Posts Tagged‘video’

The Human Sonic.

I loved Sonic the Hedgehog as a kid mostly because I could simply point myself in a single direction, mash the spin button and then watch as he flitted from one side of the screen to the other at breakneck speed. Whilst the physics of that particular game aren’t rooted in reality some of the principles were namely the forces of momentum, inertia and, most importantly centripetal force. That last one is the force responsible for keeping objects pinned down when going through loop the loops although you usually only see it in action on roller coasters or special stunt vehicles. I honestly didn’t think it’d be possible for a human to accomplish what our speedy blue friend did but it seems that, like many other things, I was wrong.

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I was surprised to learn that the required speed to get around the loop safely was so low, well within the reach of anyone with a modicum of fitness. The real key here though is the technique as the way we humans generate force is vastly different to that of more traditional vehicles that can accomplish this feat. You see the force we generate isn’t in line with the surface we’re on, it’s at something of a 45 degree angle, which means that as you get to the higher parts of the loop you’ll actually be pushing yourself off it with your face heading directly towards the floor.

This becomes evident when you see the initial trial runs where he has to flip himself over at the peak of the loop. In the final, successful run you can see that when his foot hits the peak he doesn’t actually use that to generate any force. Instead he’s doing something like an upside down split kick with one foot travelling from one side of the loop to the other. It’s incredibly impressive to say the least and just goes to show that given enough practice, persistence and good old fashioned science the impossible can be achieved.

Blue Angels’ C-130 Conducting a Jet Assisted Take Off.

Most aircraft capable of Short Take -Offs and Landings (STOL) are usually small and nimble kinds of planes, usually being either designed for use in adverse conditions or, more famously, fighter jets that find their homes on aircraft carriers. The reasons for this are pretty simple: the larger you the make the aircraft the more power you require to shorten its take off and past a certain point regular old jet engines simply aren’t going to cut it any more. However there have been a few notable examples of large aircraft using JATO rockets to drastically shorten their take off profile and the most notable of which is the Blue Angels’ C-130 dubbed Fat Albert:

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If you’ve ever seen one of these beasts take off in person (or even say, an Airbus A380 which is a monster by comparison) then you’ll know that they seem to take forever to get off the ground. Strapping 8 JATOs that produce 1000lbs of thrust to the back of them makes a C-130 look a fighter jet when its taking off, gaining altitude at a rate that just seems out of this world. Of course this then begs the question of why you’d want to do something like this as it’s not often that a C-130 or any of its brethren find themselves in a situation where taking off that quickly would be necessary.

In truth it isn’t as the missions that these large craft fly are typically built around their requirements for a long runway. There have been some notable examples though with the most recent being the Iranian Host Crisis that occurred over 30 years ago. After the failure of a first rescue attempt the Pentagon set about creating another mission in order to rescue the hostages. The previous mission failure was largely blamed on the use of a large number of heavy lift helicopters, many of which didn’t arrive in operational condition. The thinking was to replace those helicopters with a single C-130 that was modified to land in a nearby sports stadium for evacuation of the extraction teams and the hostages.

The mission was called Operation Credible Sport and was tasked with modifying 2 C-130 craft to be capable of landing in a tight space. They accomplished this by the use of no less than 30 JATO rockets: 8 facing backward (for take off), 8 facing forward (for breaking on landing), 8 pointed downwards (to slow the descent), 4 on the wings and 2 on the tail. The initial flight test showed that the newly modified C-130 was capable of performing the take-off in the required space however on landing the 8 downward facing rockets failed to fire and, in combination with one of the pilots accidentally triggering the breaking rockets early, the craft met its tragic demise thankfully without out injury to any of the crew.

Even Fat Albert doesn’t do JATO runs any more as a shortage of the required rocketry spelled an end to it in 2009. It’s a bit of a shame as it’s a pretty incredible display but considering it had no practical use whatsoever I can see why they discontinued it. Still the videos of it are impressive enough, at least for me anyway.

The Intriguing Science Behind Bouncing Dead Batteries.

Everyone can relate to the frustration of having a drawer full of batteries that are in an unknown state of charge. For most people the only method they have to deduce whether they’re good or not is to try them out in a device, something that inevitably leads to frustration when your spares show up dead as well. The inclusion of battery testers on the batteries themselves (or in the packaging) seemed like a great idea however it never seemed to catch on presumably due to cost factors. Whilst geeks like myself might have a voltmeter handy to get accurate readings in an instant they’re not a ubiquitous device and an effective way of testing batteries still eludes most.

That is until they see this video:

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Honestly when I saw this video I was pretty sceptical as the video, whilst highly informative, is anything but scientific. Instead of having 2 batteries from the same brand (and preferably from the same batch) for comparison the effect could be explained by differences in manufacturing between the two. I didn’t take the opportunity to test it myself however, even though I do have a drawer full of batteries that are all in unknown states, but after seeing this video parroted around various life hacking sites I figured that if it was total bunk someone would’ve called shenanigans. It seems that the video is accurate and the science behind why empty batteries bounce is very interesting.

