Using Arroyo to Make Cool Movies

The Arroyo tutorial says that you can make movies using dwf2ppm and ImageMagick--which is true, but I at least needed a little more direction than that. Here's what I figured out, in a bit more detail.

Installing the Necessary Software

You'll need ImageMagick, the MPEG video player of your choice (e.g. xanim), and an mpeg encoder. For some reason, there does not appear to be a Debian package for mpeg2encode, which is the encoder that ImageMagick wants to use. You can get it from here (look for the mpeg2vidcodec package). It compiled out-of-the-box for me. However, it lacks a "make install" command, so you'll have to manually copy mpeg2encode into /usr/local/bin. (Lame!)

Making Images from Fits Files

I'll use the output files from simple_simulation for my demonstration here. The first step is converting from FITS to PPM with the dwf2ppm tool from Arroyo. dwf2ppm -h will give you a help screen with the options. A typical invocation might be
    dwf2ppm -m -2 -M 20 -p pupil*fits
This uses a linear scale from -2 to 20 to convert the phase (-p) in a series of pupil fits files.
If you don't specify a fixed scale on the command line, it will autoscale for each individual image, resulting in the scale fluctuating irregularly during your movie.

Hollywood Special Effects on the Cheap (or, how to make mpeg movies)

dwf2ppm creates a new .ppm file for each .fits file in its argument list. If you've properly installed mpeg2encode, then you can now just run
     convert -delay 20 pupil*ppm pupil.mpeg
in order to convert your ppm files into an MPEG movie.

You can combine multiple images side-by-side using the "montage" command from imageMagick:
 montage -geometry 250x250+10+10 -label "Pupil Phase" pupil_wf_0.0000.ppm -label "PSF" image_wf_0.0000.ppm im0.ppm
Then repeat that for all the other image pairs, and pass the resulting images to convert. With a little bit of <insert your favorite scripting language here>, you can put together some relatively fancy movies in short order.