[OSM-talk] Why place matters, slides from Vanessa Lawrence talk

[David Earl]

On 11/01/2008 00:55, Jon Burgess wrote:
> On Fri, 2008-01-11 at 00:09 +0000, martin dodge wrote:
>> Hi,
>>
>> Just found an interesting set of slides of a talk by Vanessa Lawrence, OS
>> http://www.w3.org/2007/06/eGov-dc/presentations/VL_why_place_matters.pdf
>> with some prominent mentions for OSM. I particularly liked slide 46
>>
> 
> The map in his screenshot must be from quite some time ago. The same
> area of central London now has considerably more data

I think that misses the point. There are still many, many other areas 
where there is still just as little data, but that's not the point either.

The key thing is 'how do you know?'. If you look at the current coverage 
of that London area, it probably looks quite convincing now, whereas in 
her slide it was obviously incomplete, yet I bet it isn't (in fact, I 
know it isn't - there are numerous missing streets in the densely mapped 
central London). How would I know this? How do I know whether I can 
trust this map or not? (*)

This was and remains one of my key concerns about OSM as a project. I've 
said before and I'll say again: we need a way of asserting "this area is 
complete" (for one or more definitions of completeness).

Incidentally, this is exacerbated by the lazy rendering rule for Mapnik 
- I was puzzled when someone said to me the other day "why is this 
housing estate not connected to the rest of the road network?". It was; 
but adjacent Mapnik tiles were inconsistent (both laterally and by zoom 
level - and this wasn't a recently mapped area). You may not think this 
matters, but I think this is a public face and it causes further 
confusion and mistrust.

David


(* And how would I know how to fill in the gaps if I was there without 
revisiting every already mapped street?).