Hi Moritz, Did you consider r.stats -N for checking for NULL values within the masked area, like: r.stats -N input=tile,MASK if there is *|1 in the output you have NULL cells in the tile...
For filling NULLs with a given value you could do: r.mapcalc expression=tile_filled=if(MASK,if(isnull(tile),1,tile),null()) Just an idea... Cheers Stefan -----Original Message----- From: grass-dev <[email protected]> On Behalf Of Moritz Lennert Sent: fredag 28. juni 2019 10:57 To: [email protected] Subject: [GRASS-dev] dealing with null values in rasters only within mask Hi to all, As a followup of some recent discussions concerning the handling of null values, I have a fundamental issue, and would like some feedback: I am working with irregular tiles of orthoimages. Each tile corresponds to the part of a large image mosaic that comes from a particular take. Some of these tiles contain pixels with null values (generally due to sensor saturation). I would like to be able to do the following: - detect whether there are any null values in the tile - replace the pixels values with a given value (or possibly use something like r.fill.stats) For this, I am confronted to some issues: - r.univar does not make a difference between null values in the data and those that are due to a mask (https://trac.osgeo.org/grass/ticket/3696). This means that if I create a mask to correspond to the irregular tile, I cannot use r.univar to detect whether there are any null values within the actual image tile. - If I decide to just replace all null values with a given value, r.null also does not take into account the mask. IOW, it will fill all null pixels in the entire region outside the mask with that value. - The same happens if I use r.mapcalc to replace null values with a given value. Is there any way to solve this issues with existing tools, or would this demand a change in the code, in order to differentiate null values that are null because of a mask from other null values ? Any reflections on this ? Moritz _______________________________________________ grass-dev mailing list [email protected] https://lists.osgeo.org/mailman/listinfo/grass-dev _______________________________________________ grass-dev mailing list [email protected] https://lists.osgeo.org/mailman/listinfo/grass-dev
