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[music - randy rogers band, "tonight's not the night (for goodbye)"] david malan: hello world. this is cs50 live andthis is our season finale. but boy do we have a goodepisode for you today, in particular, the latest inimage stabilization, robo soccer, and ultimately, a lookback at cs50 live itself. now you may recall that desk lampshave been a bit of a thing this year. in fact, this was kind of a spontaneousintroduction to cs50's week zero this past fall 2013.
>> just a day or so before the veryfirst lecture this past fall, i decided it would be kind of fun tobe able to visualize binary-- zeros and ones-- and so i headed tocs50's favorite store, target, and picked up these desk lamps here. now, at the end of the lecture,i found that i didn't really need these lamps for another year. and even if i did, it wouldkind of be an old bit by 2014, so i offered them up tostudents in the audience. >> now, since then of course, we've beenreceiving quite a few emails, facebook
posts, and tweets requesting these samecs50 desk lamps to be sent nationally and internationally. and so we did. and we got back this very nicenote from cs50's luigi morelli in rome, italy who wrote us this. "and here i am! thanks to cs50 staff. hey, look at thosefour books behind me." >> in fact, if you do look up there onthe top shelf, you will see four books.
and if we enhance, you'll see that it'sa canonical set of computer science books by a very renownedcomputer scientist known as donald knuth who wrote,the art of programming. so if you yourself were looking to buildyour own collection of computer science canon, go ahead and take alook at the art of programming. >> now, meanwhile, if we take a look atvideos that some of your classmates have submitted, we will see thefirst one from rian from india. hi. i'm rian [inaudible] from india.
and i'm taking cs50 online [inaudible]. and the reason i wantthe lamp is basically because i don't have alamp at all and i really need one as i'm doing [inaudible]for [inaudible] and all this stuff. and i don't have a desklamp or anything like that. so it would be really greatif you guys would send me one. i'm rian [inaudible], and this is cs50. david malan: now, yournext classmate, mauricio, you may recall from a previous video.
but this time, mauriciodecided to take it up a notch and actually deliver hisown lecture for week zero. >> mauricio rada: so this is cs50. my name is mauricio rada, and73% have no prior experience in computer science, contraryto what you might think. so today, we thought we would chipaway at that lack of familiarity, but also give you a sense of, forthose of you with more comfort, which directions you can go this semester. >> so let us start with this.
i have these little desklamps here, so-- oh. we haven't any desk lamp here. we can't go on. so you will have to end this lab here. this is not cs50. >> at the next cs50-- >> david malan: and lastly,is sid, also from india, who actually decided tocreate for us his own song. >> sid: hi, i'm sid, and i'm from india.
i want a desk lamp because--how about i put it this way. >> [music playing] >> it's kind of funny how life can changeonce you take cs50 in a matter of days. so i'm making thisvideo to show you guys why i deserve a brand new desk lamp. so it goes like this. i get yelled at every night fornot switching off the lights. speaker 2: switch off the light, man! sid: just a second.
whether i'm writing lyricsor coding some [inaudible]. speaker 2: dude, i'mswitching off the lights. sid: five minutes. just five minutes. one love for cs50. one love for the desk lamps. one love. if i don't get one, i won't survive. so please give me a desk lamp.
darkness makes me wet my pants. please give me a desk lamp. desk lamp is all i need. i hope you like it. david malan: now lest ibe shamed on the internet, it's cs50 that's an introduction to theintellectual enterprises of computer science and the art of programming. but professor donald knuth'sbooks, if you would like to google and find them yourself, are theart of computer programming.
>> now, you may recall that cs50 recentlyparticipated in this, a 48 hour film project wherein cs50 hadjust 48 hours to create a short film with afew required elements. now, one of the scenes fromthat film was this one here wherein daven wasdesperately running along the charles river near harvardtrying to just say hello. now, what you might not have realizedis that running in front of these two were actually three guys. in fact, pictured hereis some of cs50's team.
and if we zoom in, you'll see ianholding the camera, patrick holding ian, and dan directing the scene. >> now, in fairness, if we zoomout, you'll see cs50's own ramon galvan who was just running. now, what ian washolding with the camera was this device herewhich performs something called image stabilization which is thetechnology with which we were keeping that shot along the river so relativelysteady even though those guys were all running backwards.
