I want to make this phone app that can measure distance. I want to know how far away something is from the phone. So let's say I want to know how far away a wall is...I'd like my phone to tell me.
So how might this work? Well, I can shine an ordinary red laser pointer against the wall (in the dark) and have the phone's camera "see" the dot.
The further away the phone is from the dot, the smaller the dot will be. The picture below shows the dot from 1 foot, 5 feet, 10 feet, 20 feet, and 25 feet away. I think the app could then measure the size of the dot and figure out how far away the dot actually is from the phone. And then it could use a simple ratio or formula to determine distance for other sizes.
So my question is: Would this likely work for measuring distance?