[talk-au] Vicmap data copying

[Steve Bennett]

On Mon, May 19, 2014 at 4:22 PM, David Bannon <dbannon at internode.on.net>wrote:


> No, no Steve, I worded my last letter really badly and totally apologise
> if I unintentionally offended anyone. My comment related specifically to
> your line -
>

Ok, no worries :)


>
> > Yeah. I'm still deciding what to do about places where Vicmap shows a
> > track in the bush that can't be seen on any imagery - probably because
> > the vegetation is too dense.
>
> I meant leave the 'grey' areas to the survey people. There are many
> roads (and particularly tracks) that cannot been seen clearly on the
> imagery, and many more where some parts cannot be seen. I'd rather the
> people working with imagery or other non (recent) survey data such as
> Vic Maps did not make "educated guesses" but go and have a look, or ask
> some else to go and have a look.
>

Yeah, it's a real issue. Like I said, I'm still trying to work out how best
to proceed. My general approach is to be a bit more liberal with roads that
don't go through, and more conservative with ones that do. I'm also trying
to use fixme=* to express doubt:

fixme=unverified from vicmap (ie, I can't see through the vegetation, so
I'm taking vicmap's word for it)
fixme=verify access (I can see a track, vicmap has a track, but I'm still a
little skeptical that it's public access)

Sometimes I also use highway=path rather than highway=track if I'm dubious
that the public can drive a vehicle down it.

My intention in all this is to minimise the chance that someone gets routed
down a road that is not publicly accessible, or otherwise impassable.
Personally, I think it's ok to show dead-end 4WD tracks that happen to not
be driveable, because I think the people that use those kinds of maps
expect that. But definitely willing to discuss this point, and open to all
opinions...


>
> I have had a road (into a new estate) removed, apparently because it did
> not show up on Bing. Very annoying to a new owner there who was
> directing tradies via OSM ! But that in no way means I don't value the
> armchair mappers contribution.


I'd suggest adding notes on to the road in question, like "note=This road
was built in early 2014 and is surveyed."


> I'd just like them to double check their
> data, one way or another before committing.
>

To be honest, I go so much faster if I'm not doing any checking - you might
be surprised how fast I map :) It doesn't really make sense to spend 10
minutes verifying a road that I created in 10 seconds - I just take the
chance that I'm introducing a couple of errors. But mostly I'm doing stuff
out in the bush. I'm usually pretty cautious about deleting anything like
you describe. I have come across a couple where I just couldn't fathom why
someone had drawn a road somewhere, but I'll usually cross-check against a
couple of other sources.

Example: http://www.openstreetmap.org/way/172612474


> Maybe what we need is some sort of register ? The people studying
> imagery are good at picking up anomalies, differences between image and
> map. They could log it and have some local go and check ? Better than
> just jumping in.
>

Are there enough of us to make it worthwhile? Anyway, a better mechanism
would probably be through fixme=*, so you can go and look for fixme's in
your area at your leisure.


>
> You may be amused to know that some years ago, I was shocked to discover
> I had apparently built my house in the middle of the Bendigo Region
> National Park. I was waiting to get a letter telling me to move it when
> I realised someone had just followed the tree line, assuming all was
> national park. They had swept up the Park it self, the Welsford State
> Forest, Sugarloaf Conservation Park and a large number of private
> properties. A very quick check would have prevented that error.
>

Yeah, that seems pretty silly. Although IMHO we need a better approach to
maintaining administrative boundaries - it doesn't really make sense for
anyone to be able to move them at will, since there is a genuine authority
for each.


>
> I am pretty sure all we want is for the database to have accurate,
> relevant data.
>
>
You left out "comprehensive" and "useful". I think I have a higher
tolerance for error because I want OSM to be useful and complete-ish *now*.
I use it on a regular basis for planning trips, and I can't wait a few
years for all the checking. I'd rather a pretty complete map with a few
errors which will be corrected over time.

But that's all it is - different priorities. Maybe I think 98% accuracy is
enough, whereas you want 99.5% - and someone else might want 99.95%...

Steve
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