Hi Christoph, OK, I will rule out the GIMP land/sea raster mask as a source for coastline vectorization.
For placenames in the North East Greenland, I'll ask my colleague and former Sirius patrol member Peter Schmidt Mikkelsen, who is also active in a group of old Sirius soldiers, who are restoring the old cabins of the region. They have prepared a number of reports which might include place names - cabin locations will be of interest, too. I have a collection of Landsat8 files covering the country selected after lowest cloud cover and summer season. They are not processed yet and still in zipped files. If I find time I could mix them in GDAL in RGB+pan, transform to EPSG:3857 and build Mapbox tiles for the imagico service? But it would take some time and require assistance to do it most efficiently. Karl 2015-07-29 8:58 GMT-02:00 Christoph Hormann <[email protected]>: > On Wednesday 29 July 2015, Karl Zinglersen wrote: > > > > On the data quality, I agree, that particularly a portion of North > > East Greenland near Daneborg is filled with problems, possibly > > because of ice conditions, shadows and more. Unhappily this is more > > or less the same regions as the GADM coastlines. Otherwise I feel, > > that the coastline is more reasonable in other areas, [...] > > From looking at a few locations all around Greenland it seems while the > problems are most significant in the northeast they actually all occur > throughout all of Greenland. > > > Positioning: I am afraid that many images, also from DigitalGlobe via > > Bing are badly positioned in Greenland. A couple of months ago, I > > realized a new hi-res satellite image for Nuuk instead of the older > > aerial image from Asiaq Greenland Survey. Furthermore the rest of the > > Asiaq aerials had disappeared also. The new imagery was in some > > places 30 m misplaced. I had to contact Wolfgang Walcher from > > Microsoft to bring back the Asiaq aerials (some 15 years old), I > > delivered to them some years ago, so Bing imagery was aligned with > > OSM vectors and the real world in the towns and settlements. I have > > promised Wolfgang to make a list of DigitalGlobe scenes to be > > included in Bing - to cover the less covered wilderness areas. > > Note a good source for aligning images might be data from operation > icebridge (http://nsidc.org/data/icebridge/index.html). However at sea > level newer DigitalGlobe imagery is probably pretty accurate. > > > Placenames across Greenland are managed by Oqaasileriffik, the > > Language Secretary, also a governmental body, whom I know very well. > > I could certainly explain and ask for openess and OSM use of their > > quite comprehensive data set. > > This is probably the best place to start since they should have a > genuine interest in making their names available. > > Currently the most promising and legally sound approach to find names of > features in remote areas of Greenland is to study expedition reports > and publications and cross check them with GEUS maps. Having name > lists, preferrably of course with coordinates and the permission to use > them, would be very helpful here. > > In general the individual names are never subject to copyright, it is > just the collection of names that might be protected as a database. > > > Chris, how do you suggest I, and hopefully others, should proceed for > > Greenland? Using new Landsat8 imagery for classification? Follow up > > on getting Microsoft to add more WorldView scenes to the map service, > > and map manually? Digitizing coastlines on the baselayer of Bing with > > only Landsat7 mosaic is probably not recommended. > > Yes, using up-to-date images is generally the best approach. Priorities > of image providers like Bing and Mapbox to add new images are usually > not in remote areas so i see little chance in that outside major > settlements and prime tourist areas (like Ilulissat Fjord). The > limiting factor will always be work power since there are few mappers > who are interested in mapping these areas. Especially in light of this > it is important to not waste these ressources by letting them map from > outdated and poor quality images. > > If there is a particular area you or other Greenland mappers are > interested in i can put up suitable images for mapping as i did for > Devon Island: > > http://maps.imagico.de/#map=9/75.001/-80.113&lang=en&l=sat&r=osmim&o=3&ui=8 > > but i don't have the time do this prophylactically on a larger scale. > > -- > Christoph Hormann > http://www.imagico.de/ > -- Karl Brix Zinglersen
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