010/1/1 Ulf Möller > > You can check the satellite screen on the Garmin. It should show an > > estimated position accuracy. > > > The eTrex often claims 10m accuracy when in fact it is 50m off, so that > doesn't really help. Using two different GPS receivers is a good idea if > you don't want to

Re: [OSM-talk] Defective GPS trace

Craig Wallace wrote: > But I'd still agree with Shaun - a single GPS trace is not really > accurate enough for adding ways to OSM IMO. Whilst I agree - more the merrier, just because you have only one trace it's not a valid reason not to upload it. If you feel it's an accurate representation, g

Re: [OSM-talk] Defective GPS trace

Steve Bennett wrote: > I've got a trace from today which is significantly out of sync with a > path I traced from Nearmap: > > http://www.openstreetmap.org/edit?lat=-37.880138&lon=145.193417&zoom=19&gpx=594988 > >

Re: [OSM-talk] Defective GPS trace

Liz wrote: > On Sat, 2 Jan 2010, Michael Hufer wrote: > >> On the Oregon 550(t) you will find the satellite almanac-screen if you >> touch the "five-bars" satellite reception indicator. >> >> > Thanks, will try it. > Later I might read the instructions. > > I wouldn't bother, they're n

Re: [OSM-talk] Defective GPS trace

On Sat, 2 Jan 2010, Michael Hufer wrote: > On the Oregon 550(t) you will find the satellite almanac-screen if you > touch the "five-bars" satellite reception indicator. > Thanks, will try it. Later I might read the instructions. ___ talk mailing list

Re: [OSM-talk] Defective GPS trace

Thanks for the comments, everyone. In all my playing with nearmap, I have little reason to doubt their accuracy. There are a couple of little seams here and there, but nothing more than a couple of metres. Giving the way this trace here meanders all over the place, I'm pretty confident that the nea

Re: [OSM-talk] Defective GPS trace

2010/1/2 Anthony : > This seems like somewhere that the wisdom of crowds actually applies.  I > think I'd trust the average of a bunch of independent GPS traces to a single > orthorectified aerial - especially in an area which isn't extremely flat. > But I guess I might be convinced otherwise, if I

Re: [OSM-talk] Defective GPS trace

2010/1/2 Aun Johnsen : > Than they have done a hell of a job on aligning the fotos, cudos to them. I > know that Yahoo imagery varies from less then 1 meter to at least 30 meters > on the hi-res, havn't seen nearmap, and as I understand its only for > Australia, so I would not have any data to comp

Re: [OSM-talk] Defective GPS trace

2010/1/2 Anthony : > Where are you getting that "sub-metre accuracy" claim from?  This thread > (http://www.mail-archive.com/talk...@openstreetmap.org/msg03414.html), which > you contributed to, throws out "3-5 meters", "1-4 meters", and "5 meters or > so". They claim the imagery should be sub-met

Re: [OSM-talk] Defective GPS trace

On Fri, Jan 1, 2010 at 6:49 PM, John Smith wrote: > 2010/1/2 Aun Johnsen : > > Even if you have access to good arial photography, remember that it might > be > > out of alignment, it can be a good advise to gather some good fixes to > check > > the alignment of your photos, this can be several GPS

Re: [OSM-talk] Defective GPS trace

On Fri, Jan 1, 2010 at 11:49 PM, John Smith wrote: > 2010/1/2 Aun Johnsen : > > Even if you have access to good arial photography, remember that it might > be > > out of alignment, it can be a good advise to gather some good fixes to > check > > the alignment of your photos, this can be several GP

Re: [OSM-talk] Defective GPS trace

> 2010/1/2 Steve Bennett : >> When I looked up WAAS on wikipedia a while ago, it appeared that we do >> have >> an equivalent system in Australia (although the term WAAS is american), >> but >> I'm not sure how to tell whether it's functioning in a given area. I >> switched the WAAS capability on t

Re: [OSM-talk] Defective GPS trace

2010/1/2 Aun Johnsen : > Even if you have access to good arial photography, remember that it might be > out of alignment, it can be a good advise to gather some good fixes to check > the alignment of your photos, this can be several GPS tracks along your > trail. I'm pretty sure the imagery he's r

Re: [OSM-talk] Defective GPS trace

2010/1/2 Steve Bennett : > When I looked up WAAS on wikipedia a while ago, it appeared that we do have > an equivalent system in Australia (although the term WAAS is american), but > I'm not sure how to tell whether it's functioning in a given area. I > switched the WAAS capability on the GPS on, b

