On Wednesday 15 July 2015 10:21:54 Homme Zwaagstra wrote: > Hello, > > I've got the following raster exported from GRASS using `r.out.gdal`: > > gdalinfo ppp-2015.tif > Driver: GTiff/GeoTIFF > Files: ppp-2015.tif > ppp-2015.tif.aux.xml > Size is 432017, 216009 > 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 = (-180.000000000000000,90.000000000000000) > Pixel Size = (0.000833300541414,-0.000833298612558) > Metadata: > AREA_OR_POINT=Area > Image Structure Metadata: > COMPRESSION=DEFLATE > INTERLEAVE=BAND > Corner Coordinates: > Upper Left (-180.0000000, 90.0000000) (180d 0' 0.00"W, 90d 0' 0.00"N) > Lower Left (-180.0000000, -90.0000000) (180d 0' 0.00"W, 90d 0' 0.00"S) > Upper Right ( 180.0000000, 90.0000000) (180d 0' 0.00"E, 90d 0' 0.00"N) > Lower Right ( 180.0000000, -90.0000000) (180d 0' 0.00"E, 90d 0' 0.00"S) > Center ( 0.0000000, 0.0000000) ( 0d 0' 0.01"E, 0d 0' 0.01"N) > Band 1 Block=256x256 Type=Float32, ColorInterp=Gray > NoData Value=nan > Metadata: > COLOR_TABLE_RULES_COUNT=5 > COLOR_TABLE_RULE_RGB_0=0.000000e+00 1.681282e+03 255 255 0 0 255 0 > COLOR_TABLE_RULE_RGB_1=1.681282e+03 3.362563e+03 0 255 0 0 255 255 > COLOR_TABLE_RULE_RGB_2=3.362563e+03 5.043845e+03 0 255 255 0 0 255 > COLOR_TABLE_RULE_RGB_3=5.043845e+03 6.725127e+03 0 0 255 255 0 255 > COLOR_TABLE_RULE_RGB_4=6.725127e+03 8.406408e+03 255 0 255 255 0 0 > Generated_with=GRASS GIS 7.0.0 > > As you can see the NoData is set to `nan`. However, within the data it is > actually `-nan`: > > gdallocationinfo ppp-2015.tif -wgs84 42.0776 30.9305 > Report: > Location: (266503P,70886L) > Band 1: > Value: -nan > > I have tried to force the NoData to `-nan` as follows but with no joy: > > gdal_translate -a_nodata '-nan' -of VRT ppp-2015.tif ppp-2015.vrt > > gdalinfo ppp-2015.vrt > Driver: VRT/Virtual Raster > Files: ppp-2015.vrt > /data/data/ppp_v2c_2015/ppp-2015.tif > Size is 432017, 216009 > 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 = (-180.000000000000000,90.000000000000000) > Pixel Size = (0.000833300541414,-0.000833298612558) > Metadata: > AREA_OR_POINT=Area > Image Structure Metadata: > INTERLEAVE=BAND > Corner Coordinates: > Upper Left (-180.0000000, 90.0000000) (180d 0' 0.00"W, 90d 0' 0.00"N) > Lower Left (-180.0000000, -90.0000000) (180d 0' 0.00"W, 90d 0' 0.00"S) > Upper Right ( 180.0000000, 90.0000000) (180d 0' 0.00"E, 90d 0' 0.00"N) > Lower Right ( 180.0000000, -90.0000000) (180d 0' 0.00"E, 90d 0' 0.00"S) > Center ( 0.0000000, 0.0000000) ( 0d 0' 0.01"E, 0d 0' 0.01"N) > Band 1 Block=128x128 Type=Float32, ColorInterp=Gray > NoData Value=nan > Metadata: > COLOR_TABLE_RULES_COUNT=5 > COLOR_TABLE_RULE_RGB_0=0.000000e+00 1.681282e+03 255 255 0 0 255 0 > COLOR_TABLE_RULE_RGB_1=1.681282e+03 3.362563e+03 0 255 0 0 255 255 > COLOR_TABLE_RULE_RGB_2=3.362563e+03 5.043845e+03 0 255 255 0 0 255 > COLOR_TABLE_RULE_RGB_3=5.043845e+03 6.725127e+03 0 0 255 255 0 255 > COLOR_TABLE_RULE_RGB_4=6.725127e+03 8.406408e+03 255 0 255 255 0 0 > Generated_with=GRASS GIS 7.0.0 > > Even editing the VRT to contain `<NoDataValue>-nan</NoDataValue>` yields a > positive nan value in gdalinfo. > > This looks like it might be a GDAL bug to me? Is there a way I can specify > `-nan` as the NODATA value for this dataset without regenerating it > (it's quite > large)?
Hi Homme, I wasn't aware of this negative not a number variation. Could you create a ticket with a small extract of the dataset so as to inspect the hexadecimal representation of this -nan value ? Even > > Many thanks, > > Homme > > _______________________________________________ > gdal-dev mailing list > [email protected] > http://lists.osgeo.org/mailman/listinfo/gdal-dev -- Spatialys - Geospatial professional services http://www.spatialys.com _______________________________________________ gdal-dev mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/gdal-dev
