On Tue, Jul 20, 2010 at 08:11:46AM +0000, Ed Avis wrote: > However I'd like to point out that 'ground survey' versus 'OS' is a false > dichotomy. Firstly the existing OSM topology is not always from ground > surveys. > More often than not it will be a trace from Yahoo aerial imagery. Secondly, > how do you know that the Ordnance Survey does not also use ground surveys?
It’s not just about “ground survey” versus “OS”, I should have made the subject more general. It’s about assuming your collected data is better than others. I emphasise ground surveys, not because another data provider might not do them, but because the user who gathered the data has been there and seen what’s really there. (Of course, we don’t really have a way to properly verify this.) > But also, let's get priorities straight. Surely the purpose of OSM is to > create > a freely usable, complete and high-quality map. Providing a fun hobby for > people > who like to walk around with GPS units is only a side-effect. Anything which > helps us complete or improve the map is to be welcomed. I didn’t say any different, but I did say that one of OSM’s things is to map what’s actually on the ground. > (Personally, I have found the OS data provides plenty of motivation to > resurvey areas which I had previously considered complete.) This is what I hope people use the OS data for: Filling in the gaps, and using it to help verify existing data. Not simply replacing data, especially if it loses some of it. Of course, it’s not lost, we can always revert data, or re‐add missing attributes, but I would like to avoid having to do that in the first place. My full disclosure is that I haven’t done even minor fixups, let alone surveying, for quite some time. I just saw it mentioned in the IRC channel, didn’t like the idea that people were replacing detailed surveying with OS Opendata and removing attributes, and brought it to the list. I would be just a little bit disgruntled if someone were replacing my detailed data with poorer quality data, whatever the source. Simon -- A complex system that works is invariably found to have evolved from a simple system that works.—John Gall
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