now, you might know of this kindof technology from yesteryear. in fact, if you grew upwith the so-called gyro bowl, which looked a littlesomething like this, this is a very simple device thatessentially spins on three axes so that you have some cerealinside of this bowl, in theory, it should never fall outbecause the handles will always keep the bowl itselfin an upright position. now, i recently had anopportunity to spend time with cs50's own dan coffey, who wentinto more technical detail as to how
more modern image stabilization works. >> so i'm here with cs50'sown dan coffey, jogging along the charles riveron harvard's campus. now if dan were just usinga camera to shoot this, the image would be prettyshaky, definitely not stable. he's using a technique called imagestabilization which should, hopefully, be stabilizing the image. can we shoot the rest of this inside? >> ok.
image stabilization. what is it? how does it work? dan coffey: so for many years,the tv and film industry have been trying to get more dynamicshots by introducing movement, but it's a challenge tokeep them stabilized. you've seen the west wing maybewhere they do the walk and talk shot? and basically what they usefor that is a steady cam, which is a big rig that you wear.
it's a vest with an arm that isolatesthe camera from the user and counter balances it with a series of weights. but it takes a reallylong time to set up and it's very complicatedto actually use. >> there are new developments in softwarethat you can use where you can make adjustments in mac or pc whichsometimes work, sometimes they don't. but one of the latestdevelopments is actually this. this is the movi m10. it's a really neat piece of equipmentfrom our friends at freefly systems.
and basically, it uses a series ofgimbal axes to stabilize your camera. david malan: what's a gimbal? dan coffey: so a gimbal is a set ofrings that each spins on its own axis and basically isolates each direction,either the x, the y, or the z. and really just makes itvery smooth and fluid. so this m10 is a large gimbaland has three axes on it-- one here for the tilt, it's got one inthe back for the roll, and one up top for the pan. and i can actually show you if youwant to see how these actually work.
>> david malan: yeah, sure. >> dan coffey: so if youlook here in the software, this is their freefly configurator. and it's basically outputtingdiagnostic information right now. but you see we have motor tilt,motor roll, and motor pan. and as i actually panthe camera, you're going to see the blue linesstart to go up and down. >> david malan: ok. so that represents the--
>> dan coffey: it's the resistanceof the motor pushing back against me because the m10always wants to come back to rest in the same position. so the taller, the lower thebar, the more resistance. dan coffey: yeah, the more intensitythat the motor's using to fight me. if i tilt, you can see thered line doing the same thing. and then roll-- >> david malan: the green line up and down. >> dan coffey: so these are the threeaxes we're stabilizing against.
and so this is not normally howyou would operate it, right? so if i actually pickthis up-- and here, why don't you actually hang on to it. thank you. >> dan coffey: and nowyou can see how little the camera moves when you hit the edge. the window, if you will,it starts to pan with you. that's actually set inthe software as well. >> david malan: i see.
>> dan coffey: but there'sanother really neat feature. if you are in a more complicatedshoot, you can turn on this remote, have a second camera operatoractually do the nitty gritty control. so i can now pan, flex this control. i can tilt and i can actually roll. so in this set-up, you would actuallybe the one moving the camera physically and i would connect awireless video transmitter to the camera, put areceiver here on a monitor, and then i could actually, just like avideo game, operate the camera for you.
>> david malan: nice. >> dan coffey: so i'll put itback in single operator mode, but you can get a sense ofhow smooth it actually is. >> david malan: yeah, no, absolutely. and i have an idea. want to follow me? dan coffey: sure. david malan: ok. so we're here in the bathroom to testout some actual image stabilization
in front of, well, theonly mirror we have. and i thought it'd be interesting tosee just how much the camera moves when i actually move my armsup, down, left and right. dan coffey: so let'ssee the pan, tilt, roll. david malan: all right. here we go. i'm really moving it. dan coffey: so i see a littlebit movement, but i mean, you would never operateit like that either.
>> david malan: no, definitely not. dan coffey: all right. so david, let's get serious this time. we'll do a test where youactually go up the stairs and i will lead you withthe stabilized movi, and andrew will actuallycome next to me. come on over andrew. and we'll see what itlooks like side-by-side. >> david malan: got it.
>> dan coffey: ok. ready to go up the stairsin three, two, one, go. hi shelley. all right, david, whydon't you take this? take all that you've learnedtoday and put it together and we'll get the final shot. >> dan coffey: and now,60 seconds of gimbals. >> speaker 3: uh-oh. look out!
