No Plans For The Weekend? Learn Raytracing!

Weekends can be busy for a lot of us, but sometimes you have one gloriously free and full of possibilities. If that’s you, you might consider taking a gander at [Peter Shirley]’s e-book “Learning Raytracing in One Weekend”.

This gradient is the first image that the book talks you through producing. It ends with the spheres.

This is very much a zero-to-hero kind of class: it starts out defining the PPM image format, which is easy to create and manipulate using nearly any language. The book uses C++, but as [Peter] points out in the introduction, you don’t have to follow along in that language; there won’t be anything unique to C++ you couldn’t implement in your language of choice.

There are many types of ray tracers. Technically, what you should end up with after the weekend ends is a path tracer. You won’t be replacing the Blender Cycles renderer with your weekend’s work, but you get some nice images and a place to build from. [Peter] manages to cram a lot of topics into a weekend, including diffuse materials, metals, dialectrics, diffraction, and camera classes with simple lens effects.

If you find yourself with slightly more time, [Peter] has you covered. He’s also released books on “Raytracing: The Next Week.” If you have a lot more time, then check out his third book, “Raytracing: The Rest of Your Life.”

This weekend e-book shows that ray-tracing doesn’t have to be the darkest of occult sciences; it doesn’t need oodles of hardware, either. Even an Arduino can do it..

Got Fireflies? Try Talking To Them With A Green LED

[ChrisMentrek] shares a design for a simple green LED signal light intended for experiments in “talking” to fireflies. The device uses simple components like PVC piping and connectors to make something that resembles a signal flashlight with a momentary switch — a device simple enough to make in time for a little weekend experimenting.

Observe and repeat flashing patterns, and see if any fireflies get curious enough to investigate.

Did you know that fireflies, a type of beetle whose lower abdomen can light up thanks to a chemical reaction, flash in patterns? Many creatures, fireflies included, are quite curious under the right circumstances. The idea is to observe some fireflies and attempt to flash the same patterns (or different ones!) with a green LED to see if any come and investigate.

[ChrisMentrek] recommends using a green LED that outputs 565 nm, because that is very close to the colors emitted by most fireflies in North America. There’s also a handy link about firefly flashing patterns from the Massachusetts Audubon society’s Firefly Watch program, which is a great resource for budding scientists.

If staying up and learning more about nocturnal nightlife is your thing, then in between trying to talk to fireflies we recommend listening for bats as another fun activity, although it requires a bit more than just a green LED. Intrigued? Good news, because we can tell you all about the different kinds of bat detectors and what you can expect from them.

Adorable Desktop Disc Sander Warms Our Hearts And Our Parts

Casually browsing YouTube for “shop improvements” yields a veritable river of project ideas, objects for cat amusement, and 12 INCREDIBLE SHOP HACKS YOU WON’T BELIEVE, though some of these are of predictably dubious value. So you might imagine that when we found [Henrique]’s adorable disc sander we dismissed it out of hand, how useful could such a tiny tool be? But then we remembered the jumbo tub o’ motors on the shelf and reconsidered, maybe a palm sized sander has a place in the tiny shop.

Electrically the build is a simple as can be. It’s just a brushed DC motor plugged into a wall wart with a barrel jack and a toggle switch. But what else does it need? This isn’t a precision machine tool, so applying the “make it out of whatever scrap” mindset seems like a much better fit than figuring out PWM control with a MOSFET and a microcontroller.

There are a couple of neat tricks in the build here. The most obvious is the classic laser-cut living hinge that we love so much. [Henrique] mentions that he buys MDF in 3 mm sheets for easy storage, so each section of the frame is built from layers that he laminates with glue himself. This trades precision and adds steps, but also give him a little flexibility. It’s certainly easier to add layers of thin stock together than it would be to carve out thicker pieces. Using the laser to precisely cut holes which are then match drilled through into the rest of the frame is a nice build acceleration too. The only improvement we can imagine would be using a shaft with a small finger chuck (like a Dremel) so it could use standard rotary tool bits to avoid making sanding disks by hand.

What could a tool like this be used for? There are lots of parts with small enough features to be cleaned up by such a small tool. Perhaps those nasty burrs after cutting off a bolt? Or trimming down mousebites on the edges of PCBs? (Though make sure to use proper respiration for cutting fiberglass!)

If you want to make one of these tools for your own desk, the files are here on Thingiverse. And check out the video overview after the break.

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