So ive had this idea for sometime now and no one has developed anything even close,
its called snap to black and its for car modellers, the idea being that you click a button after loading your car blueprint and then the cursor will snap to any part of the image that is RGB 0,0,0, it could be taken one step further and a start and end point could be placed and rhino would then find the closest matching line to the one between the two points, if anyone wants to develop this, feel free, i would just like to see it in rhino.