Download Geogebra Classique 5: https://www.geogebra.org/download

GeoGebra Classic 6 Installer for Windows (offline installer file, recommended for all Windows versions, updates automatically)

Draw easily the figure, just by copy/paste of 2 lines data from the Eratos Google spreadsheet

Download and open one of the 3 model files: Download Zip File

NN (for 2 shadows towards the north)

NS (for one shadow towards the north and  one shadow towards the south)

SS (for 2 shadows towards the south)

Link to the shared google spreadsheet to register your measurement: