What is the purpose of a Waters projection?

What will be an ideal response?

Images the maxillary, frontal, and ethmoid sinuses. The chin is tipped up in this projection to avoid superimposing the bony petrous ridges and base of the skull structures on the maxillary sinuses. In this way, the lower one-third of the maxillary sinus can be viewed free of superimposition from the skull base structures.