The Ghost Climber

An Instructables post by user PenfoldPant, a laser-guided "ghost climber," caught my attention today as a really cool project worth discussing.

Penfold explains that as an amateur rock climber, he frequently sees other climbers climb a route and wonders if he can do that route, too. However, he can't always remember the route the other person took when he tries to duplicate it. His solution is a laser pointer on a turret. Two stages are used: a recording stage, in which an operator keeps the laser pointer aimed at the climber as the climber climbs, and a playback stage, where the laser pointer replays the recording so a second climber can attempt to duplicate the route.

While I think the project is uber cool, it got me to thinking how I might solve this problem.

I see two main issues with the project. The first issue is that during the record phase, only one point on the climber's body is tracked. I'm not a climber, but I imagine that if I were trying to duplicate another climber's route I'd want to know which holds he used for each of his four limbs. (Can anyone correct me if I'm wrong?)

The second issue is a little bigger. During playback of the route, the laser pointer is projected in the same place it was during the record phase, which is on the climber's body, which means it can't be seen by the climber trying to duplicate the route!

That, my friends, is an engineering challenge! So.. how would I approach the problem? Well, I'd want to track 4 points on the climber during recording: each wrist/hand and each ankle/foot. Maybe use an IR LED fastened by velcro? A colored ball? I think the solution would involve some kind of image/video recognition which admittedly is not easy. As luck would have it, Zdenek Kalal recently released his "Predator" video object tracking software as open source software; that could certainly be part of a solution.

Once the route is recorded, motion analysis could find the holds the climber used by looking for places where the limb stops moving for, say, a second or so.

During playback, a second climber could wear the 'limb trackers' and  colored lights projected onto the wall could be used to indicate which limb goes where. The computer could even automatically determine when each limb is on the correct hold (because the second climber is also wearing the limb trackers) and automatically advance the indicator to the next hold for that limb for practice, or play back the recorded route at recording speed for competitions.

This system would solve the playback issue as well, since the projected target would be where the climber's limb should go and would probably not be occluded by the climber's body in most cases. (Of course, there will always be instances where the climber's body occludes the sensor/projector. Addressing that issue is an interesting thought experiment in itself.)

While it sounds like a fun project, it's probably not one that I'll ever have the time or inclination to address. It is a fun thought experiment, though.

How would you attack this project?

A Real DIY Electron Microscope

This story has been all over the web lately, and deservedly so. Ben Krasnow has built a scanning electron microscope, from scratch, in his garage!

This type of project is the essence of hacking and is the type of thinking and project building that I want to be doing and showcasing here on the hacker workshop.

Go view Ben's video. He does a great job explaining his invention. And did I mention he built an electron microscope from scratch, in his garage!

Amazing. Ben, my hat's off to you. I can't wait to see further refinements of his project.

Etch a PCB with Ingredients from your Kitchen

Steve Hobely was out of "Ferret Chloride" and "Bureaucratic Acid" and needed to etch a circuit board. What did he do? He grabbed some vinegar, some hydrogen peroxide, and some table salt and concocted a new etchant! He explains the recipe in this post, complete with a detailed description of the reaction by his Ph.D-in-Chemistry sister.

Other People’s Projects: Gameduino, Laser Cutter v2

My RSS feeds dumped two really intriguing products into my lap today: an Arduino-compatible shield that produces VGA output, and an open source laser cutter.

The Gameduino is a VGA output device that can be driven by a microcontroller. It outputs a 800x600 display in 512 colors. It's powered by an FPGA (I haven't yet been able to determine which one) and has a host of pretty cool features:

  • video output is 400x300 pixels in 512 colors
  • all color processed internally at 15-bit precision
  • compatible with any standard VGA monitor (800x600 @ 72Hz)
  • background graphics
    • 512x512 pixel character background
    • 256 characters, each with independent 4 color palette
    • pixel-smooth X-Y wraparound scroll
  • foreground graphics
    • each sprite is 16x16 pixels with per-pixel transparency
    • each sprite can use 256, 16 or 4 colors
    • four-way rotate and flip
    • 96 sprites per scan-line, 1536 texels per line
    • pixel-perfect sprite collision detection
  • audio output is a stereo 12-bit frequency synthesizer
  • 16 independent voices 10-4000 Hz
  • per-voice sine wave or white noise

Really cool. Graphics are sent to the Gameduino over a SPI bus. I was thinking of building something similar in the future for a project, but I wouldn't have included many of the features that this device has. The builder has some sample videos up that show the power of this little gem. It's really, really cool stuff! Definitely click on the sample images to see just how powerful this platform is.

The Gameduino is currently seeking funding on Kickstarter. I pleged $53 which should get me an assembled and tested unit from the first production run. Well worth it! (I'm obviously not the only one who thinks so. The Kickstarter project has a goal of $3,333 but has already raised over $10,000 in pledges with 27 days to go!)

The other project is Buildlog.net 2.x Laser laser cutter. This is a homemade laser cutter design shared under a Creative Commons license. I haven't looked at in detail yet but I suspect I'll be building one of these. Even if it costs as much as a commercial unit (~$2,000), it'll be worth the fun and the experience to build my own.