Re: [Talk-GB] man_made=survey_point

[Nick]

Thanks Jass - I was not aware of this excellent piece of work by Greg - 
do we know if the proposals "Possible import" were followed through?


I wonder if OS have other data for the 'benchmarks i.e. more precise 
than the data currently available.


On 23/08/2020 15:26, Jass Kurn wrote:
Gregrs has provided converted data for trig points, with the data 
obtained from a FOI request. They created a page to explain the 
process, and made available the converted data as a gpx file 
https://wiki.openstreetmap.org/wiki/Ordnance_Survey_triangulation_stations .


Jass

On Sun, 23 Aug 2020 at 15:13, Nick > wrote:


My thinking was that most people surveying would not use accurate
and precise systems such as differential GPS and/or RTK. So if
these systems were used to accurately and precisely locate
distinct local markers (i.e. trig points, benchmarks etc.) then
local surveys could potentially use these to refine/check their
own surveys. This approach would still be based on community input
but could be used as an approach to education (e.g. local schools
involved) as to how surveying works in practice.

On 23/08/2020 12:27, SK53 wrote:

This approach has been advocated in other European countries, and
the Spanish community imported all the points of the national
geodesic network (e.g., for Extremadura
).
They more or less violate the idea of OSM as something which is
community contributed (IIRC each point has "DO NOT MOVE") and
often interfere with objects which do need mapping (churches are
a particular point). It's not clear that this import has assisted
improved accuracy of mapping in Spain.

Many trig pillars are now way out of alignment and mainly of
interest as an artefact. Even benchmarks might not have much
relevance as OS surveying mainly uses differential GPS with
reference to their own base network (OS Net

).
(From the OS website "Ordnance Survey (OS) benchmarks and their
heights haven't been regularly maintained for over 40 years.").

OS Net is effectively proprietary, there are a limited number of
open base stations for differential GPS in the UK. I do believe
differential GPS (RTK) has a role to play in OSM surveying,
although for specific purposes rather than generic improvement of
feature alignment.

Regards,

Jerry

On Sun, 23 Aug 2020 at 10:05, Nick mailto:n...@foresters.org>> wrote:

I have been looking at what is recorded under this tag in my
area. I see
that there aren't that many and those that are on OSM refer
to trig
points (see also http://trigpointing.uk/). My thinking is
that if these
are accurate and precisely marked on OSM then perhaps they
could be used
for resolving issue such as aerial imagery offsets.

I therefore wondered if it was worth using other data under
this tag -
specifically benchmarks
(https://www.ordnancesurvey.co.uk/benchmarks/)
as there are huge numbers in the UK. If these were marked on
OSM and
their accuracy and precision verified (OS open data is to the
nearest
10m square and transforming that adds errors), they could be
helpful in
local surveys where they are less than accurate but also for
ensuring
that moving all nodes in an area is valid (not just to match
aerial
imagery). A possible linked organisation with data is
https://www.bench-marks.org.uk/

Incidentally, the benchmarks can be helpful if you need to align
historical maps which have benchmarks shown.

Any thoughts?


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Re: [Talk-GB] man_made=survey_point

[Jass Kurn]

Gregrs has provided converted data for trig points, with the data obtained
from a FOI request. They created a page to explain the process, and made
available the converted data as a gpx file
https://wiki.openstreetmap.org/wiki/Ordnance_Survey_triangulation_stations .

