[Talk-gb-westmidlands] Personal Survey Points

[Andy Robinson]

Some trig points are also part of the OS's GPS reference system so their
definitive position is listed. However the majority of trig point and all
benchmarks are basically now redundant historical monuments only.

 

Cheers

Andy

 

From: rob.j.nickerson at gmail.com [mailto:rob.j.nickerson at gmail.com] 
Sent: 26 May 2012 16:22
To: Philip Barnes; talk-gb-westmidlands at openstreetmap.org
Subject: Re: [Talk-gb-westmidlands] Personal Survey Points

 

For recording trig points in OSM you can use [1], but there is nothing to
stop someone moving the location of the node (e.g. to line up with aerial
imagery). Do we know how accurate trig points are? If you feel this page
needs expanding, feel free to send comments to this mailing list.

As for GPS surveys, accuracy varies day to day and can deteriorate in built
up areas (where line of sight to satellite is reduced and the chance of
signals being reflected of buildings is increased). Unless you have a very
strong reason to believe the aerial imagery is misaligned, I would be
tempted to base your mapping on that.

[1] http://wiki.openstreetmap.org/wiki/Survey_point

Regards,
RobJN




On , Philip Barnes <phil at trigpoint.me.uk> wrote:
> On Fri, 2012-05-25 at 15:50 +0100, Big Fat Frog wrote:
> 
> > Thanks Gregory and Andy for your feedback.  You're right, next day I got
> 
> > a different result but only about 2 or 3 metres out.
> 
> >
> 
> > I long been convinced that the arial imagery is out and I've read as
> 
> > such elsewhere but if I use an offset then my changes are at odds with
> 
> > the the bulk of what others have done.
> 
> >
> 
> > So which is the yardstick?  Imagery, accurate survey points or something
> 
> > else? Also, if you beleive you have a hyper accurate surevy point, then
> 
> > shouldn't that be uploaded to OSM?
> 
> 
> 
> +1
> 
> I think they should. Am not certain if there are tags for things like
> 
> benchmarks and trigpoints, but there really should be.
> 
> http://en.wikipedia.org/wiki/Benchmark_%28surveying%29
> 
> 
> 
> My first post in Talk-West-Midlands, I tend to follow the group but as I
> 
> am based in deepest darkest Shropshire, the meet ups tend to be a bit
> 
> far away.
> 
> 
> 
> Phil (trig222)
> 
> 
> 
> 
> 
> 
> 
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> 
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> 
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> 
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> 
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