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I'm trying to calculate viewshed from a set a points (gpkg). From what I can understand, I first need to run the "create Viewpoints" algorithm. After I do it, a new layer named "output" is created, but I don't understand what my next step should be. If I try to simply run the viewshed command (from the visibility analysis plugin), it does not work, indicating that no viewpoints exist in that area.

What am I missing here? This used to be quite a simple task in versions 2.14 and 2.18.

As a workaround, I've tried manually creating observ_hgt and radius fields in the points layers and then runing the Viewshed command. It seemed to be working, but in the end I got the following error:

Traceback (most recent call last):
File "C:/Users/tiago/AppData/Roaming/QGIS/QGIS3\profiles\default/python/plugins\ViewshedAnalysis\algorithms\viewshed_raster.py", line 231, in processAlgorithm
interpolate = precision > 0)
File "C:/Users/tiago/AppData/Roaming/QGIS/QGIS3\profiles\default/python/plugins\ViewshedAnalysis\algorithms\modules\visibility.py", line 159, in viewshed_raster
dem.open_window (point["pix_coord"])
File "C:/Users/tiago/AppData/Roaming/QGIS/QGIS3\profiles\default/python/plugins\ViewshedAnalysis\algorithms\modules\Raster.py", line 347, in open_window
self.rst.ReadAsArray(*self.gdal_slice ).astype(float)
File "C:\PROGRA~1\QGIS3~1.2\apps\Python36\lib\site-packages\osgeo\gdal.py", line 1944, in ReadAsArray
callback_data = callback_data )
File "C:\PROGRA~1\QGIS3~1.2\apps\Python36\lib\site-packages\osgeo\gdal_array.py", line 263, in DatasetReadAsArray
callback_data = callback_data )
File "C:\PROGRA~1\QGIS3~1.2\apps\Python36\lib\site-packages\osgeo\gdal_array.py", line 339, in BandReadAsArray
buf_obj = numpy.empty([buf_ysize,buf_xsize], dtype = typecode)
ValueError: negative dimensions are not allowed

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