Buildning alignment

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Buildning alignment

Arne Jakobsson
Hi all,
I draw buildings, and was taught somewhere that we should align the building outline with its roof. Doing this, I ran into some trouble. http://i.imgur.com/vaOFIb5.gif
The road intersect the building. This would not happen if we instead just kept to aligning the building outline with its base.
Is there a right way to do this?

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Re: Buildning alignment

Enock Seth Nyamador
Hi Arne,

If it were me, I would just move the road outside as in reality it doesn't pass through the building. This am sure is as a result of the height of the building,

Hope this helps.

Best,

- Enock
twitter: @Enock4seth
enockseth.github.io | [[User:Enock4seth]]


On Fri, Jun 12, 2015 at 9:16 AM, Arne Jakobsson <[hidden email]> wrote:
Hi all,
I draw buildings, and was taught somewhere that we should align the building outline with its roof. Doing this, I ran into some trouble. http://i.imgur.com/vaOFIb5.gif
The road intersect the building. This would not happen if we instead just kept to aligning the building outline with its base.
Is there a right way to do this?

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Re: Buildning alignment

Matt Williams-2
In reply to this post by Arne Jakobsson
Hi Arne,

I was always taught to align buildings with their base. Often the
easiest way to do this is to trace the outline of the roof and then
move the whole shape to align with the base but either way, the base
should be aligned. This is to avoid exactly this type of problem.

I'm not sure where you got the information to align to the roof but if
it's somewhere public we should probably make sure that it is changed.

Cheers,
Matt

On 12 June 2015 at 10:16, Arne Jakobsson <[hidden email]> wrote:

> Hi all,
> I draw buildings, and was taught somewhere that we should align the building
> outline with its roof. Doing this, I ran into some trouble.
> http://i.imgur.com/vaOFIb5.gif
> The road intersect the building. This would not happen if we instead just
> kept to aligning the building outline with its base.
> Is there a right way to do this?
>
> _______________________________________________
> newbies mailing list
> [hidden email]
> https://lists.openstreetmap.org/listinfo/newbies
>



--
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http://milliams.com

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Re: Buildning alignment

Florian Lohoff-2
In reply to this post by Arne Jakobsson
On Fri, Jun 12, 2015 at 11:16:41AM +0200, Arne Jakobsson wrote:
> Hi all,
> I draw buildings, and was taught somewhere that we should align the building outline with its roof. Doing this, I ran into some trouble. http://i.imgur.com/vaOFIb5.gif
> The road intersect the building. This would not happen if we instead just kept to aligning the building outline with its base.
> Is there a right way to do this?

Typically you dont have exact images from the top as you can see on your
image. So you would take the roof as the measurement because it can be
seen completely and make it a box. Then you shift the box until the
corner matches the ground truth of the building. We map stuff at ground
level typically.

Then your road will not overlap the roof - its just a
imaging/parallax/projection issue you have.

Flo
--
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Re: Buildning alignment

SomeoneElse-2
In reply to this post by Arne Jakobsson
On 12/06/2015 10:16, Arne Jakobsson wrote:
Hi all,
I draw buildings, and was taught somewhere that we should align the building outline with its roof. Doing this, I ran into some trouble. http://i.imgur.com/vaOFIb5.gif
The road intersect the building. This would not happen if we instead just kept to aligning the building outline with its base.
Is there a right way to do this?


Personally I always try and align building footprints with the base rather than the roof (otherwise very tall buildings would look very odd indeed).

I can see why (if you were mapping lots of small buildings in e.g. a HOT response) it would be easier to say "just trace the roofs" - it'd get more buildings traced quickly at a good enough quality (which surely is the aim there), but as a general principle where time isn't an issue I'd certainly try and trace the building footprint.

Cheers,

Andy


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Re: Buildning alignment

Arne Jakobsson
In reply to this post by Enock Seth Nyamador
Are you sure moving THE ROAD is the way to go? I mean, the road is where it is. A map map roads primarily. 
Having posted this issue here I have now come to my own conclusion to always stick to aligning with building bases and not roofs. Depending on the angle the aerial photo was taken, the building roof will displace by a varying amount and thus cover objects behind it.
Thank you for your reply though, it made the issue more clear to me.


On 12 Jun 2015, at 11:36, Enock Seth Nyamador <[hidden email]> wrote:

Hi Arne,

If it were me, I would just move the road outside as in reality it doesn't pass through the building. This am sure is as a result of the height of the building,

Hope this helps.

