[Talk-ca] Internal CanVec conflicts

[Dan Charrois]

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 
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