[Talk-ca] Surrey Imagery

Paul Norman penorman at mac.com
Thu Dec 15 08:11:03 GMT 2011


Thanks to iandees, the imagery from Surrey BC is now mirrored with an OSM US
server. It can be accessed with an imagery URL of
tms[10,20]:http://{switch:a,b,c}.tile.osm.osuosl.org/tiles/bc_surrey_2011/{z
oom}/{x}/{y}.png in JOSM, or
http://a.tile.osm.osuosl.org/tiles/bc_surrey_2011/$z/$x/$y.png in Potlatch2.


This URL should bring up PL2 in Queens Park, New Westminster with the
imagery loaded.
http://www.openstreetmap.org/edit?editor=potlatch2&lat=49.215&lon=-122.903&z
oom=17&tileurl=http://a.tile.osm.osuosl.org/tiles/bc_surrey_2011/$z/$x/$y.pn
g

The tiles are cached on the osuosl server but uncached tiles are accessed
from my home server. This is blazingly fast for me, but not so fast for
everyone else. Expect a bit of a delay at high zooms as it fetches the data.
I have pre-fetched the lower zooms.

The data is licensed under the PDDL and suitable for tracing from. Running
off of my home server, this service is only for OSM and not for other
projects. 

The imagery was flown in April-May 2011 and captured digitally at a 10cm
resolution. There are moderate leafs on the trees. The imagery is more
accurate than consumer grade GPS. The extents of the imagery are the north
end of the Port Mann, 800m south of the US border, 204 Street in Langley,
and a line running from approximately 19th Ave and 2nd St in Burnaby through
the east part of Queensborough and Annacis Island and down near 104th Street
in Delta. This includes all of Surrey, most of New Westminster, a large part
of Pitt Meadows, Barnston Island, most of North Delta, part of Langley City,
all of White Rock and part of Burnaby and Coquitlam.

Technical details: The imagery was converted from mrsid files to GeoTIFFs
and then a parallized version of gdal2tiles converted it into TMS tiles with
lanczos resampling.

If the load becomes excessive I will have to throttle my server but I do not
anticipate the need to do so. Many thanks to Ian for mirroring this.

My standard offer of the imagery to anyone who supplies the dual-layer DVDs
necessary to transfer it applies.




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