It’s not, as many have speculated, related to a reduction in weight between a full battery and a discharged one. Batteries like this are a closed system, chemically speaking, so save for a few milligrams here and there due to handling or (more catastrophically) a breach in them batteries don’t change their weight. Instead it’s a quirk of the manufacturing process and the change in densities of the various materials inside the battery, all of which result in it becoming bouncy.

In a typical alkaline battery the chemical reaction that takes place to produce charge also results in the materials shrinking. The reason for this is that as the battery discharges oxygen molecules from the cathode (negative ) manganese oxide terminal migrate to the anode (positive) zinc anode, producing zinc oxide. When this occurs the total volume decreases as the oxygen atoms are able to pack themselves much tighter on the zinc oxide terminal than they can on the manganese oxide. This results in the internals shrinking somewhat and, as a consequence, tugs on the side of the pressure seal on the bottom of the battery. This causes it to bow outwards providing a spring like structure which results in the bounce when dropped.

Now I haven’t looked at a lot of batteries recently but I can image that some other designs might make this trick fail due to the design of the cathode terminal. This also means that the trick is probably unique to the cylinder style batteries (A, C, D, etc.) as whilst other types of batteries have similar chemical reactions their construction is vastly different. So I wouldn’t recommend dropping your car or latern batteries to try and test them out, lest you want to spend some time in the chemical burn ward and paying for a large chemical spill.

See What Felix Baumgartner Saw.

It doesn’t seem that long ago that Felix Baumgartner leapt from his balloon 39KMs above the Earth’s surface, breaking Joseph Kittinger’s long standing record. The whole journey took only minutes and the entire journey back down captivated millions of people who watched on with bated breath. Curiously though we only saw one perspective of it for a long time, that of the observation cameras chronicling Felix’s journey. Now we can have front row seats to what Felix himself saw on the way down, including the harrowing spin that threatened to end everything in tragedy.

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Absolutely stunning.

How Gravity Really Works.

We’re all familiar with the concept of gravity: 2 bodies of mass, no matter how or small and regardless of the distance between them, are attracted to each other. As a force it’s pretty weak, even when the two bodies are close to each other, as you can overcome the gravitic forces of an entire planet by simply standing up. However the fact that its range is unlimited and that it doesn’t appear to discriminate as to what it acts on is what makes it such a fundamental force in our universe.

Whilst that understanding is probably good enough for a general understanding of its mechanism of action it in fact is far more complicated and interesting than that and the following video is probably the best way of describing it I’ve seen in a long time:

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It’s not a perfect simulation, as they mention in the video, but it does give you a really great insight into how the general relativity way of explaining gravity works and how it works with other well known theories like orbital mechanics. I reckon with a little additional engineering you could make something that functioned like a nearly ideal gravity field something which would be awesome in a science museum like Questacon here in Canberra. It’s still great in its current form though and hopefully we see similar things make its way into the science labs at our schools.

A Distant Ancestor of the Programmable Computer.

Ask any computer science graduate about the first programmable computer and the answer you’ll likely receive would be the Difference Engine, a conceptual design by Charles Babbage. Whilst the design wasn’t entirely new (that honour goes to J. H. Müller who wrote about the idea some 36 earlier) he was the first to obtain funding to create such a device although he never managed to get it to work, despite blowing the equivalent of $350,000 in government money on trying to build it. Still modern day attempts at creating the engine with the tolerances of the time period have shown that such a device would have worked should have he created it.

But Babbage’s device wasn’t created in a vacuum, it built on the wealth of mechanical engineering knowledge from the decades that proceeded him. Whilst there was nothing quiet as elaborate as his Analytical Engine there were some marvellous pieces of automata, ones that are almost worthy of the title of programmable computer:

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The fact that this was built over 240 years ago says a lot about the ingenuity that’s contained within it. Indeed the fact that you’re able to code your own message into The Writer, using the set of blocks at the back, is what elevates it above other machines of the time. Sure there were many other automata that were programmable in some fashion, usually by changing a drum, but this one allows configuration on a scale that they simply could not achieve. Probably the most impressive thing about it is that it still works today, something which many machines of today will not be able to claim in 240 years time.

Whilst a machine of this nature might not be able to lay claim to the title of first programmable computer you can definitely see the similarities between it and it’s more complex cousins that came decades later. If anything it’s a testament to the additive nature of technological developments, each one of them building upon the foundations of those that came before it.

Some Things Are Much Simpler Than You Think.

There’s a lot of things in this world that I think I have a sound understanding of that, usually after a Wikipedia binge or YouTube bender, just aren’t inline with reality. These usually aren’t fundamental things (although my recent dive into corporal discipline of children was something of an eye opener) but more and more I find myself astonished at just how wrong my intuition can be. The most recent example is the simple petrol pump and the mechanism that stops the flow when your tank is almost full.

