implementation details
Multiple peaks may be detected (echoes - audio version of multipath interference)
Two heuristics for eliminating echos:
- Difference in distance between two measurements can’t be larger than the distance between the two microphones.
- If so, larger one must be a reflection
- Do statistical tests to identify outliers; repeat until variance is low or only 3 points remain
Nice extension: use 3 tags to detect 3d pose as well as position of objects