3d printing

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Let’s get visual. Last in the series, for now.

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Next in the continuing series. In this episode Jaimie finds that the world is an illusion and she’s a butterfly’s dream, while Wilson works out his plumbing problems.

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Andrew Glassner and I are running a fun little workshop called “Freezing Time” this Sunday, as part of Making @ SIGGRAPH. Details: 12:15-1:45 PM, South Hall G – Studio Workstation Area

We’ll be teaching how to use T2Z, “Time To Z”, a program that lets you generate a 2D animation and then turn it into a 3D printable sculpture. Participants will be provided workstations, and there will be high-speed 3D printers available after the workshop. Can’t make it? Read on… Can make it? Get the code now and have fun on the plane ride to Los Angeles.

T2Z takes the frames of your animation and stacks them to form a 3D sculpture. This three.js program shows the transition for a number of animations – use the mouse to change the camera’s view. It’ll also get your cooling fan cranking, if your GPU is like mine. Turning “cycles” down to 1 keeps it sane.

Here’s a simple example. This animation:

squib animation

gives this sculpture when you stack the frames:

squib sculpture

The (self-imposed) challenge is to create an interesting, looping animation that also creates a visually-pleasing and printable sculpture. This example is pretty good, though the animation doesn’t quite perfectly loop. It would be easy enough to make it loop, but then we lose the base it can sit on. Tricky! If you want to hack on this code, it’s the Wobbly animation in T2Z.

There are many more examples in our gallery. I’ve been playing with the idea of data translation in general; you’ll see some experiments there. It’s been a great excuse for me to learn to use various tools at the local makerspace, Artisan’s Asylum, though I’ve not worked up the courage to actually use the plasma cutter yet. There are also plenty of fun & free tools for data manipulation, such as 123D Make, third-generation Photosynth, Sketchfab, 123D Catch, and on and on.

Even if you can’t attend the workshop, you can easily do this sort of experimentation at home. The T2Z code is free and open source, and well-documented. Companies such as Shapeways give you the ability to print high-quality models. We have lots of little animations in Animations.pde – go mess with them! There are also super-hacky “animations” at the end of this file: AnimatedGifReader turns a GIF into an STL 3D print file, FolderOfFramesReader does the same for a set of PNGs, and HeightField takes a grayscale image and uses the gray as a measure of height, e.g.

Skull3dRelief

skull_relief

Processing is entirely fun to hack on (Debugger? We don’t need no stinkin’ debugger, println() is our only friend). It’s Java plus stuff to make graphics easy. I like the fact that to run the program you are faced with the code – the system invites you to start poking at the program from the outset. Andrew wrote most of the code, being a Processing pro (he wrote a book and teaches a course in it; the first half of his course is free). Me, I translated the Marching Cubes code to Processing: each pixel of each image is treated as a voxel, the 3D model is from the isosurface formed between the objects and the background.

We hope to see you on Sunday! Or better yet, online, where we hope to see you sending us animations for the gallery and pull requests for code you’ve added.

 

Where did all this come from? Last year around May Andrew started making a series of looping GIFs using Processing, taking after the Bees & Bombs Tumblr feed. His goal was to make animations worth posting. These can now be found on Andrew’s Tumblr feed. Steve Drucker and I were the critics, over more than half a year.

During this time I was attending and organizing 3D printer meetups in the Boston area. Mark Stock pointed out a fascinating way of modeling: instead of explicitly using union operations on 3D models, the traditional CAD approach, he instead deposited objects into a large voxel grid. It’s much simpler and faster to figure out if a voxel is inside some given primitive vs. performing a union or other constructive solid geometry operation on a set of models. For example, computing the union of thousands upon thousands of spheres will bring most CAD modelers to their knees. Voxel in/out functions are trivial to compute for spheres, and Marching Cubes then guarantees a watertight, well-formed model with no geometric singularities, precision problems, etc. 3D printers themselves have limits to precision, so using voxels is a good match. Here’s an example of Mark’s work:

Dendrite by Mark Stock

So, for me, these two things combined: animations could be used to define voxels, and Marching Cubes used to generate 3D representations. I made an exceedingly slow GIF to STL converter in Perl and ran a bunch of Andrew’s GIFs through it. A few interesting forms turned up and that got me started on playing with what I call “323,” converting from some three-dimensional form of data (an animation being 2D plus time) to another (a sculpture).

Seeing the call for Making @ SIGGRAPH, we decided to go further and give a workshop on the process. The T2Z program that resulted is massively faster than my original Perl program, generating sculptures in a few seconds. It’s also much more usable, allowing you to make your own animations, hook up sliders to variables, and easily export them as GIFs, a set of PNGs, or a 3D STL model. Programming all this sucked up way more time than expected, and of course was highly addictive. Andrew made this Processing program do things that Nature did not intend (e.g., binary STL output and multi-window UI).

Personally, I find this whole design process entertaining. In idle moments (or at the dentist) I imagine what might make both an interesting animation and a worthwhile sculpture. It’s a fun way to think about modeling and animation, and one where my intuition doesn’t always pay off. The more I play, the more I learn.

