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oreilles | 7 months ago

The USGS provides exactly what the author was looking for, free of charges, no computation required, no download required:

https://elevation.nationalmap.gov/arcgis/services/3DEPElevat...

Preview in QGIS: https://ibb.co/B5T49YBj

discuss

jvanderbot|7 months ago

Yeah the moment you reach for pixel level processing tricks in GIS you need to pause and rtfm.

Grade calculations are right in qgis docs and part of their lessons, and are also top Google hits.

https://docs.qgis.org/3.40/en/docs/training_manual/rasters/t...

Even better, you'll learn about DEMs vs topo maps.

avidphantasm|7 months ago

For more advanced terrain analysis, see GRASS GIS (https://grass.osgeo.org/). It’s a but clunky, but accessible from QGIS via a plugin. Whitebox also has some nice terrain analysis tools (https://www.whiteboxgeo.com/).