Re: Boundaries and Roads

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Re: Boundaries and Roads

Dudley Ibbett
Hi

I could do with some advice on joining field boundaries to roads.  I have been doing this as the mapping style I am use to never has the field boundary running along the side the road.  If the field boundary along the road is well set back then I would consider drawing it however in most cases it is within a few meters of the road and sometimes there is not gap at all.  I believe the OSM application can in theory go down to 3m.  Drawing a field boundary along a road where the gap is less than 3 meters between the boundary (wall,fence) and the end of the road would therefore seem unrealistic.

Should I try and draw the field boundary along the road in all situations or only do this when there is a large gap > 3m?

If I don't draw the field boundary along the road should I link to the road or should I stop the boundary just short of the road?

Some guidance would be appreciated as I don't want to link boundaries to roads if this could cause problems.

Many thanks in advance.

Regards

Dudley

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Re: Boundaries and Roads

John Sturdy
On Sat, Apr 7, 2012 at 7:24 PM, Dudley Ibbett <[hidden email]> wrote:

> Should I try and draw the field boundary along the road in all situations or
> only do this when there is a large gap > 3m?
>
> If I don't draw the field boundary along the road should I link to the road
> or should I stop the boundary just short of the road?
>
> Some guidance would be appreciated as I don't want to link boundaries to
> roads if this could cause problems.

I think practices vary on this; I prefer to make them separate, partly
because the "road" is just the midline of the road, which is not where
the field ends, and partly for practicality of later editing: that
it's hard(er) to select a way that uses the same points as another
one.

What I've found is quite easy, and I think looks reasonably neat, is
to use the "make a parallel way" tool (in Potlatch, I haven't learnt
JOSM yet but I expect it has this too) to take a copy of the road, and
move it slightly aside to where the field boundary is, and cut it to
be just the piece you need for that field; then turn it into whatever
kind of barrier there is around the field (hedge, fence, etc) and also
use it as the edge of the field.  (That doesn't follow my suggestion
of making each way separate for easier selection, but I think it's
less likely to want to do things separately to the field and its
barrier, than to want to do things separately to the field and the
neighbouring road.)

__John

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Re: Boundaries and Roads

Xan-3
Al 08/04/12 17:12, En/na John Sturdy ha escrit:

> On Sat, Apr 7, 2012 at 7:24 PM, Dudley Ibbett<[hidden email]>  wrote:
>
>> Should I try and draw the field boundary along the road in all situations or
>> only do this when there is a large gap>  3m?
>>
>> If I don't draw the field boundary along the road should I link to the road
>> or should I stop the boundary just short of the road?
>>
>> Some guidance would be appreciated as I don't want to link boundaries to
>> roads if this could cause problems.
> I think practices vary on this; I prefer to make them separate, partly
> because the "road" is just the midline of the road, which is not where
> the field ends, and partly for practicality of later editing: that
> it's hard(er) to select a way that uses the same points as another
> one.
>
+1 for make separate.

Xan.

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Re: Boundaries and Roads

Bernd Vogelgesang
In reply to this post by Dudley Ibbett
Well,
from a GIS-persons point of view, you alway should avoid gaps in your map ( = in your data).
Cartographic work is always generalizing the world, and only because you COULD go into detail in the sub-meter sphere technically with the digital means nowadays, you should should ask yourself: what is it good for?

So, what would be the information you provide, leaving a blank space between a field and a road?
Actually none, cause you do not specify what this gap is, although its quite clear that it's something between the road and the field.
But when its already obvious that there are strips of surface which do not belong neither to roads nor fields, you could right away leave them out and align the border of the field directly to the road.

In digitizing you normally decide about the map scale of the end product. With OSM-maps, thats a little bit difficult, cause there is no common sense about the usage, and therefor also about the production-scale.

The planned scale is important, cause it decides about the precision you need to get a satisfying result.
E.g. when you want to have a map in 1:5000, you normally digitize your features at a scale of 1:2500 or 1:2000.
The human eye can not distinguish features smaller than half a millimeter on a screen or on paper.

With a map in 1:5000, 1/2mm on screen is 2,5 meters in reality. Thats the planned "error" you are "allowed" to produce, cause on the planned scale, you can't even see it.

So the question should always be: what is the planned usage and what is the benefit from increasing the accuracy?

A field border outside a village is much less interesting than borders and features in a town center.
When the mapped part is mostly relevant for navigating, so as a real street map, you could easily set your planned scale to 1:25000 or even higher (with the resulting need for generalization), as normal users will watch it in that scale anyway to get the overview they need.
If it's a feature of high interest, you could set your planned scale to 1:1000 or lower, with a resulting need of higher accuracy.

Hope that helped a bit.
Bernd

(please be aware: this opinion might be in conflict with some holy OSM-rules set up by some OSM-priests i do not know and do not care about. This is just cartographic common sense)


Am 08.04.2012, 13:00 Uhr, schrieb <[hidden email]>:

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> Message: 1
> Date: Sat, 7 Apr 2012 18:24:26 +0000
> From: Dudley Ibbett <[hidden email]>
> To: <[hidden email]>
> Subject: Re: [OSM-newbies] Boundaries and Roads
> Message-ID: <[hidden email]>
> Content-Type: text/plain; charset="iso-8859-1"
>
>
> Hi
>
> I could do with some advice on joining field boundaries to roads. I
> have been doing this as the mapping style I am use to never has the
> field boundary running along the side the road. If the field boundary
> along the road is well set back then I would consider drawing it however
> in most cases it is within a few meters of the road and sometimes there
> is not gap at all. I believe the OSM application can in theory go down
> to 3m. Drawing a field boundary along a road where the gap is less than
> 3 meters between the boundary (wall,fence) and the end of the road would
> therefore seem unrealistic.
>
> Should I try and draw the field boundary along the road in all
> situations or only do this when there is a large gap > 3m?
>
> If I don't draw the field boundary along the road should I link to the
> road or should I stop the boundary just short of the road?
>
> Some guidance would be appreciated as I don't want to link boundaries to
> roads if this could cause problems.
>
> Many thanks in advance.
>
> Regards
>
> Dudley
>
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Re: Boundaries and Roads

