Online Cortex » animation

Aaron Koblin’s Flight Patterns

drknuth — Sat, 07 Mar 2009 03:25:07 +0000

Aaron Koblin, an artist whose focus is to visualize human systems, has made some glorious animations of air traffic flight patterns over the continental United States.

Aaron Koblin states that:

Data from the U.S. Federal aviation administration processed to create animations of flight traffic patterns and density.

In addition to illustrations, you can watch an animation on his web site.
I highly recommend it as it is fascinating to watch how the flights in the air change throughout the day. You can see the red-eye flights leaving California around midnight and when they arrive in the early morning on the east coast, air traffic erupts in a fury of activity. It really is fascinating!

Aaron Koblin's Flight Path Illustration

Enjoy!
Kevin Knuth
Albany NY

Naughty Nestor

drknuth — Mon, 07 Apr 2008 08:05:15 +0000

Its fun to build with LEGOs, but Nestor has other plans…

http://naughtynestor.com

When You’re Holding the Moon for Ransom…

drknuth — Fri, 25 Jan 2008 05:53:29 +0000

When you’re holding the moon for ransom, you value stability in an application. Linux gives us the power we need to crush those who oppose us…

Check out the fun Flash cartoon here…

OK.
I admit it!
I want Steve’s cool Rocket Chair.

Kevin Knuth
Albany NY

Lego Central Drive Animation

drknuth — Mon, 23 Apr 2007 03:00:31 +0000

I am slowly constructing my first intelligent instrument. It will be an instrument that learns the acoustic radiation pattern emitted by a speaker. It is not a perfect acoustic experiment—nor is it meant to be. Uncertainties and errors abound, especially since I am using the Lego NXT Mindstorms system to construct the instrument.

The design is sufficiently complex that I found that I need to document it using the LDraw system, specifically MLCAD. I have been practicing my animation skills as well. Here you can see a short animation of the central drive shaft for the acoustic platform. The gears are turning at the appropriate rates and everything. However, there is an aliasing effect in this downsampled image (which used to be referred to as the wagon wheel effect). So it may look as if some gears are rotating backwards, or not at all. If you click on the image, you can download a 6 MB version that is much smoother.

The longer animation will appear in two talks I am giving at the University at Albany this week:
NTIR 2007 and PASCAL 2006.

Kevin Knuth
Albany NY

Lego Geneva Mechanism

drknuth — Sat, 14 Apr 2007 07:40:11 +0000

I recently designed a Geneva Mechanism that I will be using in my Lego Laser Scanner. The Geneva Mechanism takes smooth rotary motion and converts it to intermittent rotary motion. One can think of it in electronics terms as changing the duty cycle of the oscillation.

Geneva mechanisms were invented in Switzerland for use in clockwork so that the hands of a clock would snap rapidly to their new positions rather than move smoothly across the face of the clock. They are also used to advance film in film projectors. They are responsible for that clicking noise that film projectors make.

Above is an image of my design rendered using the Lego CAD LDraw tools that I discussed in earlier posts.

I have been practicing with animating Lego designs, and I have figured it out. Below is an animated GIF of my Geneva Mechanism. It is a pretty big file, so it may take some time to download. Notice that I cheated a little and included just enough frames to rotate the wheel 90 degrees, since it is mostly 4-fold symmetric (but not exactly).

The animation was challenging in that there are three moving parts: the rotating arm, the latch, and the wheel. I designed each of the pieces in MLCAD and made sure that they were positioned so that the origin of the three pieces was centered on the axis that I wished to rotate the image about. The rotating arm simply rotates a single rate described by 155-clock, where the clock is a variable in the ray-tracing program POV-Ray that I have set to cycle from 0 to 360. One can see that when clock equals zero, the arm starts at 155 degrees.

The arm is only able to rotate the wheel over a 50 degree range, while the wheel rotates a full 90 degrees. This lead to the following equation that I used the describe the motion of the wheel:

[tex]angle = 45+(clock-310)*9/5[/tex]

Note that the wheel starts turning when the rotating arm gets to 310 degrees, and moves almost twice as fast (9:5 ratio) so that it turns 90 degrees while the clock which controls the rotating arm counts only 50 degrees.

The latch was especially difficult as it is pushed outward by a cam, and I did not have the details of the shape of the Lego cam, nor did I have the patience to measure it myself. The latch arm moves slowly at first away from the wheel and then slows down as it approaches the limit of its motion. My first approximation was a cosine:

[tex] 5-25*cos((clock-237)/(305-237)*3.1415) [/tex]

Note that the latch does not start moving until the clock is at 237 degrees. At this point, the argument of the cosine is zero, and its value is 1 giving a angular position of -20 degrees. The cosine picks up speed and slows down again as it approaches 30 degress. Once the cam is out of the way, a rubber band (not shown in the illustration) rapidly snaps the latch back into place. To describe this, I merely treated its motion as an acceration:

[tex]-50*((clock-305)/55)*((clock-305)/55))+30[/tex], where I have implemented the square by multiplying twice. The result is a more realistic motion.

Enjoy,
Kevin Knuth
Albany NY