One thing is to find the edges of the plate, another is using scrap plate that can have holes from already cut parts. If you just want to find edges and always have square plates the you can use capacitive, laser range sensors or almost anything that senses metal.
In my mind the time saved is quite minimal and only works for squares or rectangles. Well of course you could run a line on all edges but would it be worth it, not really sure.
The camera stuff would be way nicer, example stuff like this
Trumpf cut and drop
.
Libellula Optia
the video could show case it better but basically you take a picture of the sheet and then you can nest to it.
