Usually, in remote areas of the north that I've dealt with, there is often little else already there than the Landsat lakes. And usually, in a given tile, there is usually just a handful of lakes.
In pretty much every case I've dealt with so far, I've replaced the Landsat lakes with Canvec data. Landsat lake outlines have a much lower resolution, and being derived by an automatic process themselves, are subject to the errors associated with that. But I wouldn't necessary erase all the Landsat data from a tile without checking first to make sure that there will be Canvec data replacing it (I always work with my Canvec data in a separate layer and merge things in one "feature" at a time as it's checked). Using Bing imagery may be a good idea to check any issues where Landsat data may exist and Canvec doesn't - even low resolution Bing imagery is usually sufficient for the Landsat lakes. I have yet to encounter a place where there is a Landsat lake and not a corresponding Canvec one of roughly the same shape, but it could happen. I have yet to find a situation where the Landsat lake data is better than the Canvec data. Dan On 2012-Nov-16, at 12:11 PM, Pierre Béland wrote: > Looking at all of north of Canada, I see that most of it has been first > mapped using Lakewalker Plugin and Landsat imagery. > I see tags created_by=Dshpak_landsat_lakes or source=Landsat. > > Those of you that have imported Canvec data in such regions are surely > familiar with that problem could confirm and help document Canvec Import > Guidelines to facilitate imports by newcomers. > > What procedure do you recommend? Do you agree that we should recommend to > erase Landsat imagery before importing Canvec data? > > This can be done easily in JOSM. We just have to use the find filter > created_by=shpak_landsat_lakes and erase the selected objects. > > Too risky? > > Pierre -- Syzygy Research & Technology Box 83, Legal, AB T0G 1L0 Canada Phone: 780-961-2213 _______________________________________________ Talk-ca mailing list [email protected] http://lists.openstreetmap.org/listinfo/talk-ca
