Colin Smale <colin.sm...@xs4all.nl> writes: > I meant my question seriously, not hypothetically.... I assume all these > boundary posts are tagged with something like "source:location=MA State > Data Set 2015-01-19"? If not, how is a mapper to compare his > "correctness" to the existing "correctness"?
There are changeset tags, yes. And looking at https://wiki.openstreetmap.org/wiki/Massachusetts one is directed to MassGIS imports https://wiki.openstreetmap.org/wiki/MassGIS which as https://wiki.openstreetmap.org/wiki/MassGIS#Town_Boundaries_from_Survey_Points_Layer which links to the state page about this. > Without this provenance information in the database, the accuracy is > unknown to other mappers, and may in fact be worse (for example an > armchair mapper digitising from small scale map). When it isn't clear that what you're doing is an improvement, you should message the other people involved. In the Mass case, most of the active mappers know each other. Basically my point is that absent having a good basis to know that what you're doing is an improvement, you should be careful. And a phone/hiking GPSr that shows within 10-20m is not presumption that the new data is better. If the phone GPS is showing 200m off, then yes, the existing data is bad. I have actually written to people when I have tracks for hiking trails in nearby towns that are off about 20m, to ask how they did it. And usually they say - "just my phone, feel free to fix". And if you're not local, and definitely if you're not actually on the ground, you should be extra careful.
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