Computer Vision Maps Christmas Lights

November 3, 2020 by Bryan Cockfield 26 Comments

There’s a small but dedicated group of folks out there who spend all year planning their Christmas decorations. These aren’t simple lawn ornaments or displays, either, but have evolved into complex lightning performances that require quite a bit of computer control. For some things, hooking up a relay to a microcontroller can get the job done, but [Andy] has turned to computer vision to solve some of the more time-consuming aspects of these displays.

Specifically, [Andy] has a long string of programmable RGB LED lights to wrap around a Christmas tree, but didn’t want to spend time manually mapping out each light’s location. So he used OpenCV to register the locations of the LEDs from three different camera angles, and then used a Python script to calculate their position in the 3D space. This means that he will easily be able to take the LEDs down at the end of the holidays and string them back up next year without having to do the tedious manual mapping ever again.

While [Andy] notes that he may have spent more time writing the software to map out the LEDs than manually doing it himself, but year-after-year it may save him a lot of time and effort, not to mention the benefits of a challenge like writing this software in the first place. If you want to get started on your own display this year, all you really need is some lights and a MIDI controller.

Raspberry Raven Pi Security Camera Does Double Duty

November 3, 2020 by Kristina Panos 11 Comments

The worst thing about holiday decorations is that while you could leave them up all year, your neighbors probably won’t like you very much for it. Christmas lights on your house are one thing, but as far as Halloween decorations go, [MisterM]’s raven security camera is one of the few exceptions to this rule.

Nevermore will [MisterM] wonder who goes there. As soon as this raven lays its beady red LED eyes on whatever is lurking in the garden, it comes to life with a bit of head swiveling and some random sounds. The bird either goes CAW! or quotes Christopher Lee’s reading of Edgar Allen Poe’s “The Raven”.

Inside this bird’s chest cavity is a Raspberry Pi 2 and standard camera, a servo to swivel the head, and an audio amplifier and speaker. This bird is running MotionEye on top of the Raspi OS so it can run a script whenever it senses motion.

We like that [MisterM] was able to find right-sized bits of plastic to mount the servo in the neck and the horn to the head. It just goes to show that not everything needs a 3D printer, a CNC, or woodworking. Check out the scary demo after the break.

Want to scare the whole neighborhood? Check out the science behind good-looking house projections.

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Animated Pumpkins Sing And Scare On Halloween

October 30, 2020 by Lewin Day 5 Comments

The animated video combined with the 3D-printed prop makes for an excellent effect.

Carving Jack O’ Lanterns out of pumpkins is a favorite Hallowe’en tradition for many, but relying on candles and knives is decidedly low-tech. [Lewis] of [DIY Machines] decided to whip up something a little more animated to scare the local trick-or-treaters instead.

The build consists of 3D printed pumpkins, lit from behind with a low-cost projector. Driven by a Raspberry Pi, the projector plays video files that project animated faces onto the pumpkins. The effect is great, giving the illusion of a real anthropomorphic Jack O’ Lantern sitting on your very porch. To control the system, a series of arcade buttons are hooked up to the Raspberry Pi allowing visitors to activate a song, a scare, or a story.

It’s a fun build that is a great way to add some interactivity to your Hallowe’en decorations. If you want to take your work up a notch, consider projecting on to your whole house. Video after the break.

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Projecting Halloween Peril

October 28, 2020 by Matthew Carlson 3 Comments

Every holiday has a few, dedicated individuals committed to “going all out.” Whether they’re trying to show up the neighbors, love the look, or just want to put a smile on the faces of those passing by; the results are often spectacular. A recent trend in decorations has been away from analog lights and ornaments and towards digital light shows via a projector. [Georgia Clegg] and [Luma Bakery] have written up a fantastic guide detailing the involved process of house projection for those feeling the holiday spirit.

There is more to the effect than simply pointing a projector at a home and running a video clip. The good displays make use of the geometry of the home and the various depths of the walls don’t distort the picture. The house itself is mapped into the image being displayed.

