[Talk-ca] Terminating British Columbia Mosaic imagery

Alan Richards alarobric at gmail.com
Thu Jun 14 05:23:44 UTC 2018


Thanks for providing this great service for the Lower Mainland for so long
Paul! It's been an invaluable resource for mapping in the area.

I would note that Richmond still does not have very good imagery from any
provider. BC Mosaic is far clearer and has better angles, but as you
mentioned, it's getting quite outdated in some areas of heavy construction.
I suppose this is more a fault of Richmond City not opening up any of their
orthophoto data. I've been tending to use ESRI or Bing to compare what's
actually on the ground, but fall back to BC Mosaic for fine detail if
possible.

Alarobric

On Wed, Jun 13, 2018 at 9:58 PM, Paul Norman <penorman at mac.com> wrote:

> I will be shutting down the "British Columbia Mosaic" imagery in the near
> or medium future. I set this up in about 2011, and the system has been
> running without many updates since then.
>
> When I started hosting it, we had access to Bing and Yahoo. Between the
> two of them, we had acceptable for the time imagery in Vancouver, and poor
> imagery in Burnaby and east. Living in New West, this was a problem for me,
> so I put together the layer. My main sources were 10cm 2009 imagery
> covering Vancouver, 2009 20cm imagery for Burnaby, 2011-2012
> <https://maps.google.com/?q=Burnaby,+2011-2012&entry=gmail&source=g> 10cm
> and 40cm for Surrey, and a few other minor sources.
>
> The accuracy and colour range of the Surrey imagery was exceptional for
> the time, and remains exceptional by today's standards. The accuracy of
> other sources was also good, but colours weren't the best. This allowed an
> imagery layer that could be assumed to have accurate positions without
> checking GPS traces everywhere, and its accuracy was ahead of the data in
> OSM at the time, as well as being recent enough.
>
> Times have changed, and we have more imagery hosts. In particular, we
> normally have commercial imagery hosts who will host the open imagery that
> is available, and handle any legal matters about its usage. I remember
> trying to get Bing, Mapbox, or anyone to use the Surrey imagery in Surrey,
> which was better than what they were using in every way and free, and
> having no luck. The data in OSM is frequently more recent than the imagery.
>
> Before deciding to shut it down, I reviewed the available imagery in a few
> areas, and recommend defaulting to ESRI imagery in all of the Lower
> Mainland, with the exception of some cloudy parts of Ladner.* In Ladner,
> and if slightly more recent imagery is needed elsewhere, I recommend
> DigitalGlobe Standard Imagery as a lower quality but more recent source.
> Both have excellent alignment. I would not recommend Mapbox Satellite or
> Bing anywhere in the region.
>
> Instead of shutting down, why am I not moving it to a different server?
> Time, mostly. With all of the sources I had used out of date, I'd have to
> find new ones. This would take a lot of time to find and process sources,
> and a lot of time to sort out the legal mess that is open data in Canada. I
> would also probably take a different approach, with multiple independent
> layers that the editor software picks between.
>
> I believe there is still a place for user-hosted imagery, but at least
> here, it will never offer such an increase in quality again, because the
> commercial hosts are offering a much better "baseline".
>
> * Alignment in Hope was possibly worse, but I haven't done extensive
> research into the accuracy of BC Mosaic in that region. I couldn't find any
> good objects to compare with in Whistler, I kept finding stuff had changed
> on the ground, which is a good reason in itself to avoid BC Mosaic.
>
>
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