[talk-au] Uploading traces (Was; Hi all ...)

[Andy Owen]

On Thu, 2009-06-18 at 13:21 +1000, Ross Scanlon wrote:
> The greater good is supported by the end product not by data (GPX files)
> that, although supports the end product, is not shown in the final map or
> routing solutions.
> 

There is actually a fair bit of value in having the raw traces
available, even if we aren't using it at the moment. Some examples -
none of which are being done at the moment (that I know of), but all of
which would be improved by having more gpx files (these are just off the
top of my head, so please don't take issue with the fact that some of
them will be really hard to do well):

* improving routing information, by working out average speed on roads
(at different times).
* improving height maps, by taking (lots of) samples where altitude
information was present.
* automatically guessing the number of lanes on a road, by looking at
the variance of traces over sections in each direction.
* automatically marking ways which haven't been looked at for a long
time, so someone can revisit them to make sure they haven't changed.
* (insert your imagination here)

A situation which has actually happened for me is when our map disagrees
with a commercial map. e.g:

http://www.openstreetmap.org/?lat=-33.739698&lon=151.102868&zoom=18&layers=B000FTFT
http://maps.google.com.au/?ie=UTF8&ll=-33.739691,151.10239&spn=0.001891,0.002398&z=19

If we had a trace here showing a person getting to a dead end, turning
around and going back around the other way, then it would be much more
convincing that the OSM data is correct. As it is, it is our word
against google's.

(on the other hand, when I saw this and so went to check it to make sure
we were right, I didn't have a gps either, so there is still no trace)

So in summary, you aren't a bad person if you don't upload your traces,
but there are interesting and useful things that can be done with them,
so if it is possible and convenient to do so, then you should. This is
Open Street _Map_, not Open GPS Traces, so you are right that the gpx
files aren't the focus... but maybe one day they will be used to improve
the maps.

(and I don't think clogging the database is a valid concern. on a hunch,
I'd say that the traces are miniscule in comparison to the rest of the
data they are storing)

Andy