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.
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