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Sunday 3 July 2011

CG project : viewing FITS files in Blender

Warning : this post may contain or allude to content of a scientific nature.

Any technology that is sufficiently advanced is indistinguishable from magic, and any technology that is indistinguishable from magic is sufficiently advanced. However, there's another, lesser-known part of this maxim, which is that any technology capable of viewing FITS files is also sufficiently advanced and therefore magical.

What the hell am I blathering about ? Well I have this crazy notion that if data is 3-dimensional, then it should be viewed in 3-dimensions. Neutral hydrogen - HI to its friends - data is a good example, because the data records both position on the sky and recessional velocity (which is a half-decent proxy for distance away from us). Such data is recorded in a Flexible Image Transport System files. What does not currently exist - as far as I'm aware - is a good way of looking at such files in 3D in realtime. Instead, we're reduced to panning through data cubes one slice at a time.

I'm not convinced that this needs to be the case. To that end, I've written a series of IDL and Python programs to import FITS files into Blender. Actually viewing the files in Blender is the easy part. The difficult bit is cleaning the files enough so that Blender can handle them. This is probably more a software than a hardware issue - Blender isn't optimised to handle thousands of different objects and materials, let alone the tens of millions that make up most data files. So for now, this specialised project is only of use in even more specialised cases where most of the data is noise and can be rejected.

However, for those cases where it does work, it works extremely well. Here is the famous "dark galaxy" VIRGOHI21 rendered in Blender, in realtime. It probably could use a minimalist new-age soundtrack, but never mind.

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