[HN Gopher] Overengineering a way to know if people are in my un...
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Overengineering a way to know if people are in my university's CS
lab
Author : nicosalm
Score : 180 points
Date : 2024-10-21 19:12 UTC (1 days ago)
(HTM) web link (www.amoses.dev)
(TXT) w3m dump (www.amoses.dev)
| readthenotes1 wrote:
| Scotch tape. Those poor students couldn't afford duct tape!
| ethbr1 wrote:
| These are CS students, not MEs.
|
| Which is to say, heathens who have yet to accept our lord and
| savior Duct into their hearts. (And its latter day saint WD-40)
| fullstackchris wrote:
| Love the motivation! Reminds me of the first stuff I built back
| in my university days.
|
| One thing from and old cranky dev that I notice: it would seem
| the yml you post has redundancies: either have 4 endpoints, no
| payload or 4 different payloads, one endpoint (the endpoint
| itself can tell you what you need to do) However, from the
| express script it looks like you arrived at this in the final
| solution anyway. Not sure if I missed something though, is there
| a reason the API needs such a shape? Cheers!
| amosesdev wrote:
| Hi! Author here. The yml is from a configuration in Home
| Assistant. Whenever it received an event from the sensors, it
| would fire the corresponding POST request (which you have to
| specify ahead of time, hence the configuration being a little
| redundant). The main reason for switching to the Express setup
| is that I was having a few random people look at the code &
| send their own requests to fudge what the status appeared as. I
| could have added some security/authentication to the endpoints,
| but I liked the idea of having the frontends simply querying
| the site (or my proxy) instead of having to cache a POST
| request.
| grahamj wrote:
| You can read and write HA entities via HTTP API so I think
| you could have done this with nothing but HA, but either way
| it's a fun project :)
|
| One of my more fun HA project was scraping my snow removal
| service's tractor tracking API and passing the result for the
| closest tractor into HA so I can be notified (by voice with
| Alexa and/or push notification) when there's one nearby in
| case I need to move the car.
| amosesdev wrote:
| Do you mean outside of the API that I talk about in the
| article? If I exposed the HA API via the frontend, users
| would be able to just take the bearer token and do whatever
| they wanted with it (even deleting the entities used for
| the doors). That's why the express server is sitting in the
| middle to only expose the relevant information (proxying w/
| the bearer token, which the end users have no access to)
| alkh wrote:
| I swear to God that all of these CS labs at different unis look
| the same. I am getting flashbacks of labs in Toronto that looked
| exactly like pictures in the post
| whimsicalism wrote:
| even the physics labs i worked in looked like this
| chaboud wrote:
| The physics computer lab in Chamberlin Hall at UW in the 90's
| was a secret treasure trove of idle NeXTstation Turbo
| machines in an almost always empty room cooled to near
| refrigeration temperatures. I used to light up at least half
| of that room to run distributed simulations. There's probably
| still a 30 year old key to that lab in a junk drawer
| somewhere.
|
| Eventually I realized that it just made sense to suck it up
| and get my own hardware, as it was either going to be
| esoteric "workstation" hardware with a fifth of the
| horsepower of a Pentium 75 or it was going to be in a room
| like the UPL jammed with CRT's and the smell of warm Josta.
|
| How do students operate these days? Unless one is interacting
| with hardware, I'd be very tempted to stay in "fits on a
| laptop" space or slide to "screw it, cloud instances" scale.
| Anyone with contact in the last 5 years have a sense of how
| labs are being used now?
| amosesdev wrote:
| I can only speak for the UPL, but, yeah, it was a hallmark
| of labs at the time that one of the benefits you were
| getting was the _equipment._ Nowadays, most people just
| come in with their laptops -- we have a kubernetes cluster
| for projects, but most of the actual computing equipment is
| brought in by students when they want to hang
| alkh wrote:
| In my university you could technically use any computer but
| must ensure that your code would work/compile on lab PCs
| cause that's where TAs would check it. As a result, during
| labs most people would just use computers there(too much
| hassle otherwise)
| AStonesThrow wrote:
| I went through community college about 6 years ago. And
| they still had _bona fide_ computer labs with in-person
| tech support.
