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To get a coloured picture of the AHN DEM, add a NODATA value of -2147483647 in the Transparency tab. In the Style tab, load the Extrema ( not the default 2% to 98%) and select one channel pseudo colour. With the Spectral colour ramp [x] inverted, the output looks like this: For the viewshed, I clipped the data to my area of interest and converted the ...


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Maybe a slightly different approach will match your needs. Try looping thru all the elevations that you will be snipping from felt, and create a raster for each, then convert each to a polygon vector. You'll end up with lots of separate polygons, one for each elevation, ready for the scissors. For e in 10 20 30 40 50 60 70 80 90 100; do r.mapcalc ...


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Short answer, use the DEM. Handheld GPS units of the type you mention (consumer grade), can potentially use two different methods to figure elevation - the calculated GPS position or an internal barometric altimeter. Because of the way GPS works (explained at the page mkennedy originally linked to in a comment, and elsewhere), without high-grade, corrected ...


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assuming that the goal is to determine an elevation with a user-supplied set of coordinates, there should be a way to do this with gdal - i use a function like this, which came almost verbatim from this answer (assumes raster is not rotated). rast = 'myIMGfile.img' mx = XCOORDINATE my = YCOORDINATE def readRastPix(rast,mx,my): src_ds=gdal.Open(rast) ...


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It sounds like you have a DEM and you want to augment the accuracy of that DEM with some elevation data you collected as points. That's totally possible but the process probably isn't as linear as you would like it to be. That is - you can't (to my knowledge) update the values of raster cells from vector points directly. You have to go through the process ...


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This may be the tool you are looking for: Extract values to points.



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