[gdal-dev] Using a MapQuest TMS via GDAL

[Chris Hanson]

  I'm trying to access a web mapping service (MapQuest in this case) using
the GDAL WMS driver.

  Inspired by this page:
http://www.3liz.com/blog/rldhont/index.php?post/2012/07/17/OpenStreetMap-Tiles-in-QGIS

  and this
http://developer.mapquest.com/web/products/open/map

 I formulate an XML string such as this:

<GDAL_WMS><Service name="TMS"><ServerUrl>
http://otile1.mqcdn.com/tiles/1.0.0/sat/${z}/${x}/${y}.png</ServerUrl></Service><DataWindow><UpperLeftX>-1.035240e+007</UpperLeftX><UpperLeftY>5.297933e+006</UpperLeftY><LowerRightX>-1.035144e+007</LowerRightX><LowerRightY>5.297055e+006</LowerRightY><TileLevel>1</TileLevel><TileCountX>1</TileCountX><TileCountY>1</TileCountY><YOrigin>top</YOrigin></DataWindow><Projection>EPSG:3857</Projection><BlockSizeX>256</BlockSizeX><BlockSizeY>256</BlockSizeY><BandsCount>3</BandsCount><Cache
/></GDAL_WMS>

  I was hoping this was going to return a georeferenced raster of just the
area I'm interested in (defined by the DataWindow) but instead it seem to
return a virtual image comprising the whole world. However, it comes
bearing georeferencing info

Corner Coordinates:
Upper Left    (-10352400.000, 5297933.000)
Lower Left    (-10352400.000, 5297055.000)
Upper Right   (-10351440.000, 5297933.000)
Lower Right   (-10351440.000, 5297055.000)
Center        (-10351920.000, 5297494.000)

That indicates it IS the area I requested. But when you look at it, it's
the whole world image.

  Is the DataWindow just ignored here?

  What is the proper process for requesting a DataWindow region and getting
a proper reoreferenced raster subset back?

  And yes, we are within the license term for MapQuest. They've been
helping us, but it looks like this issue isn't really them, it's how I'm
using GDAL.

  Google, VirtualEarth and OSM all react the same way -- ignoring the
DataWindow.


-- 
Chris 'Xenon' Hanson, omo sanza lettere. Xenon at AlphaPixel.com
http://www.alphapixel.com/
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