Here’s a screenshot, to whet your appetite – click it for the full-size readable version:

screenshot

So download the thing, install Processing and three little libraries (easy!), and start sliding sliders, pushing buttons, and hacking code! And let us know what you find.

BTW, if you want just one link to bookmark, it’s this: http://bit.ly/t2zspot

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Here we go:

  • Beautiful demo of various effects, the realtime hybrid raytracing demo RIGID GEMS. Do note there are controls. The foreground blurs for the depth-of-field are a little unconvincing, but the rest is lovely! (thanks to Steve Worley for the tip)
  • Books to check out at SIGGRAPH, or now (I’m sure there are more – let me know):  OpenGL Insights and Shadow Algorithms Data Miner. Five chapters of OpenGL Insights are free to read here. There are quite a few graphics books published since last SIGGRAPH, we have them listed here.
  • Scalable Ambient Obscurance looks worthwhile, and there’s even a demo and source.
  • I can’t say I grok it all yet, but Bringing AAA Graphics to Mobile Platforms (from GDC) has a lot of chewy information on what’s fast and slow on typical mobile hardware, as well as how it works. PDF version on the Unreal Engine site.
  • A somewhat older (a whole year or so old) article on changing resolution on the fly to maintain frame rate. (Thanks, Mauricio)
  • 3D printing opens up a wide range of legal issues, It Will Be Awesome if They Don’t Screw it Up gives an overview of some of these. There are a number of areas where the law hasn’t had to concern itself yet.
  • Echo chamber: stuff you should probably know about already, but just in case. 1) Ouya, a monster money-raiser Kickstarter project for an open console. Tim Lottes comments; my take is “Android games on a console? Weak.” but I’d love to see them succeed. 2) Source Filmmaker, a free film making system from Valve. People are getting busy with it.

To conclude, a photo that looks like a rendering bug; read about it here. If you like these sorts of things, see more at the “2 True 2B Good” collection.

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Bloxing Day

My crazy-person project for the month is done. It’s a little program called Mineways, which is a bridge between Minecraft and Shapeways, the 3D printing service. You can grab a chunk of a Minecraft world for rendering or 3D printing. See the Mineways Flickr group for some results.

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Shapeways has an amusing concept: take two headshot photos – front and side – and in a few minutes you can make a 3D version that can then be sent to a 3D printer there. The cost in the video was less than $25, plus shipping etc.

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7 things, with images for each as some quick eye candy – is it worth my adding these images?

  • Here’s a nice rundown of much of the graphical goodness (and badness, e.g. temporal antialiasing) of the Halo: Reach beta. It’s worth a skim just to get a sense of the state of the art in a wide range of areas. The motion blur video appears to not be available currently. (thanks, Mauricio)
  • Unlimited Detail Technology is a voxel-based renderer with an interesting history: it was developed by a self-taught hobbyist who once ran a supermarket chain. There’s been interest in voxels for awhile, e.g. Jon Olick’s SIGGRAPH presentation in 2008 (slides here). Voxel rendering reminds me of the CPU-side heightfield renderer used in Novalogic’s Comanche and Delta Force game series from 1992 on. Novalogic’s was a 2.5 D system using contour following, while the Unlimited Detail system is full 3D voxels. Looking at UD’s presentations, it seems like a form of 3D clipmapping, where the level of detail of the voxels needed are determined by distance. The look reminds me of dribble sand castles. The coolest part: no GPU needed, it’s all CPU. I can imagine 18 limitations to this system: animation/deformation, sharp-edges not possible, shading models have limitations, transparency doesn’t work, textures are difficult to apply, fuzzy objects can’t be rendered, etc. Still, fun to see and a fascinating option. (another thanks, Mauricio)
  • The Ruin Island demo was created by some students in France. Parallax occlusion mapping, depth of field, NPR toon rendering, motion blur, glow and bloom, and more – it’s a grab-bag of effects in OpenGL. What’s nice is that the source code is provided. (Geeks3D)
  • Norbert Nopper has a small set of standalone OpenGL 3.2 and GLSL 1.5 tutorial programs with code for various effects. (Morgan McGuire)
  • The demoscene demo agenda circling forth uses particle clouds for a beautiful look. Note that the links for the video and demo are just under the image at the top of the page.
  • The photorealistic Octane Renderer uses CUDA for acceleration. To try it out you’ll need a fairly up-to-date NVIDIA driver, the demosuite, and the executable. It’s actually pretty cool to see the frameless rendering in action, it’s quite interactive for their simple scenes. There’s golden thread rendering: the longer you sit, the better the image gets. (Geeks3D)
  • 3D printing with ice. (BoingBoing)

Halo: Reach motion blur:

Unlimited Detail voxel image:

Ruin Island demo:

OpenGL 3.2 Nopper demo image:

agenda circling forth:

Octane Rendering, after 2 merged frames (interactive update) and after 5685 frames (a few minutes):

3D ice printing:

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Clearing the Queue

I’ve have a goal this week (it should be clear by now) of clearing my queue of stored-up RTR links by my birthday, today! (Hint: I want a pony.) So excuse the excessively-long list o’ links. Next task on my list, update the main RTR page itself.

