This would require QgsExpression to be extended to support rasters. Not sure how much work that would be. On 25/04/2014 7:02 pm, "kimaidou" <[email protected]> wrote:
> Hi Andreas, > > I totally agree with the benefit of using SQL-like syntax as in > expressions to calculate rasters. > > I would prefer something like > CASE > WHEN raster1@1 > raster2@1 THEN raster1@1 > ELSE raster2@1 > END > > Having to multiply the result of a condition (0 or 1) by the band value to > actually get the band values seems cumbersome for some users. > Thanks for raising this issue. > > Michael > > > 2014-04-24 15:25 GMT+02:00 Andreas Neumann <[email protected]>: > >> Hi Carlos, >> >> Thanks a lot. This works fine. >> >> Seems I first have to get used to the raster calculator syntax. Would be >> great if it would use the expression editor as is used almost everywhere >> else. >> >> Andreas >> >> Am 24.04.2014 12:57, schrieb Carlos Cerdán: >> > Hi Andreas: >> > >> > Yes, it always evaluates to true because of "OR" condition , so try: >> > >> > (lake_mask > 0) * lake_mask + (lake_mask<=0)*dtm >> > >> > Good luck >> > >> > Carlos >> > >> > >> > >> > >> > 2014-04-24 1:53 GMT-05:00 Andreas Neumann <[email protected]>: >> > >> >> Hi, >> >> >> >> I have a hard time understanding the raster calculator syntax. >> >> >> >> I would like to merge two rasters: DTM and lake mask. Let's call the >> one >> >> dtm and the other lake_mask. >> >> >> >> When the lake_mask has a value > 0 then I would like to take the value >> >> of the lake_mask, otherwise the value of the dtm. >> >> >> >> What would an appropriate syntax look like? >> >> >> >> I tried something along >> >> >> >> ((lake_mask > 0) * lake_mask) OR dtm >> >> >> >> But all I get in the resulting grid are values of 1. I guess it is >> >> because it always evaluates to true? >> >> >> >> Thanks for your help. >> >> >> >> Andreas >> >> _______________________________________________ >> >> Qgis-user mailing list >> >> [email protected] >> >> http://lists.osgeo.org/mailman/listinfo/qgis-user >> >> >> > >> > >> > >> > _______________________________________________ >> > Qgis-user mailing list >> > [email protected] >> > http://lists.osgeo.org/mailman/listinfo/qgis-user >> > >> >> _______________________________________________ >> Qgis-user mailing list >> [email protected] >> http://lists.osgeo.org/mailman/listinfo/qgis-user >> > > > _______________________________________________ > Qgis-user mailing list > [email protected] > http://lists.osgeo.org/mailman/listinfo/qgis-user >
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