[OSM-talk] Mapping with no GPS data

[Barnett, Phillip]

I tend to agree with this, but this will only really work in
towns/suburbs etc. On the occasions when I travel longdistance by car to
another town, I always have my GPS running. Obviously, I make a
reasonable effort to try and note road names, (as a passenger, clearly )
but this isn't always possible. Rather than just throw these logs away,
if I'm the first OSM person to travel that route, I'll probably create
segments and upload, and trust someone more familiar with the territory
to add names.

Phillip 

-----Original Message-----
From: talk-bounces at openstreetmap.org
[mailto:talk-bounces at openstreetmap.org] On Behalf Of David Earl
Sent: 17 October 2006 13:45
To: OSM
Subject: Re: [OSM-talk] Mapping with no GPS data

Joerg said:
> My Idea is that people without a gps living in the area with the 
> segments created have enough knowledge to add ways and tags to the 
> segments. This way we could easily split the workload for creating our

> complete dataset.

I think that's a nice idea, but I don't think it works except for the
more major roads.

I've lived here for over 20 years and I think I know my area very well
indeed. But when I started mapping, I found numerous streets I didn't
know existed, and many more that I didn't know the names of, even
withing a km of home. Housing estates are warrens of tiny culs-de-sac. I
quickly discovered I had to trace every street, even if I could see the
other end of my trace so could in principle join it up with a straight
line later, because inevitably there would be a small close or avenue or
service road leading off it that I hadn't known about.

So I think to get it right, someone has to survey the all streets. Now
it's true that one person could supply accurate GPS traces, and another
get street names referring to that data, but to get it right, I think
that person has to go around the streets.

Someone previously said you don't have to go into every street to do
this.
True, but does that help much? In the lung-like estates, the last little
alveoulus is usually only a few metres long. The area I did yesterday
took me 3 hours on my bike. I reckon to do the same just to collect
street name info would still have taken at least two hours, and I might
have saved 1/2 hour by not doing this myself.

Adding the data to the database accuratelty with all the ways and
details then seems to take me about the same again: 3 hours in this
case.

So I think for the sake of noting down a small amount of information
while collecting GPS, there's a lot of incomplete data building up which
is likely never to get completed without re-surveying, and I'm not
optimistic about that happening.

People will work in their own ways, of course, but I think it is better
to do less at once but with all the detail and accuracy, than to try to
cover too much at once, if we are to get a useful and reliable map at
the end of it.

David


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