On 21/09/15 10:23, Alistair Young wrote:
thanks for that. I downloaded the TFW and TAB files from the Ordnance Survey, put them
in the same directory as the tif and did: > > gdal_translate -of VRT -a_srs
EPSG:27700 sx88.tif out.vrt >
The TFW and tab files should provide this the georeference and
coordinate system
information. This means you should just be able to skip the
gdal_translate step
and use sx88.tif directly. You can run `gdalinfo sx88.tif` to verify this.
And ran ctb-tile on out.vrt. It tiled it but into what appear to be weird
columns and rows. E.g. Col 14, row 16046 etc. The SDK fails to read this as I
suspect it expects 20 cols and 20 rows (it’s 5 metres per pixel resolution)
The weird columns and rows reflect your use of the TMS geodetic profile.
Passing `-profile mercator` to ctb-tile will use the Mercator profile.
I've not
used the OSGB SDK but if I had to guess I would assume it uses web
mercator.
The resolution of the tiles will vary with the zoom level that you are
looking
at. When you say 'it’s 5 metres per pixel resolution' what are you
referring to
by 'it'?
I’m not sure what ullr is for. There’s no information about the tif (it’s a
British National Grid Square 20kmx20km) but I’ve no idea what lat/lon it covers.
ullr specifies the extent of the dataset. Assuming sx88.tif refers to
the OSGB
national grid square SX88 (which would be 10kmx10km), your gdal_translate
command would be:
gdal_translate -of VRT -a_ullr 280000 90000 290000 80000 -a_srs
EPSG:27700 sx88.tif out.vrt
As mentioned, however, the TFW and TAB files should provide this
information.
If you need further help with using ctb-tile, it may be best to email me
directly rather than risk polluting the GDAL mailing list.
Best regards,
Homme.
> Alistair > > > ----------------- > mov eax,1 > mov ebx,0 > int 80 >
> From: <[email protected]> on behalf of Homme Zwaagstra
<[email protected]> > Date: Monday, 21 September 2015 08:29 > To:
"[email protected]" <[email protected]> > Subject: Re:
[gdal-dev] Generating 200x200 tiles > > > > On 19/09/15 08:14, Alistair
Young wrote: > > Thanks for that. I tried ctb but just got "Could not
get transformation > information from source dataset². Chaning
gdal2tiles to output 200x200 > worked ok but the SDK failed to display
the tiles. I just have a 4000x4000 > > tif with no geo referencing
information so I can only generate raster > profile tiles. > > Alistair,
you'll have trouble getting anything useful out of any geospatial >
tools without inputting datasets that are correctly georeferenced with
an > appropriate spatial reference system. Assuming you know the
extents of your > 4000x4000 raster, you should be able to do this by
creating a virtual raster > with gdal_translate using options along the
following lines: > > gdal_translate -of VRT -a_srs srs_def -a_ullr
ulx uly lrx lry in.tif out.vrt > > Passing out.vrt to ctb should resolve
the error, and you'll have more chance > with other tools too. > > Best
regards, > > Homme > > > > Alistair > > > ----------------- > mov eax,1
> mov ebx,0 > int 80 > > > > > On 18/09/2015 00:36,
"[email protected] on > behalf of Brad > Hards" >
<[email protected] on behalf of [email protected]> >
wrote: > >> On Thu, 17 Sep 2015 06:03:15 PM Alistair Young wrote: >>>
I've been using gdal2tiles to generate zoom levels and tiles and it's
>>> working fine but unfortunately the tiles > are 256x256 and don't
work with >>> the UK Ordnance Survey mapping SDK, which requires 200x200
tiles. Is >>> there >>> a way to generate these 200x200 tiles? I can
generate them using >>> gdal_retile but it can't generate the zoom
levels. >> I'd suggest just > hacking the python script. Make a copy,
and edit the >> __init__() function to change the tileSize member init
to be 200 vs 256. >> >> Worth a quick try at least. >> >> Brad >> >> >>
_______________________________________________ >> gdal-dev mailing list
> >> [email protected] >> > >
http://lists.osgeo.org/mailman/listinfo/gdal-dev > >
_______________________________________________ > gdal-dev mailing list
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http://lists.osgeo.org/mailman/listinfo/gdal-dev > >
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