30 октября 2011 г. 0:32 пользователь Brian Case <[email protected]> написал: > Darafei, > > Are you seeing this when zoomed out with mapserver? If so I think what > your seeing is actually caused by mapserver not by gdal. Try adding > PROCESSING "RESAMPLE=AVERAGE" to your layers in the mapfile
If I add that option, I get black borders on geotiff DATA edges: http://latlon.org/~komzpa/screenshots/mapserver_resample_average.png Vertical stripes don't disappear, too. > Brian > > On Sun, 2011-10-30 at 00:00 +0300, Komяpa wrote: >> Hi, >> >> 2011/10/29 Frank Warmerdam <[email protected]>: >> > On 11-10-29 12:18 PM, Komяpa wrote: >> >> >> >> Still, there are some things I would like to clear / discuss. >> >> >> >> 1) gdaladdo final.tif 2 4 8 16 32 64 128 256 makes not beautiful >> >> overviews. If I add -r average, some artifacts start appearing, like >> >> the vertical stripes on the link above. Any good ways to fix that? >> > >> > Darafei >> > >> > I would be interested in reproducing this at my end and investigating. >> > Could you provide something I can work with? I presume the issue >> > relates to the average overview builder not understanding nodata >> > masking. Are you using GDAL "trunk"? >> >> You can grab geotiffs from http://dev.latlon.org/tiff/baloon/ >> Mapserver map file: http://dev.latlon.org/tiff/all.map >> >> I am using gdal 1.8.1-2~exp2 from debian experimental. >> >> >> >> 3) JPEG compression artifacts. >> >> Black field outside makes outmost blocks appear darker and be "dirty": >> >> >> >> http://latlon.org/maxi?zoom=18&lat=56.32465&lon=30.61984&layers=0000000000000FF0000FBT >> >> This can be avoided, as far as I can see, in two ways: >> >> a) easier one, on compression, if we fill NODATA region inside these >> >> blocks not with black, but with bilinear average of other data inside >> >> block, there will be no black blocks. >> >> b) harder one, make custom jpeg decompressor that will take exact >> >> value for nodata region into account and try to restore values for >> >> DATA region (not sure if it's really possible). >> >> >> >> Same about compressing overviews. Probably nearblack can be patched to >> >> fill regions not with black but with any kind of average, as >> >> quick-and-dirty solution? >> > >> > I don't see this as the role of nearblack, but I can see it might >> > be helpful to have a way of doing this to an image under the nodata >> > mask as a distinct utility. Alternatively since this is mostly an >> > issue with the jpeg compressor, perhaps just to do it within the >> > geotiff through jpeg writing code in GDAL. >> >> Would be nice if geotiff jpeg writer can just fill NODATA region with >> garbage that will help DATA look nicer (and compress better). >> >> >> > Can you provide something that helps me isolate this problem to >> > work on? >> > >> > Best regards, >> > -- >> > ---------------------------------------+-------------------------------------- >> > I set the clouds in motion - turn up | Frank Warmerdam, >> > [email protected] >> > light and sound - activate the windows | http://pobox.com/warmerda >> > and watch the world go round - Rush | Geospatial Software Developer >> > >> > >> > _______________________________________________ >> > talk mailing list >> > [email protected] >> > http://host134.hostmonster.com/mailman/listinfo/talk_openaerialmap.org >> > >> >> >> > > > -- Darafei "Komяpa" Praliaskouski OSM BY Team - http://openstreetmap.by/ xmpp:[email protected] mailto:[email protected] _______________________________________________ talk mailing list [email protected] http://host134.hostmonster.com/mailman/listinfo/talk_openaerialmap.org
