Comment on 'The role of 3-D interactive visualization in blind surveys
  of HI in galaxies'
  Punzo et al. (2015) recently reported on the state of the art for
visualisation of H I data cubes. I here briefly describe another program,
FRELLED, specifically designed for dealing with H I data. Unlike many 3D
viewers, FRELLED can handle astronomical world coordinates, easily and
interactively mask and label specific volumes within the data, overlay optical
data from the SDSS, generate contour plots and renzograms, make basic spectral
profile measurements via an interface with MIRIAD, and can switch between
viewing the data in 3D and 2D. The code is open source and can potentially be
extended to include any astronomical function possible with Python, displaying
the result in an interactive 3D environment.