Best,

- Enock
twitter: @Enock4seth
enockseth.github.io | [[User:Enock4seth]]


On Fri, Jun 12, 2015 at 9:16 AM, Arne Jakobsson <[hidden email]> wrote:
Hi all,
I draw buildings, and was taught somewhere that we should align the building outline with its roof. Doing this, I ran into some trouble. http://i.imgur.com/vaOFIb5.gif
The road intersect the building. This would not happen if we instead just kept to aligning the building outline with its base.
Is there a right way to do this?

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[hidden email]
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Re: Buildning alignment

Arne Jakobsson
In reply to this post by Florian Lohoff-2
I will hence align with building base. Thank you for your reply.

Sent from my iPhone

> On 12 Jun 2015, at 11:54, Florian Lohoff <[hidden email]> wrote:
>
>> On Fri, Jun 12, 2015 at 11:16:41AM +0200, Arne Jakobsson wrote:
>> Hi all,
>> I draw buildings, and was taught somewhere that we should align the building outline with its roof. Doing this, I ran into some trouble. http://i.imgur.com/vaOFIb5.gif
>> The road intersect the building. This would not happen if we instead just kept to aligning the building outline with its base.
>> Is there a right way to do this?
>
> Typically you dont have exact images from the top as you can see on your
> image. So you would take the roof as the measurement because it can be
> seen completely and make it a box. Then you shift the box until the
> corner matches the ground truth of the building. We map stuff at ground
> level typically.
>
> Then your road will not overlap the roof - its just a
> imaging/parallax/projection issue you have.
>
> Flo
> --
> Florian Lohoff                                                 [hidden email]
>     We need to self-defense - GnuPG/PGP enable your email today!
> _______________________________________________
> newbies mailing list
> [hidden email]
> https://lists.openstreetmap.org/listinfo/newbies

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Re: Buildning alignment

Florian Lohoff-2
In reply to this post by SomeoneElse-2
On Fri, Jun 12, 2015 at 10:56:30AM +0100, SomeoneElse wrote:

> On 12/06/2015 10:16, Arne Jakobsson wrote:
> >Hi all,
> >I draw buildings, and was taught somewhere that we should align
> >the building outline with its roof. Doing this, I ran into some
> >trouble. http://i.imgur.com/vaOFIb5.gif
> >The road intersect the building. This would not happen if we
> >instead just kept to aligning the building outline with its base.
> >Is there a right way to do this?
> >
>
> Personally I always try and align building footprints with the base
> rather than the roof (otherwise very tall buildings would look very
> odd indeed).
>
> I can see why (if you were mapping lots of small buildings in e.g. a
> HOT response) it would be easier to say "just trace the roofs" -
> it'd get more buildings traced quickly at a good enough quality
> (which surely is the aim there), but as a general principle where
> time isn't an issue I'd certainly try and trace the building
> footprint.
As the parallax-shift is the same for the full of the sat image you can
also draw 100 Buildings and shift them at once

Just make shure that you are not shift already shifted buildings or
buildings taken from images with a different parallax problem.

Flo
--
Florian Lohoff                                                 [hidden email]
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Re: Buildning alignment

Enock Seth Nyamador
Thanks all.

Best,

- Enock
twitter: @Enock4seth
enockseth.github.io | [[User:Enock4seth]]


On Fri, Jun 12, 2015 at 10:15 AM, Florian Lohoff <[hidden email]> wrote:
On Fri, Jun 12, 2015 at 10:56:30AM +0100, SomeoneElse wrote:
> On 12/06/2015 10:16, Arne Jakobsson wrote:
> >Hi all,
> >I draw buildings, and was taught somewhere that we should align
> >the building outline with its roof. Doing this, I ran into some
> >trouble. http://i.imgur.com/vaOFIb5.gif
> >The road intersect the building. This would not happen if we
> >instead just kept to aligning the building outline with its base.
> >Is there a right way to do this?
> >
>
> Personally I always try and align building footprints with the base
> rather than the roof (otherwise very tall buildings would look very
> odd indeed).
>
> I can see why (if you were mapping lots of small buildings in e.g. a
> HOT response) it would be easier to say "just trace the roofs" -
> it'd get more buildings traced quickly at a good enough quality
> (which surely is the aim there), but as a general principle where
> time isn't an issue I'd certainly try and trace the building
> footprint.

As the parallax-shift is the same for the full of the sat image you can
also draw 100 Buildings and shift them at once

Just make shure that you are not shift already shifted buildings or
buildings taken from images with a different parallax problem.

Flo
--
Florian Lohoff                                                 [hidden email]
     We need to self-defense - GnuPG/PGP enable your email today!

