[Talk-ca] Your new coastline
G. Michael Carter
mikey at carterfamily.ca
Fri Sep 2 21:34:27 BST 2011
I wish they'd updated the Bing high resolution images.... In Orangeville
there's a new mall, but only one image (of three tiles) has the new mall,
the other has the cleared field from when they started. I can only put in
half the buildings.
Any ideas on how often they update the high res?
On Fri, Sep 2, 2011 at 3:08 PM, Andrew MacKinnon <andrewpmk at gmail.com>wrote:
> On Thu, Sep 1, 2011 at 11:15 PM, James A. Treacy <treacy at debian.org>
> > On Thu, Sep 01, 2011 at 10:30:34PM -0400, Andrew MacKinnon wrote:
> >> Given that this sort of work is time consuming it will take a while to
> >> finish. However, 99% of the work that requires importing coastlines
> >> from CanVec is done, and realigning coastlines using Bing is a lot
> >> less disruptive and less error-prone.
> > I'm curious why you would trust the Bing imagery more than canvec. In
> > addition to not being very high resolution, I would think that Bing
> > would suffer from problems with registration (alignment of images to
> > lat/lon) which would have to be checked against ground readings. Of
> > course canvec should also be checked for accuracy with local readings.
> > Further, my understanding is that much of the canvec data is generated
> > from local surveying, which uses high end GPS which are extremely
> > accurate.
> > Locally (Kitchener-Waterloo) I have found that the canvec data is very
> > accurate and most imagery less so.
> I have been using the Bing imagery where high resolution imagery is
> available and Canvec where high resolution Bing imagery is not
> available. My impression is that for coastlines, tracing from Bing
> imagery is more accurate than the Canvec data.
> Keep in mind that some of the Canvec data is VERY out of date. While
> the road data in Canvec is fairly up to date, the rest of the Canvec
> data seems to be old (1990s, 1980s even?) Canvec data shows woods,
> buildings etc. which clearly haven't existed for many years, for
> example it often shows forests in areas where new subdivisions have
> been built recently, old industrial buildings which were torn down 10
> years ago and replaced with housing, long-ago abandoned rail spurs to
> industrial areas and long-demolished agricultural buildings. I would
> not trust anything except the roads layer in Canvec to be up to date.
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