1. A method of detecting an article on a conveyor, the method comprising: directing a first laser trace laterally across a surface of the conveyor from an acute angle; directing a second laser trace laterally across the surface of the conveyor, in spaced apart alignment with the first laser trace, from an acute angle; imaging from above a field of view that encompasses at least a portion of the first and second laser traces; detecting a presence or absence of portions of the first and second laser traces; and determining a feature of the article on the conveyor based upon the detecting of the presence or absence.