|
| Computers were also ubiquitous in places like the
| coffeehouse, the library, practically every classroom, etc.
| And, of course, there were ubiquitous WiFi and USB charging
| ports, so that students with BYOD could get by (although
| WiFi was often overloaded and contentious.)
|
| Within the main computer lab I was using, there was also a
| networking hardware lab, with genuine Cisco equipment such
| as routers and switches. The Cisco certification prep
| classes would go in there and do experiments on the
| hardware, so that students could get accustomed to seeing
| it in action, however outdated it may be.
|
| The lab itself was chock-a-block with both Apples and
| Windows PCs, as well as scanners and printers available,
| and even headphones you could borrow from the desk
| attendant. You'd need to sign in and sign out. There were
| strict rules about silence and not leaving your station
| unattended. There was always space for more users and a
| generally relaxed atmosphere, where people could feel
| comfortable studying or doing homework.
|
| I believe that there was also an A/V lab where students
| could get access to cameras and recording equipment, as
| well as software for that kind of thing.
|
| The library, in addition to allocating lots of space for
| Windows PCs and Apples, would also loan out Chromebooks to
| any student, and I believe they had other things for loan,
| such as WiFi hotspots, for kids who couldn't afford to
| carry around their own Internet.
|
| There were also Tutoring Centers, such as the Math one,
| where most of the desks featured a computer where you could
| log in to your collegiate account, and access your online
| course materials.
|
| And the Testing Center was essentially a big computer lab,
| with cameras and in-person proctors monitoring it. It was
| partnered with Pearson and CompTIA, so I took more than one
| certification exam in there.
|
| There is a fully-staffed IT Help Center on campus, so
| during office hours, you could count on a 1:1 in-person
| interaction to help you get logged in, debug your device's
| WiFi, or whatever.
|
| Despite having a great computer setup in the comfort of my
| own home, and plenty of online courses on my schedule, I
| still appreciated the immersion of collegiate computer
| labs, and especially the relaxed coffeehouse access, where
| I could use Apple systems to work on my English homework
| and essays.
|
| During the COVID-19 pandemic, all this went topsy-turvy,
| and a lot of these labs closed down, or took extreme health
| precautions, and of course, a lot more classes went online-
| only. But I was done with classes by that time.
| whimsicalism wrote:
| > Unless one is interacting with hardware, I'd be very
| tempted to stay in "fits on a laptop" space or slide to
| "screw it, cloud instances" scale. Anyone with contact in
| the last 5 years have a sense of how labs are being used
| now?
|
| In my recent physics experience, this is basically what it
| was unless you had to rely on some proprietary software
| only on the lab machines like _shudders_ LabView
| hansvm wrote:
| It's been nearly a decade now, but we shared a machine with
| 128 newish physical cores, a terabyte of RAM, and a lot of
| fast disk. Anyone with a big job just coordinated with the
| 1-2 other people who might need it at that level and left
| 10% of the RAM and disk for everyone else (OS scheduling
| handled the CPU sharing, though we rarely had real
| conflicts).
|
| It's firmly in "not a laptop" scale, and for anything that
| fit it was much faster than all the modern cloud garbage.
|
| The other lab I was in around that time just collected
| machines indefinitely and allocated subsets of them for a
| few months at a time (the usual amount of time a heavily
| optimized program would take to finish in that field) to
| any Ph.D. with a reasonable project. They all used the same
| in-house software for job management and whatnot, with nice
| abstractions (as nice as you can get in C) for distributed
| half-sparse half-dense half-whatever linear algebra. You
| again only had to share between a few people, and a few
| hundred decent machines per person was solidly better than
| whatever you could do in the cloud for the same grant
| money.
| kredd wrote:
| That's exactly what I thought! "Is that UofT?"
