The map features an optical illusion.

[LTK]

I just noticed that the map in the antechamber causes an optical illusion known as the grid illusion[en.wikipedia.org]. If you look at any point on the map, you may notice that in your peripheral vision, the square rooms located at intersections seem to be tinted grey, but they are definitely white when you look at them directly. Fitting for a game such as Antichamber.