Is tracing an image 'cheating'? I think not. A traced drawing is merely another way to construct an image.
David Hockney's Secret Knowledge examines the use of both camera obscura and camera lucida technology - tracing mechanisms. His book and the supporting BBC film contextualise the sophisticated use of this often dismissed drawing approach.
It's also worth watching this interview with Hockney (1st of 3)
Modern equivalents of the camera lucida: NeoLucida
and SimmTrace - one I find harder to trace (no pun intended)....