Build lighting gives unrealistic shadows

Hi all
I have uploaded 2 pictures, when I build production lighting I get very strange and unrealistic shadows, for instance in the two pictures, the window is a perfect rectangle with no artifacts in the way of the lighting coming through the window, yet on the floor the lighting looks like some weird wiggly line? what is going on? thanks in advance.

Hi, you need to change the lightmap resolution on the face that receive the shadow, click on the floor, on the righ panel properties, change the lightmap resolution to a small value like 4.0 (default is 32.0).

Awesome thank you for the help Almusx