Comment on Programmer tries to explain binary search to the police

• CosmicCleric@lemmy.world ⁨10⁩ ⁨months⁩ ago

  You didn’t get what was talked about here. Re-read the topmost parent comment.

  How do you binary search for two people arriving, one punches the other, they both leave?

  I was responding to this …

  Part of my job is to review security footage for reported incidents.

  If there is a long-lasting visual cue that the event has or has not happened yet (e.g. a window is either broken or not), then a binary search is very useful.

  If the event lasts only a moment and leaves no visual cue (e.g. an assault), then binary search is practically useless.

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  • LUHG_HANI@lemmy.world ⁨10⁩ ⁨months⁩ ago

    Maybe I’m not understanding both arguments here but I’d like to understand. I’ve had to review footage of a vending machine being shaken to release drinks.

    You have no before or after visual clue as to when the event took place. The only indication is when you physically see it happening. The same could be said for an assault. If nothing is changed in the before or after static still how can you pinpoint the incident?

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    • CosmicCleric@lemmy.world ⁨10⁩ ⁨months⁩ ago

      You have no before or after visual clue as to when the event took place.

      That wouldn’t necessarily be true. If you shook it hard enough to move the contents inside the vending machine and the vending machine had a glass front then you would have a static change that would last from the time the event happened until a human being came to work on the machine. That change would be detectable.

      Or from the shaking the vending machine is moved an inch forward and an inch to the left. That change would be detectable.

      Everyone arguing against me is trying to focus the point that the event is such a short duration that it’s not detectable afterwards, and what I’ve been arguing the whole time and that people keep ignoring is that most of the time after an event happens that the environment around the event changes, and it’s detectable afterwards.

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• CosmicCleric@lemmy.world ⁨10⁩ ⁨months⁩ ago

  In the same way the OP talks about it …

  You don’t watch the whole thing, he said. You use a binary search. You fast forward to halfway, see if the bike is there and, if it is, zoom to three quarters of the way through. But if it wasn’t there at the halfway mark, you rewind to a quarter of the way though. Its very quick. In fact, he had pointed out, if the CCTV footage stretched back to the dawn of humanity it would probably have taken an hour to find the moment of theft.

  Instead of a bike, you look for the aftereffects of a fight happening (chairs knocked down, tables turned over, etc.). You can even look at how many people congregate around the location of the fight before and after the video as a ‘marker’ to the point of time the fight was happening/just finished.

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  • TheSanSabaSongbird@lemdro.id ⁨10⁩ ⁨months⁩ ago

    You are seriously confused. OP specifically said that you’re fucked if there is no visual cue.

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    • CosmicCleric@lemmy.world ⁨10⁩ ⁨months⁩ ago

      You are seriously confused.

      And you are seriously trying ot kill the messenger.

      OP specifically said that you’re fucked if there is no visual cue.

      And I’m saying there’s ALWAYS a visual clue/cue, always. Either the bike is there one minute and gone another, or a fight breaks out and trashes the place from the fight. There’s always a visual difference.

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      • nexguy@lemmy.world ⁨10⁩ ⁨months⁩ ago

        Absolutely not true. Guy walks bye and shoots someone well offscreen. Momentary action with no visual cue before or after. Why are you arguing this useless point?

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      • starman2112@sh.itjust.works ⁨10⁩ ⁨months⁩ ago

        Ok but the text that you replied to, that you quoted, was “If the event lasts only a moment and leaves no visual cue (e.g. an assault), then binary search is practically useless.” Emphasis mine. If you’d started out saying “there’s ALWAYS a visual cue,” then you likely wouldn’t be getting dragged, but you started out arguing from this position without clarifying it, which makes it seem like you didn’t know what you were talking about. You can’t say that you can simply look for visual cues when the other person specified that there were none.

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  • Kialdadial@iusearchlinux.fyi ⁨10⁩ ⁨months⁩ ago

    Your adding things that would allow a binary search work, but the question was in a situation where the only evidence is the conflict itself

    2 guys enter one guy punches the other guy they both leave. Nothing is moved no blood was created,

    you could not use a binary search effectively to duduce when it occurred.

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    • CosmicCleric@lemmy.world ⁨10⁩ ⁨months⁩ ago

      Your adding things that would allow a binary search work, but the question was in a situation where the only evidence is the conflict itself

      I’m describing the vast majority of fights that happen in the public. Also, you’re trying to move the goalposts by focusing on a fight, when the discussion is about the theft of a bike.

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      • Kialdadial@iusearchlinux.fyi ⁨10⁩ ⁨months⁩ ago

        What does that have to do with a binary search If a camera has AI on it then two things. A you have a system that already would be capturing movement or motion so you already have flags that you can check which would make a binary search mostly unnecessary. and B it’s not binary search. Which is this whole discussion.

        Cool you’re adding information to the question to make yourself “right” but even your comment says that’s only the vast majority of fights and also you had to clarify in public so there are edge cases where the situation still stands that binary search wouldn’t work or wouldn’t be feasible.

        A solution doesn’t have to work for 100% of things for it to still be a good solution.

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      • starman2112@sh.itjust.works ⁨10⁩ ⁨months⁩ ago

        I’m describing the vast majority of fights that happen in the public.

        But the comment you replied to already addressed those fights, and bike thefts, and the vast majority of cases that you’re talking about, by saying

        If there is a long-lasting visual cue that the event has or has not happened yet (e.g. a window is either broken or not), then a binary search is very useful.

        No one is moving goalposts. The parent comment said that binary search is useful in situations like bike thefts where visual cues are present, and not useful in situations where visual cues are not present.

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  • Ardyssian@sh.itjust.works ⁨10⁩ ⁨months⁩ ago

    What about this hypothetical scenario:

    Suppose the objective is to review highway cam footage of the day to verify that a (non-speeding) car with a particular license plate passed by the area / used this route. We know on average cars that drive past this camera only appear for 3 seconds on the footage. How can binary search be used to find the car within 24 hours of footage, if the target car only appears for 3 seconds within the 24 hour span?

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