Left: kids stomping spiders projected on a driveway. Right: the setup.

Make This Halloween A Spider-Stomping Good Time

September 30, 2021 by Kristina Panos 11 Comments

We can count on one hand the number of times that we haven’t needed a coat on Halloween night around here. Even if it was fair and sunny the day before, you can count on Halloween being appropriately windy, cold, and spooky. Trick-or-treating only keeps a kid so warm, and we would have loved to happen upon a house with a spider-stomping sugar-burning good time of a game going on in the driveway.

[Kyle Maas] built this game a few years ago, and it has proved quite popular ever since. It’s so popular, in fact, that they have to have someone on duty with a vaudeville hook to yank spectators off the playing field. The point is to stomp as many spiders as you can in a set amount of time, though you only need to stomp one to win. It can handle one to four players, depending on the size of the projection, but [Kyle] says it’s kind of hard to track more than two at a time.

The setup is fairly simple, provided you can reliably affix your projector to something sturdy. [Kyle] used a Structure sensor for the 3D scanner, but you could easily use a Kinect instead. Conversely, the calibration was challenging. [Kyle] ended up using a DSP math trick known as the inverse bilinear transform to be able to calibrate the system using the 3D scanner itself.

If you’re more into scaring the children, just rig up a coffin bell. Either way, don’t forget about our Halloween Hackfest contest, running now through Monday, October 11th. There are more details over on IO. While you’re there, why not check out the list of entries?

Up Close And Personal With An Unusual 3D Printer Kit

September 21, 2021 by Tom Nardi 28 Comments

While there are still plenty of folks out there tinkering with custom 3D printers, it’s safe to say that most people these days are using a commercially-available machine. The prices are just so low now, even on the resin printers, that unless you have some application that requires exacting specifications, it just doesn’t make a whole lot of sense to fiddle around with a homebrew machine.

As it so happens, [Nicolas Tranchant] actually does have such an application. He needs ultra-high resolution 3D prints for his jewelry company, but even expensive printers designed for doing dental work weren’t giving him the results he was looking for. Rather than spend five-figures on a machine that may or may not get the job done, he decided to check out what was available in kit form. That’s when he found the work of [Frédéric Lautré].

He purchased the unique “Top-Down” SLA kit from him back in 2017, and now after four years of working with the machine, [Nicolas] decided he would share his experiences with the rest of the class. The basic idea with this printer is that the light source is above the resin vat, rather than below. So instead of the print bed being pulled farther away from the resin on each new layer, it actually sinks deeper into it.

Compared to the “Bottom-Up” style of resin printers that are more common for hobbyists, this approach does away with the need for a non-stick layer of film at the bottom of the tank. Printing is therefore made faster and more reliable, as the part doesn’t need to be peeled off the film for each new layer.

[Nicolas] goes into quite a bit of detail about building and using the $700 USD kit, including the occasional modifications he made. It sounds like the kit later went through a few revisions, but the core concepts are largely the same. It’s worth noting that the kit did not come with the actual projector though, so in his case the total cost was closer to $1,400. We were also surprised to see that [Frédéric] apparently developed the software for this printer himself, so the tips on how to wrangle its unfamiliar interface for slicing and support generation may be particularly helpful.

Unfortunately, it sounds like [Frédéric] has dropped off the radar. The website for the kit is gone, and [Nicolas] has been unable to get in touch with him. Which is a shame, as this looks to be a fascinating project. Perhaps the Hackaday community can help track down this mysterious SLA maestro?

Running Six VGA Projectors From A Single ESP32

August 18, 2021 by Lewin Day 6 Comments

Today’s microcontrollers are high-speed powerhouses that can do absolutely wonderous things. By virtue of fast clock speeds and special DMA hardware, it’s often possible to achieve great feats that seem almost ridiculous at face value. [Bitluni] decided to demonstrate just that, running six (6!) VGA displays from a single ESP32. (Video, embedded below.)

