Those are bamboo blinds. There are three of them. All are rolled up and the lines are drawn together and held behind the chair on the left. There was nothing in that area. Unless of course a rope came loose, moved to the right and then went back to where it was.

You can see the 3 lines from top to bottom, hooked onto the chair. The floor is all concrete and the color difference is probably due to the roof panels. About 1/4 of them are transparent (more natural light) and the rest are solid. Also the lighter concrete section, is elevated a bit.