Video Noodlings: Moon Edition


Continuation on a theme; this very theme in fact. The last time we were here I posted a GIF animation loop showing off the effect of atmospheric turbulence on my astrophotography.

To review: the moon, it did ripple and wave, thanks to the slight variations in the refractive index of air you get from density and temperature gradients. Since this sequence was shot from our refractor dome on a fairly warm night, most of what we saw represented turbulent mixing in the bottom few hundred meters of the atmosphere; the important factor there being the recently sun-warmed ground and buildings driving convection. (This never really stops, but in the winter when the ground's nice and chilly, it quiets down a lot. Not that this helps much with the dome seeing, since in winter it's generally already full of air that's much warmer than outside.)

Now in addition to assembling animated GIFs (in, say, GIMP), there are a number of command-line tools that will take a big collection of images and run them together into some kind of MPEG encoded movie. Which ordinarily wouldn't be so attractive to me, since it's always a pain to figure out what movie formats one's audience is able to view. But with the advent of YouTube I just have to work out how to encode for their system (320x240, MPEG-4) and away we go. So we have this movie now, which is a bit lower resolution than the original GIF loop, but since one can stick a great many more frames in an MPEG movie than in a GIF file, it's possible to make up the difference in the time domain. Check it out:


And I WOULD have to try to access the video during YouTube site maintenance. This happened just the other day with my bank's website. Is there a vast conspiracy afoot?

I doubt THEY would like it if I answered that question, silly.

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This page contains a single entry by Milligan published on November 14, 2006 10:40 PM.

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