[OSM-dev] getnodes query optimization

[Lars Aronsson]

Christopher Schmidt wrote:

> I can't help with gathering line segments: I have a full dataset 
> which would be of about 20x higher quality level than TIGER, and 
> is released under an Attribution license, but with the request 
> not to load the database more than is neccesary, I'm not going 
> to load it. (The data, for the record, is the MassGIS department 
> of transportation roads layer -- but like TIGER, it's an 
> accurate, high-density data source which

That's good for Massachusetts, but it won't help us in Europe. 
Free GIS data is unheard of here.  In my theory this is because 
European governments are more shrewd and skilled in how to make 
money off of their subjects than the amateur U.S. government(s).

Anyway, suppose that you could load this data into OSM.  That 
would mean breaking up structured data into line segments, right?  
And then we use OSM (the map wiki) to edit it, improve it, make it 
more up to date. Could you ever assemble the structured data out 
of that again?  The purpose would be to allow MassGIS users to 
benefit from the improvements we've made.  It's not really like 
OSM allows you to set a (CVS) tag after the import, that can be 
used to generate a global diff of everything that's changed since 
that tag.  Isn't that kind of functionality what we'd need?

I have this doubt about TIGER.  Ben is importing TIGER into OSM, 
which I'm sure is a fun exercise. But what is it good for, really? 
There are applications that use the TIGER data, i.e. that are able 
to import data in the format used by TIGER.  Will these apps ever 
be able to use anything that comes out of OSM, after people have 
edited the TIGER import?  What's the next step after the import?

In my mind we should use OSM as a factory for producing 
TIGER-formatted free GIS data for Europe (and Africa and Asia), so 
that existing TIGER-based applications can be used here too.  But 
I'm not sure what the purpose of OSM can be for the U.S., since 
you already have TIGER and other free GIS data sources.


-- 
  Lars Aronsson (lars at aronsson.se)
  Aronsson Datateknik - http://aronsson.se