[Talk-us] USGS Large-Scale Imagery degraded this month :(

Ian Dees ian.dees at gmail.com
Sun Dec 18 19:59:22 UTC 2016


I run the tile.openstreetmap.us server and noticed this change. Thanks for
finding the USGS link: I saw it a while ago but then couldn't find it when
I was trying to debug the problems with the server. The "usgs_large_scale"
layer on tile.openstreetmap.us is now caching the USGSNAIPPlus layer, but
the URL they provide both has worse imagery and is run from a much slower
server (so my caching operation takes quite a bit longer and results in
occasional 404s to the end user).

I will try to contact a couple of the folks I know at USGS (maybe they're
still on this list and could respond?), but it might be the case that we
need to request the imagery and build the desired layer ourselves...

On Sun, Dec 18, 2016 at 2:43 PM, David Kewley <david.t.kewley at gmail.com>
wrote:

> For a lot of my satellite imagery tracing, I've found it very useful to go
> back and forth between Bing and USGS Large-Scale Imagery, which provides at
> least 1-m resolution across the U.S., and in some areas (e.g. urban areas)
> provides nice 1-foot resolution orthoimagery that aligns very well in my
> local area with Bing imagery.
>
> Well, I should say "provided", past tense. For the past couple of weeks or
> so, I've noticed that the the USGS LSI has seemed to degrade in many of my
> local imagery tiles, and I've finally looked into why that might be so.
>
> For example, at this location, today (current state of imagery tile
> caching, perhaps mostly local to me?)
>
> https://www.openstreetmap.org/edit?changeset=44464607#map=
> 19/33.56194/-117.67451
>
> when using USGS LSI, I see the NE, NW, and SW imagery tiles look fine, but
> the SE tile is much lower quality, clearly from a different set of imagery.
> I could swear this area was formerly seamless with the good imagery.
>
> It looks like this month's degradation is probably a downstream effect of
> this change:
>
> https://www.usgs.gov/news/usgs-national-map-orthoimagery-map-services-
> transition-and-other-map-service-changes
>
> Before USGS made this change, I saw identical imagery if I used iD's
> built-in USGS LSI, versus using the following setting in Custom imagery in
> iD:
>
> http://whoots.mapwarper.net/tms/{z}/{x}/{y}/0/http://raster.
> nationalmap.gov/arcgis/services/Orthoimagery/USGS_EROS_Ortho
> /ImageServer/WMSServer?
>
> The OSM built-in USGS LSI was faster than this custom link, I believe
> because the custom link is dynamic (not cached by whoots), and it takes two
> round trips, a lookup by iD to whoots, then by whoots to USGS, and probably
> a dynamic conversion by whoots. I'm not an expert in this, so could easily
> have some of this wrong.
>
> USGS LSI seemed faster -- perhaps it was static on the backend, or cached
> better or something. The OSM built-in USGS LSI imagery appears to be served
> by openstreetmap.us, though I know none of the details of how it's served.
>
> Anyway now per the above announcement link, the *USGS_EROS_Ortho* URL is
> deprecated, and is no longer served, and it seems like the following whoots
> dynamic lookup imagery is the appropriate one, based on the
> USGS-recommended replacement for the deprecated imagery:
>
> http://whoots.mapwarper.net/tms/{z}/{x}/{y}/1/https://
> services.nationalmap.gov/arcgis/services/USGSNAIPPlus/MapServer/WMSServer?
>
> Indeed when I use this in the Custom imagery setting in iD, I see the same
> degraded imagery that the built-in USGS LSI setting now gives me.
>
>
> Can anyone shed further light or corrections on any of this? Any idea
> whether it's technically possible and legally permissible to have
> openstreetmap.us serve the older, better USGS LSI instead of the newer,
> worse stuff? If so, upon further discussion I'd probably support such a
> move, and possibly even offer to help with the conversion. :)
>
> Thanks!
> David
>
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>
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