Jass

On Sun, 23 Aug 2020 at 15:13, Nick  wrote:

> My thinking was that most people surveying would not use accurate and
> precise systems such as differential GPS and/or RTK. So if these systems
> were used to accurately and precisely locate distinct local markers (i.e.
> trig points, benchmarks etc.) then local surveys could potentially use
> these to refine/check their own surveys. This approach would still be based
> on community input but could be used as an approach to education (e.g.
> local schools involved) as to how surveying works in practice.
> On 23/08/2020 12:27, SK53 wrote:
>
> This approach has been advocated in other European countries, and the
> Spanish community imported all the points of the national geodesic network
> (e.g., for Extremadura
> ).
> They more or less violate the idea of OSM as something which is community
> contributed (IIRC each point has "DO NOT MOVE") and often interfere with
> objects which do need mapping (churches are a particular point). It's not
> clear that this import has assisted improved accuracy of mapping in Spain.
>
> Many trig pillars are now way out of alignment and mainly of interest as
> an artefact. Even benchmarks might not have much relevance as OS surveying
> mainly uses differential GPS with reference to their own base network (OS
> Net
> ).
> (From the OS website "Ordnance Survey (OS) benchmarks and their heights
> haven't been regularly maintained for over 40 years.").
>
> OS Net is effectively proprietary, there are a limited number of open base
> stations for differential GPS in the UK. I do believe differential GPS
> (RTK) has a role to play in OSM surveying, although for specific purposes
> rather than generic improvement of feature alignment.
>
> Regards,
>
> Jerry
>
> On Sun, 23 Aug 2020 at 10:05, Nick  wrote:
>
>> I have been looking at what is recorded under this tag in my area. I see
>> that there aren't that many and those that are on OSM refer to trig
>> points (see also http://trigpointing.uk/). My thinking is that if these
>> are accurate and precisely marked on OSM then perhaps they could be used
>> for resolving issue such as aerial imagery offsets.
>>
>> I therefore wondered if it was worth using other data under this tag -
>> specifically benchmarks (https://www.ordnancesurvey.co.uk/benchmarks/)
>> as there are huge numbers in the UK. If these were marked on OSM and
>> their accuracy and precision verified (OS open data is to the nearest
>> 10m square and transforming that adds errors), they could be helpful in
>> local surveys where they are less than accurate but also for ensuring
>> that moving all nodes in an area is valid (not just to match aerial
>> imagery). A possible linked organisation with data is
>> https://www.bench-marks.org.uk/
>>
>> Incidentally, the benchmarks can be helpful if you need to align
>> historical maps which have benchmarks shown.
>>
>> Any thoughts?
>>
>>
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>> Talk-GB mailing list
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>>
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>
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Re: [Talk-GB] man_made=survey_point

[Nick]

My thinking was that most people surveying would not use accurate and 
precise systems such as differential GPS and/or RTK. So if these systems 
were used to accurately and precisely locate distinct local markers 
(i.e. trig points, benchmarks etc.) then local surveys could potentially 
use these to refine/check their own surveys. This approach would still 
be based on community input but could be used as an approach to 
education (e.g. local schools involved) as to how surveying works in 
practice.


On 23/08/2020 12:27, SK53 wrote:
This approach has been advocated in other European countries, and the 
Spanish community imported all the points of the national geodesic 
network (e.g., for Extremadura 
). 
They more or less violate the idea of OSM as something which is 
community contributed (IIRC each point has "DO NOT MOVE") and often 
interfere with objects which do need mapping (churches are a 
particular point). It's not clear that this import has assisted 
improved accuracy of mapping in Spain.


Many trig pillars are now way out of alignment and mainly of interest 
as an artefact. Even benchmarks might not have much relevance as OS 
surveying mainly uses differential GPS with reference to their own 
base network (OS Net 
). 
(From the OS website "Ordnance Survey (OS) benchmarks and their 
heights haven't been regularly maintained for over 40 years.").


OS Net is effectively proprietary, there are a limited number of open 
base stations for differential GPS in the UK. I do believe 
differential GPS (RTK) has a role to play in OSM surveying, although 
for specific purposes rather than generic improvement of feature 
alignment.


Regards,

Jerry

On Sun, 23 Aug 2020 at 10:05, Nick > wrote:


I have been looking at what is recorded under this tag in my area.
I see
that there aren't that many and those that are on OSM refer to trig
points (see also http://trigpointing.uk/). My thinking is that if
these
are accurate and precisely marked on OSM then perhaps they could
be used
for resolving issue such as aerial imagery offsets.

