Noura, First, note that osm tiles are presented in EPSG:900913 reference system.
The usual way of requesting the tiles is based on the extent coordinates. GDAL's WMS driver[1] can be used to access it. For that you need an XML file[2] specifying the service. Once you obtain the coordinates like Saâd explained, convert them to EPSG:900913 and use it obtain the tiles. [1]: http://www.gdal.org/frmt_wms.html [2]: http://www.gdal.org/frmt_wms_openstreetmap_tms.xml On Tue, Apr 10, 2012 at 2:17 PM, Saâd HESSANE <[email protected]>wrote: > DTED files are really simple to undertand. A DTED CD-ROM is organized like > this : > > - *dted (folder)* > - *D### (folder)* > - H##.dt# (file) > - H##.dt# (file) > - ...* > * > - *D### (folder)* > - *... > * > - *gazette (folder) > * > - *text (folder) > * > - dmed (file) > > # : digit > D : The direction of the tiles E for East and W for West > H : The hemispher of the tile : N for North and S for South > > > A DTED file represent data elevation of a square of 1°x1°. So the folder > "e055" contain dted files that have longitude 55E. If the folder contain > the file "n33.dt0", that mean the file contain data elevations of a 1°x1° > square starting at 55E 33N (ending at 56E 34N). > > Note about DTED specification : > > - The DTED specification don't tell if the lettre have to be in > capital lettre or not. So you can have "n33.dt0" or "N33.dt0". Be careful > with that. > - The specification don't tell to have contigu file or folder. So you > can have a folder E055 and E060 without the folder between 55 and 60. > > > I hope I answerd your question. > > > > > > 2012/4/10 len lee <[email protected]> > >> hello; >> i downloaded dted data dt0 from raster roam website and there are 3 >> folders e055, e056 and e057 and within each folder there are 3 dted files >> and i guess each dted file here represent a tile within my terrain. now >> what am trying to do is requesting the terrain tiles according to my dted >> data .. any idea how can i do that with gdal lib? >> i tried this: >> poDataset = (GDALDataset *) GDALOpen( " >> http://tile.openstreetmap.org/15/23687/15190.png";, GA_ReadOnly ); >> >> to request a specific tile from openstreetmap server but as you can see i >> need to know the exact coordinate system for that tile ... >> >> please all what i need is to understand the process of requesting the >> tiles according to my dteds files; >> >> i will appreciate any help; >> thanks in advance; >> >> _______________________________________________ >> gdal-dev mailing list >> [email protected] >> http://lists.osgeo.org/mailman/listinfo/gdal-dev >> > > > _______________________________________________ > gdal-dev mailing list > [email protected] > http://lists.osgeo.org/mailman/listinfo/gdal-dev > -- Best regards, Chaitanya kumar CH. +91-9494447584 17.2416N 80.1426E
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