[Talk-GB] building shapes from OS Street View

TimSC mapping at sheerman-chase.org.uk
Tue Apr 6 17:26:19 BST 2010

Andy Allan wrote:
> On Tue, Apr 6, 2010 at 12:46 PM, TimSC <mapping at sheerman-chase.org.uk> wrote:
>> If we use only manual surveying, we can only
>> achieve coverage of about 1%. I don't think that is satisfactory. Imports
>> are therefore very much appropriate for buildings.
> You're missing the point on several levels. For buildings it's quite
> possible to trace the outlines from aerial imagery, where we have it.
> And in some parts of the country, we have better imagery than the
> building outlines shown on Street View - yahoo, and soon the Surrey
> imagery, for starters. So it's not a case of Street View or nothing. I
> hope you have seen the vast tracts of London that have building
> outlines in OSM already - all of much higher detail than Street View?
It's not vast, it doesn't even get to the edge of the underground zone 
1. And the detail is comparable to my eye, except for many omissions in 
OSM. I am not sure how you are quantifying quality. I suspect that the 
OSM data is more up to date (even if Yahoo is a few years out of date), 
but OSM still very incomplete even in this supposedly well mapped area. 
I suspect with the few OSM contributors doing tracing the various 
sources and given their limited coverage, we are still looking like 
converging on poor overall coverage given years of effort, so my 
original point still stands. I say we can compliment our other sources 
with automatic tracing (be that by importing or editor tools).

I guess the question is how much progress can we make on building 
outlines over different time scales, given different approaches?
> If you are not talking
> about "bulk imports" then please don't call your ideas imports,
> otherwise you confuse people as to your intentions. 
I am discussing automatic tracing which applies to both editor tools and 
imports. There is no rule that I have to discuss one option exclusively. 
But I was leaning towards more the import paradigm, while the majority 
seems to be for editor tools. Andy, from my perspective, you have not 
given a single justified reason against doing imports, so I can't really 
rebut your position (although other people have made valid points). I 
suggest you get a bit more constructive and outline your vision for the 
way ahead on this issue? Continue, as is, with Yahoo and so on?

Robert's point was along the lines I am thinking along:

> My preferred solution would be doing a country-wide generation of a buildings.osm which users can merge from. Hence no need for special plugins or tools to be distributed to regular contributors.
I would think this takes less effort than a JOSM map processor plugin 
and also result in a better quality conversion due to the rectification 
artifacts I mentioned in my previous post. Who is the technical expert 
on the Street View rectification? Any comments on that issue?


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