| analog31 wrote:
| 2nd law at work. Just like all cups filled with ice cubes look
| different, but all cups half-filled with liquid water look the
| same. ;-)
| iwontberude wrote:
| I have a stealth startup that designs privacy first solutions to
| share coarse data about what is inside of rooms without
| disclosing secrets. This is useful for many use cases, from
| detecting the number of people in a room to other motion sensing
| devices which are critical for health and human safety. Patents
| are pending.
| bobbiechen wrote:
| That's great! It does feel like cameras generally collect more
| data than necessary for some purposes. I have a friend who
| works at Butlr, which uses thermal sensors to detect body heat
| (and avoid the privacy risks of cameras) - sounds like your
| startup is in a similar space.
|
| I know you mentioned patents pending, but is there anything you
| can share about your approach?
| Animats wrote:
| "Room occupancy sensors" are a common product. Butlr
| apparently uses a low-rez IR camera, although they avoid
| calling it that. Passive infrared is common. Millimeter wave
| is available.[1]
|
| [1] https://www.alibaba.com/product-detail/IoT-Commercial-
| People...
| moralestapia wrote:
| Nice project but it could be illegal. Check your jurisdiction.
|
| Source: have done similar hobby projects for fun, which turned
| out to be illegal.
| soggybread wrote:
| What part of this would be illegal? It's just a zigbee door
| sensor. The only issue I could see is the college getting upset
| but if anything they'd just say 'take it down'
| whimsicalism wrote:
| object detection of people from images is probably what they
| are referring to. there are maybe some state laws that could
| be stretched to include that but i would say presumptively
| legal
| ninju wrote:
| The final solution does not depend on object (people)
| detection. In fact by the end of the article he has totally
| eliminated the camera
| oniony wrote:
| Doors have rights too!
| sceadu wrote:
| I guess depending on how you open them they do indeed
| have the right to bear arms
| whimsicalism wrote:
| this isn't facial recognition
| moralestapia wrote:
| ???
|
| Who's talking about that?
| whimsicalism wrote:
| why would it be illegal?
| moralestapia wrote:
| Generally, you cannot just record people without their
| consent; but this also largely depends on the
| jurisdiction/situation.
|
| Almost nowhere (or actually nowhere?) are you allowed to
| set up a surveillance device into a space that is not
| public and it is not owned by you.
| packetlost wrote:
| Public university labs are generally public as they're
| state property (in this particular case, UW Madison is a
| public state University). Further, recording video or
| pictures of people in public places is broadly legal in
| the US. There are only "presumption of privacy"
| restrictions which apply to places such as bathrooms and
| private property that is not visible from a public
| location (ex. a sidewalk).
|
| Obv. IANAL and this is not legal advice.
| moralestapia wrote:
| >Public university labs are generally public as they're
| state property
|
| Wrong. They're state property, you even wrote it there.
|
| >Obv. IANAL
|
| Obv.
| exe34 wrote:
| what do you think public mean, they have to belong to Mr.
| P. Ublic?
| jrflowers wrote:
| This reasoning makes sense. Roads and parks aren't
| public, as they are city property. "Public" is only when
| something has no legal owner, like the moon and stars, or
| love.
| icehawk wrote:
| And thus they'd fall under the legal definition of
| public: "Under the authority of the government or
| belonging and available to the people."
|
| or
|
| "of or relating to a government"
| almostgotcaught wrote:
| By this logic the dorm room bathrooms at public
| universities are also public and I should be able to
| setup cameras /s
| ozzmotik wrote:
| just for the sake of conversation...
|
| if you did, where would you have set them up at anyway?
| Asking for a friend
| samatman wrote:
| Generally, in the United States, you can, in fact, just
| record people. Legally speaking, that is, which doesn't
| make it a polite or cool thing to do. Necessarily.
|
| If you're on someone else's property, they can of course
| set any number of rules, and trespass those who break
| those rules. But even there, recording people, if against
| the rules, is still not a crime. The crime is trespass,
| if this journalist we're speaking of sticks around after
| being trespassed off the property.
| moralestapia wrote:
| Good one, champ!
|
| Meanwhile in reality: https://leginfo.legislature.ca.gov/
| faces/codes_displayText.x....