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Re: Buildning alignment

Arne Jakobsson
In reply to this post by Florian Lohoff-2


Sent from my iPhone

> On 12 Jun 2015, at 12:15, Florian Lohoff <[hidden email]> wrote:
>
>> On Fri, Jun 12, 2015 at 10:56:30AM +0100, SomeoneElse wrote:
>>> On 12/06/2015 10:16, Arne Jakobsson wrote:
>>> Hi all,
>>> I draw buildings, and was taught somewhere that we should align
>>> the building outline with its roof. Doing this, I ran into some
>>> trouble. http://i.imgur.com/vaOFIb5.gif
>>> The road intersect the building. This would not happen if we
>>> instead just kept to aligning the building outline with its base.
>>> Is there a right way to do this?
>>
>> Personally I always try and align building footprints with the base
>> rather than the roof (otherwise very tall buildings would look very
>> odd indeed).
>>
>> I can see why (if you were mapping lots of small buildings in e.g. a
>> HOT response) it would be easier to say "just trace the roofs" -
>> it'd get more buildings traced quickly at a good enough quality
>> (which surely is the aim there), but as a general principle where
>> time isn't an issue I'd certainly try and trace the building
>> footprint.
>
> As the parallax-shift is the same for the full of the sat image you can
> also draw 100 Buildings and shift them at once
>
> Just make shure that you are not shift already shifted buildings or
> buildings taken from images with a different parallax problem.
>
> Flo
> --
> Florian Lohoff                                                 [hidden email]
>     We need to self-defense - GnuPG/PGP enable your email today!
> _______________________________________________
> newbies mailing list
> [hidden email]
> https://lists.openstreetmap.org/listinfo/newbies

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Re: Buildning alignment

Bill & Kathy Patterson
In reply to this post by Florian Lohoff-2
I haven't had any training in this, but as soon as I outlined my first couple of buildings on OSM a few months ago,  the solution as described by Matt Williams quickly jumped out as the correct approach.  Also, I have to respectively disagree with Florian's statement "As the parallax-shift is the same for the full of the sat image you can also draw 100 Buildings and shift them at once." on two counts.  Firstly, if the photographic axis is truly vertical, then the parallax shift is in opposite directions to the right and left of the photo centre (i.e. the buildings will all be appearing to "lean" away from the centre of the photo.  Secondly, the shift in the roof of a 50 floor building will be 5 times that of a 10 floor building at the same location.  While I don't disagree with shifting several buildings concurrently, I should think that they should be relatively close to each other and roughly the same height.

Bill


From: Florian Lohoff <[hidden email]>
To: Help for newbie mappers <[hidden email]>
Sent: Friday, June 12, 2015 6:15 AM
Subject: Re: [OSM-newbies] Buildning alignment

As the parallax-shift is the same for the full of the sat image you can
also draw 100 Buildings and shift them at once

Just make shure that you are not shift already shifted buildings or
buildings taken from images with a different parallax problem.


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Re: Buildning alignment

Arne Jakobsson
In reply to this post by Florian Lohoff-2
Thanks for the tip! I will keep that in mind when re-iterating, correcting previous work.

Sent from my iPhone

> On 12 Jun 2015, at 12:15, Florian Lohoff <[hidden email]> wrote:
>
>> On Fri, Jun 12, 2015 at 10:56:30AM +0100, SomeoneElse wrote:
>>> On 12/06/2015 10:16, Arne Jakobsson wrote:
>>> Hi all,
>>> I draw buildings, and was taught somewhere that we should align
>>> the building outline with its roof. Doing this, I ran into some
>>> trouble. http://i.imgur.com/vaOFIb5.gif
>>> The road intersect the building. This would not happen if we
>>> instead just kept to aligning the building outline with its base.
>>> Is there a right way to do this?
>>
>> Personally I always try and align building footprints with the base
>> rather than the roof (otherwise very tall buildings would look very
>> odd indeed).
>>
>> I can see why (if you were mapping lots of small buildings in e.g. a
>> HOT response) it would be easier to say "just trace the roofs" -
>> it'd get more buildings traced quickly at a good enough quality
>> (which surely is the aim there), but as a general principle where
>> time isn't an issue I'd certainly try and trace the building
>> footprint.
>
> As the parallax-shift is the same for the full of the sat image you can
> also draw 100 Buildings and shift them at once
>
> Just make shure that you are not shift already shifted buildings or
> buildings taken from images with a different parallax problem.
>
> Flo
> --
> Florian Lohoff                                                 [hidden email]
>     We need to self-defense - GnuPG/PGP enable your email today!
> _______________________________________________
> newbies mailing list
> [hidden email]
> https://lists.openstreetmap.org/listinfo/newbies

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