Frelled: A realtime volumetric data viewer for astronomers

I present a new FITS viewer designed to explore 3D spectral line data (in particular H i) and assist with visual source extraction and analysis. Using the artistic software Blender, frelled can visualize even large (∼6003 voxels) data sets at high frame rates (≳10f.p.s.) in 3D. Blender’s interface enables easy navigation within the 3D environment, and the frelled scripts support world coordinate systems. A variety of tools are included to aid source extraction and analysis, including interactively masking data (using 3D polyhedra of arbitrary complexity), querying NED, calculating the flux in specified volumes, generating contour plots and overlaying optical data. It includes tools to overlay n-body particle data, and multi-volume rendering is supported. The interface is designed to make cataloguing sources as easy as possible and I show that this can be as much as a factor of 50 times faster than using other viewers.