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I am using a 1m DEM layer (Poland CS92, ETRS:2180). From this DEM I've computed Aspect and Slope in QGIS through grass plugins. I did a test run for 15th day of the year and 165th day of the year. The output for 165th is lower than for 15th day of the year. Wnich is physically not possible.

So I know I am doing something wrong. But I don't know what. And I've asked a couple of people, and tried different solutions, but none of those work. Here is a list of stuff I tried doing:

  • include lat/long rasters when running tool
  • trying a different DEM (Copernicus programme EUDEM)
  • exported raster to a different format (from ASCII to geoTIF)
  • set up a GRASS database, mapset and location (still running the tool from QGIS toolbox, not the GRASS one, since my grass toolbar seems to be missing r.sun)
  • computed slope and aspect in arcmap instead of qgis

And at this point I am out of ideas. What could I be doing wrong?? I am just plugging in the data into a ready model, there is nothing else to be done here. Does anyone have any idea what's going on? Has anyone successfully used this model, and could maybe give me some short walkthrough tips??

Probably worth mentioning that I don't know how to use GRASS and I don't have the time to learn it (tried), so it has to work through QGIS. The learning curve for GRASS is pretty steep, I am still a GIS newbie and I have a deadline, so I can't just move this project for few months later.

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