[gdal-dev] Slope obtained with GDAL has weird lines

[Danilo da Rosa]

Hi!

This may be a very basic question, but I can't find the answer anyware.

I am working with this DEM obtained using terraincache
<https://pypi.org/project/terraincache/>, it uses mapzen data. The SRC is
WGS 84.

[image: DEM File in QGIS] <https://i.stack.imgur.com/Sp4Sg.jpg>

I ran this GDAL command to get the slope:

gdaldem slope -s 111120 dem.tif slope.tif (I had to do scaling because of
the SRC)

The resulting image looks fine but it's not smooth, it has weird lines over
it, like contour lines.

[image: Slope file on QGIS] <https://i.stack.imgur.com/POcHR.jpg>

You can download the DEM file here: https://gofile.io/?c=Du7WnM

Does anyone have an idea of how to solve it?

Thanks in advance for your help,

Danilo

P.S. I made this question here too:
https://gis.stackexchange.com/questions/353983/slope-obtained-with-gdal-has-weird-lines
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