There are generally two approaches to mapping: point of view mapping and neutral/orthographic mapping. The first is just setting the projector in a fixed position and designing the graphics in such a way that they will look correct. The downside is that if there are multiple projectors, each projector will need to be separately designed for and they cannot be moved or adjusted. The second maps the house in an actual 3d sense and figures out how to display the content according to the viewpoint that the projector is currently at. This means you can create one source content and simply export it for the various projectors.

As you can imagine, the second is much more involved and this is where [Georgia Clegg] has stepped in. There’s a whole series that covers creating your house in MeshRoom, cleaning it up in Blender, creating the videos in After Effects, and setting up your projector to keep it running through the season.

We’ve seen other amazing projector mapping displays with lasers here at Hackaday. Now you can make one yourself. Just don’t get bogged down refurbishing your vector projector along the way.
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Trick Or Yeet Cannon Will Give Them Candy Shell Shock

October 23, 2020 by Kristina Panos 11 Comments

One of our favorite things about Halloween is the sheer number of hacks that come out of it each year. This year, hacking is almost a requirement to keep things physically distanced, but that doesn’t mean we can’t have fun. You want fun? How about a candy cannon that launches sweet projectiles at trick-or-treaters from fifty feet?

[Paul McCabe]’s cannon uses a sprinkler valve and an air compressor to launch a pair of fun size candy bars, each encased in a film canister shell. Each trick-or-treater stomps a foot switch fifty feet away at the end of the driveway, and as long as someone is there holding down the primary ignition, the cannon will fire with a nice retort that sounds like a large wind instrument playing a D note.

We were sad to learn that the parachute idea didn’t shake out, but the glow sticks are a great addition for night time. Check out the demo after the break, which is followed by a build video and then some more launches for the fun of it. Don’t have enough time to build a cannon of this caliber? You could put a spooky six-foot slide together pretty quickly.

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Stomp Button, Receive Candy

October 19, 2020 by Kristina Panos 5 Comments

If there’s any holiday that is worth adjusting for strange times, it’s gotta be Halloween. Are you inclined to leave a bowl of candy on the porch to avoid the doorbell? If so, this is the perfect year to finally figure out some sort of metering apparatus so that greedy preteens are less likely to steal your stash in one sweep. There’s still time to make something fun like [Brankly]’s automatic candy dispenser, which we think ought to stick around for many years to come. Video is posted after the break.

Underneath that skeleton’s jack-o-lantern head is the heart of this build — an orange 5-gallon bucket that matches it perfectly. Simply step on the giant lighted arcade button, and the equally giant NEMA-23 stepper motor moves a 3D-printed turntable inside the bucket with the help of an Arduino Nano. This moves the candy toward the 3D-printed ramp and out the mouth of the jack-o-lantern, where it lands in a bowl that lights up when it hits the bottom thanks to a relay and a second Nano.

[Brankly] made clever use of IR break-beam switches, which sit underneath the two square holes in the ramp. Once candy passes over one of them, the turntable stops and rotates backward to move the candy where it can’t be reached.

Frankly, we love that [Brankly] reused the sound effects module that came with the jack-o-lantern. This build is totally open, and [Brankly] is even giving away 40 PCBs if you want to make your own. For now, you can check out the code and start printing the STLs.

If time is tight, build a spooky slide that puts six feet between you and the trick or treaters.

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Making A Halloween Costume Fit For 2020

October 6, 2020 by Matthew Carlson 13 Comments

All across the country, parents are wondering what to do about the upcoming Trick Or Treat season. Measures such as social distancing, contact free treats, or simply doing it at home are all being weighed as a balance of fun and safety. [BuildXYZ] has decided to lean into the challenges this year and incorporate a mask as part of the costume for his boys.

It started with a 3d printed mask, printed in two halves, and sealed with silicon caulk and N95 filter material in the inlet and outlet holes on the sides. The real magic of the mask is the small OLED screen mounted to the front that works along with a small electret microphone inside the mask. By sampling the microphone and applying a rolling average, the Arduino Nano determines if the mouth drawn on the display should be open or closed. A small battery pack on a belt clip (with a button to flash “Trick or Treat” on the screen) powers the whole setup and can be easily hidden under a cape or costume.

This isn’t the first hack we’ve seen for Halloween this year, such as this socially distant candy slide. We have a feeling that there will be many more as the month rolls on and people start to apply their ingenuity to the season.

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