> On Jun 11, 2015, at 4:49 PM, Martin Koppenhoefer <dieterdre...@gmail.com>
> wrote:
>
> offsets are an approximation to reduce the inherent problems of some aerial
> layers, they won't solve problems like distortions. JOSM isn't more precise
> to find a "proper offset" than any other tool, I suggest you simply move the
> layer till it visually seems ok. Unless you do high precision measurements in
> the field you won't know for sure what is "right" and what is "wrong", or in
> other words: more or less accurate. IMHO, relative precision (eg alignment,
> angles, straight vs curves etc) is more important than positional precision.
I know the precision isn’t so important, but I want everything to be the same
relative location. The relative position is very important to me. I know
distortion can skew that, for hills and the like.
I was also under the impression there was a plugin for JSOM that offered
automatic imagery offset correction, something which I don’t have access to in
iD
I also deal with places where the tracings/imports are 2-5 years old, nowhere
near aligned to the imagery, has several 20m shifts every few KM, so who knows
what is right, and the trunk roads/motorways have more recent edits of several
different users aligning to past imagery with and without an offset, so there
is no place whatsoever where I can choose a dominant alignment. even inside
Narita Airport there is a 5m or so diffference betweent the buildings and the
runway mapping. and the taxiway mapping is old. So I don’t know what to trust
And I don’t want to make one up because...
Mappers using JSOM to come in and start moving all major roads over 1 lane
width and leave all the residential and alleys alone - effectively ruining
their relative positions and distorting all the intersections. This happened
*all the time* until I started requesting an alignment point from JSOM users.
I sometime micromap very tiny places, which means the space between the roads,
and when mapping towns/areas I include every single possible road (alleyways
and residental) - and having someone come through and move only the trunk road
over 2 meters throughout 20 sq km of residential roads I just meticulously
aligned is a PITA. It is impossible for me to select and shift 100,000 points 2
meters over. and now I’m starting to map landuse polygons and buildings
(correcting horribly sloppy work) - but if I lay down all of these objects,
someone coming in and shifting the road 2m Southeast makes everything look bad.
If I have someone using JSOM align a polygon that is easy for me to align my
map to each time I start iD, it is much less likely to occur.
So here I am, hat in hand, asking for that aligned point.
http://www.openstreetmap.org/edit#map=19/35.74840/140.38510
<http://www.openstreetmap.org/edit#map=19/35.74840/140.38510>
Javbw
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