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Programmer tries to explain binary search to the police
(startrek.website)
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this post was submitted on 30 Nov 2023
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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 ...
I disagree with the "leaves no visual cue" part, as I've commented on. There's ALWAYS something caught on the video to help determine things. Maybe not enough, but never nothing.
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?
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.
In the same way the OP talks about it ...
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.
Edit: One thing we didn't even mention, AI can also be used these days to notice subtle changes in the video. If a video is a static image of an alley, then two people walk in the alley and fight, even though they leave no traces behind, that moment of the fight is caught on the video with activity/movement. Motion sensor movement, basically.
You are seriously confused. OP specifically said that you're fucked if there is no visual cue.
And you are seriously trying to kill the messenger.
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. In the vast amount of cases, there's always a visual difference.
And in this case we're talking specifically about a bike, going missing.
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?
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.
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.
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.
Edit: One thing we didn’t even mention, AI can also be used these days to notice subtle changes in the video. If a video is a static image of an alley, then two people walk in the alley and fight, even though they leave no traces behind, that moment of the fight is caught on the video with activity/movement. Motion sensor movement, basically.
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.
You can have a AI do the actual binary search as described by the OP in his comment pic. Doesn't have to be a human being that does it, but the process would be done the same way by either.
My mentioning motion detection is just that an AI would be able to detect the moment of change in the video, the focus point more readily than a human being, is all.
No, I'm not. Within the moment I'm creating a comment I might save and then edit, because in the past I lost whole comments when I switch tabs in my browser. But when I'm done and hit that save I'm done, and then a few cases when I'm not I add an "Edit:" to it.
Well most fights are in public, if a public camera is recording it. If a fight is private then it's probably not being done where a camera is.
The only edge case I could think of would be if something happens in a split second and then the scene is static again, the same before and after that.
But even then if you're talking about a static scene on the camera AI would probably be able to catch that split second change happening, so binary searching can still be done.
I have a feeling you just don't understand how a binary search functions even with AI you wouldn't be using a binary search at that point
If you have camera footage from 4pm to 8pm with event lasting 1 minute but no changes occur to the background/foreground how exactly are you using recursion to determine which part of the footage even occurred without going through the entire film. Are you picking at random?
The way you're describing AI is not binary search and so it can't be used in this example. Also most public cameras are not 8K cameras they don't contain a lot of detail, so the argument that they could catch something subtle kinda gets blown out of the water. You can't just use AI as a cop out for not understanding how function behaves or works
Pretty good trolling, not gonna lie.
Not trolling at all.
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
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.
In your hypothetical situation involving AI, the AI would use visual cues that are present, and so the situation is covered by the parent comment's second paragraph. In a situation where there are no visual cues for the AI to use, it would be covered by the third paragraph. They still aren't wrong about anything.
Just repeating myself at this point, but I was responding to this (the bolded part) …
Then you should be responding to the "leaves no visual cues" part, not the "binary search is useless" part. If there WERE a situation that left no visual cues, THEN binary search WOULD be useless. It does not matter whether there ARE such situations.
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 drove past the area / used this route. The route is used 24/7 by many identical cars throughout the day and night, and that our target car is one such identical car, with the only difference being the license plate. 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 video?