Jay, The external overview files are created in TIFF format. I checked. However, most of the metadata will be lost. You can recover the metadata by using gdal_translate with "-outsize 3.125% 3.125%". It will read the metadata from the original file and the pixels from the level 32 overview.
Regarding the 2.1GB file: Check if the directory is not read-only and the disk has sufficient space. Run gdaladdo with the environment variable CPL_DEBUG set to YES and report the messages. You can also try gdalwarp multiple times with the resampling method set to something other than 'near' and 'bilinear'. However, I am not sure if this will give you want you want. On Tue, Feb 22, 2011 at 4:26 AM, Jay Jennings <jennings....@geoeye.com>wrote: > Unfortunately I can’t provide the file (it’s about 2.1 GB and not > releasable), but below is the ‘gdalinfo’ dump for it. > > > > The problem may be related to size of the input, because the same command > worked OK on a GeoTiff that is “only” 975 MB. > > > > BTW For the 975 GB run that succeeded, the created overview was named > *.ovr rather than *.tif. Is this expected ? The guidance for ‘gdaladdo’ > hints that the created *.ovr is actually a TIFF, but that’s not true here (I > tried renaming it *.tif, but no TIFF reader could open it). > > > > > > Driver: GTiff/GeoTIFF > > Files: XXXXXX.tif > > Size is 25733, 27840 > > Coordinate System is: > > GEOGCS["WGS 84", > > DATUM["WGS_1984", > > SPHEROID["WGS 84",6378137,298.257223563, > > AUTHORITY["EPSG","7030"]], > > AUTHORITY["EPSG","6326"]], > > PRIMEM["Greenwich",0], > > UNIT["degree",0.0174532925199433], > > AUTHORITY["EPSG","4326"]] > > Origin = (-100.375165330488004,29.624901844319002) > > Pixel Size = (0.000004869286704,-0.000004495684143) > > Metadata: > > TIFFTAG_DATETIME=2009:07:17 06:16:07 > > TIFFTAG_ARTIST=GeoEye > > TIFFTAG_COPYRIGHT=(C) COPYRIGHT GeoEye, All Rights Reserved > > TIFFTAG_MINSAMPLEVALUE=0 > > TIFFTAG_MAXSAMPLEVALUE=255 > > AREA_OR_POINT=Area > > Image Structure Metadata: > > INTERLEAVE=PIXEL > > Corner Coordinates: > > Upper Left ( -100.3751653, 29.6249018) ( 100d22'30.60"W, 29d37'29.65"N) > > Lower Left ( -100.3751653, 29.4997420) ( 100d22'30.60"W, 29d29'59.07"N) > > Upper Right ( -100.2498639, 29.6249018) ( 100d14'59.51"W, 29d37'29.65"N) > > Lower Right ( -100.2498639, 29.4997420) ( 100d14'59.51"W, 29d29'59.07"N) > > Center ( -100.3125146, 29.5623219) ( 100d18'45.05"W, 29d33'44.36"N) > > Band 1 Block=512x512 Type=Byte, ColorInterp=Red > > Band 2 Block=512x512 Type=Byte, ColorInterp=Green > > Band 3 Block=512x512 Type=Byte, ColorInterp=Blue > > > > *From:* Chaitanya kumar CH [mailto:chaitanya...@gmail.com] > *Sent:* Monday, February 21, 2011 4:19 PM > *To:* Jay Jennings > *Cc:* gdal-dev@lists.osgeo.org > *Subject:* Re: [gdal-dev] Downsample with averaging? > > > > Jay, > > Can you provide a sample file that gives this error? > > On Tue, Feb 22, 2011 at 1:56 AM, Jay Jennings <jennings....@geoeye.com> > wrote: > > Hello list, > > (using GDAL 1.8.0) I am trying to create a 32:1 down-sampled overview of a > GeoTiff satellite image. My first thought was gdal_translate, with args > such as “-outsize 3.125% 3.125%”… which produces surprisingly high quality > given the absence of a resampling option. However I’m looking for a > downsampling scheme that creates a result pixel by averaging all relevant > source pixels (I know, for 32:1 downsample, that means 1024 source pixels > for each result pixel !) with the hope of an output that is not “speckled” > or “grainy” insofar as possible. > > > > I also looked at gdaladdo, which does have the “-r average” resampling > option… the guidance at gdal.org seems to suggest that it can produce a > 32:1 GeoTIFF external overview with a command like this: > > > > gdaladdo -r average -ro XXXXX.tif 32 > > > > But that produces a surprising error message, namely: > > ERROR 4: `XXXXX.tif.ovr' does not exist in the file system, and is not > recognised as a supported dataset name. > > > > Am I barking up the wrong tree with gdaladdo for this purpose ? Anybody > have any suggestions for highest-quality down-sampling ? Thanks in advance. > > > > --Jay Jennings > > > _______________________________________________ > gdal-dev mailing list > gdal-dev@lists.osgeo.org > http://lists.osgeo.org/mailman/listinfo/gdal-dev > > > > > -- > Best regards, > Chaitanya kumar CH. > /tʃaɪθənjə/ /kʊmɑr/ > +91-9494447584 > 17.2416N 80.1426E > > _______________________________________________ > gdal-dev mailing list > gdal-dev@lists.osgeo.org > http://lists.osgeo.org/mailman/listinfo/gdal-dev > -- Best regards, Chaitanya kumar CH. /tʃaɪθənjə/ /kʊmɑr/ +91-9494447584 17.2416N 80.1426E
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