Hello,

There is an entire city traced from Bing, and the photo is shifted 10-20 meters in one direction. There are lots of GPS traces and the shift is clearly visible there. Everything I've checked in the city is aligned to the satellite imagery, not to the actual traces.

What is the correct way to correct such large amount of data? We are talking about 15x15km range with really a lots of nodes and ways. Also, I suppose some ways outside the city are correct since they may be mapped from somebody else from real GPS data instead from Bing imagery.

asked 21 Jul '12, 17:43

ivanatora's gravatar image

ivanatora
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It makes no sense to shift the whole region as individual users will most certainly realign stuff with imagery, or draw new stuff according to imagery, and you will be left with a horrible tangle.

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answered 21 Jul '12, 17:50

Frederik%20Ramm's gravatar image

Frederik Ramm ♦
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2

I (respectfully to my elder) disagree. OSM data should be as correct as we can make it. Imagery data and providers come and go, so binding ourselves to one faulty image sounds silly.

If a whole region is mapped 10-20m away from the imagery, people are more likely to notice that imagery needs aligning.

I'd agree with Frederik if the error was 2-3m (most people would not notice, and coherence trumps accuracy), but 10-20m is too much to ignore.

(23 Jul '12, 01:22) Vincent de P... ♦

I agree with Vincent's comment. Would contacting lots of local mappers or even the whole group telling of the problem,agreeing a realignment, shifting the Bing then all doing re-adjustment of your own work initially perhaps, then after an agreed delay open it to the whole group to complete it?

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answered 23 Jul '12, 10:12

andy%20mackey's gravatar image

andy mackey
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edited 23 Jul '12, 10:12

Assuming you use josm:

Download only a smaller section of the region (say 1km2, depending on density), fix it, and upload it before moving on to the next. Use the search function to select all the ways and perhaps the POI nodes. Look carefully through your data, and deselect anything that is correctly aligned. Move what's selected to the right position. Double-check. Upload. Repeat.

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answered 23 Jul '12, 01:34

Vincent%20de%20Phily's gravatar image

Vincent de P... ♦
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accept rate: 19%

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question asked: 21 Jul '12, 17:43

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last updated: 23 Jul '12, 10:12

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