Joakim Fors wrote:
Not having access to the cadastre layer I can't comment on the differences
between what has been traced and the source data, but I can SEE a distinct
positional difference between the bing layer and the OSM buildings. If there
was a general offset, then I would accept that there was simply a referencing
error, but the buildings were offset in different directions across the areas I
looked at. I also have buildings that do not yet appear on Bing ... no problem
with that, but the ones that appear on both SHOULD be in the same place? You
have already said that the cadastre data can't be trusted for detail?
>
A lot of times Bing imagery is distorted in different directions in a small
area. Quite easy to see in some places where you have access to very precise
ortho imagery or vector data to compare with. For example in Lund where we get
ortho imagery from the municpality; Here the Bing layer is distorted in
different directions just a few blocks apart… not to mention that the Bing
imagery is quite a few years older. Same with some vector data that
muncipalities in the region have provided to OSM where it is easy to see that
Bing imagery is quite inaccurate.
Sorry but I do not see any problem with the bing imagery in the area I
identified. I moved up to 'Prayssas' being the first identifiable location I
found, and I find it very strange that someone has imported a lot of buildings
without any reference to roads to access them. I could understand if these
buildings were then used to add the missing roads, but I've found no problem
with the location of imagery against other sources in the UK so you would have
to provide some pretty good evidence that the imagery around 'Prayssas' is
distorted! I am used to the way building heights affect the ground plan, but if
anything, the buildings are offset OVER the missing roads. The church looks
nice, but google streetview only seems to cover the outer ring road :(
--
Lester Caine - G8HFL
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