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So in my engineer brain I figured that there was some kind of sensor embedded in the end of the nozzle and, upon fuel reaching the outside of the nozzle the pump would be alerted, stopping the flow. Of course I often wondered how they managed to detect fuel on the outside of the nozzle whilst ignoring the inside but I figured that there were people much smarter than me working on that problem and it was a simple matter of engineering. Of course I was right about the latter but I never expected a fully mechanical solution to it, especially one not as elegant as they show in the video.

It really is true what they say about what happens when you assume something ;)

Box: Blending the Best of Robotics, Projection Mapping and Performance.

This requires no introduction, just watch:

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As a performance this is pretty amazing as the extensive use of optical illusions to generate a feeling of depth where there is none surpasses anything that I’ve seen before. It gets even more impressive when you find out that all of it was done in camera, I.E. none of the effects you see on there have been edited in. Initially I was a little sceptical of that, I mean this kind of stuff is child’s play to anyone with Blender and some 3D tracking software, but once I saw the robotic arms in the background I immediately understood how everything fit together and it’s incredibly impressive.

There’s 2 key components at work here the first of which is the IRIS robotic arm from Bot and Dolly. They’re essentially scaled down industrial robots with several pivot points allowing them to move freely in 3D space. These are what are holding the two white panels where most of the magic happens and you can see that they’re quite agile even with their considerable bulk. The magic here is though that the camera is also held on one of them which is what allows the next piece of technology to really shine.

As you can probably guess there’s 2 projectors (at least, there could be more) which are responsible for all the visual imagery you see: one behind the camera and one pointing down onto the floor. Now what makes all of these crazy images possible is the fact that the IRIS arms can report their exact location in three dimensions, allowing the projectors to then display images with the required perspective to generate the illusions. It’s similar to the WiiMote head tracking application that came out a while back as the demo makes use of the same principles to generate the illusion of depth.

Another cool application of robots like this is introducing motion into high speed camera shots. Traditionally high speed video usually remains static as moving the camera fast enough to get any kind of good perspective in them is nigh on impossible. This demo reel from THE MARMALADE shows a very similar kind of robot that they use to do high speed video that has significant amounts of motion in it. The result is so foreign that it feels like it’s in the bottom of the uncanny valley for me but it’s still very impressive.

Soundwaves and Synched Video.

With CGI being par for the course these days any you can’t be blamed for thinking that anything you see is fake. I think that’s why effects that are achieved without the use of computer trickery are so impressive, much in the same way as games that forego modern graphics but still manage to create an intriguing experience. Probably one of the coolest effects I’ve seen recently is the use of sound waves that are at a very similar frequency to the frame rate of the camera being used which ends up producing some pretty weird and wonderful effects.

Below is the latest one I’ve come across, and it’s pretty awesome:

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As the video alludes to the effect would appear to stem from the rolling shutter that CMOS based cameras use to create images. What’s happening is when the image is read off the sensor its done line by line and then reconstructed into a full image. However because of the way the sensor is read this allows the image to change during exposure which gives rise to all sorts of weird and wonderful effects. In this particular video it has the effect of making the speaker cone appear to have a wave travelling through it, rather than it slowly moving in and out like the creator expected. This has since been confirmed in other videos as rotating the camera shows the effect tracking the camera’s point of view.

Other interesting effects you can get is “freezing” the motion of water using a similar technique. If you fool around with frequencies slightly you can also get all sorts of other weird behaviour like water appearing to defy gravity. These are all based on sound waves however but anything that has a periodicity to it will allow you to make some really cool effects with cameras that use a rolling shutter.

The Subtle Effects of Different Lighting on a Subject’s Face.

As most readers are aware I’m an incredibly amateur photographer having dabble in it on and off again for the past 5 years but only really started taking it seriously towards the end of last year. I’m still very much in the early stages of my understanding as whilst I can produce some pictures that I (and others) like my hit rate still feels incredibly low, especially when I set out to create a very specific image. A lot of that is comes from my still nascent understanding of how to light subjects properly and how the direction/intensity changes the resulting image.

Now whilst the following video isn’t exactly the greatest introduction on how you should go about lighting your subject (in this a model’s face) it does showcase just how dramatically you can change the resulting image simply by moving the light source:

Showing this to my wife she was adamant that they were splicing video together with different models as the changes are quite dramatic. It is the same person however as if you look at the eyes you can see the light source rotating at a rather impressive clip which is what gives rise to the dramatic changes in shadows. Pausing at different sections also makes it quite clear what the impacts of the direction of light are and how they are reflected in the final image.

I wonder what the effect would be if instead of moving the light they used multiple sources then just cycled through them. Hmmmmm…….