If I am understanding correctly: you are wanting to cut around the outline of the printed figure.
If your camera is well-calibrated, you maybe able to get acceptable results doing it visually.
If it needs to be more accurate, you will likely have to use another approach, such as setting up a placement jig. I recently posted a video on aligning scores on two sides of a piece of stock. What you want to do would be similar and, you can likely figure it out from that.