OpenStreetMap 開放街圖
The Barragem de Alqueva/Embalse de Alqueva (Relation Number 1.464.895):
With a surface of 250 km2, a lakeside of 1.200 km (about 1.000 km on Portuguese territory, the rest in Spain) and a length of about 85 km the "Barragem de Alqueva" is today the biggest artificial lake in Europe.
It would have been impossible to map this object without the help of aerial imagery in the detail that BING gives us. The only other way to have mapped this for OSM would have been by using official data from some other source. It took 4 months to complete.
I do not know how many nodes and ways (and islets) it contains, as I cannot download it in JOSM as a single entity as it is too large. I think I mapped about 100-200 islets and over 10.000 nodes but it is just a guess.
View it in OSM:
osm.org/?lat=38.4006500244141&lon=-7.27157592773438&zoom=10
Pictorial Map
http://www.alqueva.de/alquevakarte.html
Website in Portugies, German, English
http://www.alqueva.eu/
討論
由 c2r 於 2011年05月14日 13時02分 發表的評論
Good going - well done!
由 olejorgenb 於 2011年05月14日 16時26分 發表的評論
Well done :) You should make some before/after shots. Not sure if there is an easy way though. (ought to be!)
由 Roman Fischer 於 2011年05月14日 16時26分 發表的評論
Simply impressive work! :)
由 kerosin 於 2011年05月14日 22時03分 發表的評論
Really impressive! But maybe it is a bit too detailed;) Bing Imagery is always just a snapshot in time and edges of lakes are not steady. They are subjected to natural changes like aridity or rising water level because of lasting rain.
Anyway, thank you for your great work!
由 malenki 於 2011年05月15日 18時21分 發表的評論
Awful impressive work indeed! Yes, it is a big relief to have a lot of good aerial imagery.
I assume working four (!) months on it you drew all of it by hand?
To complete your stats a bit:
The relation contains 275 islets, all objects have 48.996 nodes.
Its outer ways have a total length of 1.124 km (1.124.139,19 m)
Although it maybe discourages you a bit I want to mention scanaerial¹ which can trace coasts, riverbanks and such.
With its predecessor in spirit Lakewalker I traced Lake Nasser.² Though I had this great tool I needed one week (seemed much to me) to complete my work.
¹osm.wiki/Scanaerial
²osm.org/go/xijygc--
由 dcp 於 2011年05月16日 20時03分 發表的評論
Thank-you user malenki for the statistics. I am amazed at the numbers; maybe I should not have started. When I say 4 months it was not continous of course: I stoped for 5 weeks while in Portugal in March.
I looked at Scanaerial using your link. I don't think that I have the know-how to use it though.
Once again thanks
由 malenki 於 2011年05月17日 14時18分 發表的評論
So 3 months of work remain - still an unbelievable effort.
Regarding scanaerial: I have enhanced the wiki page so setup should be easier. After all, you already mastered JOSM! ;)
由 jamesks 於 2013年02月11日 17時34分 發表的評論
IMpressive. I think I sketched this in a few years ago, and wondered how it would ever get drawn in detail!