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I am trying to make a simple slope map from a DEM (tif). I already tried with the different slope-tools in QGIS (GDAL, SAGA, GRASS) and also the 3D Analyst in ArcMap. Boths bring the same result: a slope map with line shaped artefacts (see pic).

enter image description here

After reading other posts regarding this topic I tried: WARP, (bilinear)RESAMPLING, REPROJECT and changing the DEM from .asc to .tif format. The extention of the DEM is about 4x4 km; the resolution 1x1 m.

@FelixIP Yes, the conversation is with float. What made you think that it could alter the output? @lambertj The crosshatching is "bigger" than the cell size as you can see in the pics.

enter image description here

enter image description here

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  • Did you tick FLOAT during conversion to tif?
    – FelixIP
    Commented Aug 15, 2018 at 19:13
  • Does the size of the erroneous crosshatching correspond with your raster cell size?
    – lambertj
    Commented Aug 15, 2018 at 21:24
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    I doubt this is a problem with the slope algorithms. I have never had it in many years of using these tools. This looks like an underlying data problem possibly as a result of some preprocessing applied to the DEM. The cross-hatching looks very similar to artefacts you get from certain types of wavelet compression (which might have been applied at some point in the data's lifecycle) - or some other pre-processing. To provide any further help, the OP will need to provide some of the original data and some indication of provenance and any other processing steps the OP has applied first.
    – MappaGnosis
    Commented Nov 20, 2019 at 12:38

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