[HOT] Question about background image alignment

Pierre BĂ©land pierzenh at yahoo.fr
Sun Aug 10 14:20:10 UTC 2014


Thanks Blake 


We are happy that these Activations bring in new contributors. This is how I started myself with Haiti in 2010. More then having the satisfaction to help for humanitarian relief, this is a context where we have the opportunity to learn with the community that participate to this action.
Looking at the edits for Naiyama, I see that they were done by a new contributor using Potlatch 2. He does not provide information about the Imagery he has used. So far he had less then 20 Edit sessions. He does not seem to understand the basic rules of mapping. 


Looking at building outbounds, we cannot see a pattern that corresponds to what we see on the map.  The size of the buildings,  the direction of the walls do not correspond to what we see on the imagery. Potlatch 2 do not let orthogonalize the buildings. Tracing by hand, this contributor did not try to trace respecting the form of buildings.  


JOSM is better to do such a Job. If we use the shorcut key Q, this let's orthogonalize the buildings (right angles).  A better and simpler way to proceed, is to add the Building plugin in JOSM and trace using th B shortcut Key.

Inside the landuse=residential polygon, wee see a second polygon with the place=hamlet and name= tags. There is already a node to identify this place and this polygon should be simply deleted since it does not correspond to OSM mapping standards.

I also see some ways with the higway=footway tag. I cannot observe this on the map and these ways are not connected to the highway network.

Since this is a small village and the work so badly traced, the best solution to my point of view is to erase and restart.

It would be good also that one of the validators contact him providing some instructions.

 
Pierre 



________________________________
 De : Blake Girardot <bgirardot at gmail.com>
À : 
Cc : "hot at openstreetmap.org" <hot at openstreetmap.org> 
Envoyé le : Dimanche 10 août 2014 7h24
Objet : Re: [HOT] Question about background image alignment
 

Hi,

Thank you both very much for replying.

I am new to OSM and HOT so please forgive my ignorance.

It would seem that if I adjust the one section I am working on to align 
the background with the previously mapped roads and buildings, it would 
be throwing off the mapping in other sections on the larger map? Is that 
correct? Is it a problem?

The section that raises this issue for me is this one:

http://www.openstreetmap.org/edit?editor=id&#map=15/8.2224/-11.2610

specifically the village area Naiyama.

If I understand your advice correctly, I would correct the background 
image alignment to match the roads and some of the buildings and then 
fix the rest of the buildings in the village.

Regards,
Blake Girardot



On 8/10/2014 4:24 AM, Pierre Béland wrote:
> yes
>
> As I have explained before, you want to keep the general geometry of a
> village (distances, angles between the objects) to be the same. Then if
> people have traced previously, you first move the image to align with
> what was there before.
>
> If this village have 30 meter offset with the rest of the world, this is
> less a problem then 30 meters between two buildings.
> Pierre
>
> ------------------------------------------------------------------------
> *De :* Ralf Stephan <gtrwst9 at gmail.com>
> *À :* Blake Girardot <bgirardot at gmail.com>
> *Cc :* "hot at openstreetmap.org" <hot at openstreetmap.org>
> *Envoyé le :* Dimanche 10 août 2014 2h11
> *Objet :* Re: [HOT] Question about background image alignment
>
> I can only tell from my perspective, I would look what's the offset of
> the majority of
> objects in the tile and the surrounding tiles, and use that as your offset.
>
> This presupposes that you use JOSM. With the browser it would be difficult.
>
> A question would be then if you should correct the minority of
> misaligned objects. I don't know but I guess so.
>
> Regards,
>
>
>
>
> On Sun, Aug 10, 2014 at 7:22 AM, Blake Girardot <bgirardot at gmail.com
> <mailto:bgirardot at gmail.com>> wrote:
>
>     Hi, I apologize in advance if this is answered somewhere but I did
>     not find the answer.
>
>     Working on the #586 - Ebola Outbreak, Panguma (Sierra Leone) --
>     Updated Imagery, 2014-07-15 task I have seen a few places where it
>     looks like the background image is misaligned with some of the
>     mapped objects (buildings and roads), but other objects were mapped
>     with the current mis alignment.
>
>     What should a person do in that situation?
>
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>
>
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>
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