I'm working on an IPhone robot that would be moving around. One of the challenges is estimating distance to objects- I don't want the robot to run into things. I saw some very expensive (~1000$) laser rangefinders, and would like to emulate one using iPhone.
I got one or two camera feeds and two laser pointers. The laser pointers are mounted about 6 inches apart, at an angle The angle of lasers in relation to the cameras is known. The Angle of cameras to each other is known.
The lasers are pointing ahead of cameras, creating 2 dots on a camera feed. Is it possible to estimate the distance to the dots by looking at the distance between the dots in a camera image?
The lasers form a trapezoid from the
/wall \
/ \
/laser mount \
As the laser mount gets closer to the wall, the points should be moving further away from each other.
Is what I'm talking about feasible? Has anyone done something like that?
Would I need one or two cameras for such calculation?
If you just don't want to run into things, rather than have an accurate idea of the distance to them, then you could go "dambusters" on it and just detect when the two points become one - this would be at a known distance from the object.
For calculation, it is probaby cheaper to have four lasers instead, in two pairs, each pair at a different angle, one pair above the other. Then a comparison between the relative differences of the dots would probably let you work out a reasonably accurate distance. Math overflow for that one, though.
In theory, yes, something like this can work. Google "light striping" or "structured light depth measurement" for some good discussions of using this sort of idea on a larger scale.
In practice, your measurements are likely to be crude. There are a number of factors to consider: the camera intrinsic parameters (focal length, etc) and extrinsic parameters will affect how the dots appear in the image frame.
With only two sample points (note that structured light methods use lines, etc), the environment will present difficulties for distance measurement. Surfaces that are directly perpendicular to the floor (and direction of travel) can be handled reasonably well. Slopes and off-angle walls may be detectable, but you will find many situations that will give ambiguous or incorrect distance measures.