The ESP32 clocks in at 240 MHz at top speed. It also features some nifty DMA hardware along with GPIO mapping that makes it perfectly suited to this task. [Bitluni] was thus able to set it up to drive up to six VGA displays at one bit per pixel monochrome output. Alternatively, ganging up six output pins into two sets of three, he was able to run two VGA displays with 3-bit color. The resolution is an impressive 640 x 400 in both cases, and [Bitluni] demonstrated the hardware by driving six projectors with a starfield display.

Is it useful? Perhaps not yet, but there’s certainly a few applications we could think of. Share your own ideas in the comments. In the meantime, check out [Bitluni]’s other great works for the ESP32.

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Finding Fractals In The 1930’s

July 17, 2021 by Matthew Carlson 22 Comments

The mesmerizing properties of fractals are surprising as their visual complexity often arises from simple equations. [CodeParade] set out to show how simple a fractal is by creating them using technology from the 1930s. The basic idea is based on projectors and cameras, which were both readily available and widely used in television (CRT projectors were in theaters by 1938, though they weren’t in color until the 1950s).

By projecting two overlapping images on the wall, pointing a camera at the resulting image, and then feeding it back into the projectors, you get some beautiful fractals. [CodeParade] doesn’t have a projector, much less two. So he did what any hacker might do and came up with a clever workaround. He made a simple app that “projects” onto his monitor and all he has to do is point an external webcam at the screen. The resulting analog fractals are quite beautiful and tactile. Rather than tweaking a variable and recompiling, you simply just add a finger or move the camera to introduce new noise that quickly becomes signal.

Better yet, there’s a web version that you can play around with right now. For more fractals implemented in hardware rather than software, there’s this FPGA with a VHDL Mandelbrot set we covered.

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Collapsible Pattern Projector Is A Bright Idea

January 24, 2021 by Kristina Panos 13 Comments

It’s fantastic that we’re living in the age of downloadable PDF patterns, it really is. But printing out a bunch of sheets of paper and taping them together is a tedious and tiresome process that can introduce error right from the start. This goes for any type of pattern, from sewing to R/C planes.

[Quinn]’s quarantine project is designed to cover both of those and everything in between. It’s a pattern projector made from stuff already on hand — a couple of offset projectors to scavenge parts from, and a large, trapezoidal mylar mirror from an old rear projection TV. At maximum zoom it projects a 4′ x 3′ image onto the tabletop, which sounds perfect for a whole lot of sewing patterns. At minimum zoom, the projected image fits on a foam core board.

We love that this dreamy setup can be stowed away so easily on hooks in the ceiling. [Quinn] had to perform a few hacks to make it all work together, including fabricating a bracket and some adjustable ties to hold the mirror aloft at just the ~~right~~ correct angle.

Need something smaller? Check out this Pi-powered pocket projector. Want a cinema-quality setup? You just have to find the right auctions.

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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Be Anyone Or Anything With Facial Projection Mask

October 31, 2019 by Dan Maloney 18 Comments

In the market for a low-poly change to your look? Hate the idea of showing up for a costume party only to find out someone is wearing the same mask as you? Then this face changing front-projection mask may be just the thing for you.

To be honest, we’re not sure just how much [Sean Hodgins]’ latest project has to do with cosplay. He seems to be making a subtle commentary about dealing with life in the surveillance state, even though this is probably not a strategy for thwarting facial-recognition cameras. [Ed Note: Or maybe it’s just Halloween?]

The build consists of a Raspberry Pi and a pico projector of the kind we’ve seen before. These are mated together via a custom PCB and live inside a small enclosure that’s attached to the end of a longish boom. The boom attaches to the chin of 3D-printed mask, which in turn is connected to the suspension system of a welding helmet. Powered by a battery pack and controlled by a smartphone app, the projector throws whatever you want onto the mask – videos, effects, even images of other people. Even with some Photoshop tweaks to account for keystone distortion from the low angle of projection, there’s enough distortion that the effect is more artistic than masquerade. But honestly, having your face suddenly burst into flames is pretty cool. We just wonder what visibility is like for the wearer with a bright LED blasting into your eyes.

As a bonus, [Sean] has worked this build into a virtual treasure hunt. Check out 13thkey.com and see what you can make from the minimal clues there.

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