[OSM-talk] Antarctica coastline/shelf-ice import

[Maarten Deen]

On 2013-03-05 16:22, Jochen Topf wrote:
> On Tue, Mar 05, 2013 at 09:57:31AM -0500, Serge Wroclawski wrote:
>> I worked on an Ozone monitoring instrument briefly in my career, and
>> my understanding is that the polar ice caps change often.
> 
> No, they don't change all that much. Of course they change a little 
> bit all the
> time, the ice cap moves about 10m a year at the South Pole for 
> instance, and
> sometimes large icebergs break off from the shelf-ice, but for the 
> resolution
> we are talking about here, the resolution interesting for OSM, they 
> are
> basically static.
> 
>> Are you proposing that we change them every N months?
> 
> No.
> 
>> If so, I think we have better solutions at our disposal than trying 
>> to
>> delete/reimport huge areas like this.
> 
> This is a misunderstanding. The reason the old data is bad is not that
> Antarctica changed so much between then and now. I don't know why the 
> old
> data is so bad, maybe it is because satellite images etc. have 
> improved
> since then so better data could be derived.

In the beginning the coastline was very coarse. So much that the then 
current algorithm of generating tiles (especially for T at H) sometimes 
didn't find data to work with (because nodes were so far apart) so it 
rendered an empty tile.
I did a lot of work making it more precise according to the aerials 
available. I haven't checked in recent years how it correlates to 
current aerials.

Regards,
Maarten