| alexchantavy wrote:
| Bunch of restaurants use those fancy Nest cams that remember
| faces. Is this illegal too? Feels like it should be controlled
| in some way.
| moralestapia wrote:
| >Feels like it should be controlled in some way.
|
| It is. Check your jurisdiction.
| rithikjainNd01 wrote:
| UW Madison UPL on Hacker News! Great to see, you guys are
| awesome!
| nicosalm wrote:
| Thank you!
| djsavvy wrote:
| Neat to see discord channel names being used as an information
| channel.
| thrdbndndn wrote:
| It's a common practice/trick in Discord communities
| (particularly gaming) to pin some status, but yeah, I always
| find it neat.
| teddarific wrote:
| This is neat. I worked on something similar to college where we
| built an app to track how long the line was at a popular cafe. We
| set up a camera + raspberry pi in the cafe and tried to the
| number of people. There was a lot of noise from overlapping
| people, random people walking in and out of line, etc. Cool
| seeing all the techniques and approaches you tried!
| nullhole wrote:
| > It then set the name of a channel to the results (either
| 1-person-in-upl or X-people-in-upl), which others could check.
|
| I'm not suggesting you don't do this, but you /could/ setup a
| speaker to play the classic remix of Steve Ballmer's "developers!
| developers!" whenever there are >=2 people in the room. On April
| 1st, of course.
| cptaj wrote:
| I am, in fact, suggesting you do this.
| alwayslikethis wrote:
| > I'm not suggesting you don't do this
|
| I hope this is intentional
| nullhole wrote:
| >> I'm not suggesting you don't do this
|
| > I hope this is intentional
|
| I mean, it's not unintentional..
| eduction wrote:
| I love this company. Yeah!
| urbandw311er wrote:
| Another state of the art people counting system would be ultra
| wideband. It can literally count the number of heartbeats in a
| room. See https://m.youtube.com/watch?v=adiUegDxZEs
| davidteather wrote:
| UPL UPL UPL UPL
| nicosalm wrote:
| UPL!
| zdw wrote:
| Back in the 90's we used finger - IIRC it would tell you the last
| machine someone logged into, which could be in the lab
|
| Someone wrote a script to finger everyone in the entire CS
| department and tell when the lab was busy, by counting people
| logged in.
|
| This work fine, except for on intro courses where some labs had
| lots of non-CS majors in them.
| bks wrote:
| I had finger running on login to `finger stacy` I was at SDSU
| on a very large SunOS system and she was at a private school
| and I assume that computer was a bit more limited.
|
| `Finger Stacy` would run every minute and typically be running
| for 15 minutes max... that is until I moved into the dorms and
| my machine was online all the time.
|
| A few weeks go by and I get an email from the SDSU admin
| requesting that I stop fingering stacy as it was bothering the
| other Sysadmin. I remarked with a grin that all I was trying to
| do was in fact try to `name of the command` and they promptly
| deleted the script from the account.. It still makes me smile
| as I write this.
| hotspot_one wrote:
| fdisk or mount?
| elcritch wrote:
| Sincerely doubt he had permissions for either operation. ;)
| vasco wrote:
| Everyone knows the right order of commands is date,
| finger, mount.
| neilparikh wrote:
| I built a similar system for my school's CS club. I considered
| using a door sensor, but the eventual solution I settled on was a
| light sensor, because it's almost always true for us that the
| lights are on iff the door is open.
|
| This way, we don't need to mount anything on the door, we just
| have a microcontroller plugged into one of the machines.
|
| Our previous solution was a webcam that pointed to the lights
| that did a similar thing (implemented by someone before my time)
| but then it stopped working due to some driver issues, and I
| didn't want to spend time investigating them.
| _visgean wrote:
| In edinburgh we had this: https://devpost.com/software/the-
| marauder-s-app which showed who was using which computer based on
| logins.
| withinrafael wrote:
| I saw "over-engineering" in the title and half expected to see
| Wi-Fi signals being abused to detect human bodies in the room.