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>> speaker 3: gyrobowl's innerbowl rotates 360 degrees and magically stays openside up, no matter what! so the gyrobowl keeps all yoursnacks inside, however you bounce, swing, or fly! now, kids can use the amazinggyrobowl as a super snack contraption. fill it up with raisins orcereal and rev up the action! >> speaker 5: kids loves theamazing gyrobowl because it's fun and it never spills! >> speaker 3: pack crackers andgrapes and get on with the chase!
and when mom drivesto the store, gyrobowl keeps the snacks off the floor. david malan: now, youmay recall, i recently spent time with hiscs50's own colton ogden. and this guy here, the nao robot thatwas loaned to us by cs50's friend professor radhika nagpalin the robotics group. now, of course, robotsdon't all take this form. in fact, we recently sawthis guy here playing soccer with president barack obama.
>> but it turns out thateven soccer playing robots can come in different forms. in fact, pictured hereare two custom made robots by professor radhika nagpal's researchgroup, with whom we sat down recently to better understand how they andyou can build your own soccer playing robots and pit them incompetition against each other in an international robocup competition. radhika nagpal: my name radhika nagpal. i'm a professor at harvard university.
and i do bio-inspired robotics. so i'm really interested in howgroups can work together really well. eric schluntz: so myname is eric schluntz. i'm studying electricalengineering at harvard university, >> kate donahue: i'm kate donahue. i'm a sophomore at harvard collegeand concentrating in math and physics. so i'm part of rfc cambridge. it's a joint harvard/mit team. we basically buildrobots that play soccer.
radhika nagpal: so the challenge ofthe robocup competition-- and it's an international competition thatwas started by people in the us and japan actually-- is to create a teamof robots that can play and possibly win against the worldchampions at the world cup. kate donahue: there are teamsfrom all around the world. and because we're so far spreadout, it's really hard for us to get to test the robotsagainst each other. so it's basically just sortof like a soccer match. there will be some round robingames and then a final competition.
and it's a chance to seehow our robots stack up against others and just exchange ideas. >> radhika nagpal: if you think aboutlittle kids playing soccer and older people playing soccer andthink about the difference, like all the things that a little kidcannot do that an older person can, computer science hasto fill that whole gap. >> eric schluntz: so youcould say, i want the robot to go behind the ballto set up for a shot. but what you really haveto tell the computer to do
is find the vector between the ball andthe goal and go there, minus an offset. and you really need the computer sciencepeople to express yourself in a way that the robots can understand. kate donahue: we all work on verydifferent parts of the robot, but we really need to coordinate. it's a big challenge and it's greatwhen we all work on something together. so we'll build themechanical part of it, and then the electrical engineerswill make the circuit boards, and the computer science peoplewill have done their simulations
and then try and figure out howthey can combine that and make the robot actually move. >> radhika nagpal: i think reallyrobotics is often about iteration. you do take one step forward. you take two steps back. you try to make one thing better. it makes something else worse. >> eric schluntz: on the computer scienceteam, we've made a lot of progress on our artificial intelligence.
we threw out all the oldstrategy code and have been making something that'smuch more adaptive to how the other team is playing. so on defense, we do things likeranking the most dangerous players and covering them in a manto man defense based on that. and then our offense, we generate thesemaps over the entire field of how good the spot is and then assign ourrobots to these dynamically. radhika nagpal: theyneed to be able to see. they need to be able tounderstand the world.
they need to be able to movefast and turn and manipulate. they need to be able tonotice their teammates and understand what they're doing. they need to have a strategy. and they need to adapt theirstrategy because their opponent will be doing things all the time. and so you can't havea pre-determined plan. you have to be able to adapt. >> kate donahue: sincelast year's competition,
we've done a lot of advances,especially in the wheel design. we've shifted the motorsdown and made everything much more compact, which has allowedus to move our center of gravity down, which allows us togo faster and also put in a dribbler, which is somethingwe've wanted for a long time but just haven't been ableto make fit until now. eric schluntz: so each of thecircuit boards on the robot has a different purpose. the four big ones, there, there, andthere, each control one of the motors.
so that basically takes asignal from the computer, decides how fast the wheelshould spin, and sends the correct voltage tothe wheels to do that. so like this board herecontrols this motor and this one here controls this motor. >> we also have these twoboards in the middle. this one right here controls chargingthese big capacitors for the kicker. this board here controls when the robotkicks by using this light sensor right here to see when theball is in front of it.
it also controls the dribbler herewhich we use to put backspin on the ball so we can move backwards with it. >> kate donahue: it's notjust you're trying to win. it's that you're tryingto advance knowledge. and so you work on whateveryou work on and then you have to release a paper sayingexactly what you did that's so cool, and how other people can do thatand they can build on your work. and so if there's something soadvanced that someone comes up with, everybody can sort of draw on that.
