[gdal-dev] Mosaicking Orthos
Marius Jigmond
mariusjigmond at hotmail.com
Mon Feb 21 08:17:10 EST 2011
On Mon, 2011-02-21 at 13:31 +0530, Chaitanya kumar CH wrote:
> Zoltan,
>
> The creation of 0394w.tif failed. Does the process have write
> permission on directory?
> I note that you did not specify the -of option for nearblack. In it's
> absence, nearblack creates the output file in Erdas Imagine format.
True :), regardless of the extension you specify.
>
>
> On Sun, Feb 20, 2011 at 10:50 PM, Zoltan Szecsei
> <zoltans at geograph.co.za> wrote:
> Hi Chaitanya (& all),
> I tried your nearblack comment, and got:
>
> nearblack -white -o 0394w.tif 0394.tif
> Warning 1: TIFFFetchNormalTag:ASCII value for tag
> "ImageDescription" does not end in null byte
>
>
> Warning 1: TIFFFetchNormalTag:ASCII value for tag
> "ImageDescription" does not end in null byte
> Warning 1: TIFFFetchNormalTag:ASCII value for tag "Software"
> contains null byte in value; value incorrectly truncated
> during reading due to implementation limitati
> ERROR 4: Creation of file 0394w.tif failed.
>
>
> I think I am having trouble understanding the setting/using of
> nodata values.
> I have now also downloaded and compiled gdal 1.8.0 (but
> nearblack remained on v1.7.3) on ubuntu 10.04 LTS, and
> recreated my vrt, to no improvement.
>
> To recap: I have 179 3*8bit RGB band aerial images that have
> been orthorectified. The resulting skewness in the images has
> created white slivers in the corners, and I am presuming that
> these white slivers are recognised as "nodata". (My first
> mistake?)
>
> I use the following to create a vrt:
> gdalbuildvrt -addalpha -hidenodata -srcnodata "255 255 255"
> -vrtnodata "0 0 0" -input_file_list files
> 177_untiled_orthos_nodata_180.vrt
>
> Thinking that the above will tell gdalbuildvrt that, for the
> input orthos, white should be recognised as 'nodata', and in
> the VRT, those white pixels should be converted to black, as
> nodata.
> Well, as you've guessed, it didn't happen this way, and I
> still have the white bits after mosaicking my VRT thus:
> gdal_translate -projwin -16000 -3520650 -13000 -3525650
> 177_untiled_orthos_nodata.vrt try1.tif
>
> I tried re-running gdalbuildvrt specifying -vrtnodata "255 255
> 255" (to match the input ortho files) and the outside border
> of my vrt turned white, but the slivers between the mosaicked
> orthos were still present.
>
> Please can someone show me the correct way to address this
> problem.
>
> I have included gdalinfo results for both an individual ortho,
> and for the vrt itself.
>
> Thanks & regards,
> Zoltan
>
>
>
>
>
>
> ********************************** GDALINFO on indicidual
> ORTHO ****************************************
> geograph at gs0:~/vrt_177$ gdalinfo --version
> GDAL 1.8.0, released 2011/01/12
> geograph at gs0:~/vrt_177$
> geograph at gs0:~/vrt_177$
> geograph at gs0:~/vrt_177$
> geograph at gs0:~/vrt_177$
> gdalinfo /mnt/geo_lvm0/ngi_jobs/orthos_8bit/NGI_177_untiled_orthos/0003.tif
> Warning 1: TIFFFetchNormalTag:ASCII value for tag
> "ImageDescription" does not end in null byte
> Warning 1: TIFFFetchNormalTag:ASCII value for tag "Software"
> contains null byte in value; value incorrectly truncated
> during reading due to implementation limitations
>
>
> Mask Flags: PER_DATASET ALPHA
> Band 4 Block=128x128 Type=Byte, ColorInterp=Alpha
> geograph at gs0:~/vrt_177$
> *******************************************************************************************************
>
>
>
>
>
> On 2011-02-16 19:39, Chaitanya kumar CH wrote:
> > Zoltan,
> >
> > Have you tried the nearblack GDAL utility on the original
> > 176 images?
> > http://www.gdal.org/nearblack.html
> >
> > On Wed, Feb 16, 2011 at 5:25 PM, Zoltan Szecsei
> > <zoltans at geograph.co.za> wrote:
> > On 2011-02-16 12:20, Zoltan Szecsei wrote:
> > Hi All,
> > I've built a vrt with 176 images.
> >
> > I now need to mosaic this whole area into
> > roughly 5 x 5 ortho images.
> >
> > How can I force the white edges into
> > background of the overlapping orthos?
> > I'm a little cautious of simply (finding a
> > way to) making "white" transparent as it is
> > only the white on the edges that need to be
> > backgrounded.
> >
> >
> > Hi again,
> > Since the above post, I have tried different ways to
> > set nodata, but to no avail - I still get the white
> > edges:
> > (see jpeg sent with my original post)
> >
> > gdalbuildvrt -addalpha -hidenodata -input_file_list
> > files 177_untiled_orthos_nodata.vrt
> > gdalbuildvrt -srcnodata "0 0 0" -addalpha
> > -hidenodata -input_file_list files
> > 177_untiled_orthos_blk.vrt
> > gdalbuildvrt -srcnodata "255 255 255" -addalpha
> > -hidenodata -input_file_list files
> > 177_untiled_orthos_white.vrt
> >
> > How should I be masking out the nodata (or even
> > white pixels) so that when I mosaic a bunch of tiffs
> > together, I dont get the white stripes in the
> > resulting image?
> >
> > Using GDAL 1.7.3, released 2010/11/10 on Ubuntu
> > 10.04
> > Viewing with Quantum GIS - 1.6.0-Trunk on Ubuntu
> > 10.04 (same box).
> > ...but running the whole lot in xterms with Xming &
> > putty from my WinVista box.
> >
> >
> > Regards,
> >
> > Zoltan
> >
> >
>
>
> --
>
> ===========================================
> Zoltan Szecsei PrGISc [PGP0031]
> Geograph (Pty) Ltd.
> P.O. Box 7, Muizenberg 7950, South Africa.
>
> 65 Main Road, Muizenberg 7945
> Western Cape, South Africa.
>
> 34° 6'16.35"S 18°28'5.62"E
>
> Tel: +27-21-7884897 Mobile: +27-83-6004028
> Fax: +27-86-6115323 www.geograph.co.za
> ===========================================
>
> ______________________________________________________________
>
>
>
>
>
>
>
>
> --
> Best regards,
> Chaitanya kumar CH.
> /tʃaɪθənjə/ /kʊmɑr/
> +91-9494447584
> 17.2416N 80.1426E
> _______________________________________________
> gdal-dev mailing list
> gdal-dev at lists.osgeo.org
> http://lists.osgeo.org/mailman/listinfo/gdal-dev
More information about the gdal-dev
mailing list