[Talk-us] Reminder: OSM US Tile Server

Ian Dees ian.dees at gmail.com
Sun Jul 15 19:19:38 BST 2012

These come from the USGS's seamless imagery server. They are scanned and
probably hand-georeferenced, so I'm not surprised they're not perfect.

I don't have an immediate solution for this, but I do have some contacts at
the USGS that might be interested in making sure it's georeferenced
correctly. Feel free to find other areas that have a similar problem.

On Sun, Jul 15, 2012 at 1:13 PM, Apollinaris Schoell <aschoell at gmail.com>wrote:

> Ian,
> something is wrong with the USGS scanned topo map layer.  At low zoom the
> alignment is perfect and when zooming in it suddenly jumps approx 50-100m
> east. I can see this in San Francisco and from there south to Mountain
> View.  It looks like an L-shaped area with SF at the north end. North and
> East of SF is good. then extends further south-east to at least to Mountain
> View but no more than Sunnyvale.
> I have started to trace the areas but not yet finished. One place in SF
> reminded me of the same problems on the terra server. Is this data a mirror
> of the terra server? I know a couple other places to check but it will take
> some time to verify.
> For California and I think also for the rest of US there are far better
> sources of scanned topo maps. Any chance to fix these? I can offer some
> help to get the scanned maps and eventually with tiling too if there is
> some documentation available.
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