CGI Motion Capture With Only A Camera

Computer-generated imagery (CGI) has largely replaced physical models in major film productions these days, but the transition didn’t exactly happen overnight. For a time there was an effort to blend the physical and digital, which allowed animators on productions such as Jurassic Park to work with newer technology in a way they were familiar with. [Corridor Crew] took this concept a step further by manipulating digital models with nothing but a webcam.

Early in the production of CGI, animators found a purely digital workflow to be less intuitive than the use of physical elements such as puppets. Feeling the weight and touch of a miniature with joints and limbs made for a more natural animation, so they created the dinosaur input device to map movements of a physical model into a digital recreation.

Puppeteered humanoid input device for the film Species

Unfortunately for the future of dinosaurs made of motion sensors, none of these devices really caught on and the technology is essentially non-existent today. [Corridor Crew] decided to give the concept another chance with the application of newer motion capture research. Using just a camera and a small human miniature allowed for full animations to be made using one’s own hands. The motion capture plugin can be found here if you want to try it for yourself!

At the end of the day, the need for a stop motion intermediate was found to be unnecessary. That being said, there is some really cool tech discovered throughout its history. If you want to discover even more film tech, maybe try out an adventure making your own film camera!

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Process 4 Billion Pixels Per Second From 16 DIY Cameras For The Best V-Tubing Rig Ever

[Dennis] is on YouTube with his channel “Made By Dennis,” but for the record he is a maker, not a V-tuber. On the other hand, his latest project– creating a profesisonal-level tracking rig with DIY IR cameras and a whole lot of moxie–does mean he’s now equipped to make the move to the prestigious, high-status world of pretending to be an anime girl.

That is of course not why he did it. Like most projects around here, the motivation was more a case of “I wonder if I can…”– in this case [Dennis] wondered what it would take for him to pull off the same sort of optical motion capture, or MoCap, that is used in Hollywood studios. Optical mocap has the advantage of being very precise, able to track things at high speeds, and not being in any way limited to the human form like the slew of AI-assisted methods hitting the market right now. The disatvantage is that you need to place markers on any part of your subject you want tracked, film them from all angles, and process a whole lot of pixels. In [Dennis]’s case, it ended up being about four billion. Keeping in mind that actually locating those points in 3D space is dependent on knowing exactly where your cameras are: if you want sub-millimeter precision, your cameras need to be fixed with sub-millimeter tolerance. It’s a big project, hence a long video, which is embedded below.

The DIY cameras use a AR0234 MIPI camera on a custom PCB with M12 lenses and IR filters. To improve the signal-to-noise ratio on optical MoCap, it’s standard to use near-IR light. The camera boards, as you might expect given the MIPI interface, hook into Raspberry Pi compute modules– the cheapest CM4 should work, though he’s using CM5s. The compute modules sit on custom boards that provide PoE, and some other niceties– like a small microcontroller driven by the pulse-per-second pin to help trigger the cameras in sync.

Each camera gets a ring light of near-IR LEDs that pulse at 160 W, which would be way more than PoE is specced to provide, but since the LEDs are only on when the camera is taking a frame, the average power is well within allowable limits. With 16 cameras each having their own ring light, that’s a lot of near-IR photons. Don’t forget your safety squints!

Rather than process the images with OpenCV, he has his own custom solution optimized for this use-case that [Dennis] reports is 300x faster. Luckily, he’s put his implementation on GitHub, along with the rest of the project. Even if you don’t have any v-tubing ambitions, this project is very impressive and worth checking out in its entirety.

Optical MoCap isn’t the only game in town, of course. If you want to do this cheap and easy, you can strap a bunch of IMU sensors to yourself– just don’t expect the same precision.

Thanks to [Dennis] for the tip!

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Hackaday Links: January 29, 2023

We’ve been told for ages that “the robots are coming for our jobs!” It’s true that we’ve seen robots capable of everything from burger flipping to bricklaying being demonstrated, and that’s certainly alarming for anyone employed in such trades. But now it looks like AI has set its sights set on the white-collar world, with the announcement that ChatGPT has managed a passing grade on a Wharton MBA exam.

For those not in the know, the University of Pennsylvania’s Wharton School of Business is in the major league of business schools; earning a Master’s in Business Administration from that august institution is no mean feat, and is likely to put the budding executive on a ballistic career trajectory. So the fact that ChatGPT could pass the exam is significant. But before you worry about a world in which our best and brightest business leaders are replaced with soulless automatons, relax. The exam presented to ChatGPT was just a final exam for one course, Operations Management, so it’s not like it aced everything an MBA is expected to know, and it took a lot of hints from a human helper to get it that far. It’s also reported that it made a lot of simple math mistakes, too, so maybe a Wharton MBA isn’t that much of a big deal after all.

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Art With Technology Hack Chat

Join us on Wednesday, June 16 at noon Pacific for the Art with Technology Hack Chat with Cory Collins!

