Thanks Nyall, Sorry for the delay, I was at FOSS4G last week. I tested this out and confirms it is working now as intended. Any clue on when it might be available in a 2.8 update?
Thanks again! matt Matthew Hanson Applied GeoSolutions (603) 659-3363 x91 http://appliedgeosolutions.com [email protected] On Thu, Mar 5, 2015 at 11:24 PM, Nyall Dawson <[email protected]> wrote: > 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 problem the more outdated it gets.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 >
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