All posts

It's common knowledge that MacBooks and iMacs can be controlled with any Apple remote. This feature is turned on by default, so unless people manually disable remotes, or pair a specific remote to their computer, they are easy victims for a simple prank. You can control the volume, start/pause songs in iTunes, advance and go back a song in the library, and, most annoyingly, enter FrontRow by pressing the appropriate button on the remote. Of course, it would be nice not to actually have to approach the "prankee" with a conspicuous Apple remote. It would be far nicer to have a microcontroller mimic the IR codes and control everything remotely...

Thanks to Kevin Ford and Janneke Hille Ris Lambers at UW I recently had the opportunity to get access to a very good-looking LIDAR data set for the area around Mount Rainier, WA. They obtained a high-resolution LIDAR map of Mt. Rainier National Park from the Puget Sound Lidar Consortium. Kevin and Janneke approached me to ask whether it's possible to create a 3D print of Mount Rainier and, naturally, I was extremely intrigued by this idea.

The data Kevin gave me covered a bit more than 30 by 30 km with circa 10 million elevation samples. This incredibly high resolution made the map look incredibly beautiful in GIS software, but it also presented a substantial problem for me. In order to create anything printable, I had to drastically down-sample the data points. Another problem was that the elevation data behaves like a 2D sheet floating in 3D space, but in order to print something on a 3D printer, I needed nodes that describe a closed 3D volume. The project therefore involved a fair bit of data manipulation, which I describe below.

Below is a PDF of my presentation and the code for a tutorial on making elaborate multi-axes movies with Matlab. The tutorial was part of the "hallway salon" series that has become a tradition in the Daniel Lab.

The code contained on this page contains a framework for saving movies from MATLAB that should be easily adaptable for your own work. I tried to add as many comments in the code, so it should be fairly self-explanatory.

I developed the camera trigger unit in order to synchronize various events and actions during free-flight experiments with hawkmoths in the wind tunnel described in a previous post. More specifically, the goal was to trigger multiple high-speed cameras and have LEDs that indicate the exact timing of electrical stimuli delivered via a miniature stimulus chip carried by a hawkmoth. (Electric stimulation of the moth is also triggered by the unit.)

The trigger is based on an Arduino micro-controller board (http://www.arduino.cc/) and provides a timed sequence of events after a trigger is elicited either manually, or automatically with the optional laser module. The latter is used to monitor a volume in space (the trigger volume) that, when occupied by an object (a moth, for example), elicits the trigger sequence. The module can be used with one or two red or infrared laser diodes. When using one laser beam, an object crossing anywhere along the beam will elicit a trigger event. When using two beams, the volume in space in which the two beams cross defines the trigger volume.