As hackers, we naturally see the beauty of technology. We often talk in terms of the aesthetics of a particular hack, or the elegance of one solution over another, and we can marvel at the craftsmanship involved in everything from a well-designed PCB to a particularly clever reverse-engineering effort. Actually using technology to create art is something that’s often harder for us to appreciate, though, and looking at technological art from the artist’s side can be pretty instructive.

Cory Collins is an animator and artist with a long history of not only putting tech to work to create art, but also using it as the subject of his pieces. Cory’s work has brought life to video games, movies, and TV shows for years; more recently, he has turned his animation skills to developing interactive educational material for medical training. He has worked in just about every physical and digital medium imaginable, and the characters and scenes he has created are sometimes whimsical, sometimes terrifying, but always engaging.

Cory will stop by the Hack Chat to talk about what he has learned about technology from the artist’s perspective. Join us as we dive into the creative process, look at how art influences technology and vice versa, and learn how artistic considerations can help us address the technical problems every project eventually faces.

join-hack-chatOur Hack Chats are live community events in the Hackaday.io Hack Chat group messaging. This week we’ll be sitting down on Wednesday, June 16 at 12:00 PM Pacific time. If time zones have you tied up, we have a handy time zone converter.

Click that speech bubble to the right, and you’ll be taken directly to the Hack Chat group on Hackaday.io. You don’t have to wait until Wednesday; join whenever you want and you can see what the community is talking about.

Building A Motion Capture Suit On The Cheap

Motion capture is a technology used in many films, particularly the animated variety. It makes giving characters realistic movements a cinch, as they’re all based on those of a real person. [Checkered Bug] worked with a middle school group who were looking to get started, so he whipped up a capable rig on a budget.

The rig is based around a chest unit that connects out to several satellite units placed at points on the body. Each unit contains a Bosch IMU which is used to measure the acceleration and rotation of the user’s various body parts. The data is fed back to an Arduino Mega, where it’s then passed to a PC running Blender. Motion sequences can be recorded live in Blender, or saved to an SD card and imported later. Files are available on Github for those keen to recreate the project.

It’s a tidy setup that does good motion capture on a low budget. Such a rig would have been inordinately expensive back in the day, but can now be whipped up for just a few hundred dollars. We’ve seen other motion capture systems before, too. Video after the break.

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Giant Bearing Is At The Heart Of A Camera Mount

We bet you have all some cool part in your bin that is just gnawing at you to build something cool. That doodad, possibly from a garage sale, surplus store, or clearance rack deserves a project fitting of its near-infinite potential. [isaac879] finally marries a giant ball bearing with his passion for photography in the form of a pan-tilt camera mount for his Canon DSLR. The problem with tossing your golden-ticket part into a project is that not everyone has a MacGuffin, or a brand new one might be bank-breakingly expensive, so he does us a favor and makes a drop-in replacement that you can print and fill with 6mm brass bbs. This sort of thing is why we love hackers.

The camera mount has the features we expect to see in a robust stepper mount, such as infinite spinning, time delay, and an Xbox controller interface. Inside the base is the industrial bearing or its plastic replica, and that wide base won’t be tipping over anytime soon. Gearing all around is of the herringbone style, of the type you find in classroom pencil sharpeners because they transfer power smoothly. Speaking of things going smoothly, we enjoyed his assembly montage where every part fits together perfectly and there is not a naughty word to be uttered. Just like real life.

If you like homemade bearings, check out this slew bearing that looks like it was made with Perler beads, and we have a self-aligning camera tripod mount for the photography buffs.

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Dyeing Fabric To Create Sensors

Fabrics with electrical functionality have been around for several years, but are very rarely used in mainstream clothing. The fabrics are very expensive and the supply can be unreliable. Frustrated by this, [Counter Chemists] developed PolySense, simple open-source technology to make any fibrous material into a conductive material that can be used to sense pressure, stretch, capacitive touch, humidity, or temperature.

PolySense uses a process called in-situ polymerization, effectively dying a fabric to become piezoelectric. This is done by first soaking the fabric in a mixture of water and the organic compound pyrrole, and then adding iron chloride to trigger a reaction. The polymerization process that takes place wraps the individual fibers of the fabric in conductive polymer chains.

Instead of just uniformly coating a fabric, various masking techniques can be used to dye patterns onto the fabric for various use cases. The video after the break shows a range of these applications, including using polymerized gloves and leggings for motion capture, a zipper that acts like a linear potentiometer, and touch-sensitive fabric. The project page lists sources for the required chemicals in both Europe and the US, and we look forward to seeing what other applications the community can come up with.

The project is very well documented, with a number of scientific papers covering all the details. [Counter Chemists] will also be presenting PolySense at the 2020 Virtual Maker Faire.

This technology can also be used to make a fabric piano with a lot less effort. On the more mechanical side of things, you can also 3D print on pre-stretched fabric to make it pop into 3D shapes.

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