The VOISE Algorithm: a Versatile Tool for Automatic Segmentation of Astronomical Images

The auroras on Jupiter and Saturn can be studied with a high sensitivity and resolution by the Hubble Space Telescope (HST) ultraviolet (UV) and far-ultraviolet Space Telescope Imaging Spectrograph (STIS) and Advanced Camera for Surveys (ACS) instruments. We present results of automatic detection and segmentation of Jupiter's auroral emissions as observed by the HST ACS instrument with the VOronoi Image SEgmentation (VOISE). VOISE is a dynamic algorithm for partitioning the underlying pixel grid of an image into regions according to a prescribed homogeneity criterion. The algorithm consists of an iterative procedure that dynamically constructs a tessellation of the image plane based on a Voronoi diagram, until the intensity of the underlying image within each region is classified as homogeneous. The computed tessellations allow the extraction of quantitative information about the auroral features, such as mean intensity, latitudinal and longitudinal extents and length-scales. These outputs thus represent a more automated and objective method of characterizing auroral emissions than manual inspection.

[1]  Santiago,et al.  Bayesian Image Reconstruction Based on Voronoi Diagrams , 2007, 0712.4140.

[2]  C. H. Acton,et al.  Ancillary data services of NASA's Navigation and Ancillary Information Facility , 1996 .

[3]  Michele Cappellari,et al.  Adaptive spatial binning of integral-field spectroscopic data using Voronoi tessellations , 2003, astro-ph/0302262.

[4]  Travis W. Hill,et al.  Inertial limit on corotation , 1979 .

[5]  I. Prigogine,et al.  Exploring Complexity: An Introduction , 1989 .

[6]  Jonathan D. Nichols,et al.  Oscillation of Saturn's southern auroral oval , 2008 .

[7]  Peter J. Rousseeuw,et al.  Finding Groups in Data: An Introduction to Cluster Analysis , 1990 .

[8]  Sandra Chapman,et al.  Avalanching and Self-Organised Criticality, a paradigm for geomagnetic activity? , 2000 .

[9]  H. J. Hilhorsta.  Statistical properties of planar Voronoi tessellations , 2008 .

[10]  V. Vasyliūnas,et al.  Plasma distribution and flow , 1983 .

[11]  Renée Prangé,et al.  More about the structure of the high latitude Jovian aurorae , 2000 .

[12]  Denis Grodent,et al.  Jupiter's polar auroral emissions , 2003 .

[13]  Denis Grodent,et al.  Jupiter's main auroral oval observed with HST-STIS , 2003 .

[14]  B. Bonfond,et al.  Ultraviolet Io footprint short timescale dynamics , 2007 .

[15]  E. Jantsch.  The self-organizing universe : scientific and human implications of the emerging paradigm of evolution , 1980 .

[16]  Sandra C. Chapman,et al.  A simple avalanche model as an analogue for magnetospheric activity , 1998 .

[17]  Jerry L Prince,et al.  Current methods in medical image segmentation. , 2000, Annual review of biomedical engineering.

[18]  D. Gurnett,et al.  Multiple Alfven wave reflections excited by Io: Origin of the Jovian decametric arcs , 1981 .

[19]  J. H. Waite,et al.  Ultraviolet emissions from the magnetic footprints of Io, Ganymede and Europa on Jupiter , 2002, Nature.

[20]  R. Weygaert,et al.  A cosmic watershed: the WVF void detection technique , 2007, 0706.2788.

[21]  Raúl E. Sequeira,et al.  Discrete Voronoi Diagrams and the SKIZ Operator: A Dynamic Algorithm , 1997, IEEE Trans. Pattern Anal. Mach. Intell..