Bug report #20978
QGIS does not display raster maps from a GRASS mapset
|Affected QGIS version:||3.7(master)||Regression?:||Yes|
|Operating System:||Windows, Linux||Easy fix?:||No|
|Pull Request or Patch supplied:||No||Resolution:|
|Crashes QGIS or corrupts data:||No||Copied to github as #:||28797|
Raster layers in GRASS mapsets are not rendered by QGIS 3.4.3 and master.
But, at least for some raster data types, just opening the layer properties and doing 'Ok', QGIS assumes a default color ramp and the raster shows up (see the attached gif).
So, it seems that QGIS 3.x is not interpreting GRASS color tables by default.
Using QGIS Value Tool plugin, the raster values are displayed correctly, even without the raster being rendered in canvas.
Veronica Andreo had tested in Linux. Her report is here: http://osgeo-org.1560.x6.nabble.com/QGIS-does-not-display-raster-maps-from-a-GRASS-mapset-td5390774.html
In QGIS 2.18.27, raster layers from GRASS Mapsets work without problems.
I don't know if this behaviour is somehow related, but using GRASS algorithms from QGIS Processing, when the outputs are rasters, the error message 6 from gdal is showed:
ERROR 6: SetColorTable() only supported for Byte or UInt16 bands in TIFF format.
#2 Updated by Alexander Bruy over 2 years ago
As I understand, ERROR 6 comes from GDAL and caused by limitations of the TIFF format. If GRASS produces rasters with Float data type, then GDAL can't apply color map to them during confersion. Confirmed by Markus Neteler here https://gis.stackexchange.com/a/102605.