First the two point grid:
Then the overlay:
This didn't turn out that well. The line weight is all messed up and the drawing is not that clear.
However the lighting turned out really well. For artificial lighting, every wall/surface has a different base point for the light. So doing shadows for the staircase was very complicated and time consuming. But the hard work did pay off!
This is the overlay for the artificial light shadows.
and that's the final. I could still add some more detailing with some blending and some form shadows, but I'll leave that for later.