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I was wondering if it were at all possible to manipulate/massage rasters (eg Geotiff) using Qgis plugins or Grass?? By manipulate, I mean manually smooth off interpolation artefacts, blended surface disagreement, etc. Like a photoshop 'touch up tool' if you will. I've had a crack at trying with GIMP, but I lose all my geotiff info. If anyone hasn't already developed it, they should.

Update: GIMP Works for 8bit Geotiff files, however, all data below 0m and above 255m are lost. Need to find a software package that deals with float64 Geotiffs.

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  • I am not an expert on GIMP, but I don't lose georef info. I do the edits then overwrite the file (option in the file menu). – Willy Nov 6 '13 at 6:44
  • Hmm, thats strange. I get absolutely no data when I open the tiff in Gimp 2.8. I used GDAL_rasterize to create the raster too. – user2608653 Nov 6 '13 at 7:01
  • So it turns out its an issue with the Geotiff and Grid itself. Tiffs created from a vertical mapper grid contain colour bands - as specified in vertical mapper. GIMP recognises this as an actual geotiff, and opens it perfectly. Tiffs created from a surfer grid contain only 1 band. For some reason, Gimp does not recognise it as a geotiff and does not assign any data. So i'm either stuck with an extremely buggey vertical mapper, or need to ifnd a way to assign additional bands to the surfer derived tiff. – user2608653 Nov 7 '13 at 4:19
  • GRASS has several image "massaging" tools that might help you. r.neighbors comes to mind. And using r.mapcalc, you can cook up any "filter" that you want. – Micha Nov 7 '13 at 20:34
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In recent QGIS, there is a Serval plugin which is useful to manually change cell values. It works on rasters of various bit depth, including Float64.

The "touch up" operation has to be done on each pixel at one click... so it may be a little bit hard when the raster is large.

enter image description here

(Example: Drawing mode by setting pixel value to 50.0).

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