Jason Cunningham-2
In reply to this post by John Sturdy
On 8 April 2012 16:12, John Sturdy <[hidden email]> wrote:
On Sat, Apr 7, 2012 at 7:24 PM, Dudley Ibbett <[hidden email]> wrote:

> Should I try and draw the field boundary along the road in all situations or
> only do this when there is a large gap > 3m?
>
> If I don't draw the field boundary along the road should I link to the road
> or should I stop the boundary just short of the road?
>
> Some guidance would be appreciated as I don't want to link boundaries to
> roads if this could cause problems.

I think practices vary on this; I prefer to make them separate, partly
because the "road" is just the midline of the road, which is not where
the field ends, and partly for practicality of later editing: that
it's hard(er) to select a way that uses the same points as another
one.

What I've found is quite easy, and I think looks reasonably neat, is
to use the "make a parallel way" tool (in Potlatch, I haven't learnt
JOSM yet but I expect it has this too) to take a copy of the road, and
move it slightly aside to where the field boundary is, and cut it to
be just the piece you need for that field; then turn it into whatever
kind of barrier there is around the field (hedge, fence, etc) and also
use it as the edge of the field.  (That doesn't follow my suggestion
of making each way separate for easier selection, but I think it's
less likely to want to do things separately to the field and its
barrier, than to want to do things separately to the field and the
neighbouring road.)

__John

Areas attached to roads are one of my pet hates in OSM, in large part due to the difficulties in editing things later on.
I agree with John's statement that highways mark the centreline of the road, and as far as I'm concerned giving the edge of the field as the centre of the road is misleading.

Jason

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Re: Boundaries and Roads

Sam Kuper
In reply to this post by Bernd Vogelgesang
On 8 April 2012 20:51, Bernd Vogelgesang <[hidden email]> wrote:
from a GIS-persons point of view, you alway should avoid gaps in your map ( = in your data).
Cartographic work is always generalizing the world, and only because you COULD go into detail in the sub-meter sphere technically with the digital means nowadays, you should should ask yourself: what is it good for?

So, what would be the information you provide, leaving a blank space between a field and a road?
Actually none, cause you do not specify what this gap is, although its quite clear that it's something between the road and the field.
But when its already obvious that there are strips of surface which do not belong neither to roads nor fields, you could right away leave them out and align the border of the field directly to the road.

In digitizing you normally decide about the map scale of the end product. With OSM-maps, thats a little bit difficult, cause there is no common sense about the usage, and therefor also about the production-scale.

The planned scale is important, cause it decides about the precision you need to get a satisfying result.
E.g. when you want to have a map in 1:5000, you normally digitize your features at a scale of 1:2500 or 1:2000.
The human eye can not distinguish features smaller than half a millimeter on a screen or on paper.

With a map in 1:5000, 1/2mm on screen is 2,5 meters in reality. Thats the planned "error" you are "allowed" to produce, cause on the planned scale, you can't even see it.

So the question should always be: what is the planned usage and what is the benefit from increasing the accuracy?

A field border outside a village is much less interesting than borders and features in a town center.
When the mapped part is mostly relevant for navigating, so as a real street map, you could easily set your planned scale to 1:25000 or even higher (with the resulting need for generalization), as normal users will watch it in that scale anyway to get the overview they need.
If it's a feature of high interest, you could set your planned scale to 1:1000 or lower, with a resulting need of higher accuracy.

[...]
(please be aware: this opinion might be in conflict with some holy OSM-rules set up by some OSM-priests i do not know and do not care about. This is just cartographic common sense)

Amen; and I don't see any reason why we shouldn't be aiming for OSM to be as accurate as possible.

I'd be thrilled if the fine scale maps used by local authorities to settle boundary disputes and planning applications and so on were scanned and used to refine OSM, and see no technical reason why this shouldn't, in time, occur - except for the archaic insistence that in OSM, roads must be unrealistically represented as lines.

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Re: Boundaries and Roads

Pieren
In reply to this post by Jason Cunningham-2
On Tue, Apr 17, 2012 at 1:16 AM, Jason Cunningham
<[hidden email]> wrote:
> Areas attached to roads are one of my pet hates in OSM, in large part due to
> the difficulties in editing things later on.

Editing things later when not attached is also difficult, e.g. if you
have to adjust misaligned imagery sources.

> I agree with John's statement that highways mark the centreline of the road,
> and as far as I'm concerned giving the edge of the field as the centre of
> the road is misleading.

Not less misleading than traffic_signals or pedestrian crossing on
junction nodes or lanes/width/surface values changing on short
distance and therefore ignored, etc. We do approximate and simplify
with vector mapping. And we have to accept the different levels of
simplication depending on the contributors.

Pieren

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Re: Boundaries and Roads

Steve Bennett-3
In reply to this post by Dudley Ibbett
On Sun, Apr 8, 2012 at 4:24 AM, Dudley Ibbett <[hidden email]> wrote:
> I could do with some advice on joining field boundaries to roads.  I have
> been doing this as the mapping style I am use to never has the field
> boundary running along the side the road.  If the field boundary along the

Methods for this vary. My suggestion: try several methods, and see
what works best for you. Discuss with other people in your area, and
do what they do.

There are pros and cons either way.

Steve

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