Comment on Programmer tries to explain binary search to the police
CosmicCleric@lemmy.world 7 months agoIn 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.
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.
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.
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.
What does that have to do with a binary search If a camera has AI on
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.
Cool you’re adding information to the question to make yourself “right”
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.
but even your comment says that’s only the vast majority of fights and also you had to clarify in public
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.
so there are edge cases where the situation still stands that binary search wouldn’t work or wouldn’t be feasible.
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’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.
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.
Just repeating myself at this point, but I was responding to this (the bolded part) …
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.
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.
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?
TheSanSabaSongbird@lemdro.id 7 months ago
You are seriously confused. OP specifically said that you’re fucked if there is no visual cue.
CosmicCleric@lemmy.world 7 months ago
And you are seriously trying ot 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. There’s always a visual difference.
nexguy@lemmy.world 7 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?
CosmicCleric@lemmy.world 7 months ago
The person dropping to the ground dead would be the visual cue.
starman2112@sh.itjust.works 7 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.
CosmicCleric@lemmy.world 7 months ago
Last time I checked, I’m allow to disagree with a comment someone made, and argue the opposite. Just because they say ‘no visual cue’ does not mean that is no visual cue.
Yes I can. Of course I can (unless you’re advocating I’m not allowed to disagree and argue that point).
Its called “disagreeing” with what the other person is speaking of. Its a discussion.