Hi Evan
Indeed, the external libtiff is used and is version
libtiff-3.9.4-1.el6_0.3.x86_64.
In the mean time I did a quick compile of gdal-1.9.0 with internal
libtiff and the square disappeared.
Probably it would be a wise decision to switch to libtiff4 quickly, as
far as ELGIS is concerned.
Thanks,
Peter
On 02/03/2012 01:41 PM, Even Rouault wrote:
Peter,
Does ELGIS GDAL uses internal libtiff (4.0beta) or external libtiff (3.8 or 3.9)
? I guess it is external libtiff, and then it could explain the issues you have
with overviews and JPEG compression. There have been fixes in libtiff 4 to
better support that situation (multiple IFDs with compression). Altertantively,
you could probably workaround that by generating external overviews (add -ro to
the gdaladdo command line), but no guarantees. By the way, the --config
COMPRESS_OVERVIEW JPEG --config INTERLEAVE_OVERVIEW PIXEL --config
JPEG_QUALITY_OVERVIEW 90 options only apply to external overviews, not internal
ones.
I'm doing quite some experiments with GDAL and image compression these days
I do have an issue with geotiff 1.3/gdal 1.8.1 on CentOS 6 with packages
from ELGIS. The story goes like this:
I create tiffs with
gdal_translate -of GTiff -co COMPRESS=JPEG -co JPEG_QUALITY=90
-co "TILED=YES" -co "BLOCKXSIZE=512" -co "BLOCKYSIZE=512"<infile>
<outfile>
and then add overviews with (I do have to add the overlays in distinct
steps, otherwise gdaladdo aborts with an error message).
gdaladdo --config COMPRESS_OVERVIEW JPEG --config INTERLEAVE_OVERVIEW
PIXEL --config JPEG_QUALITY_OVERVIEW 90 -r average<outfile> 3
gdaladdo --config COMPRESS_OVERVIEW JPEG --config INTERLEAVE_OVERVIEW
PIXEL --config JPEG_QUALITY_OVERVIEW 90 -r average<outfile> 9
gdaladdo --config COMPRESS_OVERVIEW JPEG --config INTERLEAVE_OVERVIEW
PIXEL --config JPEG_QUALITY_OVERVIEW 90 -r average<outfile> 27
gdaladdo --config COMPRESS_OVERVIEW JPEG --config INTERLEAVE_OVERVIEW
PIXEL --config JPEG_QUALITY_OVERVIEW 90 -r average<outfile> 81
(Trying with power-of-2-steps gives the same result. If I drop all
options from gdaladdo: same result).
I'll create a WMS service with MapServer 5.6.7 and do get a big red
square in the image. The square is "fixed" to the geografical position,
e.g. if I move the extend the square moves too. The square is situated
in the corner of the tiff file.
It appears only at some scales. If I change it very slightly, the square
remqins, if I change for more then approx 1%, it disappears.
I've put the two images at
http://www.r3-gis.com/gdal_issues/tiff_with_jpegcompression_and_overviews.jpeg
and
http://www.r3-gis.com/gdal_issues/tiff_with_nocompression_and_overviews.jpeg
.
The problem disappears if I do not run gdaladdo on the images or when I
do not use Jpeg compression:
gdal_translate -of GTiff -co "TILED=YES" -co "BLOCKXSIZE=512" -co
"BLOCKYSIZE=512"<origfile> <targetfile>
There are some hits for
http://www.google.com/search?client=ubuntu&channel=fs&q=mapserver+artefacts+in+raster+gdal&ie=utf-8&oe=utf-8,
but mostly related to older versions of GDAL and without resolution.
Thanks,
Peter
--
Peter Hopfgartner
R3 GIS Srl - GmbH
www.r3-gis.com
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--
Peter Hopfgartner
R3 GIS Srl - GmbH
web : www.r3-gis.com
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