I'm using a Aster tile DEM to perform some terrain analysis on an area in the French alps (original CRS:EPSG 4326-wgs 84), using QGIS 3.2. My projected coordinate reference system is EPSG:2154-RGF93/Lambert-93.
If I re-project the original tile with the warp tool and then perform a slope analysis in degrees (z factor 1), I obtain an acceptable result from 0 to 89 degrees. If then I try to obtain the slopes in percentages (z factor always 1), I have absurd results in the order of thousands and poor visualization.
Is this a possible correct result or is there an issue?