Viewing FITS files in Blender


FITS files are the main file type used in astronomy. They generally hold a lot more information than standard image file formats, like the coordinate system used to map the image onto the sky. They can also contain 3D information. But alas, there's no easy way to view their full 3D glory in realtime. Usually, the only way to access the  3D information is to "slice" through the cube, viewing a series of ordinary 2D planes. This means all we get to look at are animations of 2D data. Here's a real example - this is what I get to look at all day...
In radio astronomy we look through every part of these "data cubes" looking for anything that's brighter than the background noise that might be a real source (they don't normally have the nice high contrast of the example above). Typically this involves looking at many thousands of image slices, which is a painstaking and damned frickin' boring process (that's a technical term). So being able to view the cube in realtime could make life not only a whole lot faster, but a hell of a lot more fun.

Programs do exist to display the 3D information in a more intuitive, volumetric way. The most popular in radio astronomy is X-ray (part of the karma package). But this has limited uses. The controls are not at all obvious, and you have to press an "update" button whenever you move the viewpoint. Really it's only intended for creating simple animations of cubes, not for working with them to any great extent.

That's where I think Blender can make a real difference. It already has a user-friendly, fully realtime interface. With at least 1GB of video memory on most modern cards, pretty large data sets can be displayed. Using Blender, there's no need to pan through channels or slices - the whole cube can be viewed at once (and individual slices can still be selected, if required). Also, it's really cool. Trust me. Skip ahead for prettier examples if you don't believe me.

In the following pages I describe the 3 main approaches I've been developing to try and make Blender into a powerful FITS viewer. Each has advantages has disadvantages. The pages also contain links to the scripts so if anyone wants to try them, please do ! They are incredibly specialist tools, so email me if you want any further information.
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