Day: April 12, 2023

Signed Distance Functions: Modeling In Math

April 12, 2023 by 13 Comments

What if instead of defining a mesh as a series of vertices and edges in a 3D space, you could describe it as a single function? The easiest function would return the signed distance to the closest point (negative meaning you were inside the object). That’s precisely what a signed distance function (SDF) is. A signed distance field (also SDF) is just a voxel grid where the SDF is sampled at each point on the grid. First, we’ll discuss SDFs in 2D and then jump to 3D.

SDFs in 2D

A signed distance function in 2D is more straightforward to reason about so we’ll cover it first. Additionally, it is helpful for font rendering in specific scenarios. [Vassilis] of [Render Diagrams] has a beautiful demo on two-dimensional SDFs that covers the basics. The naive technique for rendering is to create a grid and calculate the distance at each point in the grid. If the distance is greater than the size of the grid cell, the pixel is not colored in. Negative values mean the pixel is colored in as the center of the pixel is inside the shape. By increasing the size of the grid, you can get better approximations of the actual shape of the SDF. So, why use this over a more traditional vector approach? The advantage is that the shape is represented by a single formula calculated at many points. Most modern computers are extraordinarily good at calculating the same thing thousands of times with slightly different parameters, often using the GPU. GLyphy is an SDF-based text renderer that uses OpenGL ES2 as a shader, as discussed at Linux conf in 2014. Freetype even merged an SDF renderer written by [Anuj Verma] back in 2020. Continue reading “Signed Distance Functions: Modeling In Math” →

The Challenges Of Producing Graphene In Quantity

April 12, 2023 by 26 Comments

We’ve all heard the incredible claims made about graphene and its many promising applications, but so far the wonder-material has been held back by the difficulty of producing it in large quantities. Although small-scale production was demonstrated many years ago using basic Scotch tape, producing grams or even kilograms of it in a scalable industrial process seemed like a pipedream — until recently. As [Tech Ingredients] demonstrates in a new video, the technique of flash Joule heating of carbon may enable industrial graphene production.

The production of this flash graphene (FG) was first demonstrated by Duy X. Luong and colleagues in a 2020 paper in Nature, which describes a fairly straightforward process. In the [Tech Ingredients] demonstration it becomes obvious how easy graphene manufacturing is using this method, requiring nothing more than carbon black as ingredient, along with a capacitor bank, vacuum chamber and a number of reasonably affordable items.

Perhaps best of all is that no refinement or other complicated processes are required to separate the produced graphene from the left-over carbon black and other non-graphene products. Using multiple of these carbon black-filled tubes in parallel, producing graphene could conceivably be scaled up to industrial levels. This would make producing a few kilograms of graphene significantly easier than coating hard drive platters with the substance.

Continue reading “The Challenges Of Producing Graphene In Quantity” →

A milled PCB next to a woman wearing a dress that includes it

Elegant Evening Dress Sports Servo-Actuated Flowers

April 12, 2023 by 13 Comments

There’s been plenty of research into “smart fabrics”, and we’ve seen several projects involving items of clothing with electronics integrated inside. These typically include sensors and simple actuators like LEDS, but there’s no reason you can’t integrate moving electromechanical systems as well. [Rehana Al-Soltane] did just that: she made an elegant evening dress with flowers that open and close on command.

It took [Rehana] a bit of experimentation to figure out a floral design that opens and closes smoothly without crumpling the fabric or requiring excessive force to actuate. She finally settled on a plastic sheet sandwiched between two layers of fabric, with pieces of fishing line attached that pull the edges inward. The lines are guided through a tube down the back of the dress, where a servo pulls or releases them.

The mechanical flower can be operated by touch — [Rehana] made one of the other flowers conductive by embedding copper tape between its petals and connected it to the capacitive touch sensor interface of an Atmel microcontroller. The micro is sitting on a custom PCB that’s worn on the hip, with wires going to the servo at the back. You can see how the system operates in the video embedded below.

The dress is [Rehana]’s final project for the famous “How To Make (almost) Anything” course at MIT, and required a wide variety of skills: the cable guide was 3D printed, the flower petals were laser cut, the PCB was milled, and the end product was sewn together. [Rehana] has a knack for making electronics-infused clothes and accessories, including the flexible PCB crown that she’s wearing in the image above. Continue reading “Elegant Evening Dress Sports Servo-Actuated Flowers” →