Let me add that pen and ink drawings are very unforgiving. Vision, sight lines, my life experience and perspective are just some of the things that go into the beginning of my drawing. Most of my drawings are a conglomeration of normally 4 to 6 drawings that together bring the history to life. This cannot be done with a single photograph or drawing.
And while programs such as Photoshop allow one to stitch numerous photos together, I prefer to do it in my head.