Computer Vision

Boxes and Overlap

A detector does not hand you one box for one object. It hands you a heap of overlapping guesses with scores on them, and two rules turn that heap into an answer: a number for how much two boxes are the same box, and a procedure that keeps the best and deletes its neighbours. Step through it one decision at a time.

a real objectkeptdeleted for overlapping a better onestill waiting its turn

Stage 2 of 2: thin the heap · step through the decisions, or click any box to compare it yourself

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Values
boxes in the heap—
kept—
deleted—
objects found—
false alarms—
how well they sit—
overlap being judged—

What to observe

  1. This is stage 2 of the pipeline thatFinding an Objectstarts: a heap of scored, overlapping guesses (drawn here on a robot scene of its own). Step through non-maximum suppression: keep the best box left, delete what overlaps it by more than the threshold.
  2. Raise the overlap that counts as the same box to 0.8 and only near-identical boxes delete each other, so each robot keeps a stack.
  3. Drop it to 0.2 and the small robot in front of the first disappears: their real boxes already have an IoU of 0.37. No single threshold handles crowds.
  4. The two false alarms overlap nothing, so no overlap rule removes them. Raisethe score needed to enter to 0.6 and they are gone.

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