[OSM-talk] Mapping with no GPS data

[David Earl]

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