What kind of sensor could you use to detect the shape of a shadow falling on something, say the shadow of a hand on a wall?
I first thought of an array of LDRs but the resolution would be quite low, and you would need quite a lot of them. Or is this feasible?
Then I thought of a camera with image recognition software, but the problem is that the object causing the shadow would get in the way of the camera's view. Unless maybe the camera was at an extreme angle.
Is there any obvious solution for this?
EDIT: Sorry, yes it is not necessarily an analog sensor so I have adjusted the title. The application is to use different shadow shapes to control a robot, as an interface.