I used that tool: https://github.com/jantman/python-wifi-survey-heatmap and yes the floor plan was generated by Sweet Home 3D 
In my option I don't think it worths the time. I prefer the method I did after. Choose some strategic points where I will use the devices and compare only these points using values. See here: Dumb AP around 50/60Eur - #59 by metropt