Nicole, The problem is reading the source file itself. GDAL is unable to find any valid pixels. Check if you are using the latest GDAL binaries. Use "gdalinfo -version". Use qgis to view the input and output. GIMP can't handle anything except basic pixel types. The -mm option should find some valid pixels if everything is good.
Later, you should scale the pixel values to 0-255 range to represent them in PNG. -- Best regards, Chaitanya Kumar CH On 15-Apr-2014 4:40 pm, "Nicole Stoffels" <stoff...@f2e.de> wrote: > Thank you both for your answers. I have applied your suggestions. > > Making a single command works but does not change the result. > > Concerning the compression, I used LZW instead of NONE. However, it also > does not make any difference. > > I also changed the srcwin parameters. I do not get any errors and the > gdalinfo says that the subarea is within the original area. > > I skipped the png part to make it easier first. And after trying to open > the new tif with gimp and getting an error message that the float32 data > cannot be displayed I added the ot-flag. Here is my new command line: > > $ gdal_translate -ot Byte -srcwin 0 0 4000 4000 -co COMPRESS=LZW > EUD_CP-DEMS_6500035000-AA.tif test.tif > > What I get is a completely black tif. Here are the two gdalinfo-outputs, > that I get: > > $ gdalinfo -mm EUD_CP-DEMS_6500035000-AA.tif > Driver: GTiff/GeoTIFF > Files: EUD_CP-DEMS_6500035000-AA.tif > Size is 40000, 40000 > Coordinate System is: > PROJCS["ETRS89 / ETRS-LAEA", > GEOGCS["ETRS89", > DATUM["European_Terrestrial_Reference_System_1989", > SPHEROID["GRS 1980",6378137,298.2572221000027, > AUTHORITY["EPSG","7019"]], > AUTHORITY["EPSG","6258"]], > PRIMEM["Greenwich",0], > UNIT["degree",0.0174532925199433], > AUTHORITY["EPSG","4258"]], > PROJECTION["Lambert_Azimuthal_Equal_Area"], > PARAMETER["latitude_of_center",52], > PARAMETER["longitude_of_center",10], > PARAMETER["false_easting",4321000], > PARAMETER["false_northing",3210000], > UNIT["metre",1, > AUTHORITY["EPSG","9001"]], > AUTHORITY["EPSG","3035"]] > Origin = (6000000.000000000000000,4000000.000000000000000) > Pixel Size = (25.000000000000000,-25.000000000000000) > Metadata: > TIFFTAG_DOCUMENTNAME=EUD_CP-DEMS_6500035000-AA.tif > TIFFTAG_IMAGEDESCRIPTION=File written by egcs_wrgtif 2.1 > TIFFTAG_SOFTWARE=IDL 8.2, Exelis Visual Information Solutions, Inc. > TIFFTAG_DATETIME=2013:09:17 21:00:27 > TIFFTAG_XRESOLUTION=100 > TIFFTAG_YRESOLUTION=100 > TIFFTAG_RESOLUTIONUNIT=2 (pixels/inch) > AREA_OR_POINT=Area > Image Structure Metadata: > COMPRESSION=LZW > INTERLEAVE=BAND > Corner Coordinates: > Upper Left ( 6000000.000, 4000000.000) ( 37d47'0.49"E, 56d 7'28.33"N) > Lower Left ( 6000000.000, 3000000.000) ( 32d47'35.21"E, 47d45'16.08"N) > Upper Right ( 7000000.000, 4000000.000) ( 51d32'27.75"E, 51d55'27.24"N) > Lower Right ( 7000000.000, 3000000.000) ( 44d57'3.39"E, 44d18'11.63"N) > Center ( 6500000.000, 3500000.000) ( 41d41'39.51"E, 50d15'46.40"N) > Band 1 Block=40000x1 Type=Float32, ColorInterp=Gray > ERROR 1: Failed to compute min/max, no valid pixels found in sampling. > > $ gdalinfo -mm test.tif > Driver: GTiff/GeoTIFF > Files: test.tif > Size is 4000, 4000 > Coordinate System is: > PROJCS["ETRS89 / ETRS-LAEA", > GEOGCS["ETRS89", > DATUM["European_Terrestrial_Reference_System_1989", > SPHEROID["GRS 1980",6378137,298.2572221010002, > AUTHORITY["EPSG","7019"]], > AUTHORITY["EPSG","6258"]], > PRIMEM["Greenwich",0], > UNIT["degree",0.0174532925199433], > AUTHORITY["EPSG","4258"]], > PROJECTION["Lambert_Azimuthal_Equal_Area"], > PARAMETER["latitude_of_center",52], > PARAMETER["longitude_of_center",10], > PARAMETER["false_easting",4321000], > PARAMETER["false_northing",3210000], > UNIT["metre",1, > AUTHORITY["EPSG","9001"]], > AUTHORITY["EPSG","3035"]] > Origin = (6000000.000000000000000,4000000.000000000000000) > Pixel Size = (25.000000000000000,-25.000000000000000) > Metadata: > TIFFTAG_DOCUMENTNAME=EUD_CP-DEMS_6500035000-AA.tif > TIFFTAG_IMAGEDESCRIPTION=File written by egcs_wrgtif 2.1 > TIFFTAG_SOFTWARE=IDL 8.2, Exelis Visual Information Solutions, Inc. > TIFFTAG_DATETIME=2013:09:17 21:00:27 > TIFFTAG_XRESOLUTION=100 > TIFFTAG_YRESOLUTION=100 > TIFFTAG_RESOLUTIONUNIT=2 (pixels/inch) > AREA_OR_POINT=Area > Image Structure Metadata: > COMPRESSION=LZW > INTERLEAVE=BAND > Corner Coordinates: > Upper Left ( 6000000.000, 4000000.000) ( 37d47'0.49"E, 56d 7'28.33"N) > Lower Left ( 6000000.000, 3900000.000) ( 37d10'18.23"E, 55d18'7.26"N) > Upper Right ( 6100000.000, 4000000.000) ( 39d16'14.71"E, 55d46'30.54"N) > Lower Right ( 6100000.000, 3900000.000) ( 38d38'6.52"E, 54d57'38.92"N) > Center ( 6050000.000, 3950000.000) ( 38d12'51.64"E, 55d32'35.70"N) > Band 1 Block=4000x2 Type=Byte, ColorInterp=Gray > Computed Min/Max=0.000,0.000 > > Am 14.04.2014 19:51, schrieb Etienne Tourigny:> > >> >> >> On Mon, Apr 14, 2014 at 11:16 AM, Nicole Stoffels <stoff...@f2e.de >> <mailto:stoff...@f2e.de>> wrote: >> >> Dear Gdal-List, >> >> I have a large ASTER file (downloaded from >> http://www.eea.europa.eu/data-__and-maps/data/eu-dem#tab-__ >> european-data >> <http://www.eea.europa.eu/data-and-maps/data/eu-dem#tab-european-data >> >) >> in the GeoTIFF-format. It is compressed with LZW. What I want to do >> is: >> >> 1. unpack it >> 2. seperate a smaller region from it >> 3. convert this regional GeoTIFF to a PNG >> >> What I am doing: >> >> $ gdal_translate -co COMPRESS=NONE EUD_CP-DEMS_6500035000-AA.tif >> tmp1.tif >> >> $ gdal_translate -srcwin 6500 3300 1000 1000 tmp1.tif tmp2.tif >> >> $ gdal_translate -of PNG tmp2.tif tmp2.png >> >> When I display the info with gdalinfo the first step seems to >> produce a decompressed file. The line COMPRESSION=LZW is not there >> anymore. >> >> >> You need to set the compression options on any gdal command, it does not >> use the compression of the input file. Also, you specifically asked for >> no compression, so it's doing what you told it to. >> use "-co COMPRESS=LZW" >> > > > >> However, if I want to display the min and max with gdalinfo, I get >> the following error. >> >> ERROR 1: Failed to compute min/max, no valid pixels found in sampling. >> >> >> try without changing the extents and see if a single command (as >> suggested by Jean-Luc) works >> >> >> I thought that the file might be too large, but if I change the >> data_type from float 32 to e.g. Int16 I get 0 as min and max value. >> That's why I assume that already the first gdal_translate does not >> work as I actually want it to work. >> >> >> your input values are probably between 0 and 1 in this case >> >> >> The other two transformations work without error messages. However, >> in the end I get a black png. >> >> I have tried all types of transformation with various options. But >> as I am new in the subject and do not know much about gdal, I have >> no further ideas how to generate a file from my large GeoTIFF to >> continue working with. >> >> I hope someone has an idea, what's going wrong with my >> gdal_translations. Thanks very much in advance. >> >> Best regards >> Nicole >> _________________________________________________ >> gdal-dev mailing list >> gdal-dev@lists.osgeo.org <mailto:gdal-dev@lists.osgeo.org> >> http://lists.osgeo.org/__mailman/listinfo/gdal-dev >> <http://lists.osgeo.org/mailman/listinfo/gdal-dev> >> >> >> > > > _______________________________________________ > gdal-dev mailing list > gdal-dev@lists.osgeo.org > http://lists.osgeo.org/mailman/listinfo/gdal-dev >
_______________________________________________ gdal-dev mailing list gdal-dev@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/gdal-dev