|
| https://arxiv.org/abs/2301.00250
| TrackerFF wrote:
| My first thought was to put some motion sensors inside the room,
| along with a sensor for the door (open/closed), as well as some
| sensor for counting the people walking through the door. Maybe
| even some co2 sensor to detect changes.
| zanchey wrote:
| The University Computer Club at UWA also has a door sensor!
|
| https://door-status.ucc.asn.au/ucc
|
| Runs off a Raspberry Pi with a bodged-up version of
| https://github.com/ide/pico-door-sensor/tree/main
|
| This is at least the third iteration; some previous iterations
| are documented here:
|
| https://www.ucc.asn.au/services/door.ucc
| dbetteridge wrote:
| Still works better than the uwa door card readers
| mdberkey wrote:
| Love to see the UPL on hacker news :)
| fartfeatures wrote:
| Point the camera at the door, use the camera to detect if the
| door is open.
| grahamj wrote:
| Mount the camera on the door facing down and watch for a moving
| floor
| fartfeatures wrote:
| That's a clever solution that would use less processing
| power. A camera pointed at the door provides the benefit of
| being useful for other purposes e.g. person detection /
| recognition and standard security camera purposes.
| lazide wrote:
| Until someone accuses you of looking down their shirt
| anyway.
| changexd wrote:
| Very interesting and fun read! thanks for the post, when I saw
| the public restful api endpoint I immediately tried to see if I
| can make request just to see the "NICE TRY!" message, haha, then
| I kept on reading how you managed this issue.
| kleiba wrote:
| This would be a nightmare to implement from a legal standpoint in
| Europe.
| lormayna wrote:
| Even if you collected aggregated data and not storing any PII
| or images?
| preston4tw wrote:
| room presence detection has been a long standing challenge in the
| smart home / home assistant community. it's cool to see home
| assistant used and adapted for this use case.
| zimpenfish wrote:
| Back in the man.ac.uk of the early 90s, there were no cameras or
| YOLO models but we still wanted to know when machines (especially
| the colour ones! LUXURY!) were available.
|
| We just had "`rlogin` to every machine in the lab, run `who`, and
| collate the output". IIRC there was an early version written by
| 'flup that I extended with a tidier output (including an X11
| window), auto-refreshing, and easier machine selection (eg. you
| could select rooms by name with regex filtering.)
|
| Good times.
| amingilani wrote:
| If you're okay using Cloudflare tunnels, just use Tailscale to
| create a VPN instead.
| q3k wrote:
| Another solution in the age of portable electronic devices:
| detect presence based on active DHCP leases. You can let then
| people register themselves by MAC on some web portal so they can
| be visible by name if they're comfortable with that.
| lormayna wrote:
| Or Bluetooth. There are some problems (like MAC randomization)
| to get a real tracking with BLE, but to have a rough
| estimation, it's a good technique. And you can do it with just
| an ESP32.
| JohnBooty wrote:
| Hmmm... interesting. How would that work? Just count the
| number of BT signals in a room?
|
| How many BT devices is the average student or faculty member
| toting around with them at a given point?
|
| Could conceivably be 4+ with some combination of: phone,
| smartwatch, tablet, BT speaker, game device, etc.
| lormayna wrote:
| The idea is to scan every minutes for BLE MAC Addresses and
| send to a backend. On the backend you can identify what is
| the manufacturer of every MAC addresses and make some
| correlation. A very simple idea is to filter only the phone
| MAC addresses and use as presence counter estimator; it's a
| bit unlikely that a university student will have more than
| one phone.
|
| A better method would try to correlate not random MAC
| addresses (headphones, BLE trackers, wearebles, etc) that
| are frequently together and mark as a single person.
| QuantumSeed wrote:
| When I was in the CS department at NMSU, the Computer Science
| building was open to the public 24-hours a day. I suppose that's
| not commonly the case nowadays.
| ericpauley wrote:
| FWIW the building from the article is open to visitors during
| extended working hours.
|
| Source: Currently in the building.
| IvyMike wrote:
| Back in my day we just looked at the ctime of /dev/mouse
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