On Thursday, 26 May 2011, at 21:55:38 +0200, Oliver Eichler wrote: > These are error messages from GDAL. And yes it is slow. GDAL does not > cache the tiles and it blocks until the complete screen is read. That is > why QLGT has it's own tile server support. > Well, as it seems I was unable to make the tile server support introduced in QLGT 1.1.2 work as expected with custom URL, I took another (apparently unexplored) route: taking advantage of GDAL's WMS/TMS support to real-time load map data from remote servers, according to an XML definition as described on the following URL:
http://www.gdal.org/frmt_wms.html Which, as I understand it, links to the following paragraph from your last post: > Forget about WMS_CLIENT. That is old code. It's not functional in any > way. It's just there because I did not clean up so far. WMS support is > done 100% by GDAL. From QLGT's point if view it's just another map > format supported by GDAL. > So the support for remote WMS/TMS in QLGT thanks to support for them in recent GDAL versions seems known and expected but, as far as I have been able to see, scarcely used, if at all. See the following inline GDAL XML definition for Google map services I've been successfully using: <GDAL_WMS> <!-- Data is subject to term of use detailed at http://code.google.com/intl/nl/apis/maps/terms.html and http://www.google.com/intl/en_ALL/help/terms_maps.html --> <Service name="TMS"> <!-- Google Map --> <ServerUrl>http://mt1.google.com/vt/lyrs=m@155000000&hl=es&x=${x}&y=${y}&z=${z}&s=Gali</ServerUrl> <!-- Google Streets --> <!-- <ServerUrl>http://mt.google.com/vt/lyrs=h@155000000&hl=es&x=${x}&y=${y}&z=${z}</ServerUrl> --> <!-- Google Satellite --> <!-- <ServerUrl>http://khm0.google.es/kh/v=86&x=${x}&s=&y=${y}&z=${z}&s=</ServerUrl> --> </Service> <DataWindow> <UpperLeftX>-20037508.34</UpperLeftX> <UpperLeftY>20037508.34</UpperLeftY> <LowerRightX>20037508.34</LowerRightX> <LowerRightY>-20037508.34</LowerRightY> <TileLevel>20</TileLevel> <TileCountX>1</TileCountX> <TileCountY>1</TileCountY> <YOrigin>top</YOrigin> </DataWindow> <Projection>EPSG:900913</Projection> <BlockSizeX>256</BlockSizeX> <BlockSizeY>256</BlockSizeY> <BandsCount>3</BandsCount> <MaxConnections>5</MaxConnections> <Cache /> </GDAL_WMS> From inside QLGT, if you "File" -> "Load Map" and select the above XML file, you get a real-time Google Maps raster layer quite useable and with zoom and image resolution adapting fine to QLGT zoom levels (and checking "quadratic zoom", one on my previous complaints is gone). Furthermore, it seems (recent) GDAL versions have a working caching mechanism (see the GDAL URL above) I have been experimenting with successfully. A block like the following added to the XML GDAL file for the map resource speeds things up (a lot), and helps reduce network load: <Cache> <Path>/tmp/gdalwmscache</Path> <Depth>2</Depth> <Extension>.jpg</Extension> </Cache> Although this real time raster layer support is far from perfect, it is a very important feature that enables the use of QLGT for people used to more featured programs. The only severe problem I have noticed so far is if I try to overlay a Garmin vector map on top, no matter what I try, the program starts eating memory like crazy, until it ends up crashing due to an out of memory condition (seems to die by itself, Linux out of memory killer seems not to kick in). I don't know if all the above information is well known, but at least I was unable to find if that was possible or not, and could deserve a place into the wiki or on the "features" page for the program. A way to see if there is a remote WMS/TMS being used from QLGT would also be nice (currently there seems to be no way to tell if there is any WMS/TMS in use). Anyway, great piece of software. Nice, and getting better. Hope it helps. Greetings, -- Jose Luis Domingo Lopez Linux Registered User #189436 Linux Kubuntu 11.04 (Linux 2.6.38-8-generic-pae)
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