>> you can have that for one year and maybenobody else can use it for that year. but then the next year,everybody will have modified it and have done the same thing. so it's really just moving forwardsand not staying in the same place. >> eric schluntz: i definitely want tobe working on robotics in my career. i think that there's justa lot of amazing things that can be done to automatethings, to make cars safer, to make just really everything workautomatically so that people don't have to do things that are dangerous or dull.
there's just so many things thatrobots can do better than people. and i think that as a society we needto start doing those to free people up to do more interesting things. >> david malan: this is indeed our seasonfinale and our 10th of 10 episodes. and it's truly remarkablehow in just 10 episodes how many mistakes we have made. in fact, cs50's own shelley westover--whom you may recall from such films as-- recently went through hoursof footage of both live episodes and rehearsals thereof to findsome of our favorite memories
to share them with you. >> hello world. this is cs50 live. so if you see me trip, if you seeme misspeak, if you see me screw up, all of that is happening literallyright now in cambridge, massachusetts. oh, hi world. drum roll. persp-- uh, persec-- pause the videoif you would like. [inaudible]. [stuttering]
>> is mark zunkerburn's favorite pa--to protect our nuclear missile. keeping an eye as usual. bugle itself. gaggles. good episude for you. it's actually quite-- ah, it ends. you may recall. head to this ur here. >> speaker 6: this is cs50.
ah. david malan: and now imade the blooper reel. fantastic. speaker 7: should we redo the ending? how should we do the ending? >> david malan: photos of jasonhirschhorn dressed as a punmpkin. speaker 8: oh, boy. i don't know if i wantpeople to see that. >> david malan: no.
now it's photos of jasonhirsch dressed as a boy. speaker 9: and if you're interested,i can actually show you how-- david malan: yeah, absolutely. speaker 9: he's a littleoff-balance this morning. he hasn't had his coffee yet. >> speaker 10: whoa! oh god. >> david malan: from-- where's he from? >> speaker 11: right about--right where my arm is,
you can see like the white characters. there's the pole. david malan: they don't knowthat's the-- you should point here. speaker 11: oh. >> david malan: can you hear me, world? ramon galvan: hello world. welcome to cs50 live. i'm ramon galvan. >> david malan: and-- and i'm david malan.
>> ramon galvan: and today,i'm hosting today's episode. >> david malan: well, with me. ramon galvan: ok. ok. oh, [bleep] >> speaker 12: don't say[bleep] on the air! ramon galvan: oh, [bleep] he'llbe the robin to my batman, the andy richter to my conan,the cheech to my chong today. this is most definitely a seriousthing that we're doing today.
this is not a joke. dropbox has been quite a fuss latelybecause i know nothing about this. what is this about? that was all above me. and this is something i don't know of. we also take a tour ofthird glass-- third deg-- david malan: right there. it allows you to swipe creditcards on your iphone in order to process payments.
ramon galvan: i have a flip phone. let's play the clip. one, two-- >> david malan: that was the first ever. ramon galvan: what? david malan: that was the first ever. to host the first ever-- david malan: i was ingraduate school at the time. ramon galvan: and i was in fourth grade.
although i love zamyla, iwould much rather not spend-- david malan: spend halfas much time with her. ramon galvan: exactly. >> david malan: come on out, zamyla! this was cs50, and this was terrifying. ramon galvan: this is terrifying. made a little sizzle roll to encapsulatethe debauchery that took place. >> david malan: i love you. aww.
>> ramon galvan: i love you. unlike david, who circles you. david malan: where are my slides? oh. that's it for cs50 live. thanks so much to thisweek's contributors, to every one behind thecamera, and thank you to you for tuning in this whole season. this was cs50.
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