I therefore wondered if it was worth using other data under this
tag -
specifically benchmarks
(https://www.ordnancesurvey.co.uk/benchmarks/)
as there are huge numbers in the UK. If these were marked on OSM and
their accuracy and precision verified (OS open data is to the nearest
10m square and transforming that adds errors), they could be
helpful in
local surveys where they are less than accurate but also for ensuring
that moving all nodes in an area is valid (not just to match aerial
imagery). A possible linked organisation with data is
https://www.bench-marks.org.uk/

Incidentally, the benchmarks can be helpful if you need to align
historical maps which have benchmarks shown.

Any thoughts?


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Re: [Talk-GB] man_made=survey_point

[SK53]

This approach has been advocated in other European countries, and the
Spanish community imported all the points of the national geodesic network
(e.g., for Extremadura
).
They more or less violate the idea of OSM as something which is community
contributed (IIRC each point has "DO NOT MOVE") and often interfere with
objects which do need mapping (churches are a particular point). It's not
clear that this import has assisted improved accuracy of mapping in Spain.

Many trig pillars are now way out of alignment and mainly of interest as an
artefact. Even benchmarks might not have much relevance as OS surveying
mainly uses differential GPS with reference to their own base network (OS
Net
).
(From the OS website "Ordnance Survey (OS) benchmarks and their heights
haven't been regularly maintained for over 40 years.").

OS Net is effectively proprietary, there are a limited number of open base
stations for differential GPS in the UK. I do believe differential GPS
(RTK) has a role to play in OSM surveying, although for specific purposes
rather than generic improvement of feature alignment.

Regards,

Jerry

On Sun, 23 Aug 2020 at 10:05, Nick  wrote:

> I have been looking at what is recorded under this tag in my area. I see
> that there aren't that many and those that are on OSM refer to trig
> points (see also http://trigpointing.uk/). My thinking is that if these
> are accurate and precisely marked on OSM then perhaps they could be used
> for resolving issue such as aerial imagery offsets.
>
> I therefore wondered if it was worth using other data under this tag -
> specifically benchmarks (https://www.ordnancesurvey.co.uk/benchmarks/)
> as there are huge numbers in the UK. If these were marked on OSM and
> their accuracy and precision verified (OS open data is to the nearest
> 10m square and transforming that adds errors), they could be helpful in
> local surveys where they are less than accurate but also for ensuring
> that moving all nodes in an area is valid (not just to match aerial
> imagery). A possible linked organisation with data is
> https://www.bench-marks.org.uk/
>
> Incidentally, the benchmarks can be helpful if you need to align
> historical maps which have benchmarks shown.
>
> Any thoughts?
>
>
> ___
> Talk-GB mailing list
> Talk-GB@openstreetmap.org
> https://lists.openstreetmap.org/listinfo/talk-gb
>
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[Talk-GB] man_made=survey_point

[Nick]

I have been looking at what is recorded under this tag in my area. I see 
that there aren't that many and those that are on OSM refer to trig 
points (see also http://trigpointing.uk/). My thinking is that if these 
are accurate and precisely marked on OSM then perhaps they could be used 
for resolving issue such as aerial imagery offsets.


I therefore wondered if it was worth using other data under this tag - 
specifically benchmarks (https://www.ordnancesurvey.co.uk/benchmarks/) 
as there are huge numbers in the UK. If these were marked on OSM and 
their accuracy and precision verified (OS open data is to the nearest 
10m square and transforming that adds errors), they could be helpful in 
local surveys where they are less than accurate but also for ensuring 
that moving all nodes in an area is valid (not just to match aerial 
imagery). A possible linked organisation with data is 
https://www.bench-marks.org.uk/


Incidentally, the benchmarks can be helpful if you need to align 
historical maps which have benchmarks shown.


Any thoughts?


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