  • StructureSynth. This looks pretty cool, and I love procedural models (my ancient SPD package was all about this, back in the days when downloading models was oppressively slow). I do wish they just provided an executable – building looks like a pain.
  • That previous link was on Meshula.net, which also blogs about Pixel Bender Fractals. Great stuff, sort of steampunk computer graphics: you must click this link, if no other on this page, and look on in awe.
  • Shapeways has a blog, and it’s not just dull company announcements. I’m glad they find people as pixels as interesting as I do. They also cover exporting Spore characters to Collada files (which is a great addition to Spore) and creating physical models from these.
  • In related news, The Economist has a reasonable summary of some trends in 3D printing. Their Technology Quarterly also has articles on Augmented Reality, 3D displays, and CAPTCHAs, among other topics.
  • This is one more reason the Internet is great: an in-depth article on normal compression techniques, weighing the pros and cons of each. This sort of article would probably not see the light of day in traditional publications, even Game Developer – too long for them, but all the info presented here is worthwhile for a developer making this decision. Aras’ blog has other nice bits such as packing a float into RGBA and SSAO blurring.
  • I need to add a link to the article itself to the object intersection page, but Morgan McGuire recently verified that he found this ray/box algorithm super-fast in SIMD. Code’s downloadable from that page, free version of article is downloadable here. Morgan uses this test in the ray tracer for his cool photon mapping paper at HPG 2009; if nothing else, you should at least see the video.
  • In related news, I am happy to see that AK Peters is beginning to put past journal of graphics tools articles online. At $15 each, the price of an article is quite high for individuals (or at least this individual), but current journal of graphics (gpu, & game) tools subscribers have full access to this archive for free. The mechanism to get access is a little clunky right now: if you’re a subscriber, you need to register with Metapress, then tell AK Peters your userid and they’ll provide you access.
  • Related to this, I hope Google Books conquers the world (or anyone else doing similar work, as long as it isn’t Apple or Amazon or other overcharging closed-box “we’re just protecting the authors, who get 10% or less for a purely digital sale with nil physical cost to us per unit” retailers – rant over, and I do understand there are fixed start-up costs for the retailer/publisher/etc., but really…). Google Books is so darn handy to look for short articles in books at Google’s repository, such as this one giving a clean way to build an orthonormal basis given a vector, from Graphics Tools: The JGT Editors’ Choice.
  • Humus provides a whole slew of new cubemaps he captured, if you’re getting tired of Grace Cathedral.
  • CUDA itself (vs. others) may or may not be a critical technology, but what it shows about the underlying GPU architecture is fascinating.
  • It should be mentioned: August 2009 DirectX SDK is available. Includes the first official release of DirectX 11.
  • This is hilarious, and possibly even useful!
  • I love seeing things like this: build your own multitouch display. Not that I’ll ever do it, but I hope others will.
  • You might be sick of Larrabee news (ship one, already!), but I found Phil Taylor’s article pleasantly hype-free and informative.
  • ATI’s Eyefinity (cute marketing name, I must admit – now I want to use the word everywhere) seems to me to solve a problem that rarely occurs: too much GPU for too few screens. Still, it’s nice to have the option. Eyefinity allows up to six monitors to be driven by a single GPU. I guess Eyefinity is useful when running older flight simulator programs on newer GPUs; otherwise, Eyefinity is pretty irrelevant. Eyefinity, eyefinity, eyefinity. At work I find two displays is plenty, one to run, one to debug. Anyway, the sweet spot for the monitor:GPU ratio is 13:1, as can be seen here:
    Flight Simulator - living the dream
  • There’s an article on instancing animated grass using DX10 on Gamasutra.
  • Humus’ summary of z interpolation is a good summary of the topic. He gives some of the key tricks, e.g., if you’re using floating point, use a near=1.0 and far=0.0 to help preserve precision.
  • Here’s a basic tutorial on different projection methods used in videogames, with lots of visual examples (add “Zaxxon” and it’s complete, for me). The one new tidbit I learnt from it was about reverse perspective, an effect I’ve made myself once every now and then when I screw up a projection matrix.
  • While I’ve been on break (one of the reasons I’ve been posting so much – Autodesk gives wonderful 6 week “sabbaticals”, aka “long vacations”, to U.S. employees every four years you’re there; it’s like being French or Swedish every fourth year), the rest of the company’s been busy: this new sketch application for the iPhone looks pretty cool, at the usual $2.99 “cup of coffee” type price.
  • Caustics can be dangerous. I can attest to this myself; a goofy award Andrew Glassner gave me long ago sat on my windowsill for years (I moved once, as you should discern from the picture), until I noticed what was happening to the base:
    caustics
  • I usually don’t have time to keep up with Slashdot, but SeenOnSlash, the funny bits of SlashDot, is sometimes entertaining. Graphics-related example: AMD’s latest chip.

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