Bug report #6786
Poor handling of float nodata value
|Affected QGIS version:||master||Regression?:||No|
|Operating System:||ubuntu||Easy fix?:||No|
|Pull Request or Patch supplied:||No||Resolution:||wontfix|
|Crashes QGIS or corrupts data:||No|
I am trying to process some bioclimatic raster files, such as can be downloaded from http://www.worldclim.org/current (bioclim set). They seem to have nodata values set to -3.4e+38 according to QGIS (looking at the output of gdalinfo, it's -3.39999999999999996e+38).
QGIS picks up the nodata value (attached nodata_dialog.jpg), but does not apply it. In the layer styling, there's an entry for -3.4e+38 set to 100% transparent, but it still displays such values, even though the "Identify features" picker shows them as having value -3.4e+38 (nodata.jpg).
A workaround was to first use gdalwarp to change the nodata value to an integer, or to use gdal_translate to convert from a float to integer raster file. See discussion at http://gis.stackexchange.com/questions/42555/what-to-do-with-3-4e38-nodata-values/ for more.