Bug report #857
Option to ignore transparency values in "Load Min Max From Band" button
|Affected QGIS version:||Regression?:||No|
|Operating System:||Gentoo||Easy fix?:||No|
|Pull Request or Patch supplied:||Resolution:||fixed|
|Crashes QGIS or corrupts data:||Copied to github as #:||10916|
I am working on a dem that has a nodata value of -9999. The person who created this also used the value -999 as a "novalue". So, I made -999 transparent. When I click on the "Load Min Max From Band" button, I wish it would not consider the transparent values.
#1 Updated by ersts - over 12 years ago
The NoDataValue should not be considered for sure. As for Transparent values, it may be possible to consider 100% transparency pixels as "no data" but this could lead to so other strange behaviour. This is an enhancement that should be reviewed by the Steering Committee.
#2 Updated by ersts - almost 12 years ago
- Resolution set to fixed
- Status changed from Open to Closed
The NoDataValue is now excluded in both the estimated and internally computed min-max.
As for the second idea, after some thought I don't think excluding 100% transparent values will be possible or really appropriate.
1) The raster class is currently heavily reliant on GDAL, and uses GDAL's GDALComputeRasterMinMax to get the estimated min-max values. This function does not have the ability to ignore values other then the nodatavalue - as far as I understand
2) The transparency setting is just that, a way to change the transparency of pixel values. It is not really an on the fly recoding capability. I think a simple raster reclassify plugin would be the way to go, which could be a great core feature as well but not something that will be possible for v1.0
This idea should be revisited toward v2.0