On 5 March 2015 at 03:17, Matthew Hanson <[email protected]> wrote: > Hello, > > I filed a bug report on this some weeks ago: > http://hub.qgis.org/issues/11573 > > But it hasn't gotten the required attention. It's a rather egregious bug, > which currently is restricting us to QGIS v2.2, which is becoming more of a > problem the more outdated it gets. > > In short, when using a floating point gain with integer images the datatype > is not promoted, so you end up with an image that is rounded to the nearest > integer. It's fairly common practice to store indices, like NDVI, as an > Int16 with a gain of 0.0001 as it is half the space. But in QGIS, these > images end up being rounded to mostly 0. > > The feature of auto-applying the gain is nice in practice, but without > promoting the data type of the output it is counter-productive. It would > be good to either revert this feature or properly promote the datatype. > > I'd be happy to do more digging and try fixing this and issue a PR if > someone could get me started by pointing me in the general direction of the > code responsible for this.
This should be fixed in master now - can you please test and confirm? If so, I'll backport to 2.8. Nyall _______________________________________________ Qgis-developer mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/qgis-developer
