Bug report #6786

Poor handling of float nodata value

Added by Rudi von Staden over 4 years ago. Updated over 4 years ago.

Status:Closed
Priority:Normal
Assignee:-
Category:Rasters
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

Description

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.

nodata_dialog.jpg (45.5 KB) Rudi von Staden, 11/29/2012 08:10 AM

nodata.jpg (38.8 KB) Rudi von Staden, 11/29/2012 08:10 AM

History

#1 Updated by Giovanni Manghi over 4 years ago

  • Status changed from Open to Feedback

rasters have been overhauled in qgis master, have you tested it?

#2 Updated by Jürgen Fischer over 4 years ago

  • Resolution set to wontfix
  • Status changed from Feedback to Closed

closing for the lack of feedback

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