Thu, Nov 26: The Day of Tofurky

00122 00022

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Wed, Nov 25: Home, sweet home

IMG 1566

Exploring Julia in 4 dimensions

The discovery of the Mandelbulb awekened my old passion for fractals.

So I took the time to re-encode my old rendering of the Quaternion Julia set done with POV-Ray. Behold:

The sound track is UranChrome, an old-skool Amiga SoundTracker module composed by TorbJ0rn in 1989.


If your browser sucks at HTML5, you can directly download the video files, available in several formats:

julia4D.ogv (Ogg)1280x7206000Kbit/sTheoraVorbis60MB
julia4D-640x360.ogv (Ogg)640x3201200Kbit/sTheoraVorbis13MB
julia4D .avi1280x7206000Kbit/sH.264-60MB

Rendering notes

It took about 2 weeks of computation on a dual-core machine to render the 2048 high resolution frames contained in 82 seconds of video. My previous renderings at lower resolution and lower iteration count were much faster.

A The high iteration count actually makes the fractal surface a little too polverized to appreciate. Adding transparency and gradients is another bad idea as it complicates things even more. If I find the time and motivation to re-render the animation, I'll look for better balance.

In case someone wants to experiment, these are the scene source and ini file I used.

Video encoding notes

The files were encoded from a sequence of PNG frames generated by POV-Ray, using ffmpeg and mencoder:

# hires mpeg4
please mencoder 'mf://julia4D????.png' -mf fps=25 \
        -ovc x264 -x264encopts bitrate=6000:pass=1:threads=2 -o julia4D.avi 

# lores mpeg4
please mencoder 'mf://julia4D????.png' -mf fps=25 -vf scale=640:360 \
        -ovc x264 -x264encopts bitrate=1200:pass=1:threads=2 -o julia4D-640x360.avi 

# hires theora
please ffmpeg -f image2 -i julia4D%04d.png \
        -threads 2 -vb 6000k -vcodec libtheora -acodec libvorbis -f ogg julia4D.ogv \
        -i UranChrome-fx-short.wav -acodec libvorbis -ab 96k -newaudio

# lores theora
please ffmpeg -f image2 -i julia4D%04d.png \
        -threads 2 -s 640x360 -vb 1200k -vcodec libtheora -f ogg julia4D-640x360.ogv \
        -i UranChrome-fx-short.wav -acodec libvorbis -ab 96k -newaudio

This is the software I have used:

MEncoder SVN-r29800-4.4.2 (C) 2000-2009 MPlayer Team
FFmpeg version SVN-r20372, Copyright (c) 2000-2009 Fabrice Bellard, et al.

The quality of the low-res Theora stream is noticeably lower than the corresponding low-res H.264. I don't know why.