[Imports] CLC meadow cleanup

[Carlos Dávila]

El 22/03/14 08:32, Paul Norman escribió:
> I was doing some CLC cleanup tonight, removing landuse=meadow polygons
> that didn't remotely match more recent imagery. Of all the meadow
> polygons, not one was worth keeping. I found small woods, roads, farms,
> residential areas, and basically anything but good data. After going at
> it piece-meal I'm wondering if we need to go after it in a systematic
> manner with a mechanical edit.
>
> There are 19k ways and 1.2k relations with CLC:id, landuse=meadow, and
> version=1. About the same number of both have version>1. Based on the
> sampling I did, if any are accurate, it is purely by chance.
>
> What I'm wondering is
>
> 1. I did the editing in Poitou-Charentes, France. Is the CLC data here
>    representative of other data?
>
> 2. Are there other CLC classifications which are just as bad?
>
> If the area I looked at is representative, I am contemplating proposing
> a mechanical edit to remove the bad data. What are peoples thoughts on
> this?
>
> I'm not getting into specific details at this point, as I'm just
> evaluating the concept. Before actually doing a mechanical edit, I'd
> provide technical details for review, and raise the question with a
> wider audience.
I have seen CLC in France only vaguely, but I am of the same opinion. 
The quality of data is really bad. An for Spain, which I know much 
better, it is also really bad. When the import of CLC-Spain was proposed 
at talk-es, there were a number of people (including me) who were 
against that import, because we knew the accuracy of that data is awful 
and it will require a huge amount of painful work to improve it, but the 
importer went ahead despite of it. I have also manually removed many CLC 
polygons in Spain which didn't match the reality.