Assertion: projector | /r/CapableOf | point down to screen
Facets:
value: from a ceiling
type: LOCATION
value: generally
type: DEGREE
Source sentences:
text: Keystone correction (trapezoidal in nature) is used when projectors have been mounted at an angle (generally pointing down from a ceiling to a screen), and the opposing angular correction needs to be applied in order for the image to be correct.