I'm currently editing a wilderness region (Val Grande National Park in Piemionte, Italy) and I'm adding small streams. The area is deeply serrated and densely forested, the deep-cut valleys' visibility on satellite imagery depends very much on the angle of the sun at the time the image was taken. So I switch between two sources (Bing sat and PCN ortofoto colore 2006) and add my local knowledge to disambiguate the data as best as I can. I'd like to quote both sources, but I can only set the 'source' tag to either one or the other.

I have a similar problem when I'm mapping trails in open territorry: I use a satellite image as a backdrop and layer my GPS track(s) on top. Where the trail is clearly visible I trace the satellite image, where it isn't, I average from the GPS tracks. So the source is really both my tracks (I suppose that's 'knowledge') and the satellite imagery.

Am I missing something?

asked 31 Jul '11, 11:32

kfj's gravatar image

accept rate: 0%

You can set "source=abc;xyz"

see Semi-colon_value_separator

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answered 31 Jul '11, 11:58

stephan75's gravatar image

accept rate: 6%

The wiki entry you quote seems to suggest this is best avoided. How relevant is the source tag, anyway? In my (limited) experience I haven't seen it used. OSM has permission to trace both sources of satellite imagery I mention. Is it necessary I add the source tag at all, then?

(31 Jul '11, 12:16) kfj

The usual problems with semicolons don't really apply to source tags. Their primary purpose is to let human mappers know what you have used. If programs actually read the tag, they cannot rely on atomic values anyway - because semi-colons in source tags are quite common, and because source value spelling varies a lot.

If you worry whether source tags are worth the effort, I recommend placing the source tags on the changeset instead of all the individual objects. Doing so reduces the burden for both you and the following editors of the objects.

(31 Jul '11, 12:45) Tordanik
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question asked: 31 Jul '11, 11:32

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last updated: 31 Jul '11, 12:45

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