Re: [OSM-talk] Defective GPS trace

On Sat, Jan 2, 2010 at 8:17 AM, Aun Johnsen wrote: > The accuracy shown on your GPS unit is not necessary the actual accuracy, > but just a calculated accuracy depending on the signals your unit is > receiving. You can experience athmospheric disturbance, plasma-effects, > signals reflected off t

Re: [OSM-talk] Defective GPS trace

The accuracy shown on your GPS unit is not necessary the actual accuracy, but just a calculated accuracy depending on the signals your unit is receiving. You can experience athmospheric disturbance, plasma-effects, signals reflected off tall buildings, canyon or urban canyon effects, bed satellite

Re: [OSM-talk] Defective GPS trace

You can also use Oregon's Waypoint Averaging function to make more accurate positioning of waypoints. But you need to do this at different times (say on you next hiking trip when you cross the same waypoint) for this to be really effective. With couple of accurate waypoints it is easier to detect t

Re: [OSM-talk] Defective GPS trace

On the Oregon 550(t) you will find the satellite almanac-screen if you touch the "five-bars" satellite reception indicator. Micha H. > On Sat, 2 Jan 2010, Craig Wallace wrote: > > You can check the satellite screen on the Garmin. It should show an > > estimated position accuracy. > > Als

Re: [OSM-talk] Defective GPS trace

On Fri, Jan 1, 2010 at 11:40 AM, Craig Wallace wrote: > On 01/01/2010 14:14, Steve Bennett wrote: > > Well...ok. But in this case I have the aerial photography, so I can just > > trace it, once I know more or less where the path goes. > > Though yes, this is not really necessary if you have ac

Re: [OSM-talk] Defective GPS trace

On Sat, 2 Jan 2010, Craig Wallace wrote: > You can check the satellite screen on the Garmin. It should show an > estimated position accuracy. > Also, you can look at which satellites its receiving. If its locked on > to a reasonable number of satellites in a decent spread across the sky, > you c

Re: [OSM-talk] Defective GPS trace

On 01/01/2010, at 17.40, Craig Wallace wrote: > But I'd still agree with Shaun - a single GPS trace is not really > accurate enough for adding ways to OSM IMO. > I'd say get at least 2, preferably 1 in each direction. If they are > close to each other you can be confident its probably accurate. I

Re: [OSM-talk] Defective GPS trace

Craig Wallace schrieb: > You can check the satellite screen on the Garmin. It should show an > estimated position accuracy. The eTrex often claims 10m accuracy when in fact it is 50m off, so that doesn't really help. Using two different GPS receivers is a good idea if you don't want to survey

Re: [OSM-talk] Defective GPS trace

On 01/01/2010 14:14, Steve Bennett wrote: > On Sat, Jan 2, 2010 at 12:54 AM, Shaun McDonald > mailto:sh...@shaunmcdonald.me.uk>> wrote: > > It is very common for GPSs to give errors for whatever reason. > Interference is very common from things like buildings. Newer units > are less lik

Re: [OSM-talk] Defective GPS trace

On Sat, Jan 2, 2010 at 12:54 AM, Shaun McDonald wrote: > It is very common for GPSs to give errors for whatever reason. Interference > is very common from things like buildings. Newer units are less likely to > have an issue. You simply need to go along that track again a few times to > get an ave

Re: [OSM-talk] Defective GPS trace

On 1 Jan 2010, at 13:07, Steve Bennett wrote: > I've got a trace from today which is significantly out of sync with a path I > traced from Nearmap: > > http://www.openstreetmap.org/edit?lat=-37.880138&lon=145.193417&zoom=19&gpx=594988 > > The trace looks like I was wandering through the grassy

Re: [OSM-talk] Defective GPS trace

Steve Bennett wrote: > The trace looks like I was wandering through the grassy paddock, but I > was actually following exactly that northern most "highway=path" in > the bush. So it looks like the trace is incorrectly recorded something > like 50m north of where I actually was. Now, since the discr

[OSM-talk] Defective GPS trace

I've got a trace from today which is significantly out of sync with a path I traced from Nearmap: http://www.openstreetmap.org/edit?lat=-37.880138&lon=145.193417&zoom=19&gpx=594988 The trace looks like I was wandering through the grassy paddock, but I was actually following exactly that northern